TABLE OF CONTENTS

Module No. Topics Page No.

1 Mechanical Engineering Laboratory 1 Structure 4-6

2 Pressure Measurement 7-16

3 Temperature Measurement 17-20

4 Area Measurement 21-24

5 Mass and Weight Measurement 25-28

6 Speed Measurement 29-32

7 Flue Gas Analysis 33-38

39-44
8 Calorimetry

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MODULE 1: MECHANICAL ENGINEERING LABORATORY 1
STRUCTURE
GENERAL OBJECTIVES OF THE MANUAL
After extensive perusal of the manual, you will be equipped with following:
o capacity to explain the constitution, principles of operation, application, care, and calibration
of metrology instruments/devices on the respective areas of measurements such as;
pressure, temperature, area, mass and weight, speed, flue gas analysis, and calorimetry.
o appreciation of the concepts and uses of many of the common transducers, and actually run
an experiment using a selection of these devices;
o capability to the use metrology instruments in small scale platform and industrial set-up
o adept in doing experimental work, expected from modern engineering professionals;
o experience in modern instrumentation, and expertise in computer aided data acquisition,
control, real time data processing and graphical display of results;
o proficient in oral and written communication, a must in the preparation of quality technical
reports of laboratory experiment/test conducted;
o team spirit to collaborate with other students in planning and performing laboratory
experiment/test.
o creative ability to introduce new concepts/ideas in experimental methods—beyond traditional
classroom instruction—backed by stock knowledge and research; and
o abreast of the emerging new technologies in metrology instruments/devices being employed
in this manual.

General Laboratory Safety Rules and Student Deportment Inside the Laboratory Before
and During the Conduct of Test/Experiments:
o strictly observe 5S inside the laboratory room;
o use proper laboratory attire and/or personal protective equipment (PPE) whenever necessary;
o do not touch anything with which you are not completely familiar;
o carelessness may not only break the valuable equipment in the lab but may also cause serious
injury to you and others in the lab;
o follow instructions precisely as instructed by your professor;
o do not start the experiment unless your setup is verified and approved by your professor.
o do not leave the experiments unattended while in progress;
o do not crowd around the equipment or do horseplay inside the laboratory;
o if any part of the equipment fails while in use, stop the operation and report the failure
immediately to your professor/laboratory head; and
o never try to fix a problem yourself, you could further damage the equipment and harm yourself
and others in the lab.
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INTRODUCTION
Metrology is defined by the International Bureau of Weights and Measures (BIPM) as "the science
of measurement, embracing both experimental and theoretical determinations at any level of
uncertainty in any field of science and technology".[14]
There are three main fields of metrology namely: scientific metrology; applied, technical or
industrial metrology, and legal metrology.[6]
o Scientific metrology is concerned with the establishment of units of measurement, the
development of new measurement methods, the realization of measurement standards, and
the transfer of traceability from these standards to users in a society. [2][3]
o Applied, technical or industrial metrology is concerned with the application of measurement to
manufacturing and other processes and their use in society, ensuring the suitability of
measurement instruments, their calibration and quality control.[2]
o Legal metrology "concerns activities which result from statutory requirements and concern
measurement, units of measurement, measuring instruments and methods of measurement
and which are performed by competent bodies". [20] Such statutory requirements may arise
from the need for protection of health, public safety, the environment, enabling taxation,
protection of consumers and fair trade.
In general, this manual deals mainly with applied metrology specifically the constitution,
principles of operation, application, care, and calibration of metrology instruments/devices on
the respective areas of measurements such as: pressure, temperature, area, mass and weight,
speed, flue gas analysis, and calorimetry.
Laboratory work is vital for improving and developing products and processes, validating designs
and for gaining fundamental understanding of how materials, parts, components or systems will
behave under a variety of conditions. As such it is essential that mechanical engineering students
be able to work productively in this setting.
The purpose of laboratory work is to study how something will actually behave. It is a
supplement for analysis – both analysis and laboratory work are critical aspects of
engineering design.
Laboratory work may reveal faulty assumptions not identified during analysis. It may identify
strengths or weaknesses overlooked in the analysis—the true behavior or performance of
materials, components and systems can only be revealed only through experiments and testing.
Prior to conducting a laboratory exercise, you should understand the purpose of the laboratory,
the procedures and equipment to be used, the instrumentation and measurements required, and
you should understand any analysis you will need to perform. A data sheet for recording results
must be prepared prior to the laboratory procedures.
Standards
The word “standard” can be defined as “something established as a rule or basis of comparison
in measuring or judging capacity” (Webster’s New World Dictionary).
Engineering standards allow for uniformity throughout the engineering community. Their use is
so ubiquitous that they go almost unnoticed and are taken for granted.
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Measurement and Analysis
Measurement error is the difference between the true value and the measured value: error =
measured value - true value the “true” value is the value one would obtain with a perfect
measurement. Since there is no such thing as a perfect measurement, the true value can never
be known (with the exception of measuring the original artifact – for example the 1 kg mass in
France).
Tests and Experiments
Many people use “experiment” and “test” synonymously, but they can mean two very different
things. They are similar to the extent that they both typically involve collecting data in a laboratory
setting. However, the two may be more clearly delineated as follows:
Testing
o evaluates performance of something (for example a test could determine the strength of a new
material).
o has “pass/fail” criteria (for example, it may answer the question does a product meet the
strength requirements).
o is performed per an existing standard, method, or procedure.
Experiments
o requires changing one or more variables to determine its effect on one or more dependent
variables.
o not associated with pass/fail, but rather evaluate “better/worse”
o conducted to learn how things work or perform under differing conditions
o conditions may be included where the outcome is known to be “bad” Proper design of an
experiment or test often requires balancing competing criteria, as does designing
components.

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MODULE 2: PRESSURE MEASUREMENT
Overview

This module provides you information that guide you to use pressure measurement devices.

You will be able to choose from a variety of sensors the right application of a certain pressure
measuring device, being adept in the operating principles, range, adaptability, response time,
benefits, and drawbacks consideration of said instrument/devices.

After successfully comprehending module 2, you should have gained the ability to:
o identify the different industrial pressure measuring instruments/devices, as to their constitution,
principles of operation, application, care, solution, and calibration;
o explain the principles on how the different pressure measuring instruments works as to how
they react to atmospheric pressure, and induced pressure;
o use the aforementioned pressure measuring instruments/devices in experimental procedures;
o adept in interpreting experimental data.
o proficient in oral and written communication, a must in the preparation of quality technical
reports of laboratory experiment/test conducted;
o team spirit to collaborate with other students in planning and performing laboratory
experiment/test on pressure measurement.
o creative ability to introduce new concepts/ideas in pressure measurement experimental
methods—beyond traditional classroom instruction—backed by stock knowledge and
research; and
o abreast of the emerging new technologies in pressure measurement instruments/devices.

Pressure Measurement

Pressure measurement is the analysis of an applied force by a fluid (liquid or gas) on a

surface. Pressure is typically measured in units of force per unit of surface area. Many techniques
have been developed for the measurement of pressure and vacuum. Instruments used to
measure and display pressure in an integral unit are called pressure meters or pressure
gauges or vacuum gauges.

