Calibrating instrumentation and control devices

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Course: Instrumentation and Control NCII
Unit of Competency: Calibrate I&C Devices
Calibrating Instrumentation and Control Devices
Module: At the end of the session, learners should be able to:
Learning outcomes:

Duration: 1. Interpret work instructions for calibration.
Situating Learning: 2. Identify tools, equipment, testing devices and materials needed for

calibration.
3. Identify PPE and OHS policies and procedures required for the

calibration job.
4. Calibrate instrumentation and control device.
5. Inspect and test calibrated instrumentation and control device.

40 hours

You are employed as an Instrumentation Technician in ICC (Industrial Controls
Corporation). ICC being a sub-contractor in SMC Polo Brewery, you are
assigned as one of the Maintenance Technician in the Instrumentation Division.
Your task is to perform calibration on instruments according to the instrument’s
periodic schedule and based on customer’s request. SMC Polo is the main
manufacturer of food and beverage in the Philippines, it is very critical for them to
make sure that all instruments will be calibrated according to the schedule in
order to maintain the quality and the safety of their products. The following are
the cases present in your job.

1. Different types of instruments can be encountered inside the plant.
2. The instruments are in different locations; some locations are difficult to

reach, others that are used for areas with hazardous chemicals, and
there are also in areas with dangerous working conditions (high pressure
and temperature).
3. Complete tools and materials are provided by the employer (ICC) and
are stored in the instrumentation shop.
4. Different calibrators are also provided for different types of instruments.
5. Instrument catalogues and manuals are provided by the client (SMC
Polo Brewery).

In performing the calibration the following must be considered:

1. The device is in good working condition and not defective.
2. Different types of instruments also differ in their working parameters.
3. Calibration procedure must comply in accordance with the established

standards.
4. The output of the calibrated instrument must conform to the

requirements of the client.
5. Each calibration done on each instruments must have a calibration

report in which to be submitted to the rightful authorities.
Upon completion of each month, your performance will be assessed by your
supervisor, and good performance will be given good credits, on the other hand
bad performance means you’re out of the job.

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Notes Format of Learner’s Guide

Assessment Interpret calibration job requirements, identify all necessary materials and
Criteria: equipment needed to perform the job, follow OHS policies and standards
and identify necessary PPEs, and perform calibration job according to
industry standards.

Learning Chunk Performance Criteria Learning Activities Learning Documents

1. Common 1.1 Define the Process Read Information Sheet
Technical Control Theory 1.1.1 Defining Process
Knowledge Control Theory
1.2 Define and
Describe the Answer Work Sheet
Function of each 1.1.2 Defining Process
Control Loop Control Theory
Components
Read Information Sheet
1.2.1 Defining Control
Loop Components

Answer Worksheet
1.2.2 Defining Control
Loop Components

2. Plan and Prepare  Calibration is planned 2.1 Define Calibration Read Information Sheet
Calibration and prepared in line Principle 2.1.1 Defining
with job requirements. Calibration Principle
2.2 Identify Different
 Instrumentation and Calibration Answer Work Sheet
control devices to Equipment 2.1.2 Defining
calibrate is identified Calibration Principle
from the Job/Service
Order or instructions Read Information Sheet
2.2.1 Identifying
 OHS policies and Different Calibration
procedures are Equipment
followed in line with
job requirements. Answer Work Sheet
2.2.2 Identifying
 Appropriate personal Different Calibration
protective equipment Equipment
is prepared

 Tools, equipment and
testing devices

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© 2010, Institute of Technical Education, Singapore

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Notes Format of Learner’s Guide

Learning Chunk Performance Criteria Learning Activities Learning Documents

3. Calibrate I&C needed for calibration 3.1 Prepare Calibration Read Information Sheet
Device are obtained and Set-Up 3.1.1 – Preparing
checked for correct Calibration Set-up
4. Test and Inspect operation and safety 3.2 Perform Calibration
Calibrated I&C  Instrumentation and Follow procedures in
Device Operation Sheet 3.2.1 –
control devices for Performing Calibration
calibration are
checked against
specifications and
requirements.

 Fault/s or problem/s
in the device is
diagnosed in line
with the standard
operating
procedures.

 Instrumentation and
control devices are
calibrated in line
with the standard
operating
procedures.

 Final inspections 4.1 Prepare Calibration Follow procedures in

are undertaken to Report Information Sheet 4.1.1
– Preparing Calibration
ensure that the
Report
calibration done on

the device conforms

with the
manufacturer’s

instruction/manual

 Report is prepared /
completed
according to
company
requirements.

5. Perform Whole 5.1 Perform Calibration Perform Job Sheet 5.1.1
Task of I&C Device Job – Perform Calibration
Calibration
Job

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© 2010, Institute of Technical Education, Singapore

Information Sheet 1.1.1 : Defining Process Control Theory

Learning outcomes:
1. Learn the Common Technical Knowledge

Learning Activity:
1.1 Define the Process Control Theory

THE IMPORTANCE OF PROCESS CONTROL

 Refining, combining, handling, and otherwise manipulating fluids to profitably produce
end products can be a precise, demanding, and potentially hazardous process. Small
changes in a process can have a large impact on the end result.

