SCM-XRD Manual Rev 4 - The Automation Group SCM2500XRD Main Screen ... 6991 Peachtree Industrial...

OPERATIONS MANUAL

Streaming Current Monitor & Streaming Current Controller

with Dura-Trac™ Remote Sensor

R 4 8/2/06 RA

SCM2500XRD SCC3500XRD

TABLE OF CONTENTS

Section Title Page

IMPORTANT INSTRUCTIONS .......................................................................... 4 WARRANTY INFORMATION............................................................................. 5

1.0 GENERAL INFORMATION................................................................................ 6 1.1 Description of Operation ............................................................................ 6 1.2 Selecting Proper Sample Point .................................................................. 6 1.3 Process Control Procedures ...................................................................... 8 1.4 System Components ................................................................................. 9 1.5 Technical Specifications ............................................................................ 10

2.0 MOUNTING AND INSTALLATION..................................................................... 12 2.1 Mounting Location ..................................................................................... 12 2.2 Power Requirement ................................................................................... 12 2.3 Signal Wiring ........................................................................................ 14 2.4 Sample Connection ................................................................................... 15 2.5 Sensor Flush Options ................................................................................ 16

2.5.1 Dura-Trac with Flush ....................................................................... 16 2.5.2 Sensor Maintenance Module ........................................................... 17

3.0 OPERATION ........................................................................................ 19 3.1 Monitor/Controller User Interface............................................................... 19 3.2 SCM2500XRD Readout, Menus and Controls ........................................... 20

3.2.1 SCM2500XRD Main Screen ........................................................... 20 3.2.2 SCM2500XRD Setup Menu (1)........................................................ 21 3.2.3 SCM2500XRD Setup Menu (2)........................................................ 22 3.2.4 SCM2500XRD Alarm Status Menu .................................................. 23 3.2.5 SCM2500XRD Flush Control Menu ................................................. 24

3.3 SCC3500XRD Readout, Menus, and Controls........................................... 24 3.3.1 SCC3500XRD Main Screen ............................................................ 24 3.3.2 SCC3500XRD Setup Menus............................................................ 25 3.3.3 SCC3500XRD Alarm Status Menu .................................................. 26 3.3.4 SCC3500XRD Pump Control (1) Menu............................................ 27 3.3.5 SCC3500XRD Pump Control (2) Menu............................................ 29 3.3.6 SCC3500XRD Flow Control (3) Menu.............................................. 29 3.3.7 SCC3500XRD Flush Control Menu.................................................. 31

3.4 System operation....................................................................................... 33 3.5 Treatment Optimization Procedure ............................................................ 34 3.6 Manual Control Using Controller ................................................................ 35 3.7 Automatic Control ...................................................................................... 35 3.8 Automatic Control Setup............................................................................ 38 3.9 Flow Control ........................................................................................ 38 3.10 Tuning Constant Specifications ................................................................. 39

4.0 GENERAL GUIDELINES ................................................................................... 41 4.1 Streaming Current Value Response Factors.............................................. 41 4.2 Fundamental Streaming Current Knowledge ............................................. 42

Chemtrac Systems, Inc. Page 3

TABLE OF CONTENTS (Continued)

Section Title Page

5.0 TROUBLESHOOTING GUIDES......................................................................... 45 6.0 MAINTENANCE PROCEDURES ....................................................................... 47

6.1 Replacement Procedures .......................................................................... 47 6.2 Cleaning Procedures ................................................................................. 47 6.3 Replacement Parts .................................................................................... 48 6.4 Ordering Information.................................................................................. 50

7.0 Mechanical Specifications............................................................................... 53

LIST OF FIGURES

Figure Title Page

1 Streaming Current Profile ................................................................................. 7

2 System Components ........................................................................................ 9

3 Monitor/Controller Power Wiring ....................................................................... 12

4 Dura-Trac Sensor Power Wiring ....................................................................... 13

5 Dura-TRAC II Sensor Power Wiring.................................................................. 13

6 Signal Wires Interconnection Diagram.............................................................. 14

7 Dura-TRAC Sensor Sample Connection ........................................................... 15

8 Dura-TRAC II Sensor Sample Connection ........................................................ 16

9 Dura-TRAC Sensor with Flush.......................................................................... 17

10 SMM Tubing Connections to Dura-Trac II Sensor............................................. 18

11 Automatic Flush Timing Diagram ...................................................................... 33

12 Dura-Trac Sensor Parts Identification ............................................................... 49

13 Dura-Trac II Sensor Parts Identification ............................................................ 50

14 Streaming Current Monitor/Controller Dimensions ............................................ 53

15 Dura-Trac Sensor Dimensions.......................................................................... 54

16 Dura-Trac II Sensor with SMM Dimensions....................................................... 54

17 Dura-Trac Sensor with Flush Dimensions ......................................................... 55

18 Dura-Trac II Sensor Dimensions....................................................................... 56

19 SMM Dimensions ........................................................................................ 56


IMPORTANT INSTRUCTIONS

When using this instrument, basic safety precautions shall always be followed to reduce the risk of fire, electrical shocks and injury to persons, including the following: R Before attempting to unpack, set up, or operate this instrument, please

read this entire manual.

R Make certain the unit is disconnected from the power source before attempting to service or remove any component.

R Follow all warnings and marked on the instrument.

R Failure to follow these precautions could result in personal injury or damage to the equipment.

R Do not attempt to disassemble the unit.

R Water must not be allowed to enter the housing of the unit.

R Close and fasten the covers of the unit prior to any external cleaning to prevent water ingress.

R Do not drop or jar the unit.

R Do not modify any internal electrical wiring or electronics.

R Use a mild non-abrasive cleanser when cleaning the outer cover of the unit.

SAFETY PRECAUTIONS

In order to provide maximum user safety this instrument was designed with all electrical circuitry enclosed within a protective non-conductive housing. The label below will be visible at any location where high voltage is present.


WARRANTY INFORMATION

Chemtrac® Systems, Inc. warrants its equipment to be free from defects in material and workmanship for a period of one (1) year from date of shipment to the original purchaser. Upon receipt of written notice from purchaser, seller shall repair or replace the equipment (at option of Chemtrac® Systems, Inc.). Chemtrac® Systems, Inc. assumes no responsibility for equipment damage or failure caused by:

1. Improper installation, operation, or maintenance of equipment.

2. Abnormal wear and tear on moving parts caused by some processes.

3. Acts of nature (i.e. lightning, etc.)

This warranty represents the exclusive remedy of damage or failure of equipment. In no event shall Chemtrac® Systems, Inc. be liable for any special, incidental, or consequential damage such as loss of production or profits. Should you experience trouble with the equipment, please contact:

Chemtrac Systems, Inc 6991 Peachtree Industrial Blvd., Building 600 Norcross, GA 30092 Phone: 1-800-442-8722 (Inside US only), 770-449-6233 Fax: 770-447-0889 Email: [email protected] Website: www.chemtrac.com


SECTION 1.0 GENERAL INFORMATION 1.1 DESCRIPTION OF OPERATION

The Streaming Current Monitor/Controller includes a remote sensor module placed at the desired sample point, and a Monitor/Controller module. The monitor is a charge-measuring device. The charge that it measures is the net ionic and colloidal surface charge (positive and negative) in the sample being tested. Streaming current is related to zeta potential, however, they are not the same value. The treated water sample flows into the sample cell where it is drawn into the bore during the upstroke of the piston cycle and is expelled from the bore on the piston down stroke. Particles contained in the water are temporarily immobilized on the piston and cylinder surfaces. As the water is moved back and forth by the piston, charges surrounding these particles (+ and -) are moved downstream to the electrodes. This movement of like charges causes an alternating current to be generated, defined as "streaming current." A signal gain selector, accessed through the menu screen, is used to select the best signal amplification. The signal amplification should be set where a normal change in dosage results in a desired deviation in streaming current (normally 30 units). The displayed streaming current value (SCV) should be considered as a relative reading due to amplification of the primary signal. The streaming current amplitude and polarity is a function of sampling location in the treatment process. It is important to understand why the streaming current varies at different points in the system to properly interpret the readings, therefore, Section 1.2 should be read very carefully.

1.2 SELECTING PROPER SAMPLE POINT

The sample must be taken at a point where uniform distribution and mixing of coagulant is obtained for all flow rate conditions, and at a point that allows for a quick response to chemical feed changes as measured by the monitor (i.e. after the rapid mixer or static mixer, and before the slow mixer or flocculation basin). The lag time, or the amount of time it takes the water to travel from the point of chemical addition to the sensor, should be no greater than 3 minutes (30 seconds to 1.5 minutes are typical lag times). If uniform distribution and mixing is not being obtained at a selected sample point, the streaming current reading will oscillate. If the chemical is not being properly mixed (indicated by an oscillating monitor reading), the sample point needs to be moved further downstream away from the mixing device to allow the chemical more time to mix in with the water. Under rare circumstances, moving the sample point further downstream in order to obtain a more stable reading may result in a lag time longer than 3 minutes. Steps should be taken to improve chemical mixing under these conditions.

When possible, avoid sampling from places where sludge, grit, etc., will be drawn into the sensor sample cell. Sample lines must be sized to provide velocities that will prevent floc/sludge accumulation. Keep sample lines as short as possible to minimize delay in response time. Figure 1, Streaming Current Profile, normally observed in a typical water plant. When coagulant is added to raw water, the charge neutralization process begins immediately. The time required for this neutralization process to go to completion is primarily a function of mixing, time, raw water characteristics, type of coagulant, and to a lesser


degree, temperature. Untreated raw water has a net negative charge. Cationic coagulant charges, (alum, polymer, etc.) can produce a net positive streaming current early in the system. As shown on the graph, this current becomes less positive as negative charges react with the coagulant. At the settling basin outlet, the streaming current value can return to nearly the same as raw water. If raw water flow or sample flow rate is increased, the total time for the sample to travel from point of coagulation injection to the cell is decreased. This may cause a change in monitor reading (in the positive direction), even though the coagulant dosage (PPM) remains constant. Conversely, if raw water or sample flow rate is decreased, streaming current readings may go more negative. Plants that have a shifting set point caused by wide swings in raw water flows can minimize this effect by moving the sample point further downstream, lengthening sample line, or adding a detention pot. It is important to maintain the sample flow at +/- 10% of the rate initially set. Based upon the above discussion, the proper sample point for a specific plant depends upon the following conditions:

1. Point or points of coagulant feed.

2. Mixing efficiency of raw water and coagulant.

3. Magnitude of raw water flow swings.

4. Type and quantity of coagulants used.

FIGURE 1. Streaming Current Profile


1.3 PROCESS CONTROL PROCEDURES

Model SCC3500XRD Only In order for the monitor to be used for automatically controlling the coagulant feed (alum, polymer, ferric chloride), the following guidelines must be followed:

1. The coagulant must be thoroughly mixed with the raw water by the time the sample is taken.

2. “Lag time” (i.e., the time it takes for the monitor to see a change in coagulant feed) should be no greater than 5 minutes.

