Instrumentation and Control Valves 1
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Transcript of Instrumentation and Control Valves 1
PROCESS Variables Course
InstrumentationInstrumentation
MeasurementMeasurement Automatic ControlAutomatic Control Final Control ElementFinal Control Element
Flow Rate
Pressure
Level
Temperature
On - Off
Proportional
Integral
Derivative
Valve
Actuator
Trim
Positioner
Measurement
Reading:Number & Engineering Unit:1. Pressure: 350 PSIG2. Flow rate: 300 GPM for volume
150 Tons/Hr for mass
3. Level: 45%4. Temperature: 700° F 50° C
Control (Corrective action)
Control loop:1. Measured process variable2. Controller3. Set point4. Controlled Signal5. Final control element
(Control Valve)
Measurement
Numbers:Decimal number:•Multiple numbers: Deca X 10 Hecta X 100 Mil X 1000 Mil Mil X 1000 000
MeasurementReading References:1- Zero: Process variables:• Pressure range: 0 – 100 PSIG Zero = 0• Temperature: 100 – 500 ° F Zero = 100 ° F• Analogue Pneumatic signal: 3-15 PSIG Zero = 3 PSIG
Measurement
Reading References:1- Zero: Process variables:• Analoge electronic signal: 4 – 20 MA milli Ampere Zero = 4 MA
Measurement
Reading References:2- Max: Process variables:• Pressure range: 0 – 100 PSIG Max = 100 PSIG• Analogue pneumatic signal: 3 – 15 PSIG Max = 15 PSIG
Measurement
Reading References:2- Max: Process variables:• Analoge electronic signal: 4 – 20 MA milli Ampere Max = 20 MA
Measurement
Reading References:3- Range: Process variables:• Pressure range: 0 – 100 PSIG Measuring range from 0 to 100 PSIG• Analoge electronic signal: 4 – 20 MA milli Ampere Measuring range from 4 to 20 MA
Measurement
Reading References:4- Span: Process variables:• Pressure range: 500 – 1000 PSIG Zero = 500 PSIG Max = 1000 PSIG Range from 500 to 1000 PSIG• Span: = Max – Zero =1000 – 500= 500 PSIG
Measurement
Analogue reading:It is all values from 0 to 1 scaled by
span and biased by zero.It is all values (0 to 1) x span + zeroPressure range 500 – 1000 PSIG750 PSIG = (0.5) x 500 +500 50% value500 PSIG = (0) x 500 + 500 Zero value1000 PSIG = 1 x 500 +500 Max value
Analogue range (0 to 1)
Measurement
Analogue ValuesAnalogue signal 3-15 PSIG
50% valuePneumatic signal = 9 PSIG =
(9-3/15-3)(15-3) + 3 = (6/12)(12) + 3
Electronic signal = 12 MA = 50% = (12-4)(20-4) +4 = (8/16) (16) + 4
MeasurementEngineering Units:1. Gauge values2. Absolute valuesConditions:1. Standard conditions
(Reference)2. Operating conditions (Running)
Normal - abnormal3. Design conditions
MeasurementMeasurement requires:1- Primary element – Detector – Sensor – Transducer2- Reading: Multiplying factor – Reading factor – Engineering Unit (scale) Using: Display – Indicator - Recorder3- Transmitted signal (Transmitter)4- Receiver: Reading Using: Display – Indicator – Recorder
Measurement
Primary elements: 1- For Pressure measurements: 1.1 Diaphragm 1.2 Capsule 1.3 Bellows 1.4 Bourdon Tube 1.5 Spiral Tube 1.6 Helix Tube 1.7 Manometer
MeasurementPrimary elements: 2- For Flow rate measurements: 2.1 Differential Pressure elements 2.1.1 Concentric orifice plate 2.1.2 Segmental orifice plate 2.1.3 Venturi tube 2.1.4 Flow nozzle 2.1.5 Pitot tube and annubar 2.1.6 Target meter (No taps)
Measurement
Differential pressure taps:1- Flange taps2- Corner taps3- Vena contracta taps4- Full flow taps(pipe taps)5- Radius taps6- Elbow taps
MeasurementNon Differential pressure Elements:Linear Elements:1- Variable area rotameter2- Turbine meter3- Positive displacement meter4- Magnetic flow meter5- Thermal flow meter6- Ultrasonic flow meter7- Vortex flow meter
Measurement
Primary elements: 3- For Level measurements: A- Direct Measurement 1- Tape level device 2- Sight glass - Level gauge 3- Displacer 4- Ball shape floater 5- Disk floater
Measurement
Primary elements: 3- For Level measurements: B- Indirect Measurement 1- Head pressure 2- Radioactive system 3- Ultrasonic system 4- Capacitance probe
Measurement
Primary elements: 3- For Level measurements: B- Indirect Measurement 5- Bubblers 6- Conductivity probe 7- Diaphragm level detector 8- Thermal level sensor
MeasurementPrimary elements: 4- For Temperature measurements:1- Bimetallic strip2- Mercury-in-glass - Glass stem thermometer3- Pressure spring - Filled thermal element4- Thermocouples type J - K - S - R – T5- Resistance Thermal Detector RTD