 Variations in proportions, temperature, flow, turbulence, and many other factors must be
carefully and consistently controlled to produce the desired end product with a minimum
of raw materials and energy.

 Process control technology is the tool that enables manufacturers to keep their
operations running within specified limits and to set more precise limits to maximize
profitability, ensure quality and safety.

Process Control
Process control refers to the methods that are used to control process variables when
manufacturing a product. For example, factors such as the proportion of one ingredient to
another, the temperature of the materials, how well the ingredients are mixed, and the
pressure under which the materials are held can significantly impact the quality of an end
product. Manufacturers control the production process for three reasons:

 Reduce Variability
Process control can reduce variability in the end product, which ensures a
consistently high-quality product. Manufacturers can also save money by reducing
variability.

 Increase Efficiency
Some processes need to be maintained at a specific point to maximize efficiency.
For example, a control point might be the temperature at which a chemical reaction
takes place. Accurate control of temperature ensures process efficiency.
Manufacturers save money by minimizing the resources required to produce the end
product.

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Information Sheet 1.1.1 : Defining Process Control Theory

 Ensure Safety
A run-away process, such as an out-of-control nuclear or chemical reaction, may
result if manufacturers do not maintain precise control of all of the processing
variables. The consequences of a run-away process can be catastrophic.

*Block Diagram of Process Control

Note: * Diagram components will be explained in the latter part of this module.

CONTROL LOOP
Imagine you are sitting in a cabin in front of a small fire on a cold winter evening. You feel
uncomfortably cold, so you throw another log on the fire. This is an example of a control loop.
In the control loop, a variable (temperature) fell below the setpoint (your comfort level), and
you took action to bring the process back into the desired condition by adding fuel to the fire.
The control loop will now remain static until the temperature again rises above or falls below
your comfort level.

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Information Sheet 1.1.1 : Defining Process Control Theory

Three Tasks
Control loops in the process control industry work in the same way, requiring three tasks to
occur:

 Measurement
 Comparison
 Adjustment

PROCESS CONTROL TERMS

As in any field, process control has its own set of common terms that you should be familiar
with and that you will use when talking about control technology.

Process Variable
A process variable is a condition of the process fluid (a liquid or gas) that can change the
manufacturing process in some way. In the example of you sitting by the fire, the process
variable was temperature. In the example of the tank in Figure 7.1, the process variable is
level. Common process variables include:

 Pressure
 Flow
 Level
 Temperature
 Density
 Ph (acidity or alkalinity)
 Mass
 Conductivity

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Information Sheet 1.1.1 : Defining Process Control Theory

Setpoint
The setpoint is a value for a process variable that is desired to be maintained. For example, if
a process temperature needs to kept within 5 °C of 100 °C, then the setpoint is 100 °C. A
temperature sensor can be used to help maintain the temperature at setpoint. The sensor is
inserted into the process, and a controller compares the temperature reading from the sensor
to the setpoint. If the temperature reading is 110 °C, then the controller determines that the
process is above setpoint and signals the fuel valve of the burner to close slightly until the
process cools to 100 °C. Set points can also be maximum or minimum values. For example,
level in tank cannot exceed 20 feet.

Measured Variables, Process Variables, And
Manipulated Variables
In the temperature control loop example, the measured variable is temperature, which must be
held close to 100 °C. In this example and in most instances, the measured variable is also the
process variable. The measured variable is the condition of the process fluid that must be kept
at the designated setpoint. Sometimes the measured variable is not the same as the process
variable. For example, a manufacturer may measure flow into and out of a storage tank to
determine tank level. In this scenario, flow is the measured variable, and the process fluid level
is the process variable. The factor that is changed to keep the measured variable at setpoint is
called the manipulated variable.

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Information Sheet 1.1.1 : Defining Process Control Theory

Error
Error is the difference between the measured variable and the setpoint and can be either
positive or negative. In the temperature control loop example, the error is the difference
between the 110 °C measured variable and the 100 °C setpoint—that is, the error is +10°C.
The objective of any control scheme is to minimize or eliminate error. Therefore, it is
imperative that error be well understood. Any error can be seen as having three major
components.

Figure 2: Components of Error

1. Magnitude of the error is simply the deviation between the values of the setpoint and
the process variable. The magnitude of error at any point in time compared to the
previous error provides the basis for determining the change in error. The change in
error is also an important value.

2. Duration refers to the length of time that an error condition has existed.

3. Rate of Change is the rate of change is shown by the slope of the error plot.

4. Offset is a sustained deviation of the process variable from the setpoint. In the
temperature control loop example, if the control system held the process fluid at 100.5
°C consistently, even though the setpoint is 100 °C, then an offset of 0.5 °C exists.

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Information Sheet 1.1.1 : Defining Process Control Theory

Load Disturbance
A load disturbance is an undesired change in one of the factors that can affect the process
variable. In the temperature control loop example, adding cold process fluid to the vessel
would be a load disturbance because it would lower the temperature of the process fluid.

Manual and Automatic Control
Before process automation, people, rather than machines, performed many of the process
control tasks. For example, a human operator might have watched a level gauge and closed a
valve when the level reached the setpoint. Control operations that involve human action to
make an adjustment are called manual control systems. Conversely, control operations in
which no human intervention is required, such as an automatic valve actuator that responds to
a level controller, are called automatic control systems.