3. Variability in sample flow rates should be no greater than +/- 10 % of the initial rate.

4. Coagulant pumps must be kept in good mechanical condition to respond quickly and accurately to process changes.

5. Raw water quality should be in a stable condition (turbidity, pH, color, etc. should not change rapidly or widely) when setting up the system.

The monitor should be operated a few days in manual control to observe how it responds to normal process operation. Recording streaming current changes on a strip chart recorder is very helpful in anticipating factors that may have to be dealt with when automatic control is started. This period, if using the monitor with a recorder for monitoring, is also a good time to determine the optimum coagulant dosage and establish the operating “setpoint”. This enables the system to be put on automatic control very simply.


DURA-TRAC II SENSOR

DURA-TRAC SENSOR OR DURA-TRAC SENSOR WITH FLUSH

PATENTED MADE IN U.S.A.

DURA-TRAC II

CHEMTRACSYSTEMS, INC.

TM

SYSTEMS, INC.


DURA-TRAC TM

CHEMTRAC

Diag.Alarm

PowerService

SYSTEMS, INC.

CHEMTRAC

MANUALOPERATOR

SYSTEMS, INC.


DURA-TRAC TM

CHEMTRAC

MONITOR/CONTROLLER

SCC3500XRD

SEMSOR MAINTENANCE MODULE

FIGURE 2. System Components

1.4 SYSTEM COMPONENTS

The SCM2500XRD and SCC3500XRD system include the following:

q Monitor/Controller

q Dura-Trac Remote Sensor

q Dura-Trac Remote Sensor with Flush (Optional)

q Dura-Trac II Remote Sensor (Optional)

q Sensor Maintenance Module (Optional)

Figure 2 illustrates system components.


1.5 TECHNICAL SPECIFICATIONS

MONITOR/CONTROLLER Power ...................................... 85-264 VAC, 47–63 Hz Current Load ........................... 110 VAC @ 0.5A Max 220 VAC @ 0.25A Max User Interface.......................... Backlit Liquid Crystal Display, Menu Driven Functions,

Keypad Interface SCV Readout .......................... -1000 to +1000 Resolution ............................... Streaming Current Units Signal Gain.............................. User Adjustable 1X to 20X Zero Offset .............................. Automatic, Full Scale All Ranges Accuracy ................................. 0.5% of Full Scale Response Time ....................... 1 Second SCV Output Signal .................. Standard 4-20 mA (300 ohm Load) Optional 0-10 VDC Alarm Output ........................... 24 VDC (Solid State Relay Optional) and Auditable

Alarm for Sensor Status, High/Low Streaming Current Value and High/Low Pump Output - SC3500XRD Only

Digital Input ............................ Dry Contacts Enclosure Type ....................... NEMA 250 Type 4X, Reinforced Fiberglass Enclosure Size ........................ 9.2”W, 11.2”H, 6.3”D (234mm W, 285mm H, 161mm D) Mounting Holes ....................... 11.25”W, 7.4”H (286mm W, 188mm H) Weight..................................... 6 Pounds (2.72 kg) Control Output Alarms............. Adjustable High/Low Alarms Operating Temperature ........... 32° F to 120° F (0° C to 49° C)

Following Parameter are for SCC3500XRD Only PID Tuning Parameters........... Proportional Gain: Range 0-1000 Integral Time: Range 0-1000 PID Rate: Range 1-20 SmartTrac PID Control ............ SCC3500XRD Only Analog Input ............................ 4-20 mA Control Output Signal .............. 4 – 20 mA (300 Ohm Load) or 0 – 10 VDC Control Output Limits............... Adjustable High/Low Limits

Dura-Trac REMOTE SENSOR Power ...................................... 115 VAC, 60 Hz (standard) 230 VAC, 50 Hz (optional) Sample Flow Rate ................... 5.0 GPM Sample Cell Type .................... External Receiver, High Flow Probe Type.............................. Quick Replacement Cartridge Water Sample Connections..... Inlet: 3/4” O.D. Barb Type, Outlet: 1” O.D. Materials Contacting Sample... Delrin, Nylon, Neoprene Viton, PVC, Stainless Steel


Dura-Trac REMOTE SENSOR (Continue) Output Wiring .......................... 4 Conductors Twisted Shielded Pair, 20 AWG (6 Conductors Twisted Shielded Pair with Flush Option) Enclosure Type ....................... NEMA 250 Type 4X, Reinforced Fiberglass Enclosure Size ........................ 11.2”W, 9.2”H, 6.3”D (285mm W, 234mm H, 161mm D) Mounting Holes ....................... 7.4” W, 11.25” H (188mm W, 286mm H) Overall Height with Sensor ...... 14.7’’ (373mm) Weight..................................... 10 Pounds (4.5 kg) Operating Temperature ........... 32° F to 120° F (0° C to 49° C)

Dura-Trac WITH FLUSH (OPTION): Flush Water Connections ........ ¼’’ Quick Connect Tube Fitting, Adaptable Flush Water Pressure…. ......... 35 to 80 PSI Overall Height with Sensor ...... 17.6’’ (447mm)

Dura-Trac II REMOTE SENSOR Power ...................................... 115 VAC, 60 Hz (standard) 230 VAC, 50 Hz (optional) Sample Flow Rate ................... 10 GPM Sample Cell Type .................... External Receiver, High Flow Probe Type.............................. Quick Replacement Cartridge Water Sample Connections..... Inlet: 3/4” O.D. Barb Type, Outlet: 1-1/2” O.D. Materials Contacting Sample... Delrin, Nylon, Neoprene Viton, PVC, Stainless Steel Output Wiring .......................... 4 Conductors Twisted Shielded Pair, 20 AWG (6 Conductors Twisted Shielded Pair with Flush Option) Enclosure Type ....................... NEMA 250 Type 4X, Reinforced Fiberglass Enclosure Size ........................ 11.2”W, 9.2”H, 6.3”D (285mm W, 234 mm H, 161mm D) Overall Height with Sensor ...... 18.8’’ (477mm) without SMM Option 21.8’’ (554mm) with SMM Option Mounting Holes ....................... 9.7”W x 10.5”H (247mm W x 266mm H) Weight..................................... 15 Pounds (6.8 kg) Operating Temperature ........... 32° F to 120° F (0° C to 49° C)

SENSOR MAINTENANCE MODULE (OPTIONAL) Power ...................................... 24 VDC (Supplied From Monitor) Flush Water Connections ........ ¼’’ Quick Connect, Adaptable Flush Water Inlet PSI .............. 35 to 80 PSI Chemical Injection Pump......... 1,000 mL/min (Max) Outlet Connection.................... ¼’’ Quick Connect, Semi Rigid Tubing Enclosure Type ....................... NEMA 250 Type 4X, Reinforced Fiberglass Module Size ............................ 11.2”W, 9.2”H, 6.3”D (285mm W, 234 mm H, 161mm D) Mounting Holes ....................... 9.7”W x 10.5”H (247mm W x 266mm H) Weight..................................... 6 Pounds (2.72 kg)


SECTION 2.0 MOUNTING AND INSTALLATION 2.1 MOUNTING LOCATION

The sensor can be located several hundred feet from the monitor. The sensor must be mounted in a vertical position with the sample flowing into the inlet (3/4” barb fitting) and exiting from the outlet (PVC elbow). Typically, the sensor is mounted as closely as possible to the sampling point. Minimizing sample line lengths provides quicker response to process changes. Sample may be obtained by using a sample pump, tapping off a pressurized line, or using gravity feed system to get sample to the sensor. The sample flow rate should not exceed 5.0 GPM for Dura-Trac sensor and 10.0 GPM for Dura-Trac II sensor. Draining to atmosphere (unobstructed) is required; a closed pipe (pressurized) drain is not recommended. The Monitor/Controller module should be installed in a location, which will allow regular viewing of the display as well as easy access to the front panel menu keys. See Mounting Dimension Diagrams at end of Manual.

2.2 POWER REQUIREMENT Electrical power should be connected in the following order R Insert the ground wire into the middle terminal labeled “G”. R Insert the hot wire into the left terminal labeled “L”. R Insert the neutral wire into the right terminal labeled “N”.

For safety and proper operation, the monitor must be properly grounded through their power cord. In cases where potential noise sources could affect the performance of the equipment, a "surge suppressor" must be installed with the unit. The following drawings show power terminal connections for models SCM2500XRD and SCC3500XRD monitors, and Dura-Trac or Dura-Trac II Sensor. Figures 3 thru 5 illustrate power-wiring connections to Monitor/Controller, Dura-Trac, and Dura-Trac II Sensors.

8 9 1311 12 1514 16

1817 19 20

10

FIELD WIRING TERMINALS

POWER CORD

OFF

G

GN

D

L

L N

N

ON

FUSE: AGC-1.5A

FUSE

1

WARNING TURN POWER OFF BEFORE MAKING ANY WIRE CONNECTIONS TO AVOID DAMAGING THE ELECTRONIC CIRCUIT.

SM

M

| Sen

sor

7

**432 65

**

*

FIGURE 3. Monitor/Controller Power Wiring


543

Shield

Signal

Opto

1

+24 V

dc

Vdc G

nd

2

- Probe

6 119 10 1287

Opto (O

)

Opto (W

)

Opto (B)

Cond.

+ Probe

High

L1N

FIGURE 5. Dura-TRAC II Sensor Power Wiring

- Probe

6543

+ Probe

Shield

Signal

Opto

1

+24 V

dc

Vdc Gnd

2

L1N

119 10 1287

Opto (O

)

Opto (W

)

Opto (B)

Cond.

High

FIGURE 4. Dura-Trac Sensor Power Wiring


2.3 SIGNAL WIRING

The Dura-Trac and Dura-Trac II Sensors transmit the sensing signal to Monitor/Controller by a multi conductor wires, see Figure 7 for signal wires interconnection diagram. Twisted shielded cable should be used. The cable should be enclosed in conduit for maximum protection against damage or electrical interference. Do not run cable in same conduit with any other wiring.

CAUTIONS

R Make sure the monitor’s power switch is turn to off position before making any signal wiring connections.

(BLA

CK)

+24 V

dc

1

(RED

)

Opto (W

)

10

Shield

Signal +

Signal -

Vdc Gnd

5432

Opto (O

)

- Probe

+ Probe

Opto (B)

6 87 9

(WH

ITE)

(BLU

E)


3

SM

M

| Sen

sor

4

65

78

12

11

141312

1516

1

910

*

**

*

32 4

*865 7

19

9

20

121110

1718

(BROWN)

(WHITE)

(BLACK)

(RED)

CHEMICAL PUMP

SAMPLE ISO VALVE

24 VDC COMMON

FLUSH VALVE

64

53

21

1211

108

79

16151413

1817 19 20

FUSE: AGC-1.5A

GN

D

L N

ON

GL N

OFF

FUSE

FIGURE 6. Signal Wires Interconnection Diagram


DURA-TRAC


SAMPLE INLET3/4" BARB FITTING

TM

PVC DrainFunnel

SAMPLE OUTLET

4" Cup

2" Line

FIGURE 7. Dura-TRAC Sensor Sample Connection

2.4 SAMPLE CONNECTION

Sample shall be connected to the sample cell inlet side. A 3/4" barbed fitting connection is provided for hose connection. The PVC elbow opposite the inlet is the outlet. The outlet sample must flow to an open drain (sample receiver). The cell cannot operate properly if pressurized. Do not replace either fitting with any other type of fitting.

