A.introduction tech

• is a skilled person whose responsible for bench and field calibration of different kinds of process instruments.

• Had a proven skills also in termination, troubleshooting, loop testing, pre-commissioning, commissioning, building automation and process equipment monitoring.

Instrument Technician must have skills and knowledge in:

• Bench/Field calibration of process instruments

• Bending and installation of stainless/copper tubing

• Leak testing of process tubing

• Mounting and installation of different kinds of process instruments

• Basic principles of process instruments and devices

• Basic logic symbols and schematic diagrams.

• System logic testing, complex loops and interlocking system associated with the PLC.

• Process instrumentation diagrams.

• Instrument and accessories installation procedure.



• Local and DCS panels, field junction box installation procedure

• Linear measurements in both English and Metric System

• Identification of different kinds, type and size of instrumentation materials like fittings, tubing, piping, etc.


• Material take-off and estimate

• Basic rigging technique and scaffolding installation

• Proper use and operation of tools and equipments

• Safety practices and housekeeping

• A device used directly or indirectly to measure and/ or control a variable.

• The term includes primary elements, final control elements, computing devices and electrical devices such as switches and pushbuttons.

• a collection of instruments or their applications for the purpose of observation, measurement and control. (ISA Definition)

HISTORY OF INSTRUMENTATION

• More than two centuries has already passed since Oliver Evans used feedback control to automate a Philadelphia flourmill in 1794.

ADVANTAGES OF INSTRUMENTATION AND CONTROL

♦ Production & Quality wise

♦ Material Savings

♦ Cost Savings♦ Production Inspecting and

Testing

♦ Plant Safety and Comfort

♦ Less man power/automatic

INSTRUMENTATION APPLICATIONS

♦ Building automation, HVAC control

♦ Fire protection system

♦ Construction and Design

♦ Food and Beverage♦ Glass and Ceramics♦ Mining and metals

♦ Chemical, Petroleum, Refineries

♦ Pharmaceutical and Medical

♦ Pulp and Paper, Textile

♦ Water and wastewater

♦ Power Plant

♦ Semiconductor

♦ Robotics Technology

♦ Aerospace, Automotive and Vehicle

STANDARDS REFERENCES

ISA Instruments, Systems and Automation (formerly Instrument Society of America)

ANSI American National Standards Institute

SAMA Society of Apparatus Makers Association

ASTM American Society for Testing Materials

ISO International Organization of Standards

ASME American Society of Mechanical Engineers

IEEE Institute of Electrical and Electronics Engineers

NEMA National Electrical Manufacturer’s Association

SI International System of Units

NBS National Bureau of Standards

IN INSTRUMENTATION

Mathematics

Chemistry & Chemical

Engineering

Metallurgical & Manufacturing Engineering

Electronics & Communications

Engineering

Mechanical & Electrical

Engineering

Information Technology &

Computer Engineering

Nucleonics

INSTRUMENTATION

AND

CONTROL

Physics

Instrumentation and Control effects and interaction with Science and Technology

INSTRUMENT AND CONTROL LOOP• a group of instruments together with a process in

order to measure or control a single variable.

=Four elements of Instrument Loop=

1. Process

• pressure, temperature, level, flow, signal instrument

2. Measuring Element • Sensor, transmitter, transducers, etc.

=Four elements of Instrument Loop=

3. Receiving Element• Indicators, recorders, controllers, alarms, etc.

4. Final Control Element

• Control valve, dampers, motor drive, relay, etc.

INSTRUMENT AND CONTROL LOOP

INSTRUMENTATION LOOP BLOCK DIAGRAM

Process• A physical or chemical change of matter, or conversion of energy.

Process Control• technique of balancing supply and demand over a period of time at a pre-determined level of operation called “set point” (SP).

• The controller compares the measured variable (PV)) with the set point and then makes an adjustment in the final control element based on the difference between the set point and the measured variable and this is the error signal (e).

Process Control

PV - SP = e

Measured Variable – Setpoint = Error

•Gauges

•Valves

•Transmitters

• Switches

SOME INSTRUMENTS USE IN PROCESS CONTROL

• Alarms

• Recorders

• Surveillance

• Detection

• Controllers

INSTRUMENT PROCESS VARIABLES

1. Pressure

2. Flow

3. Level

4. Temperature

5. Viscosity, Humidity, Specific Gravity, pH, conductivity, etc.

Variable – A physical quantity or property that can be measured. Also known as the measurand.