OPEN AND CLOSED LOOP SYSTEMS

Open Loop System: A control system that can’t determine the magnitude of its output, whether it
achieves the desired goal of the input.

Example: A water sprinkler system can be turned on at its setting period regardless of the soil moisture.

Figure 3: Open loop control system.

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Information Sheet 1.1.1 : Defining Process Control Theory

Closed Loop System: A control system that can monitor it’s output and provides a feedback
to correct the deviation of the output to its desired goal.

Example: The flatiron control, once temperature setting is made, the heater will raise the
temperature, when the desired temperature is reached the thermostat will then turn off the
heater, and turns it on again whenever the temperature falls below the setting.

Figure 4: Closed loop control system.

Here is a short comparison of the two fundamental types of control systems:

OPEN LOOP SYSTEMS CLOSED LOOP SYSTEMS

Simple Design More Accurate
Accuracy Depends On Calibration Less Sensitive To Change In Environment
Unlikely To Become Unstable Smooth Response
Wider Bandwidth
Can Become Unstable

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Information Sheet 1.1.2 : Defining Process Control Theory

Learning outcomes:
1. Learn the Common Technical Knowledge

Learning Activity:
1.1 Define the Process Control Theory

Instructions: Read the problems carefully and write your answers in the blank spaces
provided.

1. It is a condition of the process fluid (a liquid or gas) that can be measured and varied to
affect the process.
_________________________________

2. It refers to the methods that are used to control process variables when manufacturing a
product.
_________________________________

3. What are the main reasons for manufacturers to control a process?
_________________________________
_________________________________
_________________________________

4. What are the three tasks that is required to occur on every control loop?
_________________________________
_________________________________
_________________________________

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Information Sheet 1.1.2 : Defining Process Control Theory

5. It is the sustained deviation of the process variable from the setpoint.
_____________________________

6. It is an undesired change in one of the factors that can affect the process variable.
_____________________________

7. It is the value of the process variable that is desired to be maintained.
_____________________________

8. What are the four components of error?
_____________________________
_____________________________
_____________________________
_____________________________

9. It is a type of control that is dependent on human operations.
_____________________________

10. A type of control system that can’t determine the magnitude of its output whether it
achieves the desired goal of the input.
_____________________________

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Information Sheet 1.1.2 : Defining Process Control Theory

Instructions: Match the following terms in SET A to the correct description in SET B.
Write the letter of the correct description that match the terms in the blank space
provided.

SET A1 ______ SET B1
(1) Load disturbance ______ (A) The factor that is changed to keep a
(2) Control algorithm ______ measured variable at set point.
(3) Manual control ______ (B) An undesired change in a factor that
(4) Manipulated variable ______ can affect the process variable.
(5) Set point (C) A value or range of values for a process
variable that must be maintained to keep
the process running properly.
(D) A control operation that directly involves
human action.
(E) A mathematical expression of a control
function

SET A2 SET B2
(1) Closed-loop, automatic control ______
(2) Closed-loop, manual control ______ (A) An operator turns off the heater coil
(3) Open-loop, automatic control ______ when the temperature transmitter outputs a
certain reading.

(B) A controller turns off the heater coil at
set intervals, regardless of the process
temperature.

(C) A temperature sensor measures
process temperature sends the result to a
controller to compare to the setpoint, and
the controller turns off the heater coil.

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Information Sheet 1.2.1 : Defining Control Loop Components

Learning Outcome:
1. Learn Common Technical Knowledge

Learning Activity:
1.2 Define and Describe the Function of each Control Loop Components

CONTROL LOOP COMPONENTS
The previous topic described the basic elements of control as measurement, comparison, and
adjustment. In practice, there are instruments and strategies to accomplish each of these
essential tasks. In some cases, a single process control instrument, such as a modern
pressure transmitter, may perform more than one of the basic control functions. Other
technologies have been developed so that communication can occur among the components
that measure, compare, and adjust.

Primary Elements/Sensors
In all cases, some kind of instrument is measuring changes in the process and reporting a
process variable measurement. Some of the greatest ingenuity in the process control field is
apparent in sensing devices. Because sensing devices are the first element in the control loop
to measure the process variable, they are also called primary elements. Examples of primary
elements include:

• Pressure sensing diaphragms, strain gauges, capacitance cells
• Resistance temperature detectors (RTDs)
• Thermocouples
• Orifice plates
• Pitot tubes
• Venturi tubes
• Magnetic flow tubes
• Coriolis flow tubes

Image 1.2.1: Temperature and Photoelectric Sensors

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Information Sheet 1.2.1 : Defining Control Loop Components

Transducers and Converters
A transducer is a device that translates a mechanical signal into an electrical signal. For
example, inside a capacitance pressure device, a transducer converts changes in pressure
into a proportional change in capacitance.
A converter is a device that converts one type of signal into another type of signal. For
example, a converter may convert current into voltage or an analog signal into a digital signal.
In process control, a converter used to convert a 4–20 mA current signal into a 3–15 psig
pneumatic signal (commonly used by valve actuators) is called a current-to-pressure
converter.