Start treated water sample through the cell at a rate of between 1 to 5 GPM. Make sure the outlet is free of obstructions. Continuous reliability of the sample flow is essential. Interruption of the sample flow will result in erroneous readings on the Monitor/Controller. For Controller model SCC3500XRD operating in AUTO mode, loss of flow to the Dura-Trac sensor will result in improper coagulant dosing. A suitable flow alarm is recommended for maximum reliability.

IMPORTANT

On the SCC3500XRD, the pump control output of the controller must be set in the MANUAL mode if the sensor is flushed or cleaned or if power to the sensor is interrupted for any reason. The controller can be placed back in AUTO once power and sample flow is restored. For system with Dura-Trac with flush with Sensor Maintenance Module (SMM), during Automatic Flushing cycles, the pump control output signal is maintained at a constant value (see Flush Menu).


2.5 SENSOR FLUSH OPTIONS

The SCM2500XRD and SCC3500XRD are available with one of two options for automatic sensor flushing/cleaning. The first option is the Dura-Trac with flush and is composed of a valve mounted onto the Dura-Trac sensor, which is connected to flush water. The second option is the SMM and is composed of a flush valve, sample isolation valve, and chemical injection pump. The Dura-Trac with flush is recommended for Drinking Water applications where high turbidity is often experienced. The SMM is recommended for Waste Water applications. These options are only supplied if specified at the time of purchase. The line of monitors offered by Chemtrac® can be upgraded to include one of these two options. To upgrade to the Dura-Trac with either options, the Dura-Trac sensor will need to be returned to the factory.

Potable water or the best quality plant water available shall be used for the flush water supply. If potable water is used for flush water, a backflow prevention device should be installed on the flush water line to prevent contamination of the potable water source. The flush water needs to maintain a pressure of 35 PSI min to 80 PSI max.

2.5.1 Dura-Trac with Flush

Connect the male NPT end of the ¼’’ MNPT to ¼’’ Quick Connect Tube adapter fitting (supplied with the unit) to the flush water supply. Connect a sufficient length of ¼’’ Teflon tubing between the flush water supply (¼’’ Quick Connect Tube adapter fitting) and the valve’s ¼” quick connect fitting (see Figure 10 on the next page). The flush valve’s outlet should already be connected to the probe flush assembly. The third valve outlet (located on the bottom of the valve and pointed towards the ground) is the drain outlet. Run this outlet to an appropriate drain using ¼’’ semi-rigid tubing. A manual control valve should be installed on the flush water line in close proximity of the unit so

SAMPLE OUTLET 45 DEGREE ELBOW


DURA-TRAC II

SAMPLE INLET3/4" BARB FITTING

TM


2" Line

4" Cup PVC DrainFunnel

FIGURE 8. Dura-TRAC II Sensor Sample Connection


that the flush water may be shut off during sensor maintenance. Do not open flush water supply valve until all connections have been made.

2.5.2 Sensor Maintenance Module

Figure 11 show tubing connections between SMM and Dura-Trac II sensor. The semi-rigid Teflon tubing is supplied with the unit. u Connect an appropriate length of ¼’’ semi-rigid Teflon tubing between the

PINCH VALVE outlet quick connect fitting on the SMM and the PINCH VALVE assembly quick connect fitting.

v Connect the male NPT end of the ¼’’ MNPT to ¼’’ Quick Connect Tube adapter fitting to the flush water supply. Connect a sufficient length of ¼’’ Teflon tubing between the flush water supply (1/4’’ Quick Connect Tube adapter fitting) and the SMM’s flush water inlet ¼’’ quick connect fitting. A manual control valve should be installed on the flush water line in close proximity of the unit so that the flush water may be shut off during sensor maintenance. Do not open flush water supply valve until all connections have been made.

w Connect an appropriate length of ¼’’ semi-rigid Teflon tubing between the PROBE FLUSH outlet quick-connect fitting on the SMM and the PROBE FLUSH assembly quick connect fitting on the Dura-Trac II Sensor.

x Connect an appropriate length ¼’’ semi-rigid Teflon tubing between the “Chemical Rinse” PUMP INLET quick connect fitting on the SMM and the chemical carboy.

25 PSI CHECK VALVE

FLUSH VALVE

DURA-TRAC



FLUSH WATER CONNECTION1/8" NPT TO 1/4" COMPRESSION

TM

FIGURE 9. Dura-TRAC Sensor with Flush


y Connect an appropriate length ¼’’ semi-rigid Teflon tubing between the “Chemical Rinse” PUMP OUTLET quick connect fitting on the SMM and the and the Dura-Trac II chemical injection port.

The SMM has a drain port on the bottom of the unit. If the drain port needs to be extended, connect an appropriate length of ¼’’ semi-rigid Teflon tubing between the SMM Drain quick-connect fitting to the nearest drain.

During the automatic flush/cleaning cycle, the chemical pump injects a cleaning solution into the sensor. This cleaning solution prevents the buildup of fouling agents, which can overtime affect the sensitivity and response of the instrument. Periodic checks of the chemical carboy should be made to ensure the chemical storage tank is at least 1/4 full.

CAUTIONS

R Acid concentration shall not exceed 15% concentration.

PINCH VALVE

25 PSI CHECK VALVE

DURA-TRAC II


TM

CARBOYTANK

DURA-TRAC II SENSOR

SENSOR MAINTENANCE

MODULE(SMM)


FIGURE 11. SMM Tubing Connections to Dura-Trac II Sensor


SECTION 3.0 OPERATION 3.1 MONITOR/CONTROLLER USER INTERFACE

The Monitor/Controller is equipped with user interface keys, LED indicators, and audible beeps. The interface keys are up (p), down (q), left (t), right (u), and function keys.

There are four LED lights to the left of the graphical display. These are: q Power –Green LED that illuminates when there is power to the unit. q Service - Yellow LED displays the status of the electronics. q Diag. – Green LED that blinks to give a diagnostic status of the remote sensor.

When this LED stops blinking, the remote sensor diagnostic alarm is in alarm condition.

q Alarm – Red LED that illuminates when the Monitor/Controller is in alarm condition. The Monitor/Controller provides the user with an audible beep feedback every time a button is pressed. The menu navigation of the Monitor/Controller is by using buttons at the front panel. The following steps explain general menu navigations.

1. From the MAIN screen, pressing any function key will gain access to other menu screens.

2. At the menu screen, on the far left hand side of the text there is a text cursor (}) that indicates the active line on the menu. By pressing the p or q key, the text cursor will move to a different menu text line.

3. To modify the parameter setting on the active menu text, first press the u key to gain access to the parameter and then press the p or q key to scroll through the parameter range. By holding down the p or q key, the number will increased or decreased with larger unit changes.

4. When finished making the parameter change, press t key to store the value. At this point, the new parameter has not been saved. After all parameters modification are completed, press the SAVE function key to accept the change or press the MAIN function key to discard the changes.

p = UP key

t = LEFT key

q = DOWN key

uu == RRIIGGHHTT kkeeyy

Graphically define function keys. Acsess by pressing on button directly below.


3.2 SCM2500XRD READOUT, MENUS, AND CONTROLS

The menu system for the SCM2500XRD is simple to navigate, below you will find the different screens accessible through the function keys (SETUP, ALARM, and FLUSH):

3.2.1 SCM2500XRD Main Screen The MAIN screen on the SCM2500XRD is the screen used under normal operation of the instrument. From this screen, all other features and menus can be accessed. The menu screen shows with Flush option.

v w x y

Definitions

u Streaming Current Value (SCV) ranges from –1000 to +1000

v Gain, signal amplification factor, adjustable from 1X to 20X

w Next Flushing Cycle (optional): If the unit include sensor flush feature, the menu display the time when the next flush will occur in days, hours, and minutes.

x Zero Offset Conditions Offset: OUT Offset condition OUT, actual SCV is display

Offset: IN Offset condition IN, adjusted SCV is displayed and the actual SCV value will be display to the right of OUT.

Offset Value: -1000 to +1000

The Offset function is used to automatically zero the current reading. Once an optimum chemical dosage has been obtained, the user can null the reading so that the setpoint becomes referenced to zero for easier interpretation (see Setup Screen Menu).

y Function Keys – There are four main menu selections across the bottom for the four buttons below. The four menus are: SETUP – SCV Setup Menu ALARM – Alarms Status FLUSH – Sensor Flush Control Menu Pressing one of these keys directly below these menu selections accesses the functions within that menu.

uu


3.2.2 SCM2500XRD Setup Menu (1)

From the MAIN screen, press SETUP function key, the SETUP screen will display. Within the SETUP screen menu, the GAIN, OFFSET, and SCV ALARMS settings can be modified.

u

v

w

x

y

z {

� Definitions

u Sensor Gain: Signal amplification factor, adjustable from 1X to 20X. The gain should be adjusted so that a regular change in dosage results in a noticeable deviation (e.g. 20 to 30 units). To select the proper gain setting let the reading stabilize for 10 minutes and record the reading. Make a normal dosage change and then allow another 5 to 10 minutes for the reading to fully stabilize. If the reading did not change noticeably, simply increase the gain setting and repeat testing. If the reading changed, but did so by more than 50 units, it is suggested to decrease the gain setting. Ideal change in Streaming Current for a normal dosage change is anywhere between 20 to 50 units. If the reading seems unstable when flow, dosage, NTU, and PH are stable, then check to ensure the probe is clean and that the sensor is getting a well mixed sample.

v Offset Mode: Offset mode can be changed to IN or OUT. Changing the Offset mode to from “OUT” to “IN” will automatically zero or null the current Streaming Current reading. For example, if the current reading was –150 and the Zero Offset was changed to “IN”, then the adjusted Streaming Current value is displayed on the Main Screen would be zero. The reading will not stay exactly at zero since the reading is always slightly changing as a result of slight changes in charge. The Offset value will display at the line below. On the Main Display, the raw Streaming Current value (with offset) will be displayed to the right of the Zero Offset: IN. The different between the Streaming Current value and the raw is the offset value. To disengage the Offset, simply change the Offset mode to “OUT” and the true Streaming Current Reading will be displayed.

w Offset Value: The Offset value indicates the amount of offset that has been applied to the reading in order to offset the reading to zero. So that, at any time the operator can see what the offset value is and if anyone has changed it from a previous offset. To disengage the offset, simply change the Offset Mode to “OUT” and the true Streaming Current Reading will be displayed. This is also the method used to re-zero the reading if the current offset no longer corresponds to optimum coagulant feed. To re-zero the reading when Offset mode is “IN”, increased or decreased the Offset Value then press Enter to SAVE.


x SCV Lo (Low) Alarm - This is the streaming current low value alarm (-1000 to +1000). This alarm should be set so that it correlates to a reading

which indicates an under dosage of chemical. Once properly set, if there is an under dosage (or total loss) of chemical feed, the streaming current value will drop below this alarm threshold and the alarm will be activated (meaning that the Main Display will show “Alarm: On” and the Alarm Output will be engaged. Once the streaming current value returns above the alarm threshold, the Alarm will deactivate.

y SCV Hi (High) Alarm - This is the streaming current high value alarm

(-1000 to +1000).and works the same way as the SCV Low alarm except this alarm value should be set to correlate to a reading which indicates an over dosage of chemical.

z SCV AO Scale – The analog output’s scaling of the streaming current value can be set for +/-1000, +/-750, +/-500, or +/-250. This setting allows the analog output to change based on different scale settings.

