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01/97 DGM SECTION 15182 1 OF 4

HVAC - WATER TREATMENT OF CONDENSER

AND CHILLED WATER SYSTEMS

DADE COUNTY AVIATION DEPARTMENT DESIGN GUIDELINES MANUAL

DIVISION 15 - MECHANICAL DATE: 01/97

SECTION 15182- HVAC-WATER TREATMENT OF CONDENSER AND CHILLED WATER SYSTEMS

1. CONDENSER WATER SYSTEMS

a. Specify equipment, pipe connections, piping, chemicals and Contractor service to treatcondenser water to minimize corrosion, scale, and biological growth in all parts of the systemfor one year.

b. Corrosion control shall be maintained and documented by tests every 30 days while theCondenser Water System is in operation. These Corrosion monitoring tests shall utilize apreweighted mild steel test coupon immersed in the recirculating Condenser Water. TheCoupon shall be installed in a one (1) inch PVC test coupon manifold having a 5-10 gpm flowrate. Each test period shall be for a 30 day duration. Twelve (12) test studies shall thus bedone each year, each for a 30 day period. The Contractor shall perform the required TestCoupon studies and report the corrosion rates found. It is required that corrosion shall bemaintained at below 2.0 mpy (mils per year) on each 30 day test. Corrosion shall not be in theform of pitting attack.

Since biological growths impact upon the corrosion rates of mild steel test coupons, especiallyin the form of pitting attack, the test coupon monitoring program will also serve to co rroboratecontrol of biological growths are within acceptable limits. Additional field test measurementsby means of Easicult test kit should be performed periodically as an aid to maintaincontinuously acceptable biological counts. Contractor shall document that the biologicalcount the recirculating condenser water is maintained below 200,000 colonial per millimeter.Tests shall be made every 45 days by Field Easicult test procedure.

c. The following equipment shall be furnished and installed by the Contractor under this section:

(1) The control system shall be housed in a corrosion resistant NEMA 12X fiberglassenclosure with a viewing window in the door and a padlocking hasp.

(2) The unit shall provide an analog display of the cooling water conductivity and shallhave a front panel selectable 0-2000 and 0-5000 umho/cm dual scale.

(3) A flow switch shall be mounted on the enclosure along with the sensor housing. Thesensor shall be pre-wired and shall include automatic temperature compensation andshall be readily removable for cleaning by a quick disconnect that requires no tools.The flow switch shall provide a visual indication of loss of water flow to the sensor andshall prevent chemical feeding upon loss of water flow to sensor.

(4) A water meter of appropriate size shall be specified for installation in the cooling towermakeup line. The water meter shall be field programmable to provide a pulse to theinhibitor pump that is proportional to the makeup water flow rate. The water metershall also totalize the flow. The controller shall have a selector switch on the frontpanel that permits control of the inhibitor pump by either pulsing from the water meter,ON-OFF control from the conductivity controller or control by a repeat cycle 30 minutepercentage timer.

(5) The controller shall have front panel calibration adjustment and shall have adjustablehigh and low conductivity alarms in addition to the front panel set point adjustment.

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01/97 DGM SECTION 15182 2 OF 4

HVAC - WATER TREATMENT OF CONDENSER

AND CHILLED WATER SYSTEMS

(6) A 7-Day biocide timer shall be housed in the controller and shall be programmableto turn the biocide pump ON and OFF at an adjustable feed frequency and duration.Inhibitor feed and bleed-off is automatically stopped during the biocide feeding andfor all adjustable length of time after biocide feeding.

(7) An electrically operated solenoid valve of appropriate size shall be supplied forinstallation in the bleed-off line and shall be wired to the controller by the installingContractor.

(8) A pre-wired, pre-plumbed panel shall be specified onto which the controllers shall bemounted along with the inhibitor and biocide pump monitors. The biocide pumpdischarge line shall be a line strainer and sampling valve pre-plumbed into themonitoring line.