• i/p converter – current to pressure
• p/i converter – pressure to current
• i/e converter – current to voltage
• e/i converter – voltage to current

Image 1.2.2: I/P Transducer

Transmitters
A transmitter is a device that converts a reading from a sensor or transducer into a standard
signal and transmits that signal to a monitor or controller. Transmitter types include:

• Pressure transmitters
• Flow transmitters
• Temperature transmitters
• Level transmitters
• Analytic transmitters

Image 1.2.3: Pressure Transmitters

Signals
There are three kinds of signals that exist for the process industry to transmit the process
variable measurement from the instrument to a centralized control system.

• Pneumatic Signals
Pneumatic signals are signals produced by changing the air pressure in a signal pipe in
proportion to the measured change in a process variable. The common industry

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Information Sheet 1.2.1 : Defining Control Loop Components

standard pneumatic signal range is 3–15 psig. The 3 corresponds to the lower range
value (LRV) and the 15 corresponds to the upper range value (URV). Pneumatic
signalling is still common. However, since the advent of electronic instruments in the
1960s, the lower costs involved in running electrical signal wire through a plant as
opposed to running pressurized air tubes has made pneumatic signal technology less
attractive.

• Analog Signals
The most common standard electrical signal is the 4–20 mA current signal. With this
signal, a transmitter sends a small current through a set of wires. The current signal is a
kind of gauge in which4 mA represents the lowest possible measurement, or zero, and
20 mA represents the highest possible measurement. For example, imagine a process
that must be maintained at 100 °C. An RTD temperature sensor and transmitter are
installed in the process vessel, and the transmitter is set to produce a 4 mA signal when
the process temperature is at 95 °C and a 20 mA signal when the process temperature
is at 105 °C. The transmitter will transmit a 12 mA signal when the temperature is at the
100 °C setpoint. As the sensor’s resistance property changes in response to changes in
temperature, the transmitter outputs a 4–20 mA signal that is proportionate to the
temperature changes. This signal can be converted to a temperature reading or an input
to a control device, such as a burner fuel valve. Other common standard electrical
signals include the 1–5 V (volts) signal and the pulse output.

Image 1.2.4: Analog Signals

• Digital Signals
Digital signals are the most recent addition to process control signal technology. Digital
signals are discrete levels or values that are combined in specific ways to represent
process variables and also carry other information, such as diagnostic information. The
methodology used to combine the digital signals is referred to as protocol.
Manufacturers may use either an open or a proprietary digital protocol. Open protocols

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Information Sheet 1.2.1 : Defining Control Loop Components

are those that anyone who is developing a control device can use. Proprietary protocols
are owned by specific companies and may be used only with their permission. Open
digital protocols include the HART® (highway addressable remote transducer) protocol,
FOUNDATION™ Fieldbus, Profibus, DeviceNet, and the Modbus® protocol.

Image 1.2.5: Digital Signals

Indicators
While most instruments are connected to a control system, operators sometimes need to
check a measurement on the factory floor at the measurement point. An indicator makes this
reading possible. An indicator is a human-readable device that displays information about the
process. Indicators may be as simple as a pressure or temperature gauge or more complex,
such as a digital read-out device. Some indicators simply display the measured variable, while
others have control buttons that enable operators to change settings in the field.

• Pressure Gauge
• Temperature Gauge
• Sight Glass

Image 1.2.6: Indicators
Recorders
A recorder is a device that records the output of a measurement device. Many process
manufacturers are required by law to provide a process history to regulatory agencies, and
manufacturers use recorders to help meet these regulatory requirements. In addition,
manufacturers often use recorders to gather data for trend analyses.

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Information Sheet 1.2.1 : Defining Control Loop Components

Controllers
A device that receives a process variable signal from a primary sensing element or transmitter,
compares that signal to the desired value for that process variable called the setpoint, and
calculates an appropriate output signal value to be sent to a final control element such as an
electric motor or control valve.

Image 1.2.8: Process Controller
Actuators / Final Control Element
It is the final control device that causes a physical change to affect manipulated variable when
signalled to do so. The most common example of an actuator is a valve actuator, which opens
or closes a valve in response to control signals from a controller. Actuators are often powered
pneumatically, hydraulically, or electrically. Diaphragms, bellows, springs, gears, hydraulic pilot
valves, pistons, or electric motors are often parts of an actuator system.

Image 1.2.9: Motor

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Worksheet 1.2.2 : Defining Control Loop Components
Learning outcomes:
1 Identify Common Technical Knowledge
Learning Activity:
1.2 Define and Describe the Function of each Control Loop Components

Instructions: Read the questions carefully and write your answer in the blank spaces
provided.