{ MAIN Function Key – Pressing this key will ignore any setting modifications on this screen and brings up the MAIN screen.

| SAVE Function Key – Pressing this key will save current setting modifications and brings up the MAIN screen.

3.2.3 SCM2500XRD Setup Menu (2)

From the SETUP MENU (1), continue pressing the down arrow key until SETUP MENU (2) menu screen display. SETUP MENU (2) menu screen is a continuation of the SETUP MENU (1) menu screen.

u v

Definitions

u SCV Filter: The filter function activate rolling average of the Streaming Current value over time. The SCV filter can be set to OFF, 30, 60, 90, or 120 seconds. The default setting is OFF.


3.2.4 SCM2500XRD Alarm Status Menu

From the MAIN screen, press ALARM function key, the ALARM STATUS screen will display. Within the ALARM STATUS menu you can view which Alarm has been triggered, as well as, turn the Monitor/Controller’s audible alarm feature on and off.

u

v

w x

y

Definitions:

u Diagnostic: Display sensor diagnostic alarm condition. When the sensor is in diagnostic alarm, it will show ALARM, the green LED (Diag.) will also stop blinking, and the Streaming Current value will show “---“. Most likely cause for a diagnostic alarm is that the motor in the sensor is not turning. Check to ensure the motor is turning. If the motor is turning, ensure the blade of crank is passing cleanly through the opto-switch. If the blade is rubbing against the opto-switch, make an adjustment by loosening the setscrew of the crank and sliding it over so that the blade lines up in the middle of the opto-switch. If the blade was rubbing, it will be necessary to use compressed air to remove any debris (dust) that may be blocking the optics of the opto-switch. Finally, check the interconnect wiring if no other cause can be found for the diagnostic alarm. A loose connection or a terminal that is screwed down on the insulation of the wire instead of the wire itself can cause the diagnostic alarm to activate.

v SCV Lo (Low): The SCV Lo Alarm indicates that the SCV fall below the SCV Lo Alarm threshold.

w SCV Hi (Low): The SCV Hi Alarm indicates that the SCV rises above the SCV Hi Alarm threshold.

x Dry Contact: Digital input status (normally open) indicates the state of digital input. When digital input is close, the ALARM condition will display.

y MAIN Function Key – Pressing this key will bring up the MAIN screen.

z Audible Alarm Indication – The Monitor/Controller is equipped with audible alarm feature. The audible alarm will beep and the red LED light will come on when any alarm condition occurred. The Ù symbol will appear when the audible alarm is enabled, see Special Function Key’s definition below to activate and deactivate the audible alarm. There are two audible alarm sound lever; high and low. When the audible alarm is enabled and alarm condition occurs, high-level beep will be generated. The method of acknowledging the alarm is to press the ALARM function from the MAIN screen, the alarm beep will switch to low level. If any new alarms occur, the high-level beep will be generated to notify the user of the new alarm.

{{

zz


{ Special Function Key – The audible alarm can be toggled ON and OFF by pressing both q and p keys. The Ù symbol will only appear when the audible alarm is enabled. Once the audible alarm is disabled, the only way to enable is to toggle with this Special Function key.

When any alarm is triggered, a +24 Vdc signal will be present on the Monitor’s digital alarm output terminals. This signal can be connected to a SCADA/DCS system to alert the operators to an Alarm condition. In lieu of a +24VDC signal, an optional solid state relay output is available (must be specified with order).

After being properly adjusted by the operator to match up with the upper and lower SCV readings that typically correlate to the acceptable window of process performance, the Hi and Lo Alarms alert the operator as to whether the SCV has exceeded acceptable limits. A Lo Alarm signify an underfeed of chemical (even possible loss of chemical feed) and a Hi Alarm signify an overfeed.

3.2.5 SCM2500SRD Flush Control Menu

This flush feature is an option that is available for the SCM2500XRD, see Section 3.3.7 for detail description.

3.3 SCC3500XRD READOUT, MENUS, AND CONTROLS

The menu system for the SCC3500XRD is simple to navigate; below you will find the different screens accessible through the function keys (SETUP, ALARM, FLUSH, and CTRL). The menu screen shows with Flush option.

3.3.1 SCC3500 Main Screen

u v w { x y z

Definitions

u Streaming Current Value (SCV) ranges from –1000 to +1000

v Gain, signal amplification factor, adjustable from 1X to 20X

w Next Flushing Cycle (optional): If the unit include sensor flush feature, the menu display the time when the next flush will occur in days, hours, and minutes.

x Zero Offset Conditions Offset: OUT Offset condition OUT, actual SCV is display

Offset: IN Offset condition IN, adjusted SCV is displayed and the actual SCV value will be display to the right of OUT.

Offset Value: -1000 to +1000

{{

uu


The Offset function is used to automatically zero the current reading. Once an optimum chemical dosage has been obtained, the user can null the reading so that the setpoint becomes referenced to zero for easier interpretation (see Setup Screen Menu).

y Coagulant Pump Control Mode Mode: AUTO or MAN PID Control Output: 0-100.00% SP (Setpoint): SCV control setpoint (-1000 to +1000)

z Function Keys – There are four main menu selections across the bottom for the four buttons below. The four menus are:

SETUP – SCV Setup Menu ALARM – Alarms Status FLUSH – Sensor Flush Control Menu CTRL – Coagulant Pump Control and Flow Based Control Menu

Pressing one of the keys directly below these menu selections accesses the functions within that menu.

{ Special Function Key – For the coagulant pump control mode, the control mode can be toggled between AUTO and MAN by pressing both q and p keys at the same time. When AUTO is present, the instrument is operating in automatic mode, sending a control signal to the coagulant pump. When MAN is present, the instrument is operating in manual mode, sending a control signal to the coagulant pump, which corresponds, to the manual value. The manual control value can be changed by the operator by pressing the p or q key, see Section 3.7 for more detail.

3.3.2 SCC3500XRD Setup Menus

From the MAIN screen, press SETUP function key, the SETUP screen will display. Within the SETUP screen menu, the GAIN, OFFSET, SCV ALARMS, and SCV Filter settings can be modified. The SETUP Menus are the same for SCM2500XRD and SCC3500XRD see Sections 3.2.2 and 3.2.3 for detail descriptions.


3.3.3 SCC3500XRD Alarm Status Menu From the MAIN screen, press ALARM function key, the ALARM STATUS screen will display. Within the ALARM STATUS menu you can view which Alarm has been triggered, as well as, turn the Monitor/Controller’s audible alarm feature on and off.

u | v } w x y z {

Definitions:

u Diagnostic: Display sensor diagnostic alarm condition. When the sensor is in diagnostic alarm, it will show ALARM, the green LED (Diag.) will also stop blinking, and the Streaming Current value will show “---“. Most likely cause for a diagnostic alarm is that the motor in the sensor is not turning. Check to ensure the motor is turning. If the motor is turning, ensure the blade of crank is passing cleanly through the opto-switch. If the blade is rubbing against the opto-switch, make an adjustment by loosening the setscrew of the crank and sliding it over so that the blade lines up in the middle of the opto-switch. If the blade was rubbing, it will be necessary to use compressed air to remove any debris (dust) that may be blocking the optics of the opto-switch. Finally, check the interconnect wiring if no other cause can be found for the diagnostic alarm. A loose connection or a terminal that is screwed down on the insulation of the wire instead of the wire itself can cause the diagnostic alarm to activate.

v SCV Lo (Low): The SCV Lo Alarm indicates that the SCV fall below the SCV Lo Alarm threshold.

w SCV Hi (Low): The SCV Hi Alarm indicates that the SCV rises above the SCV Hi Alarm threshold.

x Pump Output Lo (Low): The Pump Output Lo Alarm indicates that the pump output has exceeded the lower Alarm threshold.

y Pump Output Hi (High): The Pump Output Hi Alarm indicates that the pump output has exceeded the upper Alarm threshold.

z Dry Contact: Digital input status (normally open) indicates the state of digital input. When digital input is close, the ALARM condition will display.

{ MAIN Function Key – Pressing this key will bring up the MAIN screen.

| Audible Alarm Indication – The Monitor/Controller is equipped with audible alarm feature. The audible alarm will beep and the red LED light will come on when any alarm condition occurred. The Ù symbol will appear when the audible alarm is enabled, see Special Function Key’s definition below to activate and deactivate the audible alarm. There are two audible alarm sound lever; high and low. When the audible alarm is enabled and alarm condition occurs, high-level beep will be generated. The method of acknowledging the alarm is to press the

}}

||


ALARM function from the MAIN screen, the alarm beep will switch to low level. If any new alarms occur, the high-level beep will be generated to notify the user of the new alarm.

} Special Function Key – The audible alarm can be toggled ON and OFF by pressing both q and p keys. The Ù symbol will only appear when the audible alarm is enabled. Once the audible alarm is disabled, the only way to enable is to toggle with this Special Function key.

When any alarm is triggered, a +24 Vdc signal will be present on the Monitor’s alarm terminals 13 (+) and 14 (-). This signal can be connected to a SCADA/DCS system to alert the operators to an Alarm condition. In lieu of a +24VDC signal, an optional solid-state relay output is available (must be specified with order).

After being properly adjusted by the operator to match up with the upper and lower Streaming Current readings that typically correlate to the acceptable window of process performance, the Streaming Current Value (SCV) Hi and Lo Alarms alert the operator as to whether the streaming current value has exceeded acceptable limits. A Lo Alarm will signify an underfeed of chemical (even possible loss of chemical feed) and a Hi Alarm will signify an overfeed.