Pressure Measuring Instruments

Four basic types of pressure measuring instruments based on construction and working
principles:
o liquid column elements;
 barometer
 manometer
o elastic element gauge;
 bourdon gage
 diaphragm
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 capsule
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o electrical transducers;
  resistance and inductance type
o force–balanced devices
o dead weight gauge
o ring gauge
o bell gauge
Liquid Column Elements

Barometer

The barometer is used to measure atmospheric pressure, it is the

pressure exerted by the air surrounding the earth, that goes on
decreasing away from the earth surface while increasing its value
approaching the bottom of the sea and beyond.
Barometric liquid balances the atmospheric pressure against vacuum
and pressure head reading is obtained in the absolute units.
Construction and working principle
The Torricellian barometer has a glass tube closed at one end and
opened at the other end; the length of the tube must be greater than
760 mm.
The tube is initially filled with mercury, the open end being
temporarily plugged, the tube is inverted to a pan of mercury and
unplugged eventually.
When the plug is removed, the mercury in the tube drops by a
certain amount, creating a vacuum at the top of the tube and then
reading ‘h’ is noted. The reading ‘h’ is proportional to atmospheric
pressure acting on mercury in the pan. Note that this atmospheric
pressure reading is in absolute units.
We have stated that vacuum is present the top of the tube above mercury, but actually there is
vapor pressure of mercury acting on mercury pressure ’P’ kg/cm2 is given by P= 6.66 X 10 -3h

MANOMETER
Principle of Operation
Manometers work on the effect of the hydrostatic pressure
exerted by a liquid column. In manometer the unknown
pressure is determined by balancing it against some known
pressure or vacuum.
The U-tube manometer consists of glass U-tube partially
filled with a suitable liquid like water, mercury etc., one of the
legs of the manometer, as shown in the figure the right leg is
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connected to unknown pressure of a gas supply line to be measured while left leg is open to the
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atmosphere.
The difference of pressure between two legs of the manometer, h represents differential pressure
of the gas in the gas supply line, pgas. The static balance equation is
pgas =h ρ g
h = height difference
ρ = mass density of manometer liquid
g = the gravitational force of attraction
pgas = h (ρw) g
h = height difference
ρw = density of water

ELASTIC PRESSURE TRANSDUCERS

Transducers are devices that converts one form of energy into some other form. The following
pressure gauges have elastic element that converts pressure signal into proportional
mechanical displacement.
Bourdon Pressure Gage
Construction and Principle of Operation
Bourdon tube pressure gauges are used for the measurement of relative
pressures from 0.6 ... 7,000 bar. They are classified as mechanical
pressure measuring instruments, and thus operate without any electrical
power

Bourdon tubes are radially formed tubes with an oval cross-section. The
pressure of the measuring medium acts on the inside of the tube and
produces a motion in the non-clamped end of the tube. This motion is the
measure of the pressure and is indicated via the movement.

Diaphragm Pressure Gage

Diaphragm Pressure Working Principle

Diaphragm pressure gauges are used to measure gases and

liquids. They cover measuring spans from 10 mbar to 40
bar. The measuring element consists of one circular
diaphragm clamped between a pair of flanges. The positive
or negative pressure acting on these diaphragms causes
deformation of the measuring element. The magnitude of the
deformation is proportional to the pressure to be measured,
and it is coupled to the pointer mechanism.

It has many different uses, such as monitoring the pressure

of a canister of gas, measuring atmospheric pressure, or
recording the strength of the vacuum in a vacuum pump.

Capsule Pressure Gage

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Capsule Pressure Gauge Working Principle

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The sensing element of a capsule
pressure gauge consists of two
corrugated diaphragms welded together
at their periphery to form a capsule. The
pressure to be measured is introduced
into the capsule via an opening in the
center of the first diaphragm. The center
of the second diaphragm is connected to
the transmission mechanism so that the
deflection of the measuring element can
be transmitted to the pointer.

When the pressure rises inside the capsule, both diaphragms will slightly deform. By making use
of two diaphragms, the total deflection of the measuring element is twice as large.

Included in this category of transducers are strain gauges and

moving contacts (slide wire variable resistors). The Figure
illustrates a simple strain gauge. A strain gauge measures
the external force (pressure) applied to a fine wire. The fine
wire is usually arranged in the form of a grid. The pressure
change causes a resistance change due to the distortion of
the wire. The value of the pressure can be found by
measuring the change in resistance of the wire grid. Equation
2-1 shows the pressure to resistance relationship. R K (2-1)
L A, where R = resistance of the wire grid in ohms K =
resistivity constant for the particular type of wire grid L =
length of wire grid A = cross sectional area of wire grid IC-02 Page 6 Rev.

Pressure Detection Circuitry

Pressure Detectors - An increase in pressure at the
inlet of the bellows causes the bellows to expand.
The expansion of the bellows moves a flexible beam
to which a strain gauge has been attached. The
movement of the beam causes the resistance of the
strain gauge to change. The temperature
compensating gauge compensates for the heat
produced by current flowing through the fine wire of
the strain gauge. Strain gauges, which are nothing
more than resistors, are used with bridge circuits as shown in Figure 5. Figure 5 Strain Gauge
Used in a Bridge Circuit Alternating current is provided by an exciter that is used in place of a
battery to eliminate the need for a galvanometer. When a change in resistance in the strain gauge
causes an unbalanced condition, an error signal enters the amplifier and actuates the balancing
motor. The balancing motor moves the slider along the slidewire, restoring the bridge to a
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balanced condition. The slider’s position is noted on a scale marked in units of pressure.
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Pressure Detectors
Other resistance-type transducers combine a
bellows or a bourdon tube with a variable
resistor, as shown in Figure 6. As pressure
changes, the bellows will either expand or
contract. This expansion and contraction causes
the attached slider to move along the slideware,
increasing or decreasing the resistance, and
thereby indicating an increase or decrease in
pressure. Figure 6 Bellows Resistance
Transducer Inductance-Type Transducers
Inductance-Type Pressure Transducer Coil The
inductance-type transducer consists of three
parts: a coil, a movable magnetic core, and a
pressure sensing element. The element is
attached to the core, and, as pressure varies, the element causes the core to move inside the
coil. An AC voltage is applied to the coil, and, as the core moves, the inductance of the coil
changes. The current through the coil will increase as the inductance decreases. For increased
sensitivity, the coil can be separated into two coils by utilizing a center tap, as shown in Figure
7. As the core moves within the coils, the inductance of one coil will increase, while the other will
decrease. Rev. 0 Page 9 IC-02

Dead Weight Gage Tester

Dead Weight Tester (DWT) are usually used for

pressure gauge calibration as they come with
high accuracy, they used as primary standard,
operated with oil (hydraulic) or with air
(pneumatic).
o A deadweight tester (DWT) is a
calibration standard which uses a piston
cylinder on which a load is placed to
make an equilibrium with an applied
pressure underneath the piston.

o The formula to design a DWT is based

basically is expressed as follows

p = F / A [Pa]

where:
p : reference pressure [Pa]
F : force applied on piston [N]
A : effective area PCU [m2]
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Working Principle of Dead Weight Tester

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Parts

1 – Hand pump
2 – Testing Pump
3 – Pressure Gauge to be calibrated
4 – Calibration Weight
5 – Weight Support
6 – Piston
7 – Cylinder
8 – Filling Connection

Basics

Dead weight testers are a piston-cylinder type measuring device. As primary standards, they are
the most accurate instruments for the calibration of electronic or mechanical pressure measuring
instruments.
o They work in accordance with the basic principle that P= F/A, where the pressure (P) acts on
a known area of a sealed piston (A), generating a force (F).

o The force of this piston is then compared with the force applied by calibrated weights. The
use of high quality materials result in small uncertainties of measurement and excellent long
term stability.

o Dead weight testers can measure pressures of up to 10,000 bar, attaining accuracies of
between 0.005% and 0.1% although most applications lie within 1 – 2500 bar.

o The pistons are partly made of tungsten carbide (used for its small temperature coefficient),
and the cylinders must fit together with a clearance of no more than a couple of micrometers
in order to create a minimum friction thus limiting the measuring error. The piston is then
rotated during measurements to further minimize friction.

o The testing pump (2) is connected to the instrument to be tested (3), to the actual measuring
component and to the filling socket.

o A special hydraulic oil or gas such as compressed air or nitrogen is used as the pressure
transfer medium. The measuring piston is then loaded with calibrated weights (4). The
pressure is applied via an integrated pump (1) or, if an external pressure supply is available,
via control valves in order to generate a pressure until the loaded measuring piston (6) rises
and ‘floats’ on the fluid. This is the point where there is a balance between pressure and the
mass load.

o The piston is rotated to reduce friction as far as possible. Since the piston is spinning, it exerts
a pressure that can be calculated by application of a derivative of the formula P = F/A.

o The accuracy of a pressure balance is characterized by the deviation span, which is the sum
of the systematic error and the uncertainties of measurement.
12

o Today’s dead weight testers are highly accurate and complex and can make sophisticated
physical compensations.
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o They can also come accompanied by an intelligent calibrator unit which can register all critical
ambient parameters and automatically correct them in real time making readings even more
accurate.