1. Identify five examples of primary element/sensors in process control.
________________________
________________________
________________________
________________________
________________________

2. It is the device that makes a direct contact with the process fluid.
________________________

3. It is the device that translates mechanical signal into an electrical signal.
________________________

4. It is the device that converts a reading from a transducer into a standard signal and
transmits that signal to a monitor or controller.
________________________

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Worksheet 1.2.2 : Defining Control Loop Components
5. Identify atleast three common signal types that are used in the process control industry?
________________________
________________________
________________________

6. A human-readable device that displays information about the process or the instrument
it is connected.
________________________

7. Identify three digital signal protocols used in the industry.
________________________
________________________
________________________

8. It is the device that records the output of a measurement or a control device.
________________________

9. What device has the ability to receive input, to perform a mathematical function with the
input, and produce an output signal?
________________________

10. Identify three examples of common final control element in process control industries?
_________________________
_________________________
_________________________

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Information Sheet 2.1.1 : Defining the Calibration Principle

Learning Outcome:
2. Plan and Prepare Calibration

Learning Activity:
2.1 Define Calibration Principle

IMPORTANCE OF CALIBRATION
Today, calibration is basically used for the process of manufacturing so less and less possible
mistakes and errors can be made. This process or measuring apparatus is also used to lower
the cost of manufacture or possible production by determining or ensuring the quality.

Calibration is also ideal in minimizing possible errors because it uses scientific method to
determine impending miscalculations while doing something to correct the errors if there were
any. Calibration becomes more and more popular to companies because the method aims to
economize time, labor, and other resources in any production by means of accurate
verification.

If calibration is done incorrectly or no calibration conducted to a particular instrument, more
likely it will produce incorrect and inconsistent output; the output can be either a signal or
simply a display. Due to this inconsistency, medical and food products could be fatal rather
than vital to humans. Precision of machines in factories could also be lost resulting to waste of
products and materials.

WHAT IS CALIBRATION?
Calibration is a comparison of measuring equipment against a standard instrument of higher
accuracy to detect, correlate, adjust, rectify and document the accuracy of the instrument
being compared.

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Information Sheet 2.1.1 : Defining the Calibration Principle

CHARACTERISTICS OF CALIBRATION
 Accurate – For a calibration to be accurate, it is necessary to make sure that all
standard instruments to be used are within known accuracy.
 Within Specified Tolerance – Before instrument is considered calibrated, calibration
results should conform to the specified tolerance limits provided by the instrument
manufacturer.
 Traceable – Every calibration should always be traceable to nationally or internationally
recognized standard.
 Consider all Uncertainties – Uncertainty analysis must be performed to evaluate and
identify factors associated with the calibration equipment and process instrument that
affect the calibration accuracy.

COMMON CALIBRATION TERMS
• Test Instrument – The device being compared with the calibration standard.
• Standard Test Equipment – A standard measuring device use to verify the correctness
of a test instrument.
• Drift – The change in accuracy of a measuring instrument due to chronological aging.
• Range – The extent of coverage of the instrument’s capabilities.
• Span – The extent of coverage of the instrument for which it is calibrated.
• Zero – the absence of the phenomenon being measured, a point in calibration.
• Tolerance – the permissible limit in variation in measurement of a measuring
instrument in order for it to be accurate.
• URV – The upper limit of the instrument’s span.
• LRV – The lower limit of the instrument’s span.

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Information Sheet 2.1.1 : Defining the Calibration Principle

BENCH CALIBRATION VS. FIELD CALIBRATION
There are instances that the location to perform the calibration is an important factor to
consider.

Bench Calibration - You'd perform a bench calibration in the shop on the bench with power
supplied from an external source, if required. You may perform bench calibrations on receiving
new instruments before installation. This assures you receive the instrument undamaged. It
also allows you to configure it in a more favorable environment. Some companies perform the
periodic calibration on the bench. In this case, remove the process instrument from service,
disconnect it, and take it to the shop for calibration. In some instances, install a spare in its
place to minimize the process downtime. You might send critical flow sensors out to a certified
flow calibration facility. To prevent shutting the process down for several weeks, install a
replacement flow sensor.

Field Calibration - You'd perform field calibrations in-site, or in place, as installed. Don't
remove the instrument you're calibrating from the installed location. You may perform field
calibrations after installation to ensure proper connections and configuration. You're more likely
to perform periodic calibrations in the field, in the environment in which the instrument
operates. If you install the instrument in a harsh environment, you calibrate it for that
environment. If you remove the instrument for a bench calibration and then return it, you might
introduce some error due to the ambient conditions and orientation.

CALIBRATION METHODS
Linear Instruments
The simplest calibration procedure for an analog, linear instrument is the so-called Zero-and-
Span Method. The method is as follows:

1. Apply the lower-range value stimulus to the instrument, wait for it to stabilize
2. Move the “zero” adjustment until the instrument registers accurately at this point
3. Apply the upper-range value stimulus to the instrument, wait for it to stabilize
4. Move the “span” adjustment until the instrument registers accurately at this point
5. Repeat steps 1 through 4 as necessary to achieve good accuracy at both ends of the
range
To improve this procedure, response of instrument in several points between upper and lower
range values are also checked. An example of this is the 5 Point Calibration, where the
instrument is checked at 0%, 25%, 50%, 75% and 100% of its range values.

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302 3
Devices May 25, 2010

Information Sheet 2.1.1 : Defining the Calibration Principle

Discrete Instruments
Discrete instruments require periodic calibration just like continuous instruments. Most discrete
instruments have but one calibration adjustment: the Set-point or Trip-point. Some process
switches have two adjustments: the set-point as well as a Deadband Adjustment. The
purpose of a deadband adjustment is to provide an adjustable buffer range that must be
traversed before the switch changes state. To use our 85 PSI low air pressure switch as an
example, the set-point would be 85 PSI, but if the deadband were 5 PSI it would mean the
switch would not change state until the pressure rose above 90 PSI (85 PSI + 5 PSI).