3.3.4 SCC3500XRD Pump Control (1) Menu

From the MAIN screen, press CTRL function key, the PUMP CONTROL (1) Menu screen will display. There are PUMP CONTROL (1), PUMP CONTROL (2), and FLOW CONTROL (3) menus under CTRL function key. Use up or down arrow key to navigate between menus. Within the PUMP CONTROL (1) Menu screen, the PID tuning parameters can be adjusted. u v w x | y z { Definitions

u Pump Ctrl: The Controller’s pump output control has two mode of operation; AUTO or Manual. In AUTO mode, the pump output percent will increased or decreased automatically in response to deviations from the setpoint. In MAN mode, the pump output percent can be increased or decreased manually by setting the Man Output. The two mode can be toggle by pressing the p or q key.

v Man Output: In MAN mode, the pump output percent % can be increased or decreased by pressing the p or q key. The Man Output value can be changed from 0 to 100% at 0.1% increment. This parameter is saved in non-volatile memory. When running in Automatic mode, the Man Output setting is ignored. However, when switching from AUTO to MAN, it is important to understand that the Pump Output value will be changing from the value it was in MAN mode.


Therefore, it is recommended to change the Man Output value to match the AUTO pump output value prior to switching mode. Failing to do so can result in a significant change in the pump output when switching from AUTO to MAN control.

w SCV Setpoint: The SCV setpoint is the SCV value that the controller is programmed to maintain when in AUTO mode. The SCV setpoint value can be changed from -1000 to +1000 at one unit increment by pressing the p or q key, see Section 3.7 for determine the optimum setting. To determine the setpoint, the operator must first adjust the chemical feed manually until an optimum dosage is reached. Once the optimum dosage has been reached, the operator simply records the Streaming Current Value seen on the display and enters this as the Setpoint value. It is important that the correct polarity (+/-) be entered when programming the setpoint.

x Proportion Band: The Proportional Band setting determines the level of response, or amount of change to the pump output, when the SCV deviates from the setpoint. The Proportional Band value can be changed from 1 to 1000 at 1 unit increment by pressing the p or q key, see Section 3.7 for determine the optimum setting.

y Integral Time: The Integral Time setting determines how much adjustment is made to the pump output while the SCV is away from the setpoint. The Integral Time value can be changed from 1 to 1000 at 1 unit increment by pressing the p or q key, see Section 3.7 for determining the optimum setting.

z PID Rate: The PID Rate function serves to improve the controller’s response when higher Proportional Band and Integral Time settings appear to be too responsive for the application. The PID Rate setting is usually left at 1 for most applications since proper setting of Proportional Band and Integral Time are capable of providing proper response. Higher PID Rate settings will serve to buffer the responsiveness of the controller. The PID Rate setting should not exceed 10. The PID Rate value can be changed from 1 to 20 at 1 unit increment by pressing the p or q key, see Section 3.7 for determining the optimum setting.

{ MAIN Function Key: Pressing this key will ignore any setting modifications on this screen and brings up the MAIN screen.

| SAVE Function Key: Pressing this key will save current setting modifications and brings up the MAIN screen.


3.3.5 SCC3500XRD Pump Control (2) Menu From the PUMP CONTROL (1) menu screen, continue pressing the down arrow key until PUMP CONTROL (2) menu screen display. PUMP CONTROL (2) menu screen is a continuation of the Pump Control (1) menu screen.

u

v

w z x y Definitions

u Pump Out Min: The pump output limit define the minimum value of the pump control output signal. The minimum percent (%) value can be increased or decreased by pressing the p or q key. The minimum percent (%) value can be changed from 0 to 100% at 0.1% increment.

v Pump Out Max: The pump output limit define the maximum value of the pump

control output signal. The maximum percent (%) value can be increased or decreased by pressing the p or q key. The maximum percent (%) value can be changed from 0 to 100% at 0.1% increment.

w Output Lo: The pump output limit define the low alarm value of the pump control output signal. The low alarm percent (%) value can be increased or decreased by pressing the p or q key. The low alarm percent (%) value can be changed from 0 to 100% at 0.1% increment. When the pump control output signal fall below the low alarm value, alarm condition will occur.

x Output Hi: The pump output limit define the high alarm value of the pump control output signal. The low alarm percent (%) value can be increased or decreased by pressing the p or q key. The high alarm percent (%) value can be changed from 0 to 100% at 0.1% increment. When the pump control output signal rise above the high alarm value, alarm condition will occur.

y MAIN Function Key: Pressing this key will ignore any setting modifications on this screen and brings up the MAIN screen.

z SAVE Function Key: Pressing this key will save current setting modifications and brings up the MAIN screen.

3.3.6 SCC3500XRD Flow Control (3) Menu

From the PUMP CONTROL (2) menu screen, continue pressing the down arrow key until FLOW CONTROL (3) menu screen display. FLOW CONTROL (3) menu screen is a continuation of the Pump Control (2) menu screen. When ENABLED, the FLOW CONTROL function allows the user to control the chemical feed based on the process FLOW rate and the Streaming Current Value PID control


output. The flow control is a proportional pump output control base on the process flow rate. The proportional pump output control is set by using the four parameters; Flow Min, Pump Output Min, Flow Max, and Pump Output Max.

u

v w x | y z { Definitions

u Flow Ctrl: The flow control modes are ENABLED or DISABLED. When the flow control is ENABLED, pump output percent % will increased or decreased automatically in response to process flow changes and SCV deviation from the setpoint. When the flow control is DISABLED, the pump output percent will increased or decreased automatically in response PID loop control only. By pressing either p or q key to switch between ENABLED or DISABLED control mode.

v SCV Control Band: When flow control is ENABLED, the proportional pump output flow control will be adjusted (up and down) by the PID loop control. SCV control band value (percent) set up how much the pump output control will be effected by the PID loop control. For example, the SCV control band is set to 5% and the proportional pump output flow control is at 55%, the PID loop control can adjust the pump output control up to 60% maximum and down to 50% minimum. The SCV control band percent (%) value can be increased or decreased by pressing the p or q key. The SCV control band percent (%) value can be changed from 0 to 100% at 0.1% increment.

w Flow Min: Minimum process flow in percent set for the produce the minimum pump control output for the parameter below (Pump Output Min). The percent (%) value can be increased or decreased by pressing the p or q key. The percent (%) value can be changed from 0 to 100% at 0.1% increment.

x Pump Output Min: Pump control output for the minimum process flow set above (Flow Min). The percent (%) value can be increased or decreased by pressing the p or q key. The percent (%) value can be changed from 0 to 100% at 0.1% increment.

y Flow Max: Maximum process flow in percent set to produce the maximum pump control output for the parameter below (Pump Output Max). The percent (%) value can be increased or decreased by pressing the p or q key. The percent (%) value can be changed from 0 to 100% at 0.1% increment.

z Pump Output Max: Pump control output for the maximum process flow set above (Flow Max). The percent (%) value can be increased or decreased by pressing the p or q key. The percent (%) value can be changed from 0 to 100% at 0.1% increment.



| SAVE Function Key: Pressing this key will save current setting modifications and brings up the MAIN screen.

3.3.7 SCC3500XRD Flush Control Menu

From the MAIN screen, press FLUSH function key, the FLUSH CTRL MENU screen will display. The goal of the sensor flush is to minimize the need for operator involvement for maintenance purposes. This feature greatly enhances the reliable operation of the Streaming Current Monitor. Within the FLUSH CTRL MENU screen, the flush parameter settings can be modified. Sensor Flush is only available with the optional Sensor Maintenance Module or the Dura-Trac Flush feature.

u

v w x } y z { |

Definitions

u Auto Flush: The SMM or Dura-Trac with Flush runs an automatic flushing/cleaning sequence and will continue to flush according to the flush parameter settings. The Auto Flush can be set to ENABLED or DISABLED. When it is in ENABLED mode, the Monitor/Controller will begin flushing based on Flush time value setting. When it is in DISABLED mode, the flushing will be de-activated.

v Flush Time: The flush time period setting determines how often the flushing will take place when the Auto Flush is set to ENABLED. There are two parameters on this menu line that can be modified; number (1 to 99 at 1 unit increment) and number’s unit (DAY, HRS, or MIN). To modify the first parameter setting (number), press the u key to gain access to the parameter and then press the p or q key to scroll through the parameter range. To modify the next parameter setting (number’s unit), press the u key to gain access to the parameter and then press the p or q key to scroll through the parameter range. When finish, press the t twice to get to the next menu line.

w Flush Period: The flush period setting determines the duration of water flush to the sensor. With each flushing sequence, there are actually two flushes performed. One at the beginning of the flush cycle (before the wash) and one after the wash. The Flush setting determines the duration of each of these flushes. So that, if Flush is set for 30 sec., the actual total time of flush duration will be 60 seconds (30 seconds for each flush). The value can be increased or decreased by pressing the p or q key. The value can be changed from 1 to 99 at 1 second increment.


x Chemical Period: The Chemical period setting determines the duration of the chemical pump on time. It is recommended to use default value of 8 seconds. Excessively long chemical period (or too highly of a concentrated chemical like Acid) can damage the probe. The value can be increased or decreased by pressing the p or q key. The value can be changed from 1 to 20 at 1second increment.

y Wash Period: The Wash period setting is only applicable for the SMM. For the Dura-Trac with flush option, this setting should be left at 30 sec. The Wash Period setting determines the duration of the sensor’s chemical washing. Harder to remove scale or deposits will require longer Wash times. It is recommended to only use a Wash duration that is no longer than required to remove scale/deposits. Excessively long Wash durations (or too highly of a concentrated chemical like Acid) can damage the probe. The value can be increased or decreased by pressing the p or q key. The value can be changed from 1 to 99 at 1second increment.

z Hold Period: The Hold period setting determines how long the monitor’s output will be held stable (or frozen at last output value before the flush) after the flushing is finished. Flushing will cause the actual monitor reading to fluctuate, thus it would adversely affect an automatic chemical feed control program running through a Supervisory Control and Data Acquisition (SCADA) or Distributed Control Systems (DCS). For this reason, the Hold feature has been provided and must be properly set to avoid the flushing sequence from interfering with Automatic Chemical feed control. The Output of the monitor is automatically held stable during the flush, however, the operator must determine the Hold duration after the flush is finished. To determine the proper Hold setting, record the streaming current value before the flush starts and then time how long it takes for the monitor to reach the previously recorded reading after the flush is completed (this must be done while the monitor is online with treated water passing through the sensor). The simplest way of doing this will be to record the reading and then change the Man. Flush from “Off” to “On” as this will activate the flush sequence. If it takes 30 seconds for the reading to stabilize to the previously recorded reading, then set the Hold setting for 1 minute. If it takes 50 seconds, then it is recommended to set the Hold for 2 minutes. The value can be increased or decreased by pressing the p or q key. The value can be changed from 1 to 99 at 1 minute increment.


| FLUSH Function Key: Pressing this key will activate a one-time manual flush. This can be done at anytime regardless of the Auto Flush mode.

} SAVE Function Key – Pressing this key will save current setting modifications and brings up the MAIN screen.

Figure 11 shows the timing diagram of the Sensor Flush.


NOTES

R Sample Isolation and Chemical Wash is only available with the optional SMM. The Dura-Trac with flush option does not include the sample isolation or chemical pump feature; however, there will still be a delay between sensor flush and rinse.