Procedure in Calibrating Pressure Gauges

In order to create this accurately

known pressure, the following
steps are followed. The valve of the
apparatus is closed.

o known weight is placed on the

platform. Now by operating the
plunger, fluid pressure is
applied to the other side of the
piston until enough force is
developed to lift the piston-
weight combination.

o When this happens, the piston weight combination floats freely within the cylinder between
limit stops. In this condition of equilibrium, the pressure force of fluid is balanced against the
gravitational force of the weights pulls the friction drag.

o Therefore, PA = Mg + F

o Hence : P = Mg + F / A

o where, P = pressure

o M = Mass; Kg

o g = Acceleration due to gravity ; m/s²

o F = Friction drag; N

o A = Eqivalent area of piston – cylinder combination; m²

o Thus the pressure P which is caused due to the weights placed on the platform is calculated.
After calculating P, the plunger is released.

o Now the pressure gauge to be calibrated is fitted at an appropriate place on the dead weight
tester. The same known weight which was used to calculate P is placed on the platform.

o Due to the weight, the piston moves downwards and exerts a pressure P on the fluid. Now
the valve in the apparatus is opened so that the fluid pressure P is transmitted to the gauge,
which makes the gauge indicate a pressure value.
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o This pressure value shown by
the gauge should be equal to
the known input pressure P. If
the gauge indicates some other
value other than p the gauge is
adjusted so that it reads a value
equal to p. Thus the gauge is
calibrated.

Applications

It is used to calibrated all kinds of

pressure gauges such as industrial
pressure gauges, pressure
transmitters etc.

Advantages

o it is simple in construction and easy to use. It can be used to calibrated a wide range of
pressure measuring devices.

o Fluid pressure can be easily varied by adding weights or by changing the piston cylinder
combination.

Limitations

o the accuracy of the dead weight tester is affected due to the friction between the piston
and cylinder, and due to the uncertainty of the value of gravitational constant ‘g’

Bridge-Based

Of all the pressure sensors, Wheatstone

bridge (strain based) sensors are the most
common because they offer solutions that
meet varying accuracy, size, ruggedness,
and cost constraints.

Bridge-Based Sensors

Can measure absolute, gauge, or

differential pressure in both high- and low- Cross Section of a Bridge-Based Pressure Sensor
pressure applications.

They use a strain gage to detect the deformity of a diaphragm subjected to the applied pressure.
‘When a change in pressure causes the diaphragm to deflect, a corresponding change in
resistance is induced on the strain gage, which you can measure with a conditioned DAQ system.
14

You can bond foil strain gages directly to a diaphragm or to an element that is connected
mechanically to the diaphragm. Silicon strain gages are sometimes used as well. For this method,
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you etch resistors on a silicon-based substrate and use transmission fluid to transmit the pressure
from the diaphragm to the substrate.

Capacitive Pressure Sensors

A variable capacitance pressure transducer measures the

change in capacitance between a metal diaphragm and a fixed
metal plate. The capacitance between two metal plates
changes if the distance between these two plates changes
due to applied pressure.

Capacitive and piezoelectric pressure transducers are

generally stable and linear, but they are sensitive to high
temperatures and are more complicated to set up than
most pressure sensors. Piezoelectric sensors respond
quickly to pressure changes. For this reason, they are
used to make rapid pressure measurements from events
such as explosions. Because of their superior dynamic Capacitance Transducer
performance, piezoelectric sensors are the least cost-
effective, and you must be careful to protect their sensitive crystal core

Piezoelectric Pressure Sensors

Piezoelectric sensors rely on the electrical properties of quartz

crystals rather than a resistive bridge transducer. These
crystals generate an electrical charge when they are strained.
Electrodes transfer the charge from the crystals to an amplifier built
into the sensor. These sensors do not require an external
excitation source, but they are susceptible to shock and
vibration.

Conditioned Pressure Sensors Piezoelectric Pressure

Sensors that include integrated circuitry, such as amplifiers, are referred to as amplified sensors.
These types of sensors may be constructed using bridge-based, capacitive, or piezoelectric
transducers. In the case of a bridge-based amplified sensor, the unit itself provides completion
resistors and the amplification necessary to measure the pressure directly with a DAQ device.
Though excitation must still be provided, the accuracy of the excitation is less important.

Conditioned sensors are typically more expensive because they contain components for filtering
and signal amplification, excitation leads, and the regular circuitry for measurement. This is helpful
for lower channel systems that do not warrant a dedicated signal conditioning system. Because
the conditioning is built in, you can connect the sensor directly to a DAQ device as long as you
provide power to the sensor in some way. If you are working with nonconditioned pressure bridge-
based sensors, your hardware needs signal conditioning. Check the sensor’s documentation so
that you know whether you need additional components for amplification or filtering.
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Optical Pressure Sensors

Pressure measurement using optical sensing has many benefits including noise immunity and
isolation. Read Fundamentals of FBG Optical Sensing for more information about this method of
measurement.

Choice of the Right Type of Pressure Sensor

Bridge-based or piezo resistive sensors are the most common types of sensor because of their
simple construction and durability. This translates to lower cost and makes them ideal for higher
channel systems. In general, foil strain gages are used in high-pressure (up to 700M Pa)
applications. They also have a higher operating temperature than silicon strain gages (200 °C
versus 100 °C, respectively), but silicon strain gages offer the benefit of larger overload capability.
Because they are more sensitive, silicon strain gages are also often preferred in low-pressure
applications (~2k Pa).

Signal conditioning for pressure sensor

Bridge-based pressure sensors are by far the most common pressure sensors. You need to
consider several signal conditioning elements to make an effective bridge-based pressure
measurement system. You may need one or more of the following:

Topic Questions

o Discuss the various types of pressure measuring devices and show how they differ in
 construction
 use,
 accuracy, and
 adaptability.
o Explain working principle of operation each of the pressure measuring devices
o discuss why the different pressure measuring devices have limitations as to;
 the range of measurements, and
 adaptability to environment.
o Explain the reasons of choosing the different pressure measuring devices on
their respective applications.
o Discuss the principle of operation of newly invented devices that can
measure pressure in various capacities.

Links for your Additional Readings and

o http://sensing.honeywell.com/white-paper-
effectivelyusingpressureloadandtorquesensorswithtodaysdataacqusitionsystems-008883-2-
en.pdf
o http://www.sensorsmag.com/sensors/pressure/pressure-measurement-principles-and-
practice-969
16

o delajoud@compuserve.com, mgirard@dhinstruments.com
o Download the Engineer's Guide to Accurate Sensor Measurements
Page

o Learn more about NI pressure measurement hardware

MODULE 3: TEMPERATURE MEASUREMENT
Overview
In this module you will learn how to measure temperature using a diverse array of sensors.

All of the sensors infer temperature by sensing some change in a physical characteristic. There
are six devices that you consider: thermocouples, resistive temperature devices (RTDs and
thermistors), infrared radiators, bimetallic devices, liquid expansion devices, and change-of-state
devices.

OBJECTIVES

After successfully finishing the topic you should have the ability to:

o differentiate contact from non-contact thermometers.

o appropriate use of thermometer in various applications, in consideration to their respective,
ranges, response time, sensitivity to substances and environment, accuracy, and the like.
o adept with the different industrial temperature measuring instruments/devices, as to their
constitution, principles of operation, application, care, solution, and calibration.
o explain the principles on how the different thermometer works as to how they react to heat,
and induced energy.
o proficient in oral and written communication, a must in the preparation of quality technical
reports of laboratory experiment/test conducted;
o team spirit to collaborate with other students in planning and performing laboratory
experiment/test on temperature measurement.
o creative ability to introduce new concepts/ideas in temperature measurement experimental
methods—beyond traditional classroom instruction—backed by stock knowledge and
research; and
o abreast of the emerging new technologies in temperature measurement instruments/devices.

Thermometer Meaning

A thermometer is an instrument to measure temperature—temperature cannot be measured

directly (for instance, as a length is measured by its segment). Only the measurement of another
physical property being a function of temperature may provide temperature determination. A
property used to measure temperature is termed a thermometric parameter
Temperature Measurement

Temperature measurement, also known as thermometry, describes the process of measuring a

current local temperature for immediate or later evaluation. Datasets consisting of repeated
standardized measurements can be used to assess temperature trends.