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302 4
Devices May 25, 2010

Worksheet 2.1.2 : Defining Calibration Principle
Learning Outcome:

2. Plan and Prepare Calibration
Learning Activity:

2.1 Define Calibration Principle
Instructions: Write your answer in the blank space provided.

1. State the importance of calibration.

2. Give the difference between Bench Calibration and Field Calibration.

3. Identify the procedures in performing calibration and describe how these
procedures are being used.

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302
Devices May. 27, 2010 1

Worksheet 2.1.2 : Defining Calibration Principle
4. Identify the characteristics of calibration and give the description of each.

5. Identify atleast 4 common calibration terms and define each.

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302
Devices May. 27, 2010 2

Worksheet 2.1.2 : Defining Calibration Principle

Instructions: Match the definitions in column SET A to following terms in column SET
B. Write your answer in the box provided on the side of column SET A.

SET A SET B

1. It is defined as the checking of a A. Test Instrument
measuring instrument against an B. LRV
accurate standard, determining any C. Range
deviation in its measurements and D. Drift
applies adjustment in order to correct E. Calibration
this deviation. F. Span
G. Zero
2. It is the instrument being compared H. URV
with the calibration standard. I. Standard

3. A standard measuring device use to Calibration
verify the correctness of a test Equipment
instrument. J. Tolerance

4. It is defined as the change in
accuracy of a measuring instrument
due to chronological aging.

5. The extent of coverage of the
instrument’s capabilities.

6. The extent of coverage of the
instrument for which it is calibrated.

7. It is the absence of the phenomenon
being measured, a point in
calibration.

8. The permissible limit in variation in
measurement of a measuring
instrument in order for it to be
accurate.

9. The upper limit of the instrument’s
span.

10. The lower limit of the instrument’s
span.

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302
Devices May. 27, 2010 3

Information Sheet 2.2.1 : Identifying Different Calibration Equipment

Learning Outcomes
2. Plan and Prepare Calibration

Learning Activities
2.2 Identify Different Types of Calibration Equipment.

CALIBRATION EQUIPMENT
Calibration Equipment or known as “Calibrators” are like the tools of the trade in calibration.
Without these different equipment, we cannot perform calibration. In calibration we can
encounter different types of instruments, and in performing calibration the combination of these
equipment are the tools you need to finish the job.

Pressure Calibrator

The Pressure Calibrator is a standard measuring
instrument that measures the stimulated input pressure
parallel with the pressure supplied to the test instrument.
This equipment can also measure analog current.

Wallace Pneumatic Calibrator

The Wallace Pneumatic Calibrator can serve as a
pressure regulator and also a pressure measuring
instrument. this equipment is very useful for
instruments that uses pressure as their process
variable.

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302 1
Devices June 16, 2010

Information Sheet 2.2.1 : Identifying Different Calibration Equipment

Loop Calibrator

The Druck Loop Calibrator can provide analog current signal (4 – 20
ma), and can also measure current flow in a particular loop. This
equipment is very functional to use in loop calibrations.

Multi-Tester

The Multi-Tester is essential equipment needed in any
electrical task. The multi-tester can measure almost any
type of electrical parameter like voltage, current, resistance
and also continuity of a circuit.

Resistance Box

The resistance box is very
useful in simulating RTD
sensor’s behavior; it can
generate variable resistance
similar with RTD sensors. The
resistance box is used to
calibrate RTD transmitters.

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302 2
Devices June 16, 2010

Information Sheet 2.2.1 : Identifying Different Calibration Equipment

Temperature Calibrator

The temperature calibrator is a very versatile
equipment; it can generate resistance and voltage in
terms of mili-volts. This equipment can also measure
different types of electrical parameters. This
equipment is very functional in performing calibration
of temperature instruments.

Temperature Bath

The temperature bath is an equipment that can simulate

variable fluid temperatures. With the use of glycol as the

fluid medium, the temperature bath can increase and
decrease the fluid’s temperature for as to simulate

temperature changes in actual process fluids. This

equipment is used to test temperature sensors accuracy.

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302 3
Devices June 16, 2010

Worksheet 2.2.1 : Identifying Different Calibration Equipment

Learning outcomes:
2. Plan and Prepare Calibration

Learning Activity:
2.2 Identify Different Calibration Equipment

Instructions: Match the following terms in SET A to the it correct description in SET B.
Write the letter of the correct description that match the terms in the blank space
provided.

SET A1 SET B1

(1) Pressure Calibrator ______ (A) has the ability to increase and decrease
the fluid’s (glycol) temperature to simulate
(2) Temperature Bath ______ process fluid’s temperature changes.

(3) Multi-meter ______ (B) can provide analog 4-20 ma signal, and
can also measure analog current in a
(4) Druck Loop Calibrator ______ particular loop

(5) Wallace Pneumatic Calibrator ______ (C) can function as a pressure regulator
and can also measure pneumatic pressure
(6) Resistance Box ______
(D) has the ability to generate resistance
(7) Temperature Calibrator ______ and voltage in terms of milli-volts, can also
measure electrical parameters.