3.4 SYSTEM OPERATION

After sample flow is established and power has been applied to the sensor and streaming current monitor, allow 10-15 minutes or longer for the reading to stabilize. Stable conditions differ from plant to plant. The reading may fluctuate 10 to 20 units, even under stable conditions due to the chemical not being thoroughly mixed. If readings fluctuate widely, refer to Troubleshooting Guide. The monitor’s reading may be negative, zero, or positive. The monitor is simply indicating the streaming current value of the sample. In most applications, the reading will be slightly negative (anionic).

After the reading has had ample time to stabilize, adjust the chemical dosage in normal increments to test the response of the monitor. For model SCC3500XRD, enter the Control menu to manually adjust chemical feed. For each dosage change, the reading should respond by changing 20 to 50 SCV units. If the response is less than 20 units, increase the gain. Likewise, if the response is greater than 50 units, it is recommended to decrease the gain (especially if the monitor is to be used for automatic chemical feed control). Next, a test should be performed to determine the Raw SCV reading. This will help determine the LO SCV Alarm setting and give a better understanding of instrument response. To determine the Raw SCV reading, shut off sample flow to the sensor and turn the outlet fitting up. Pour a sample of raw untreated water into the sensor and allow the reading to stabilize and then record the reading. This reading should serve as an absolute alarm value, which if measured by the monitor will indicate a loss of chemical feed. It is recommended to set the Lo SCV Alarm value (see Alarm setup menu) between the Raw SCV measurement and the setpoint value. Further testing will help to

ON

OFF

PUMP OUTPUT HOLD

SAMPLE ISOLATION

CHEMICAL PUMP

SENSOR FLUSH

OFF

ON

OFF

ON

OFF

ON

HOLD PERIOD

WASH PERIOD

TIME (SECONDS)

AND RINSERINSEFLUSH

FIGURE 11. Automatic Flush Timing Diagram


determine the best ideal alarm value. The HI Alarm value should be set above the setpoint value and at a point where testing shows an unacceptable amount of overfeed. After verifying proper response, the next step should be to optimize the process to establish a SCV setpoint. The SCV setpoint can then be zero’d, or offset, so that the setpoint will be adjusted to a reading of zero (0). This is done by entering the Setup menu and changing the Offset mode to “IN”. Offsetting the SCV is not necessary for normal monitor operation as it is only provided so that an easier reference of zero can be used for monitoring changes in the process. For example, if the true SCV setpoint reading was –150, and the user offset that reading to equal zero (0), if chemical dosage was decreased the reading may go from 0 to –50. If the reading had not been zero’d, then the true SCV would have gone from –150 to –200 (a –50 unit change). Once the setpoint has been zero’d, it is easier to determine whether chemical is being under or overdosed since going negative (anionic) from 0 would be an under-dose and going positive (cationic) would be an overdose. A setpoint of zero (0) is also easier for multiple operators (night and day shift) to remember. Since the setpoint will change seasonally, adjusting the setpoint so that it equals zero (0) helps to avoid confusion. A common mistake made with the monitor’s offset function is that it has been used to re-zero the reading as it drifts from the previously offset reading of zero. Once the process has been optimized and the Streaming Current Value has been zero’d at that point, it is no longer necessary or correct to re-zero the reading. If the reading changes from the setpoint of zero (or the true SCV setpoint if the offset is out), the chemical dosage should be adjusted to bring the reading back to the setpoint and not the offset function. Eventually, a new setpoint might need to be established due to seasonal changes or large excursions in turbidity, but under normal conditions, the setpoint should not be changed on a daily or even weekly basis. It is recommended to use the monitor for a few weeks in the Offset Out mode to become familiar with the operation and response of the unit.

3.5 TREATMENT OPTIMIZATION PROCEDURE

The treatment optimization process should be done slowly and stepwise. Assuming that the plant is producing acceptable water with present chemical dosages, trim approximately 10%, wait for the reading to stabilize, and record the reading as the setpoint. You may need to change GAIN setting to increase magnitude of response. If the settled and finished water quality is still acceptable at the reduced dosages, trim another increment, wait for the reading to stabilize, and record the reading as the new setpoint. Continue this process, being sure to wait long enough each time to see the full effect of the chemical feed changes on the process (i.e. settled water turbidity, appearance of floc). In between these dosage changes it will be necessary to maintain the setpoint. Failure to maintain the setpoint while trying to reach a lower dosage level could result in under dosing the chemical if turbidity starts to increase. By maintaining the setpoint, the chemical dosage is kept in check with process changes (i.e. turbidity, flow rates).

If the Offset function is being used, re-zero the monitor reading as described in section 3.3 after each reduction in chemical feed. If a cationic coagulant is being used, the streaming current value will become more negative with each reduction in dosage. The "optimum setpoint" is obtained when a minimum dosage of coagulant is being fed and produces desired results for the particular treatment process. This setpoint will remain very close to the same reading even when raw water turbidities increase or decrease. Simply adjust the coagulant dosage to maintain this setpoint reading on the monitor.


This procedure may need to be repeated on a monthly to seasonal basis to ensure the setpoint remains representative of optimum process performance.

NOTE - If automatic control is used, refer to Section 3.7 on Automatic Control.

3.6 MANUAL CONTROL USING CONTROLLER

Only available on model SCC3500XRD.

Make electrical connections between Streaming Current Controller and the chemical feed pump. The AUTO or Manual control mode is indicated on the MAIN screen. To switch between AUTO or Manual control mode can be done by pressing both p and q keys from the MAIN screen. Once in Manual control mode, the pump control output percentage can be increased or decreased by pressing the p or q key.

The AUTO or Manual control mode can also be change from the Pump Control (1) menu. Once Pump Control (1) menu is display, move the text cursor on the far left hand side of the screen (}) to “Pump Ctrl:” then press u the control text will blink. The control mode can be set by pressing the pressing p or q key, this will toggle between AUTO and MAN mode. Set the controller to MAN. Once completed, press t key then press p or q key to get to next parameters on that screen. Next press q key to “Man Output:” then press u the control number will blink. The percent (%) number will blink, the manual chemical feed control value output can now be increased or decreased the by pressing p or q key to the desire manual control value. When completed, press t key to get to other parameters on that screen. The SAVE Function Key must be pressed to save current setting modifications and brings up the MAIN screen.

3.7 AUTOMATIC CONTROL

Only available on model SCC3500XRD. Automatically controlling the treatment process with the Streaming Current Controller (SCC3500XRD) is a very simple operation, once you know how the controller works. Most controller manuals do not explain, in simple terms, the purpose of so-called "tuning constants" termed Proportional Band, Integral Time, and Rate. Controllers with these three functions are sometimes called "3-mode controllers," or "PID controllers". In order to explain the purpose of these functions, a brief review of how a simple proportional controller works may be helpful. Many water treatment plants have "flow controlled" coagulant feed, i.e., when raw water flow increases, a signal is sent to the coagulant pump that immediately increases the feed rate. In other words, there is no "lag time" between water flow increasing and coagulant increasing. This controller works extremely well in maintaining proper dosage as long as the water flow is the only thing changing. However, if turbidity is changing, the proper chemical dosage cannot be maintained with a simple proportional controller. Since the SCV is taking its sample downstream of the coagulant feed point, there will be some "lag time" before it can sense a change in turbidity, alum feed, raw water flow, etc. If, for instance, the SCV reading should start going more negative due to an increase in turbidity, it will cause the controller to increase coagulant feed. This will cause the streaming current reading to go more positive, which will cause the pump to decrease coagulant. The result is continuous cycling above and below the setpoint, thus, the


need for a controller with PID "tuning constants". The Proportional Band, Integral Time, and PID Rate functions provide a way to eliminate cycling due to the lag time between coagulant additions and streaming current sensing. The following are description of parameters used in the PID control loop algorithm:

q Process Variable: The controlled process, meaning the value at the Controller used to look at the process input (SCV).

q Setpoint: The target for the process variable, meaning the value at the setpoint input.

q PID Output: The correction signal produced by the PID loop algorithm. The output is used to control the process that effect the process variable.

q Proportional Band: The value of the property proportional constant (KP). KP = Output range / effected process range. q Integral Time: The value of the Integral constant (KI) expressed in repeats per

minute. KI = Component of the loop output reacts to the amount setpoint error.

q PID Rate: The value is a function design to improve the PID loop response. q Maximum Output: The maximum value produced by the PID loop output. q Minimum Output: The minimum value produced by the PID loop output.

The Controller’s PID loop is designed for reverse acting; process variable goes down will cause the output to go up. To set the loop to be direct acting, the minimum and maximum values need to be swapped; set minimum at maximum value and set maximum at minimum value. The following describe each PID parameter in detail.

Proportional Band The proportional band constant setting is dependent upon the response of the controller or and also, to some degree, the lag time. The more responsive the Controller, and/or the longer the lag time, the higher the proportional band constant should be set. Only through trial and error can any tuning constant be correctly established. To test proportional band constant setting, 10 to 30% changes in raw water flow rates can be made. Take note of the Controller’s response as the SCV changes.

q If the response of the pump output seems to be large for the amount of SCV change you are seeing, increase the proportional band constant setting and re-test.

q If the Controller is making too small of an adjustment for the SCV change you are seeing, the proportional band constant is set too high and should be reduced and then re-tested.

The important thing to remember about the proportional portion of PID is that proportional only changes the Pump Output as the SCV is changing. Or in other words, it responds to the change in deviation as it occurs between the actual SCV and the setpoint and does not respond to a deviation if it is not changing. So, if you notice that as the SCV goes from a reading of 0 (setpoint) to –10 that the pump output went from 50% to 60%, and you know from experience that a 10% change in Pump output produces a 20 unit change in the SCV, then you can assume that the proportional band constant is set too low and needs to be increased. In the above example, you would know that if the SCV went from 0 to –10 that the pump output would need to increase approximately 5% (since 10% produced a 20 unit change) and you would adjust the


proportional band constant so that the max change in PUMP Output as the reading is changing would be 3 to 5%. We say 3 to 5% and not just 5% because you have to consider the lag time and the Integral Time setting and its effect upon the pump output.

Integral Time A basic rule for setting the Integral Time constant setting is that the longer the lag time, the higher integral time constant should be. Unlike Proportional Band which actually responds to the changes in the SCV deviation, Integral Time only responds to the time the deviation last and will continue to correct the pump output for as long as the SCV stays away from the setpoint value (even if the deviation is not changing). A good example of this would be to place the controller into manual while the SCV is at the setpoint value and then decrease the Pump Output by 10%. Once the reading has completely stabilized at a more negative value, place the controller into Automatic mode. Since the reading will be stable at first, but away from the setpoint, the amount of Pump Output change you note on the display is being controlled by the Integral Time constant setting. Proportional Band will have no effect on the Pump Output until the SCV starts to change as a result of the higher dosage of chemical finally reaching the sensor. During the time when the SCV is stable (but not at the setpoint), you can note how much the Pump Output is changing and if it appears to be making too small or too large of an adjustment, simply change the Integral Time constant setting accordingly.