Temperature can also be measured via a diverse array of sensors. All of them infer temperature
by sensing some change in a physical characteristic. Six types with which the engineer is likely
to come into contact are: thermocouples, resistive temperature devices (RTDs and thermistors),
infrared radiators, bimetallic devices, liquid expansion devices, and change-of-state devices.
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Temperature measurement in today’s industrial environment encompasses a wide variety of
needs and applications. To meet this wide array of needs the process controls industry has
developed a large number of sensors and devices to handle this demand. to understand the
concepts and uses of many of the common transducers, and actually run an experiment using a
selection of these devices.

Fluid-Expansion Temperature Measurement Devices

Fluid-expansion devices, typified by the household thermometer, generally

come in two main classifications: the mercury type and the organic-liquid
type. Versions employing gas instead of liquid are also available. Mercury
is considered an environmental hazard, so there are regulations governing
the shipment of devices that contain it. Fluid-expansion sensors do not
require electric power, do not pose explosion hazards, and are stable
even after repeated cycling. On the other hand, they do not generate data
that is easily recorded or transmitted, and they cannot make spot or point
Thermocouple Temperature Measurement Sensors
Thermocouples consist essentially of two strips or wires made of
different metals and joined at one end. Changes in the temperature at
that juncture induce a change in electromotive force (emf) between
the other ends. As temperature goes up, this output emf of the
thermocouple rises, though not necessarily linearly
Resistance Temperature Devices (RTDs)

Resistive temperature devices capitalize on the fact that the electrical resistance of a material
changes as its temperature changes. Two key types are the metallic devices (commonly
referred to as RTDs), and thermistors. As their name indicates, RTDs rely on resistance change
in a metal, with the resistance rising more or less linearly with temperature. Thermistors are
based on resistance change in a ceramic semiconductor; the resistance drops nonlinearly with
temperature rise.

Infrared Temperature Measurement Devices

Infrared sensors are non-contacting devices. They infer temperature by

measuring the thermal radiation emitted by a material

Bimetallic Temperature Measurement Devices

Bimetallic devices take advantage of

the difference in rate of thermal
expansion between different metals.
Strips of two metals are bonded
together. When heated, one side will
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expand more than the other, and the

resulting bending is translated into a
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temperature reading by mechanical

linkage to a pointer. These devices
are portable and they do not
require a power supply, but they
are usually not as accurate as
thermocouples or RTDs and they
do n ot readily lend themselves to
temperature recording.
measurements.

Change-of-State Temperature Measurement Devices

Change-of-state temperature sensors consist of labels, pellets,

crayons, lacquers or liquid crystals whose appearance changes
once a certain temperature is reached.
o labels are use in steam traps stem lines and the like - when a
trap exceeds a certain temperature,
o slow response time
o not often do not respond to transient temperature changes.
o low accuracy
o change in state is irreversible, except in the case of liquid-crystal
displays.

Characteristics of Various Thermometers

PHYSICAL RESPONSE
DEVICE ACCURACY RANGE
THEORY TIME

THERMAL LIQUID-IN-GLASS SLOW ± 1.0% 200–1500 ˚C

EXPANSION

(DIMENSION
BIMETALLIC
CHANGES) SLOW ± 0.5% 75 –1500 ˚C
STRIP

GAY-LUSSACS
LAW PRESSURE
QUICK ± 1.0% -200–1600 ˚C
(PRESSURE THERMOMETER
CHANGES)

R&T RELATION
RESISTIVE
OF METALS
TEMPERATURE SLOW ± 0.15% -270 – 1100 ˚C
(RESISTANCE
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DEVICE (RTD)
CHANGES)
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 SEEBECK
EFFECT
THERMOCOUPLE QUICK ± 0.5% -200 – 2600 ˚C
(VOLTAGE
CHANGES)

STEFAN-
BOLTZMANN
LAW OPTICAL
--- ± 5.0% 200 – 1500 ˚C
PYROMETER
(OPTICAL
CHANGES)

Topic Questions

o Discuss the various types of temperature measuring devices and show how they differ in
 construction
 use,
 accuracy, and
 adaptability.
o Explain working principle of operation each of the temperature measuring devices
o discuss why the different temperature measuring devices have limitations as to;
 the range of measurements, and
 adaptability to environment.
o Explain the reasons of choosing the different thermometers of their
respective applications.
o Discuss the principle of operation of newly invented devices that can
measure temperature.

Links for Suggested Reading

o https://www.toppr.com › guides › science › heat-and-measuring-temperature
o https://www.wwdmag.com › water › 7-basic-types-temperature-measuring
https://sea.omega.com › prodinfo › temperaturemeasurement
https://web.mst.edu › ~cottrell › Resources › Temperature › Temperature
20
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MODULE 4: AREA MEASUREMENT
OVERVIEW

In Mechanical Engineering Practice a planimeter

is an instrument that is used to measure the area
of an indicator diagram as shown—an irregular
figure generated by an engine indicator. They
came as mechanical and digital devices, digital
engine indicator relies in digital transducers

It is imperative to know the area of the diagram, an

irregular figure, as it represents the cyclic work of
the engine, since the design and performance of
an engine relies on the accuracy of the
measurement of said parameter. Customary Indicator Diagram of a Four
Stroke Engine
OBJECTIVES
After successfully finishing the topic you should have the ability to:

o differentiate typical polar from digital planimeters as to their configurations, use, accuracy, and
adaptability
o ability to calibrate planimeters
o explain the principles on how the different planimeters work
o adept with the different industrial application of planimeters.
o use the aforementioned planimeters in measuring irregular figures like engine displacement
curves, maps, and the like
o Develop professional work ethics, including precision, neatness, safety, and ability to follow
instructions.
o proficient in oral and written communication, a must in the preparation of quality technical
reports of laboratory experiment/test conducted;
o team spirit to collaborate with other students in planning and performing laboratory
experiment/test on area measurement;
o creative ability to introduce new concepts/ideas in area measurement experimental
methods—beyond traditional classroom instruction—backed by stock knowledge and
research; and
o abreast of the emerging new technologies in area measurement instruments/devices.

Engine Indicator

An engine indicator is an instrument that graphically

record the pressure versus piston displacement
through an engine stroke cycle. It consists of a piston,
spring, stylus, and recording system.
21
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Engine Indicator Diagram

MEASAREAMENT OF AREA BY PLANIMETER

o mechanical planimeter
o digital planimeter

Mechanical Planimeter

A device that you can use to compute the area of an

figure by tracing the perimeter of a scale drawing of an
irregular figure with the tracing point on the planimeter.

In Mechanical Engineering practice, it is used to

measure irregular figures generated by Engine Indicator,
a device that measures the pressure inside the cylinder
of a working engine.

The most commonly used

instrument is called the polar
planimeter, as shown, its parts Polar Planimeter is a device used to
include an anchor point, pole; a measure the area of irregular figures
tracing point, tracer, a
vernier, measuring wheel or
roller. an adjustable arm, tracer
arm, is graduated to permit
adjustment to conform to the scale
of the drawing. This adjustment provides a direct relation between the area traced by the tracing
point and the rotation of the roller. As the tracing point is moved over the paper, the drum, and
the dial, rotate. The dial records the number of rotation.
To operate a planimeter, the user selects a starting point on the boundary of the region to be
measured, places the tracer point there, and sets the counter on the wheel to zero. The user then
22

moves the tracer point once around the boundary of the region, as shown in Figure 5. The tracer
point is typically a stylus or a point marked on a magnifying glass to facilitate the tracing. In a
Page
polar planimeter, as the tracer point moves, the elbow at the hinge will flex and the angle between
the pole arm and the tracer arm will change. In a linear planimeter, the end of the tracer arm in
the track will slide along the track. In both planimeters the wheel rests gently on the paper, partially
rolling and partially sliding, depending on how the tracer point is moved. If the pointer is moved
parallel to the tr acer arm, the wheel slides and does not roll at all. If the pointer is moved
perpendicular to the tracer arm, the wheel rolls and does not slide at all. Motion of the pointer in
any other direction causes the wheel to both roll and slide. When the tracer point returns to the
starting point, the user can read the area from the scale on the wheel

Digital Planimeter Working Principle

The working principle of the algorithm used

in the digital planimeter is based on the
green theorem. This theorem helps in
calculating the area.