(E) can generate variable resistance that
simulates behavior of RTD sensors

(F) can measure stimulated input pressure,
and can also measure electrical parameters

(G) its main function is to measure different
types of electrical parameters in different
ranges.

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302
Devices June 21, 2010 1

Information Sheet 3.1.1 : Preparing Calibration Set-Up

Learning outcomes:
3. Calibrate I&C Devices

Learning Activity:
3.1 Prepare Calibration Set-up

Preparing the Calibration set-up is one of the critical parts in calibrating I&C Devices.
Connections and parameters of devices and calibration equipment must be correct and
accurate otherwise incorrect connections may result to failure or destruction of the device and
the calibration equipment.

The I&C device parameters are:

 Range – The values of the process variable that the instrument is effectively
operational.

 Supply – The variable that is supplied to the device for it to be operational.
 Input – The variable to be fed to the device to produce a response.
 Output – It defines what type of variable is the response of the device.

Example: RTD Transmitter

Range: Temperature; 0 – 100 degrees Celsius

Supply: Voltage; 0 – 24 Volts

Input: Resistance; (ohms) based on the Resistance – Temperature Conversion Table

Output: Current; 4 – 20 mili-Amperes

In this sheet, you are provided with calibration set-up drawings. Connect the devices and the
calibration equipment as shown on the calibration set-up drawings. Double check the
connection after the set-up is done.

NOTE: Learners are assumed to have prior knowledge in the following field:

1. Basic Electricity
2. Electrical Wiring
3. Principles of Pneumatics
4. Process Variable Measurements

Legend Pneumatic Hose Connection
Electrical Wiring Connection
 Blue Lines
 Red Lines

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302 1
Devices June 6, 2010

Information Sheet 3.1.1 : Preparing Calibration Set-Up
1. RTD Transmitter Set – up (PT100)

2. DP Transmitter

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302 2
Devices June 6, 2010

Information Sheet 3.1.1 : Preparing Calibration Set-Up
3. HART Pressure Transmitter

4. Pressure Gauge

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302 3
Devices June 6, 2010

Information Sheet 3.1.1 : Preparing Calibration Set-Up
5. I/P Transducer

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302 4
Devices June 6, 2010

Operation Sheet 3.2.1 : Performing Calibration

Learning outcomes:
1 Test starting system and identify faults
Learning Activity:
1.2 Scale reading of analog/digital Voltmeter/Ammeter

Procedures in performing Calibration

Once calibration set-up is finished, we can now proceed in calibrating the I&C device. The
procedure of the calibration may vary, depending on the type of instrument. There are two
general types of instruments, discrete instruments and linear instruments. Discrete instruments
are instruments that only give outputs in maximum or minimum values, or we can say either
0% or 100% of the output, an example of these instruments are the process switches. The
other type o instrument is the linear instruments, unlike the discrete type of instruments linear
instruments have variable outputs meaning: their outputs can vary between 0 to 100% of its
value, their outputs can settle in 25%, 50%, 75% or any other value in between its maximum
and minimum. Examples of linear instruments are transmitters that feedbacks an analog signal
(4-20ma, 0-10 v, 0-5 v).

Discrete Instruments (Set-Point or Trip-Point Calibration – Deadband Adjustment)

1. Identify the device’s standard operating value.
2. Identify the device’s trip point (the value in which the instrument will produce an output).
3. Document the as-found value.
4. Compare the as-found the value with the standard operating value of the instrument.
5. If the as-found value is the same with the standard operating value of the device, then

no calibration is needed but if the as-found value is offset with the standard operating
value, adjustment on the instrument should be made.
6. Adjust the set-point or the trip-point of the device to set the device’s response in
accordance to its standard operating value.
7. Once the trip-point of the device is in the range of the tolerance of the standard
operating value, we can conclude that the I&C device is now calibrated.
8. You can repeat the steps to verify the accuracy of the device’s trip-point.
9. Document the as-left value.
10. Prepare the calibration report.

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302 1
Devices June 9, 2010

Operation Sheet 3.2.1 : Performing Calibration

Linear Instruments (Five-Point Calibration – Zero and Span Adjustment)
1. First identify device’s standard operating range.
2. From the standard operating range, derive the five points in which the device’s
response will be compared to.
3. Get the as-found data on the corresponding five points of the range.
4. If the as-found value is the same with the derived five point’s value of the device, then
no calibration is needed but if the as-found value is offset with the derived five point’s
value, adjustment on the instrument should be made.
5. Apply the lower-range value stimulus to the instrument, wait for it to stabilize
6. Move the “zero” adjustment until the instrument registers accurately at this point
7. Apply the upper-range value stimulus to the instrument, wait for it to stabilize
8. Move the “span” adjustment until the instrument registers accurately at this point
9. Once the gathered data from the adjustment made corresponds with five points values,
we can conclude that the I&C device is now calibrated.
10. Repeat steps as necessary to achieve good accuracy at both ends of the range.
11. Document the as-left value.
12. Prepare the calibration report.