PID Rate

The PID Rate function serves to improve the controllers response when higher Proportional Band and Integral Time settings appear to still be too responsive for the application. The PID Rate setting is usually left at 1 for most applications since proper setting of P Gain and Integral Time are capable of providing proper response. Higher PID F settings will serve to buffer the responsiveness of the Controller. The PID Rate setting should not exceed 10.

NOTE

R There will normally be a small amount of cycling for a few minutes after a process change, even if Proportional Band, Integral Time, and PID Rate are set correctly.

Output Limits (Min and Max) The output limits define the maximum and minimum values of the pump control output signal. This control can be used to limit the % output of the controller, high or low. On a 4-20 mA controller with Max: 50%, the Output would never be greater than 12 mA, i.e., the chemical pump could not go above 50% output. This function can be used as a safety measure to prevent overfeed or underfeed.

3.8 AUTOMATIC CONTROL SETUP

The controller can be programmed while it is operating in the AUTOMATIC mode. When the controller is in the SET-UP mode, displays can be altered to review and adjust the tuning constants. Control action continues undisturbed, except for the normal consequences of changing a certain parameter.

The AUTO or Manual control mode is indicated on the MAIN screen. To switch between AUTO or Manual control mode can be done by pressing both p and q keys from the MAIN screen. When in AUTO control mode, the pump output percent will increase or decrease automatically in response to deviations from the setpoint.


The AUTO or Manual control mode can also be changed from the Pump Control (1) menu. When Pump Control (1) menu is displayed, move the text cursor on the far left hand side of the screen (}) to “Pump Ctrl:” then press u key, the control text will blink. The controller mode can be set by pressing p or q key, this will toggle between AUTO and MAN modes. Set the controller to AUTO. When completed the change, press the t key then press p or q key to get to other parameters on that screen. The Proportional Band, Integral Time, and PID Rate can be changed by following the same procedures. The SAVE Function Key must be pressed save current setting modifications and brings up the MAIN screen. The MAIN Function Key can be used to discard any new modification made to this screen and brings up the MAIN screen. To adjust tuning constants (refer to section 3.2): Follow these three guidelines when establishing correct tuning constants:

1. Change only one control action at a time. Making two or more corrections is confusing and can cause the controller to get out of control.

2. Never make a large change in a tuning constant. Make a small change and observe the effect it has on the control action.

3. Allow plenty of time for the process to stabilize before making another change, making changes in an unstable process can be misleading.

3.9 FLOW CONTROL

Flow control is a feature that allows the Controller to perform coagulant pump control in the process that is varying their process flow. During large process flow variation, the PID control alone may not be able to response to the flow changes. The Controller monitors the process flow and uses it in the flow control calculation. The Controller is equipped with auxiliary analog input (4-20mA). When the flow control is enabled, the pump control output is proportionally changed by the amount of process flow changes in conjunction with the PID loop based on the SCV setpoint. The following are parameters used in the flow control:

q Flow Ctrl: The flow control modes are ENABLED or DISABLED. When the flow control is ENABLED, pump output percent % will increase or decrease automatically in response to process flow changes and SCV deviation from the setpoint. When the flow control is DISABLED, the pump output percent will increase or decrease automatically in response PID Loop control only.

q SCV Control Band: Percent band around the flow control proportional pump output, based on the four parameters below, that the PID loop can effect.

q Flow Min: Minimum process flow in percent set for the produce the minimum pump control output for the parameter below (Pump Output Min).

q Pump Output Min: Pump control output for the minimum process flow set above (Flow Min).

q Flow Max: Maximum process flow in percent set for the produce the maximum pump control output for the parameter below (Pump Output Max).

q Pump Output Max: Pump control output for the maximum process flow set above (Flow Max).


3.10 TUNING CONSTANT SPECIFICATIONS

Tuning constants are stored digitally in non-volatile memory and can be changed by front panel keys. Table below shows default PID Parameters preset by Chemtrac®.

PID Tuning Parameters Default Setting

Proportional Band 150

Integral Time 60

PID Rate 1

Experience has shown these values to be a good starting point for most applications. However, significant changes may be necessary to tune the controller to your specific operation.


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SECTION 4.0 GENERAL GUIDELINES 4.1 STREAMING CURRENT VALUE RESPONSE FACTORS

Upscale Excursions: (Streaming Current Value (SCV), goes more positive) Caused by:

R Decrease in pH R Decrease in raw H20 flow R Decrease in color R Decrease in raw water turbidity R Decrease in lime R Decrease in caustic R Decrease in anionic polymers Increase in aluminum sulfate, or PAC R Increase in cationic polymers Increase in chlorine

Downscale Excursions: (Streaming Current Value (SCV) goes more negative)

Caused by:

R Increase in pH R Increase in H20 flow R Increase in color R Increase in raw water turbidity R Increase in lime R Increase in caustic R Increase in anionic polymers R Decrease in aluminum sulfate, or PAC R Decrease in cationic polymers R Decrease in chlorine

Assumes that this is only parameter changing at the time.

NOTES R Potassium Permanganate usually has no appreciable effect on the SCV (at

normal dosages of 1-2ppm). R Increasing conductivity will drive the SCV toward zero. R Change in lag time may affect the SCV.


4.2 FUNDAMENTAL STREAMING CURRENT KNOWLEDGE

Introduction

It will take several weeks or maybe even a few months for an operator who has come to rely on Jar test, eye-balling, turbidity readings, or any other method for determining coagulant dosage to become comfortable using the monitor as a tool for controlling coagulant feed. Very few plants install an monitor and start controlling in Automatic mode in the first few weeks. Monitoring the response and repeatability of the monitor through several different turbidity excursions, and comparing process results obtained by controlling dosage to maintain a streaming current setpoint against the results of previous methods used to determine dosage changes is the only way to prove the reliability of the instrument and gain the confidence needed to realize the full potential of the technology. The operator will soon realize that the time consuming jar testing procedure is no longer where his comfort lies. The information provided by the monitor is equivalent to a 5 second jar test once the operator understands how to interpret the reading.

The Importance Of Trending And Manual Control

It is suggested to hook up a chart recorder, or connect the monitor to SCADA, so that the response and trend of the monitor can be monitored and compared to turbidity readings, flow rates, and coagulant dosage adjustments. The information derived from comparing the streaming current value to these other parameters will assist the operator in understanding how the monitor responds to changing conditions. During the first few weeks of operation, the monitor should be used in Manual mode and all the operators should become familiar with how to interpret the monitor reading. If the reading moves in the negative direction from the setpoint as a result of an increase in turbidity, the operator should manually increase the dosage to re-establish the setpoint and feel free to run a Jar test to compare the results with. Following this procedure and closely reviewing the monitor trends and responses will speed up the process of the operators becoming comfortable with using the monitor to determine or automatically control the coagulant dosage.

Setpoint – Why Does It Change?

It is important for the operator to understand that the ideal monitor setpoint can occasionally change due to changes in water chemistry and wear on the probe and piston assemblies. For example, a WTP may find that under the exact same turbidity conditions a setpoint of 150 works great in the summer, but that a setpoint of 50 works best in the fall. Unfortunately, there is no calibration technique that can be used to correct for the monitor’s response to seasonal, chemistry changes. This is the reason the monitor is considered a relative reading. The dominating cause for the setpoint changing is due to seasonal water chemistry changes (e.g. changes in PH or Color / Organics). Seasonal additions of chemicals such as Potassium Permanganate or Powder Activated Carbon can also have an effect on the monitor’s setpoint. Extreme changes in turbidity can result in a significant enough change in chemistry that it may effects the setpoint. Because the monitor’s setpoint can change, occasional verifications of the setpoint need to be made. If Jar testing or operator experience show that the setpoint currently being used may no longer be ideal, simply readjust the chemical feed manually to re-optimize the process and establish the new stabilized reading as the new ideal setpoint. These


verifications of the setpoint do not need to be performed daily, or even weekly, unless there is a large, sudden change in turbidity or if a chemical that was not being fed previously is going to be introduced (i.e. Potassium Permanganate). Verifying the setpoint once every few weeks should be adequate for most applications.

Maintenance Issues

To keep the monitor working properly, occasional maintenance will be necessary. Cleaning only takes a few minutes to perform and is usually needed once every 2 to 6 weeks (depending upon water quality conditions). An easy test to see if the sensor needs to be cleaned is to first verify the reading has not become “noisy” or “bouncy” and then make small changes in chemical feed to make sure the sensor has not become unresponsive. As long as the monitor is stable, responsive, and the response is no less than it has been noted in previous response testing, the sensor does not need to be cleaned. If the reading does appear to be less responsive or noisy, then record the amount of response or noise (signal drift as measured in a one minute period) and then remove the probe and piston for cleaning. First look to see if there is any obvious buildup or solids in the probe or on the piston. Then, clean the probe with a suitable cleaner (such as Comet/Ajax or Rover/CLR). Finally, rinse the parts and install them back into the sensor. After allowing the sensor time to stabilize, compare response and noise (if any) to previous results to verify the cleaning did indeed improve response. If not, the piston and/or probe may need to be replaced. Eventually the moving parts of the monitor will wear. Most notably, the probe and piston will wear the fastest and require replacement once every two years on average. Once again, to determine if the probe and piston need to be replaced simply make small chemical feed adjustments. If the probe is unresponsive and cleaning does not improve the result, the probe and piston most likely need to be replaced. Having a new set on hand to compare against is the best method of determining if the parts need to be replaced. The motor in the monitor sensor will also need replacing after 3 to 5 years of use. If the reading starts to become slightly unstable, and cleaning or replacing the probe and piston does not eliminate the unstable reading, check the shaft of the motor to see if it has excessive movement. If so, replace the motor.

The Usefulness Of Spare Parts For Determining Probe/Piston Wear

If a spare probe and piston are on hand, it is suggested to keep these put aside for comparing with the set in use and for replacing the old set when they become worn. If the spare set is routinely swapped with the other set, then both sets will experience wear. Always having a new, unused set on hand ensures you have a point of reference for determining when your old set absolutely needs to be replaced. For example, to compare the readings of your old probe and piston to a new set, simple close the sample valve and drain all the sample out of the probe block by removing the probe (you will also probably want to clean the probe and piston at this time). Re-insert the probe and turn the outlet fitting 180 degrees so that it is pointing up. Next, pour a sample of untreated, raw water into the probe block through the upturned outlet fitting. Allow the reading to stabilize and record the reading and any amount of signal oscillation (bounce) as seen in a one minute interval. Finally, remove the old probe and piston and install the new set and pour in the raw water sample. Compare the readings of the new probe and piston to the old set. If the readings from the old probe are


less than 50% of what the new probe reads and/or noticeably less stable, it is recommended to replace the old set unless the operator feels confident that the old set was performing satisfactorily. Once the signal strength from a probe and piston set has degraded down to 50% to 25% of what a new set’s signal strength is, the parts should be considered worn and probably in need of replacing. It may not be necessary to replace both the piston and the probe at the same time as usually the piston wears faster than the probe. To check this, simply install a new piston with the old probe and compare those readings to the ones obtained with the new piston and new probe combination. If the old probe and new piston combination produce a reading that is within 50% or more of the new set, then the probe can still be used as long as the new piston is installed. The same procedure should be followed with a new probe and old piston to determine if the old piston is still suitable for use. Using this procedure, the operator can determine which part, if not both, needs to be replaced. Be sure to order a replacement part(s) to have on hand as a spare once you have installed the new probe and/or piston to replace the worn part(s).