(9) The Piping Contractor shall provide 3/4" connection in the recirculating line for thecontroller monitoring line and for the inhibitor pump chemical feed line. A bleed-offline shall also be installed at the location and size specified by the water treatmentservice company.

d. Inhibitor Feed Pump: One (1) positive displacement chemical feed pump shall be specifiedfor the inhibitor feed. Both stroke length and stroke frequency shall be adjustable. The pump

shall be capable of selectively being externally pulsed by the water meter. The pump shallhave the appropriate output capacity, pressure rating and materials of construction for theapplication. The pump shall feed directly from the storage tank of inhibitor and discharge intothe cooling water recirculation line ahead of the condenser with a corporation stop andinjection assembly at the injection point. Specify polyprel pump seal rings.

e. Inhibitor Storage Tank(s): 50 gallon polyethylene storage tank with cover and with a low levelalarm shall be specified. The number of tanks shall be as required for the particularapplication.

f. Biocide Feed Pumps: One (1) positive displacement biocide feed pump of appropriate sizeshall be specified to slug feed the required dosage to the cooling water system within one (1)hour or less. The pump shall have both stroke length and stroke frequency adjustment.

Pump shall be specified with polyprel seal rings.

g. Biocide Storage Tank: Polyethylene biocide tank shall be specified. The tank shall bespecified with a low level alarm and a cover for mounting the alarm on the tank. The numberof tanks shall be as required for the particular application.

2. CONDENSER WATER SYSTEM - WATER TREATMENT CHEMICALS

a. The cooling water inhibitor and scale prevention agent shall be a phosphorate-basedtreatment. Copper corrosion inhibitor components and deposit controlling polymers shall beincluded in the formulation. The chemical treatment shall be supplied in liquid form.

b. Algae and slime controlling agent shall be specified for the control of algae and slime

accumulations in the cooling tower system. The microbicide shall be supplied in liquid form.

c. All empty shipping containers shall be immediately removed from the job site by the WaterTreatment Contractor at his own expense.

d. The use of chemicals containing chromates is not permitted.

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01/97 DGM SECTION 15182 3 OF 4

HVAC - WATER TREATMENT OF CONDENSER

AND CHILLED WATER SYSTEMS

3. CLOSED CHILLED WATER SYSTEM - CHEMICAL FEEDING AND CONTROL EQUIPMENT

a. Control Systems: One (1) control system shall be specified for the chilled water closedsystem. The controller shall continuously monitor the conductivity of the closed system waterand shall automatically add additional protective treatment as needed to maintain the desiredtreatment level. The system shall include the following features:

(1) The system shall be housed in NEMA 1 enclosure with viewing window in the door.

(2) The monitor/controller shall provide an analog display of the conductivity level andshall have a 0-5000 umho/cm scale.

(3) A 3/4" monitoring line shall be installed around the recirculating pump by the pipingcontractor.

(4) The controller for the chilled water system shall include an alarm to indicate excessivewater loss.

b. Inhibitor Feed Pumps: A positive displacement chemical feed pump shall be specified foreach closed system. Both the stroke length and stroke frequency shall be adjustable. Thepumps shall be of appropriate output capacity, pressure rating and materials of construction

for adding to the chemical treatment.

4. WATER TREATMENT SERVICES REQUIRED

a. Contractor shall begin water treatment program when system first begins to operate on aregular basis.

b. Make weekly chemical analysis of water at the beginning until water stabilizes. Bi-monthlyanalysis required thereafter. Submit a copy of each chemical analysis and a report of everyservice call and chemical adjustment made to the Chief of Maintenance, Dade County AviationDepartment. Results shall be in the mail within five business days from date of sampling.

c. Adjust chemicals as required to control scale, corrosion and biological growth. Removing

scale by quick clean acid will not be allowed.

d. Provide additional corrosion test coupons plus costs of analysis should original couponindicate corrosion.

e. Other services to be included in basic construction contract for first year:

(1) Provide space to store chemicals (DCAD to provide).

(2) Remove heads of condensers for inspection and flush-out or brush-outsedimentation.

(3) Hire independent testing laboratory to analyze the corrosion test coupons on a

quarterly basis.

(4) Clean cooling tower, minimum of 2 times per year.

f. The field service representative shall be supervised by a graduate chemist or chemical

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