A. Pressure • Is defined as force per unit area.

• It is the force exerted by an object on a certain area.

P = F / A

where,P = PressureF = Force acting on a surface A = Unit Area of Surface

1 inch1”

100 lbs.

An object weighs 10 pounds is resting on an area of one square inch, it is exerting a pressure of 100 pounds per square inch (100 psi)


Forms of Pressure Measurement

1. Atmospheric Pressure - is the pressure caused by the weight of the atmosphere.

2. Absolute Pressure - is the total pressure exerted. It is measured with respect to a reference called absolute 0 pressure less than this (meaning a negative absolute pressure.

Absolute Pressure= Atmospheric Pressure + Gage Pressure


3. Gage Pressure – is the pressure with respect to the atmospheric pressure. It can be higher than atmospheric pressure, which makes it a positive value. Or it may be lower than the atmospheric pressure, which makes it a negative value.

4. Vacuum Pressure – the negative pressure. If we call it vacuum pressure, we no longer give the value a negative sign.

5. Differential pressure – the difference between two pressures.

Forms of Pressure Measurement


Pressure Scales


• movement of a liquid, a gas, or a vapor from one place to another.

B. Flow

• may be defined as the height or depth of a liquid or solid surface from a datum or reference point.

C. Level


The level measurement can be either continuous or point values.

• Continuous level sensors measure level within a specified range and are used to know the exact amount of liquid in a certain place.

• Point level sensors only measures a specific level, generally this is used to detect high level alarms or low level alarms.


C. Level

D. Temperature

• It is a condition of a body, which determines the transfer of heat to and from other bodies.

• It is the measure of its molecular activity. Temperature is not a measure of heat.

• It is the ability to transfer heat.


SETPOINT• An input variable that sets the desired value of the controlled variable.

MANIPULATED VARIABLE• The quantity or condition that is varied as a function of the actuating error signal in order to change the value of the directly controlled variable.

CONTROLLED VARIABLE• The variable that the control system attempts to keep at the set point value. The set point may be constant or variable.

OPEN LOOP• A system in which does not use feedback.

CLOSED LOOP• A system in which the output is fed back and compared with the input.

SIGNAL• a variable that carries information about another variable it represents

IMPULSE LINE• sensing line, tubing or pipe, that connects the process to the primary measuring element of the instrument loop and is part of the process pressure boundary and containment.

IN-LINE INSTRUMENT/DEVICE• instrument/device installed in the process piping system (e.g. control valves, orifice plates, thermowell, etc.)

PROCESS AND INSTRUMENTATION DIAGRAM ( P & ID )

• This is a drawing that represents the process with their corresponding instruments.

• A schematic illustration of functional relationship of piping, instrumentation and system equipment components. It is used to operate the process system.

LOOP● A combination of two or more instruments or control functions arranged so that signals pass form one to another for the purpose of measurement and/or control of a process variable.

SYMBOLS

● A representation of an instrument valve or other process equipment often identified by letters and numbers

INSTRUMENT LOOP DRAWING

• is a drawing that shows all the connections for the instruments and other devices in a complete loop, including field junction box terminals, marshalling panel terminal blocks,down to DCS panel.

INSTALLATION DETAIL

• installation documentation in the form of standards, specifications, procedures, drawings, and quality inspection plans.

MATERIAL TAKE-OFF

• an estimate of materials showing its description or specifications, and its quantity.

LOCAL OR FIELD-MOUNTED• The location of an instrument that is neither on a panel nor mounted in a control room. Local instruments are commonly in the vicinity of a primary element or a final control element.

PANEL / BOARD• A structure that has a group of instruments mounted on it, houses the operator-process interface, and is chosen to have a unique designation. The panel may consist of one or more sections, cubicles, consoles, or desks.

PANEL-MOUNTED• A term applied to an instrument that is mounted on a panel or console and is accessible for an operator’s normal use.