Simple Functionality Test

The procedure of pouring raw water into the probe block to check the probes for wear can also be used to check the probe’s response and/or troubleshoot the system. Many times when there is a problem associated with the monitor, the operator will assume the instrument is at fault. If the operator does not have an easy method of testing the monitor’s functionality, he will most likely not look for another cause. A simple method of checking the monitor’s performance is to pour untreated, raw water into the probe as outlined above. First, verify that the raw water reading is significantly different from the treated water reading. The raw water reading should be more negative than the treated water sample by at least 50 units (taking into consideration that the gain has been properly set and that coagulant dosage is greater than a few ppm). The raw water reading will also normally be greater than –100 on 1X gain (except with samples that have a high alkalinity/conductivity). The reading on the raw water should also be stable and not erratic or oscillating. Finally, add a small amount of coagulant to the raw water sample and pour the sample into the sensor to verify the reading responds by moving in the positive direction. If the unit responds as outlined above, the unit is most likely performing within specifications. If you are unsure about your results, or cannot find another cause for whatever problems you are having with the monitor (e.g. lack of response, erratic reading), then contact the factory.


SECTION 5.0 TROUBLESHOOTING GUIDES

PROBLEMS POSSIBLE CAUSE(S) CORRECTIVE ACTION

1. Display fluctuates rapidly and widely on treated sample.

A. Incomplete dispersion or mixing of coagulant(s) in raw water at point of sampling.

B. Chemical feeders erratic or partially plugged.

C. Raw water flow-turbidity fluctuating.

D. GAIN setting too sensitive.

E. Cell bottom plug loose or

O-ring missing.

A. Check stability of readings on raw or finished water. If stable, incomplete mixing is the problem. Move sampling point further downstream, or resolve mixing problems.

B. Fix feeders.

C. Check R/W flow controls/charts, and turbidity.

D. Decrease GAIN setting.

E. Tighten plug. Check O-ring (See Cleaning Procedures).

2. Display does not change with change in coagulant dosage.

A. GAIN setting too low.

B. Wrong sample point or insufficient mixing..

C. Sample cell dirty.

D. Excessive “lag time” between coagulant injection point and sensor sample cell.

A. Increase GAIN setting.

B. Select correct sample point.

C. Clean cell (see Cleaning Procedures).

D. Move sampling point closer to coagulant feed point and/or decrease sample TRANSPORT time (See Selecting Proper Sample Point).

3. Display indicates 0.00, or closely thereto, and does not change with change in coagulant dosage.

A. No water sample to sensor.

B. Motor not turning.

C. Dirty or inoperative probe.

D. Opt switch misaligned.

E. Opt switch inoperative.

F. Sensor output connections incorrect.

G. Circuit card component faulty.

A. Establish proper sample flow.

B. Turn on motor.

C. Clean or replace probe.

D. Adjust opt switch position for maximum meter reading on water sample and tighten securely in place.

E. Replace opt switch.

F. Check wiring.

G. Replace circuit card.


SECTION 6.0 MAINTENANCE PROCEDURES The Dura-Trac sensor is supplied with two (2) probes and (2) pistons so freshly cleaned parts can always be on hand.

6.1 REPLACEMENT PROCEDURES

The following steps describe probe replacement:

1. Disconnect the lead wire from the enclosure and remove the lower retaining slip nut from the probe.

2. Remove probe by pulling on the tab. You may need to twist slightly.

3. Remove the piston using a ¼” flatblade screwdriver.

4. Clean any debris from cell housing.

5. Screw clean piston into place. Do not over tighten. Only slight torque is necessary.

6. Insert clean probe into cell housing.

7. Slip retaining nut over probe lead wire and tighten onto probe. Finger tight is adequate - be careful to avoid cross threading the nut.

8. Connect probe lead wire to side of enclosure.

9. It may take several minutes for monitor readings to stabilize with a new probe. Sensitivity to process changes may also be greater. If the Offset is used, the user must set the Offset to OUT position. After SCV reading is stabilized, set the zero Offset to the IN position to re-zero the SCV reading.

CAUTIONS

R If monitor is being used for automatic dosage control, put the controller into MANUAL mode before starting replacement procedure.

6.2 CLEANING PROCEDURES Depending on the type of contamination, see table below for different cleaning procedures recommended.


TYPE OF CONTAMINATION CLEANING PROCEDURE

Mineral scale from alum/lime addition Comet or other Abrasive Cleaner Deposits caused by raw water iron/manganese, or where ferric salts or potassium permanganate is used for treatment.

ROVER (available from Hach Chemical) 1 spoonful per pint tap water

Organics from raw water or where polymers are used.

Comet or other Abrasive Cleaner

Oil/Grease Comet or other Abrasive Cleaner

A “soak and brush” method is recommended for any contaminant. Soak only long enough to dissolve/remove the material. Probe surfaces should be thoroughly washed with clean water to remove any residual cleaning compound.

CAUTIONS

R Do not soak entire probe cartridge, only soak inside the bore. Acid concentration shall not exceed 15% concentration.

6.3 REPLACEMENT PARTS

Figure 12 AND 13 illustrates Dura-Trac and Dura-Trac II sensor parts identification with part numbers. Table below lists recommended replacement parts.

Part Number Description Replacement Interval

1701 Delrin Piston 1 to 2 years

8601 Probe Cartridge 1 to 3 years

1301 110VAC Drive Motor 3 to 5 years

5017 Viton Diaphragm 3 to 5 years

8702 Probe Washer If Lost


110 MOTOR(1301)

PROBEWASHER

(7703)

DURA NUT(4200)

DURA PLUG(8606)

O-RING(1605)

PROBE(8601)

PISTON(1701)

GUIDE(8711)

110 CRANK ASSEMBLY

(5302) MOUNTING NUT(1607)

NEOPRENEWASHER

(5016)

YOKE(5710)

ROD END(3707)

YOKE PIN(5720)

PROBE BLOCK(5622)

3/4" BARB INLET(5021)

DURA NUT(4200)

4-40 SETSCREW

MOTOR BRACKET(3311)

WASHER(1608)

6-32 SCREWS

VITON SEAL(7701)

OPTO SWITCH(1308)

EXTENSION(5611)

FIGURE 12. Dura-Trac Sensor Parts Identification


PISTON(1710)

PROBE(8601)

PROBEWASHER

(7703)

WW PROBE BLOCK(5630)

GUIDE(7720)

O-RING(1605)

DURA PLUG(8606)

DURA NUT(4200)

4-40 SETSCREWS

3/4" BARB INLET(5021)

110V MOTOR(5470)

DURA NUT(4200)

NEOPRENE WASHER(5016)

DOUBLE THICKVITON SEAL

(7702)

MOUNTING NUT(1607)

MOTORBRACKET

(3311)

YOKE PIN(5720)

YOKE(5710)

MOTOR CRANK(3300)

ROD END(3707)

6-32 SCREWS

WASHER(1608)

OPTO SWITCH(1308)

WW EXTENSION(5611)

FIGURE 13. Dura-Trac II Sensor Parts Identification


6.4 ORDERING INFORMATION To place an order for spare parts you may either call, email, or fax Chemtrac® directly or contact your local distributor or representative. The following information should be included in your request: Model number of your monitor, part number(s), qty, description of parts required, and purchase order number. Please contact Chemtrac® for up to date pricing. Parts order normally ship within 24 hours.

Chemtrac Systems, Inc 6991 Peachtree Industrial Blvd., Building 600 Norcross, GA 30092 Phone: 1-800-442-8722 (Inside US only), 770-449-6233 Fax: 770-447-0889 Email: [email protected] Website: www.chemtrac.com


SECTION 7.0 MECHANICAL SPECIFICATIONS

The following Figures 14 thru 19 illustrate enclosure and mounting dimensions for Streaming Current Monitor/Controller, Dura-Trac Sensor, Dura-Trac Sensor with Flush, Dura-Trac II Sensor, and Sensor Maintenance Module.

11.2

" [2

85m

m]

13.6

" [3

45m

m]

12.5

" [3

17m

m]

7.71" [196mm]


SCC3500XRD

9.2" [234mm]7.7" [196mm]

Service

Alarm

Power

Diag.

6.1" [155mm]6.3" [161mm]

FIGURE 14. Streaming Current Monitor/Controller Dimensions


11.2" [285mm]

9.7" [247mm]

10.5

" [2

66m

m]

9.2"

[23

4mm

]

DURA-TRAC II



TM

6.3" [161mm]

18.8

" [4

77m

m]

FIGURE 16. Dura-Trac II Sensor Dimensions

14.7

" [3

73m

m]

8.5"

[21

5mm

]

7.2"

[18

3mm

]

TM


DURA-TRAC

9.2" [234mm]7.7" [196mm]


5.3" [135mm]

FIGURE 15. Dura-Trac Sensor Dimensions


17.6

" [4

47m

m]

8.5"

[21

5mm

]

5.3" [135mm]

7.2"

[18

3mm

]


DURA-TRAC TM

9.2" [234mm]7.7" [196mm]

SYSTEMS, INC.

CHEMTRAC

FIGURE 17. Dura-Trac Sensor with Flush Dimensions


9.7" [247mm]

11.2" [285mm]6.3" [161mm]

9.2"

[23

4mm

]

10.5

" [2

66m

m]

FIGURE 19. SMM Dimensions

9.7" [247mm]

11.2" [285mm]


SYSTEMS, INC.

CHEMTRAC

6.3" [161mm]

DURA-TRAC IITM

21.8

" [5

54m

m]

9.2"

[23

4mm

]

10.5

" [2

66m

m]

FIGURE 18. Dura-Trac II Sensor with SMM Dimensions


ADDENDUM

On specific model of the SCM2500XRD, the analog output (4-20mA) representing the Offset value is provided at terminals 11 and 12; see figure below. Terminal 11 is labeled Offset Value (AO+) and terminal 12 is labeled Offset Value (AO-). The scaling for the Offset value analog output is from -1000 to +1000 streaming current value. The two analog outputs are provided to allow the customer to monitor the SCV Signal and Offset value remotely. The explanation of the Offset mode and Offset value are described in Section 3.2.2 SCM2500XRD Setup Menu (1).


3

SM

M

| Sen

sor

4

65

78

12

11

141312

1516

1

910

*

**

*

32 4

*865 7

19

9

20

121110

1718

16151413

1817 19 20

FUSE: AGC-1.5A

GN

D

L N

ON

GL N

OFF

FUSE

Signal Wires Interconnection Diagram

SCM-XRD Manual Rev 4 - The Automation Group SCM2500XRD Main Screen ... 6991 Peachtree Industrial...

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