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302 2
Devices June 9, 2010

Information Sheet 4.1.1 : Preparing Calibration Report

Learning outcomes:
4. Test and Inspect Calibrated I&C Devices

Learning Activity:
4.1 Prepare Calibration Report

CALIBRATION REPORT

A Calibration Report is a document that verifies the result of a calibration done on a particular
instrument. Whatever the result of the calibration, it should be documented to keep track on
the instrument’s performance. Also the document can serve as reference for the maintenance
of the instrument. Before a calibration report is made every raw data to be inputted into the
document must be valid and checked by the rightful personnel.

A Calibration Report is comprised of the following:

1. Test Instrument Description
a. Type ( e.g. Pressure transmitter, RTD sensor, Flowmeter )
b. Instrument ID
c. Instrument Location
d. Instrument Parameters
e. Instrument Brand

2. Calibration Description
a. Method of Calibration
b. Calibration Equipment
c. Date of Calibration
d. Traceability
e. Calibration Results

3. Remarks of Calibration

4. Signature of Involved Personnel

a. Instrument Technician
b. Instrument Operator

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302 1
Devices June 16, 2010

Information Sheet 4.1.1 : Preparing Calibration Report
Sample Calibration Report

Industrial Controls Corporation

The Automation & Instrumentation Systems House ISO 9001:2000
Certificate No. AJA06.0305
926-928 Mega Plaza Building, ADB Avenue cor. Garnet St., Ortigas Centre, Pasig City

Tel. (632) 687 4814 to 15 Fax. (632) 924-0957 E-mail: [email protected]

CALIBRATION REPORTWebsite : http:\\www.IndustrialControlsCorp.com

Customer : SAN MIGUEL BREWERY INC. – POLO BREWERY Date of Calibration : June 12 2010
Address : Mc Arthur Highway, Valenzuela City Calibration Due : n/a

Instrument Type : Pressure Gauge Input : Simulated Pressure
Type of Job : Bench Calibration Output : Pressure Display
Equipment Code : n/a Range : 0 – 30 psi
Brand : Bailey Tolerance : ± 1.0%
Location : Steam Plant Location of Equipment : Boiler Deaerator

STANDARD INSTRUMENT USED : AMETEK PRESSURE CALIBRATOR
S/N: 8285221
Cert. No: 02E-2010 041B

TRACEABILITY : Traceable to NMC, Singapore and NIST, USA thru Applied Calibration & Instrumentation System
Inc., Pasig Philippines

CALIBRATION METHOD : The Pressure Reducing Valve was calibrated using procedure # ICC-CP-PI-004.
CALIBRATION RESULTS :

Standard Calibration Reading Instrument Reading

Five Point Input Before Calibration After Calibration Percentage Error
(PSI) (PSI) %
% (PSI) 0 0 0
6.4 7.5 0
00 13.3 14.9 0.67
19.5 22.3 0.89
25 7.5 28.8 29.9 0.33

50 15

75 22.5

100 30

REMARKS :
1) The defined instrument was still suitable for its intended use, within the tolerance limit of ± 1.0% of the span.

2) The calibration results were those obtained at the time of calibration and pertain only to the particular item calibrated.

Should the instrument be modified or damaged (in any way) or develop inconsistent readings, the results may not be valid and the unit may
require recalibration.
3) This certificate shall not be reproduced except in full, without the written approval of industrial Controls Corporation.

Calibrated by : Calibration Officer:

GILBERT A. PACLIBAR / ENRICO CATINOY IRISH-LI T. CALUYA
Calibrating Technician Supervisor

.
SMB-POLO Representative

Code No. Calibrate Instrumentation and Control Date: Developed Date: Revised Page #
ELC724302 2
Devices June 16, 2010

Job Sheet 5.1.1 : Calibrate I&C Devices

Learning outcomes:
5 Perform Whole Task of Calibration of I&C Devices

Learning Activity:
5.1 Perform Calibration Job

Equipment / Resources:
 Hand Tools
 Calibration Equipment
 Multi-Testers
 Wires
 Pneumatic Hose
 Pneumatic Fittings
 Hand Pumps
 Pressure Gauges
 Compressor

After completion of all the necessary learning activities now you should be able to perform
calibration job for your assigned I&C Device.

1. Perform calibration job for a DP Transmitter
2. Identify the following:

a. List of Hand Tools and Materials
b. List of Calibration Equipment
c. I&C Device Parameters
d. Calibration Methods
3. Using the given equipment and materials connect the calibration set-up for a DP
Transmitter. (Refer to the diagram).

Code No. Servicing Starting System Date: Developed Date: Revised Page #
ALT723307
Nov. 28, 2003 Mar 01, 2006 1

Job Sheet 5.1.1 : Calibrate I&C Devices

4. Prepare the calibration report complete with the following data:
a. As Found Data
b. As Left Data
c. Percentage Error
d. Remarks in Calibration

Reflection Questions

1. What do you think are the critical points in performing the calibration job?
2. What are the difficulties you had encountered while carrying on with the job?
3. How do you manage to overcome all these difficulties?
4. What do you think could have happen if you fail to perform the calibration job?
5. From performing this practical examination and all the learning activities, state one

importance of calibration and elaborate your answer.

Code No. Servicing Starting System Date: Developed Date: Revised Page #
ALT723307
Nov. 28, 2003 Mar 01, 2006 2