The basic fundamental involved in this is the

integral calculus. In this, the whole figure is
sub-divided into different segments. The
area of these segments is calculated and
then added up in order to measure the whole
area of the figure

A digital planimeter ha a rotary encoder,

which is the equivalent of the integrating
wheel of mechanical planimeter.

An electronic circuit measures the pulses of rotary encoder and area is displayed
in digital form.

Topic Questions

o discuss the typical polar and digital planimeters and show how they differ in
 construction,
 use,
 accuracy, and adaptability
o explain working principle of
 polar planimeter and
 digital planimeter
o discuss how a planimeter measure the area of a ring shaped doughnut.
o explain the principles on how the different planimeters work
23
Page
o devise a plan on how to measure the aggregate land area of the municipalities/cities
surrounding;
 Taal lake
 Laguna lake
 Kaliraya Lake
 Lake Buhi
o Discuss the principle of operation of newly invented devices that can
measure irregularly shaped figures.

Suggested Videos and Readings

o https://youtu.be/4IN1HTyQU6
o https://youtu.be/WHpiAKMe3MA
o https://youtu.be/l_k_0hRpOA4
o https://youtu.be/aLSx1eM27P4
o Amsler, J. (1856). Ueber die mechanische Bestimmung des Flächeninhaltes, der statischen
Momente und der Trägheitsmomente ebener Figuren, insbesondere über einen neuen
Planimeter. Vierteljahresschrift der Naturforschenden Gesellschaft in Zürich. 41–
70. [Google Scholar]
o Apostol, T. M. (1957). Mathematical Analysis: A Modern Approach to Advanced
Calculus. Boston: Addison-Wesley. [Google Scholar]
o Bochner, S. (1955). Green-Goursat theorem. Math. Z. 63: 230–242.
DOI: 10.1007/BF01187935. [Crossref], [Google Scholar]
o Casselman, B., Eggers, J. (2008). The Mathematics of Surveying: Part II. The Planimeter. American
Mathematical Society Feature Column, June–July. ams.org/featurecolumn/archive/surveying-
two.html [Google Scholar]

24
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MODULE 5: MASS AND WEIGHT MEASUREMENTS
OVERVIEW

This module will clear your notion about mas and weight as they are ubiquitous in Mechanical
Engineering practice.

Measurement training, using mass and weight implements is thereby imperative for you to qualify
in the trade.

After successfully finishing the topic you should have the ability to:

o adept in the configuration, use, care, of the different mass and weighing scales.
o differentiate mechanical and electronic scales.
o proficient in the various applications, in consideration to their respective, ranges, sensitivity to
substances and environment, accuracy and the like.
o adept of the different industrial mass and weight measuring instruments/devices, as to their
constitution, principles of operation, application, care, solution and calibration.
o explain the principles on how the different mass and weight measuring devices work as to
how they react environmental conditions and the like
o proficient in oral and written communication, a must in the preparation of quality technical
reports of laboratory experiment/test conducted;
o team spirit to collaborate with other students in planning and performing laboratory
experiment/test on mass and weight measurement.
o creative ability to introduce new concepts/ideas in mass and weight measurement
experimental methods—beyond traditional classroom instruction—backed by stock
knowledge and research; and
o abreast of the emerging new technologies in mass and weight measurement
instruments/devices.

Mass is a measure of the amount of matter something contains, while Weight is the
measurement of the pull of gravity on an object.

Mass is measured by using a balance comparing a known amount of matter to an unknown

amount of matter. Weight is measured on a scale. To weigh very bulky, big objects, users need
a scale that's strong enough to resist constant, heavy-duty weighing and wide enough to
accommodate large objects.

Platform Scales

Platform scales offer a practical solution that simplifies

weighing of oversized animals or items, which can be
both intensive and time consuming. This post provides
a quick overview of platform scales, highlighting their
main features and industry applications.
25

Platform scales are usually simple tools, made of

stainless steel for easy cleaning or with a diamond plate
Page

surface for added grip. Some have wheels to be moved

more easily. They tend to be very sturdy with a high capacity, and components like cables are
shielded for extra durability. They are available in varying sizes and have functions adapted to
various applications, such as counting or check weighing. Some platforms, like the PTM, have
integrated ramps, while others have them as optional accessories.

Working Principle of Platform Scale

Platform scales can be quite versatile and usually require scale indicators to be connected to the
platform base in order to function to the best of their potential. Pairing them up with indicators
allows operators to fully use their high capacity and weighing functions including parts counting,
check weighing, and even to perform percentage weighing. They're also compatible with
accessories such as printers and computers, to keep track of the data, useful for businesses with
a lot of volume or inventory management.
Use of Platform Scales

Platform scales are used in many industries, wherever their sturdy construction and high capacity
is useful. They're often required in manufacturing and business settings to weigh bulky items such
as containers or pallets, or to count a very high amount of smaller pieces such as screws, bolts
or mechanized parts. Some veterinarians and zoos use platform scales to comfortably weigh large
animals, while doctors and hospitals can use them to weigh wheelchair bound patients. Farmers
and food processing plants use them to weigh bulk commodities or grain sacks. Regulated
platform scales are also used in airports to weigh luggage. Some platform scales, like our PT, are
trade approved when used alongside GK-M indicators and can be used in commercial settings.

Choosing the Right Platform Scale

While a platform scale seems straightforward, there is variety, and many different models in our
selection. To select the ideal platform scale for your application, first consider capacity and
readability. If you weigh or count smaller goods or animals, you don't need to spend the extra
money on a high-capacity industrial platform.

Next is the size of the platform. If you weigh small but heavy items, you can get a platform with a
high capacity but smaller dimensions, like a GB or GF, to ensure it doesn't take up too much
space. If you're going to be moving the scale around, make sure it can fit through doors and into
places where it will be used.

Consider the various types of indicators and the features you need. If your daily tasks are varied
and involve many different applications, a versatile, wash-down indicator like the IP67-
rated AE403 is probably your best bet. The GC is a more specialized indicator, ideal for counting
tasks, while the GK can perform many applications and is approved for trade use.
What you will be weighing is also important to factor in the fabrication of the platform. If you weigh
food or animals, an IP66-rated scale made of stainless steel is easy to clean. If you weigh drums
or patients in a wheelchair, the ramps enable easy access, and the added grip of the diamond
plate surface may be worth investing in.
26

Platform scales are used in many industries, wherever their sturdy construction
and high capacity is useful. They're often required in manufacturing and business
Page
settings to weigh bulky items such as containers or pallets, or to count a very high
amount of smaller pieces such as screws, bolts or mechanized parts. s website

Digital Weighing Scale

Electronic digital scales display weight as a number, usually on a liquid crystal display (LCD).
They are versatile because they may perform calculations on the measurement and transmit it to
other digital devices.
In a digital scale, the force of the weight causes a spring to deform, and the amount of deformation
is measured by one or more transducers called strain gauges.
A strain gauge is a conductor whose electrical resistance changes when its length changes.
Strain gauges have limited capacity and larger digital scales may use a hydraulic transducer
called a load cell instead.
A voltage is applied to the device, and the weight causes the current through it to change. The
current is converted to a digital number by an analog-to-digital converter, translated by digital logic
to the correct units, and displayed on the display. Usually the device is run by
a microprocessor chip.
Load Cells

Load cells are used as a part of the weighing system and to prevent overloading. The high
security factor ensures the load cells withstand demanding conditions. Application-include weigh
bridge

A weigh bridge is a platform scale that stands flush with a road and is used for weighing trucks,
livestock, etc.

