INSTRUMENTATION

Process Variables Training Course

INSTRUMENTATION

MEANS

MEASUREMENT AND CONTROL

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

CONTROL LOOP

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)

Process Variables

1.Pressure Differential Pressure

2.Flow Rate3.Level4.Temperature

Measurement

Numbers:Decimal number:•Multiple numbers: Deca X 10 Hecta X 100 Mil X 1000 Mil Mil X 1000 000

Measurement

Numbers:Decimal number:•Sub-Multiple numbers: Centi / 100 Milli / 1000 Micro / 1000 000

Measurement

Reading References:1.Zero2.Maximum (Max)3.Range4.Span

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

Primary Element Examples

Primary Element Examples