LOCAL PANEL• A panel that is not a central or main panel. Local panels are commonly in the vicinity of plant subsystems or sub-areas.

LINE MOUNTED INSTRUMENT• an instrument installed directly connected to the process piping system (e.g. temperature indicators, temperature elements rotary flow meter, control valves, orifice plates & flow switches).

LOCAL MOUNTED INSTRUMENT• an instrument installed locally on a wall, column, floor stand, etc. (e.g. transmitters,switches, indicators)

BEHIND THE PANEL• a term applied to a location that is within an area that contains (1) the instrument panel, (2) its associated rack-mounted hardware, or (3) is enclosed within the panel.

• Behind the panel devices are not accessible for the operator’s normal use.

CALIBRATION

• A comparison of two instruments or measuring devices, one of which is a standard of known accuracy traceable to international standard, to detect, correlate or eliminate by adjustment any discrepancy in accuracy of the instrument or measuring device being compared with the standard.

BENCH CALIBRATION

• Usually done in an instrument calibration van / workshop with a proper hook-up procedures and complete documentation as per manufacturers instruction manuals.

ACCURACY

• The degree of conformity of an indicated value to a recognized, accepted value, or ideal value.

• is the ratio of the error to the full-scale output.

AS-LEFT

• the final data after the calibration made.

AS-FOUND

• the initial reading/indication prior to calibration.

• the reference data for zero adjustment or a span adjustment .

POINTER ADJUSTMENT

• repositioning the pointer relative to the scale is called “re-zeroing” the gauge.

• shall be done at the minimum scale value.

SPAN ADJUSTMENT

• A potentiometer were to adjust only the span ratio expressed in percent, minimum & maximum scale of span.

HAIRSPRING ADJUSTMENT

• the hairspring's function is to take up clearance in the movement and linkage. It should be adjusted with tweezers to set them perfectly level so that when wound up approx. 360º., they will not distort.

LINEARITY ADJUSTMENT

• when the motion of the pointer slows down or speeds up at the end of the range as the pressure is increased in uniform increments, rotary movement is rotated either downward or upward.

AMBIENT TEMPERATURE

• room temperature, a certain temperature within enclosed space at which human beings are accustomed,

RELATIVE HUMIDITY (RH)

• is a ratio, expressed in percent (% RH), of the amount of atmospheric moisture present relative to the amount that would be present if the air is saturated.

SPAN• the difference between the upper range and lower range values expressed in the same units as the range.

OPERATING PRESSURE• the actual (positive or negative) pressure at which a device operates under normal conditions.

WET LEG

• a liquid filled sensing line in a differential pressure level measuring system.

PINION

• the center portion of pressure gauge where the pointer is attached.

STANCHION

• a structure wherein an instrument such as transmitter is mounted with a standad height from its base.

PIGTAIL

• A 270º or 360º loop in pipe or tubing to form a trap for vapor condensate. It is used to prevent high temperature vapors form reaching the instrument.

ROOT VALVE

• the first valve located in a sample line after it taps off the process. It is typically located in close proximity to the sample tap.

THERMOWELL

• A pressure tight receptacle connected to a temperature sensing element and provided with external threads or other means for pressure tight attachment to a vessel.

MILLIAMP (mA)• one thousandth of an ampere.

MILLIVOLT (mV)• one thousandth of a volt.

VENT valve• use for venting excess pressure or gas trap in the process line.

DRAIN valve• use for draining excess liquid or steam accumulating in the process line or seal pots.

SEAL POT

• enlarge pipe sections in measurement impulse line to provide:

a. A high area to volume displacement ratio to minimize error from hydrostatic head difference when using large volume displacement measuring elements

b. To prevent loss of seal fluid by displacement into the process.

LOCK OUT & TAG OUT (LOTO)

LOCK OUT

• to place a suitable padlock on an energy-isolating device of a machine or on equipment to prevent un-authorised or accidental operation of the machine or equipment where work is in-progress.

• Energy isolating devices includes circuit breakers, switches, valves, blocks, etc.

TAG OUT

• an information or identification tag which is securely fastened to an energy-isolating device under lock-out, to indicate the identity of the person and nature of work conducted on the said equipment or device.

LOCK OUT & TAG OUT (LOTO)

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A.introduction tech