Topic Questions

o discuss the various types of mass and weight measuring devices and show how they differ
in:
 construction,
 use,
 accuracy, and adaptability
o explain working principle of
 customary platform scale and
 digital weighing scale
o explain the principles of how various weighing work
o explain why mass and weigh area great consideration in designing a machines.
o discuss the principle of operation of newly invented devices that can measure
mass and weight.
27
Page
Sources and Further Reading Video Viewing
o (https://creativecommons.org/licenses/by-sa/4.0)]
o What is a Load Cell?
o How Does A Strain Gage-based Load Cell Work?
o Load Cell Measurement Applications
o Considerations When Using Load Cells
o https://youtu.be/DRsx7k6fRzw
o https://youtu.be/AmVaP5niv1Y

28
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MODULE 6: VELCITY MEASUREMENT
OVERVIEW
The module introduces you to various velocity measuring instruments/devices
used in Mechanical Engineering Practice, Rotating Equipment Engineers are in
charge of the design, installation, and maintenance of rotating equipment, like
drilling rig in oil industry, pumps and turbines in power plants, heavy equipment, in
mining and construction and vehicles are likewise in their care, all of which have
rotating parts.
The rotation should be kept under control to keep machines in good operation, to
avoid mechanical failures caused by irregular rotary movement. It is then
imperative to regularly measure the angular speed of rotating bodies using an
instrument/device called tachometer.

After successfully finishing the topic you should have the following capabilities:
o differentiate the various types of speed measuring devices;
o adept in the principle of operation of the respective instruments/devices for speed
measurement;
o appropriate use of speed measuring instruments/devices in industrial applications;
o proficient in oral and written communication, a must in the preparation of quality technical
reports of laboratory experiment/test conducted;
o team spirit to collaborate with other students in planning and performing laboratory
experiment/test on velocity measurement.
o creative ability to introduce new concepts/ideas in velocity measurement experimental
methods—beyond traditional classroom instruction—backed by stock knowledge and
research; and
o abreast of the emerging new technologies in area measurement instruments/devices.

Instruments/Devices in Speed Measurements

TACHOMETER

tachometer, device for indicating the angular (rotary) speed of a rotating shaft. The term is usually
restricted to mechanical or electrical instruments that indicate instantaneous values of speed in
revolutions per minute, rather than devices that count the number of revolutions in a measured
time interval and indicate only average values for the interval.

Rotation is one of basic motions, which is common in machines like motors, gears, and other
wheels. The rotation should be under control to keep machines in good operation, and a lot of
mechanical failures are caused by the rotary movement. So it is important to measure the angular
velocity.
To measure angular velocities, contact-type sensors are widely used, such as mechanical
29

tachometers, optical tachometers, photoelectric encoders, and optical encoders . These methods
are usually based on mechanical contact, and as a result, they are easily affected by the rotation
Page

of the target or the small target inertia. In the past twenty years, noncontact methods have been
developed like tomography, ultrasound, laser, and computer vision [2]. The advanced sensors
can overcome the defects of contact-type sensors, and computer vision could be more widely
used compared with the other noncontact sensors.
The device comprises of a dial, a needle to indicate the current reading, and markings to indicate
safe and dangerous levels. The word comes from the Greek ‘tachos’ meaning speed and ‘metron’
meaning measure so tachometer and speedometer have become interchangeable and
essentially both measure speed.

Historically, the first mechanical tachometers were designed based on measuring centrifugal
force: an inertial force directing away from an axis of rotation that acts on all objects as viewed
from a rotating frame of reference. In 1817, it was adapted to be used for measuring the speed of
machines and since 1840, it has been predominantly used to measure the speed of vehicles;
specifically, locomotives.

Advanced tachometers have novel uses. For example, in the medical field, a haematachometer
placed in an artery or vein can estimate the rate of blood flow from the speed at which the turbine
spins. The readings can be used to diagnose circulatory problems like clogged arteries.

Types of Tachometers

Common Types of Tachometers

o Analog tachometers - Comprised of a needle and dial-type of interface. They do not have
provision for storage of readings and cannot compute details such as average and
deviation. Here, speed is converted to voltage via use of an external frequency to
voltage converter. This voltage is then displayed by an analog voltmeter.

o Digital tachometers - Comprised of a LCD or LED readout and a memory for storage. These
can perform statistical operations, and are suitable for precision measurement and
monitoring of any kind of time-based quantities. Digital tachometers are more common
these days and they provide numerical readings instead of using dials and needles.

o Contact and non-contact tachometers – The contact type is in contact with the rotating
shaft and uses an optical encoder ot magnetic sensor. The non-contact type is ideal for
applications that are mobile, and uses a laser or optical disk. Both of these types are
data acquisition methods.

o Time and frequency measuring tachometers – Both these are based on measurement
methods. The time measurement device calculates speed by measuring the time interval
between the incoming pulses; whereas, the frequency measurement device calculates
speed by measuring the frequency of the incoming pulses. Time measuring tachometers
are ideal for low speed measurements and frequency measuring tachometers are ideal for
high speed measurements.

Working Principle

The working principle of an electronic tachometer is quite simple. The ignition system triggers a
30

voltage pulse at the output of the tachometer electromechanical part whenever the spark plug
fires. The electromechanical part responds to the average voltage of the series of pulses and it
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shows that the average voltage of the pulse train is proportional to engine speed. The signal from
the perception head is transmitted by standard twin screened cable to the indicator.
The tachometers are temperature compensated to be able to handle operations over an ambient
temperature range of – 20 to +70°C (-4 to +158°F).

The tachometer in a vehicle enables the driver to select suitable throttle and gear settings for the
driving conditions as prolonged use at high speeds can cause insufficient lubrication which will
affect the engine. It enables the driver to prevent exceeding speed capability of sub-parts such
as spring retracted valves of the engine, and overheating, thereby causing unnecessary wear or
permanent damage and even failure of engines.

Applications
The following are the key application areas of tachometers:

o automobiles, airplanes, trucks, tractors, trains and light rail vehicles

o laser instruments
o medical applications
o analog audio recording
o numerous types of machinery and prime movers
o to estimate traffic speed and volume.

Topic Questions

o discuss the various types of measuring devices for speed and show how they differ in
 construction,
 use,
 accuracy, and adaptability
o explain working principle of
 customary tachometer and
 digital tachometer
o discuss how a tachometer reading is related to linear reading of a speedometer in a car
dashboard
o explain the principles on how the different tachometers work

Related Stories

o Top to Bottom Services Monitors Real Estate Inspections Using Track What Matters GPS
Solution
o What is Torque Ripple and Cogging Torque in Electric Motors
o NASA's TES Satellite Instrument Helps Clarify What Happens to Precipitation That Falls on
Land
o
31
Page
 o why is it tachometer an indispensable instrument for rotating machine engineers
o devise a plan on how to measure the
o Discuss the principle of operation of newly invented devices that can
measure rotational speed.
o How are tachometers associated with predictive maintenance?

Sources and Further Reading Video Viewing

 ELECTRICAL TACHOMETERS (MMC SERIES)- Industrial Instruments

 Maas.S .Austin-Healey Sprite Electronic Tachometer Conversion.Nonlintec.2009
 How Do Tachometers Work? - eHow
 Digital Tachometers -Esters Elektronik
 https://youtu.be/TzWbGhELqz4
 https://youtu.be/_Eq8kuxFtvM
 https://www.academia.edu/17167761/TACHOMETERS?auto=download

32
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 MODULE 7: FLUE GAS ANALYSIS
Overview

The module helps you demystify how

flue gas analysis work on:
o efficiency of the different industrial
equipment using combustion of fuels
in their operations.
o compliance of environmental
standards enforced by “RA 8749,
Philippine Clean Air Act”,

After successfully finishing the topic you should have the ability to:

o Explain the configurations of flue gas analyzers, ranging from mechanical to electronic
analyzers.
o appropriate use of gas analyzers in various applications, in consideration to their respective,
ranges, response time, sensitivity to substances and environment, accuracy and the like.
o adept with the different industrial flue gas analyzers, as to their principles of operation,
application, care, solution and calibration.
o proficient in oral and written communication, geared towards quality laboratory
experiment/test technical reports;
o team spirit to collaborate with other students in planning and performing laboratory
experiment/test on area measurement.
o creative ability to introduce new concepts/ideas in flue gas analysis experimental methods—
beyond traditional classroom instruction—backed by stock knowledge and research; and
o abreast of the emerging new technologies in flue gas analysis instruments/devices.

Flue Gas
The term ‘flue gas’ refers to the hot gas emissions that are generated during the
combustion process and emitted via chimney or flue of an industrial plant or building.
Flue gas analysis
The flue gas analysis is performed to determine the components of flue gas, the result reveals
the correct air fuel ratio, excess air, combustion products and unburnt components.

Two methods of measurement of constituents of exhaust gases:

33

o Conventional Method
Page

o Modern Methods.
Conventional Method:
Orsat Analysis
A typical Orsat apparatus for flue gas analysis is shown in the figure have essential parts as:
o A measuring burette A, surrounded by water jacket to
maintain a constant temperature during the
experiment.
o Three absorption pipettes B, C and D which provide
for the absorption of CO2, O2 and CO respectively.
The lower end of each pipette extends almost to the
bottom of its respective chemical storage jar. Each of
the absorption pipette is connected at its upper end to
a capillary tube header and these headers are
interconnected by means of a manifold having cocks.
This manifold is connected to the measuring burette.
Each of the absorption pipettes is fitted with a number
of small glass tubes which give a great amount of
surface, wetted by the absorbing reagents, exposed
to the gas under analysis.
o A leveling bottle E, connected to the lower end of the
measuring burette.
o Breathing chamber to which breathing tubes from
absorption pipettes are connected during use. The
purpose of this expansion chamber is to provide breathing action and at the same time
prevent absorption of oxygen from the atmosphere. Carbon dioxide is absorbed in pipette
B, which is filled with caustic potash KOH. This solution will absorb about twenty times its
volume of CO2. Oxygen is absorbed in pipette C, which contains an alkaline solution of
pyrogallic- acid.
The solution for absorbing O2 will absorb only about twice its own volume of O2. It will also absorb
CO2 and, therefore, we must be very careful to be certain that all CO2 is absorbed in pipette B
before the exhaust gas sample is passed to pipette C. Carbon monoxide, is absorbed by an acid
solution of cupreous chloride in pipette D.

This pipette contains some metallic copper to keep the solution energized. This, solution will
34

absorb CO only to the extent of about its own volume. This solution will also absorb O2. Therefore,
Page
the solutions used in pipettes C and D must be protected from deterioration by absorption of
oxygen from atmosphere.

The nitrogen is obtained by difference. In order to get the correct results, the absorption must
occur in the order indicated. The reagents should be fresh and kept protected from atmospheric
air. All connections between the various parts of the apparatus must be leak proof. As the sample
of flue gas is collected over water, the above analysis is the dry flue gas analysis.

The combustion is seldom complete and some carbon monoxide will usually be present even
though excess air is supplied. The oxygen content of the dry products of combustion is a more
reliable indicator of excess air than is the carbon dioxide content.

Modern Methods
The modern methods used for exhaust gas analysis are:
o Gas chromatography
o Non-destructive Infra Red Analyzer (NDIR)
o Flame ionization detector (FID)
o Smoke meter.

Gas Chromatography:
The flue gas/emission analysis is by gas chromatography technique, an extremely versatile
method of analyzing the complex chemical mixture based on phenomenon on the preferential
absorption separation. The constituent chemical species of gas, when passed through the
absorbing systems, separate the molecules which are detected by analog sensor as they come
out of the chromatographic column.
The analog sensor detects some different property as the separated molecules. This is the only
method by which each component of exhaust sample can be identified and analyzed. However,
it is very time consuming and sample can be taken in batches.
The
35
Page

arrangements are as shown in fig.

Non-Destructive Infra-Red Analyzer (NDIR):
The analyzing system of an excellent NDIR
is using a unique micro flow type of
detection. The infra-red energy of a
particular wave length or frequency is
peculiar for a certain gas that gas will absorb
a infra-red energy of this wave length and
transient infra-red of other wave length.

The absorption board for CO is between 4.5 – 5.0. So energy absorbed at that ware length is the
indication of concentration of CO in the exhaust gas. The measurement of CO, CO2 and HC which
have clear infra-red absorption peals can be measured accurately.
However usually the exhaust gas sample to be analyzed contains other species which also
absorbed infra-red energy at same frequency. For example an NDIR analyzer is sensitive to n-
hexane for detection of HC response equally well to other paraffinic HC but not the acetylenes or
aromatics.

Flame Ionization Detector (FID)

It uses FID burner for analysis. The working principle of
FID is that H2 air flame contains a negligible amount of
ions. However, if ever trace amount of an organic
compound such as hydrocarbon are introduced in the
flame large, number of ions are produced.
If the polarized voltage is applied across we have burner
adjacent collector and ion migration will produce a
current proportional to number of ion and thus to HC
concentrations present in the flame.
The number of carbon atoms passing through a flame in
unit time decides the output of the FID. In other words
output of FID is directly proportional to velocity of carbon atoms through flame. This hexane
C6H14 would give the output.

Presence of oxygen in exhaust gas may slightly affect the FID reading but CO, CO2 water NO2 and
H2 has no affect on FID reading.
36

FID analysis is widely used because of the fact that it has very fast process and gives, accurate
Page

measurement of HC and exhaust gases concentration as low as ppm can be measured.

Components of a Flue Gas

The actual composition of flue gas will depend largely on what is being burned and how. However,
flue gas typically consists of the following:
o Carbon dioxide
o Nitrogen
o Sulfur
o Water vapor
o Oxygen
o Carbon Monoxide
o Solids (dust, soot)
o and a number of other pollutants
Of those emissions, carbon dioxide and nitrogen are the most harmful. They are both dangerous
to humans and can also have a significant environmental impact, damaging the ozone and
contributing to global warming.
Fortunately, the amount of air pollutants carried in flue gas can be mitigated through the use of
dedicated purification units and switching to low-emission fuels. However, in order to monitor and
control such processes, it is important that you are conducting regular flue gas analysis.
Importance of flue gas analysis

Flue gas can tell you a lot about the performance of a heating system or power generation plant.
Regular flue gas analysis is a great way of ensuring that the plant is achieving optimal efficiency
at all times.
Flue gas analysis will give you an indication of whether or not you are achieving maximum
possible carbon combustion in your fuel.
You can also analyze your flue gas in order to determine environmental impact and whether you
are maintaining compliance with local emissions regulations.
The environmental law, RA 8749, Philippine Clean Air Act, is stringent in emission standards
when it comes to pollutants and emissions, so regular flue gas analysis is a necessary part of
meeting those regulations and ensuring both legal and ethical obligations are maintained.
Instrument or Devise Used for Flue Gas Analysis

The right flue gas analysis for your needs will depend mainly on what type of generator you are
studying.
Different devices come with a variety of different features. Some analysis tools come with
specially designed printers that enable users to quickly and easily create simple, clear reports
while on the work site.
37
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Topic Questions

o discuss the various types of measuring devices for flue gas and show how they differ in
 construction,
 use,
 accuracy, and adaptability
 explain working principle orsat gas analyzer and
 digital gas analyzers
o relate the result of a flue gas analysis in the optimal efficiency of industrial equipment related
to combustion of fuels.
o why is it flue gas analyzer an indispensable instrument for:
 Engineers practicing thermal engineering.
 Environmental Engineers/technicians
o devise a plan on how to measure the emissions of power plant without having a flue gas
sample
o discuss the principle of operation of newly invented devices that can
measure flue gases differently from present ones being in use.

Sources for Further Readings and Video Viewing

Home ›› Thermodynamics ›› Fuels ›› Combustion ›› Measuring the Constituents of Exhaust

Gases
o www.eltra.com/combustion/analysis+49 800 7237007103
o en.tyzkkj.com/gas_analyzer/cems

38
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MODULE 8: CALORIMETRY
Overview
The module will guide you on how heating values of respective fuels in use are measured using
calorimeters. Likewise, you will learn how heating of fuels will influence the optimal performance
of things they propel, ranging from industrial plants, heavy equipment, and fuel fed engines that
include cars.
After successfully finishing the topic you should have acquired the following attributes.

o familiarity with the constitution, principles of operation, application, care, and calibration of
devices used in calorimetry.
o appropriate skills in the use, care and calibration of said device.
o adept in the use the different industrial calorimeters that measure the calorific values of
different types of fuels.
o relate acquired skills in industrial use of calorimeters.
o proficient in using calorimeters for different applications in industry.
o proficient in oral and written communication, geared towards quality laboratory
experiment/test technical reports;
o team spirit to collaborate with other students in planning and performing laboratory
experiment/test on calorimetry.
o creative ability to introduce new concepts/ideas in heat measurement experimental
methods—beyond traditional classroom instruction—backed by stock knowledge and
research; and
o abreast of the emerging new technologies in flue gas analysis instruments/devices.

Calorimetry

The science or act of measuring changes in state variables of a body for the purpose of deriving
the heat transfer associated with changes of its state due, to chemical reactions, physical
changes, or phase transitions under specified constraints. Calorimetry is performed with
a calorimeter.

Calorimeter

Calorimeter, is a device for measuring the heat developed during a mechanical, electrical,
or chemical reaction, and for calculating the heat capacity of materials.

Adiabatic calorimeter: Some heat is always lost to the container in an adiabatic calorimeter, but
a correction factor is applied to the calculation to compensate for heat loss. This type of
calorimeter is used to study runaway reactions.

o Reaction calorimeter: In this type of calorimeter, the chemical reaction occurs within an
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insulated closed container. Heat flow versus time is measured to arrive at the reaction heat.
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 This is used for reactions intended to run at a constant temperature or to find the maximum
heat released by a reaction.
o Bomb calorimeter: A bomb calorimeter is a constant-volume calorimeter, constructed to
withstand the pressure produced by the reaction as it heats the air within the container. The
temperature change of water is used to calculate the heat of combustion.
o Calvet-type calorimeter: This type of calorimeter relies on a three-dimensional fluxmeter
sensor made of rings of thermocouples in series. This type of calorimeter allows for a larger
sample size and reaction vessel size, without sacrificing the accuracy of the measurement.
o Constant-pressure calorimeter: This instrument measure the enthalpy change of a
reaction in solution under conditions of constant atmospheric pressure. A common example
of this type of device is the coffee-cup calorimeter.

Calorimeter Principle

The body at higher temperature releases heat while the body at lower
temperature absorbs heat. The principle of calorimetry indicates the law of
conservation energy, i.e. the total heat lost by the hot body is equal to the
total heat gained by the cold body.

This Module Will Focus Mainly on Adiabatic Bomb Calorimeter

Bomb Calorimeter

A bomb calorimeter is a type of constant-volume

calorimeter used in measuring the heat of
combustion or heating value of a particular reaction.
The bomb must be robustly designed to withstand the
large pressure developed during the combustion of a
sample, hydrocarbon material.
Preparation Bomb Calorimeter
o The bomb is charged with oxygen (typically at 30
atm) after filling the crucible with a weighed mass
of sample (typically 1–1.5 g) and arranged with an
ignition coil, connected to the terminals of ignition
wires.
o The charged bomb is submerged under a known
volume of water (2000 ml) before the charge is
electrically ignited.
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o After ignition heat released from the combustion
flow from the bomb to the surrounding water, thus
raising the temperature the water jacket. The
temperature change in the water is then
accurately measured with a differential
thermometer. This reading, along with a bomb
factor (which is dependent on the heat capacity
of the metal bomb parts), is used to calculate the
energy given the combustion of the sample.
o A correction is made to account for the electrical
energy input, the burning fuse, and acid
production (by titration of the residual liquid).
After the temperature rise has been measured,
the excess pressure in the bomb is released.
Basically, a bomb calorimeter consists of a small
cup to contain the sample, oxygen, a stainless steel
bomb, water, a stirrer, a thermometer, the dewar or
insulating container (to prevent heat flow from the
calorimeter to the surroundings) and ignition circuit connected to the bomb. By using stainless
steel for the bomb, the reaction will occur with no volume change observed.

Digital Bomb Calorimeter

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PREPARATION OF SAMPLES FOR DIGITAL BOMB CALORIMETER
Generally,
approximately 0.5g of a
sample is weighed into
the crucible, the cotton
thread is attached to the
wire, and the crucible is
put into the vessel. This
applies to powdery
substances. But what
about other substances?

LIQUID, NON-VOLATILE SAMPLES

This would be oils. Use a syringe to
transfer the oil into the crucible. Take
care not to have any spillage or oil on
the crucible walls or rim.

LIQUID, VOLATILE SAMPLES

The evaporation of the liquid must be prevented during the handling of the sample. This is
achieved by gluing a tape to the crucible rim and injecting the liquid through the tape with a
syringe. The complete process is a little involved :
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 Measure the calorific value of the tape as KJ/g beforehand in a normal procedure.
 Tare a crucible and glue the tape to the rim. Trim any overhang or corners with a sharp
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knife. Weigh the crucible and cover, establish the mass of the used tape.
  You can use the spike or cotton-addition method. In the cotton-addition method you have
to calculate the CV or the tape manually and add it to the cotton entry in the calorimeter. In
the spike method enter the weight into the spike mass and the CV into the spike CV.
 Tare the crucible and tape. Inject with a syringe the sample into the crucible by piercing the
tape. Enter the sample weight into the calorimeter.
 Put the crucible into the vessel with the cotton thread lying on top. Put the vessel into the
calorimeter and if needed instruct the calorimeter to perform a spike calculation.

FINE POWDER SAMPLES

The danger with these materials is that they explode after ignition and some unburned material is
deposited on the vessel walls. You need to use a gelatin capsule as follows :

 Weight a gelatin capsule

and establish its calorific
value (CV) before
proceeding with the
actual dust sample.
 Weigh a new gelatin
capsule, then tare the
balance. Fill the capsule
with the dust material,
close it, and weigh it again. This is the sample weight.
 Enter the gelatin capsule weight in the spike mass and the gelatin capsule CV into the
spike CV. Enter the dust sample weight into the sample mass. You can also use the
"cotton addition" method, but need to calculate the actual CV of the gelatin capsule before
adding it into the cotton correction.
 Perform the sample determination as normal. The gelatin capsule ignites very easy and
prevents the sample from "scattering".

GEL SAMPLES
A gel type substance would be butter or grease.
Scoop out the approximate amount and deposit it
into the crucible with a second spatula. Prevent the
material from ending up on the crucible rim.

LOW ENERGY, LOW COMBUSTIBLE SAMPLE, OR DIFFICULT TO IGNITE SAMPLES

The solution is SPIKING. This is the process in which the unknown sample is combusted in the
presence of a known material (the SPIKE), which is normally Benzoic Acid.

All DDS Calorimeters can handle spiking. The spike material is weighed first, and then the spike
mass (and if the spike material is different from Benzoic Acid: The spike calorific value) is entered
into the unit. Then the balance is zeroed and the unknown sample is weighed on top of the spike.
The unknown sample weight is entered into the calorimeter. Then the calorimeter must be
instructed to perform a spike calculation. The latest units perform a spike calculation automatically
when the spike mass is larger than zero. The calorimeter burns the complete material. It then
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calculates the complete released energy and subtracts the spike energy from it. It displays the
energy of the unknown sample only. This spiking method applies to sample which are too wet,
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don't like to ignite, and have too little energy.

Topic Questions

o discuss the various calorimeter types in terms of how they differ in;
 construction,
 use,
 accuracy, and adaptability
o explain working principle of;
 customary calorimeters
 digital calorimeters
o relate the result of a heating value of fuels the optimal efficiency of industrial equipments,
cars and related fuels propelled machines.
o why is calorimetry an indispensable tool for Engineers practicing thermal engineering.
o devise a do it yourself (DIY) plan on how to measure the heating value of fuel.
o discuss the principle of operation of newly invented devices that can measure
the heating values of fuel differently from present ones being in use.

Sources for Further Readings and Video Viewing

o https://youtu.be/EAgbknIDKNo
o https://youtu.be/yhNHJ7WdT8A
o What is a Calorimeter? - Definition, Uses & Equation - Video & Lesson Transcript |
Study.com
o en.sandegroup.com/calorimeters/coal

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