This document discusses instrumentation and measurement principles. It defines instrumentation as the study of measuring instrument principles, operations for process variables, and design of measurement equipment. Measurement involves comparing something to a known standard and stating the uncertainty. There are seven fundamental SI units including the meter, kilogram, second, ampere, kelvin, candela, and mole. Derived units include the newton, joule, coulomb, weber, farad, and ohm. Most measuring instruments have three parts - a sensor that outputs a function of the measured variable, intermediate processing elements to convert the output, and an indicator or recorder for the final output reading.

1. HND 1 AGRIC & BIO- ENGINEERING
(FARM POWER & SOIL + WATER
OPTIONS)
R R Dinrifo, Ph.D

2. Course Content
1 Introduction: Units and Basic Standards
2 Linear Displacement Measurement
3. Measurement of Force & Its Effects
4. Pressure Measurement
5. Temperature Measurement.
6. Biological properties Measurement - ph
Measurement & Relative Humidity.
7 Density Measurement.
8. Flow Measurement & liquid Level Indicators:
9: Soil Water Monitoring & Measurement
10. Workshop Measuring Instruments:

3.  Instrumentation
◦ A branch of engineering that studies the principles
and operations of measuring instruments, of
process variables and the design and
implementation of equipment and systems that
incorporate them.

4.  Measurement is finding the size or amount of
some quantity, and expressing it as a number
of defined units
◦ All measurement is based on a comparison. In
general, the thing to be measured is compared with
something that has already been calibrated, or
measured against a known reference. However, a
measurement is not complete unless it includes a
statement of its uncertainty, or the confidence one
can have in it

5. All measurements are the product of a value
and a unit. Scientists and engineers base their
measurements on the International System of
Units (SI), together with definitions of the
seven units on which it is based.
 The seven SI units provide the basis from
which all other physical quantities can be
built up, or derived

6. Quantity Standard
unit
Symbol
Length Meter M
Mass Kilogram Kg
Time Second S
Electric Current Ampere A
Temperature Kelvin K
Luminous intensity Candela Cd
Matter Mole M
FUNDAMENTAL UNITS

7. Quantity Standard
unit
Derivation Symbol
Force Newtons kgm/s2 N
Work Joule N.m J
Electric charge Coulomb As C
Magnetic flux Weber Vs Wb
Electric
capacitance
farad A s/V F
Electric resistance Ohm V/A Ω
DERIVED
UNITS

8. Parts Of Measuring Instruments
The simplest measuring systems consist basically of three
functional units

9.  This gives an output that is a function of
the measurand (the input applied to it).
For most but not all sensors, this
function is at least approximately linear.
Some examples of primary sensors are a
liquid-in-glass thermometer, a
thermocouple and a strain gauge. In the
case of the mercury-in-glass
thermometer, the output reading is given
in terms of the level of the mercury.

10.  These are needed where the output variable of a
primary transducer is in an inconvenient form
and has to be converted to a more convenient
form. For instance, the displacement-measuring
strain gauge has an output in the form of a
varying resistance. The resistance change cannot
be easily measured and so it is converted to a
change in voltage by a bridge circuit.
 In some cases, the primary sensor and variable
conversion element are combined, and the
combination is known as a transducer.

11.  Signal processing elements exist to improve the
quality of the output of a measurement system in
some way. A very common type of signal
processing element is the electronic amplifier,
which amplifies the output of the primary
transducer or variable conversion element, thus
improving the sensitivity and resolution of
measurement.
 This element of a measuring system is
particularly important where the primary
transducer has a low output. For example,
thermocouples have a typical output of only a
few millivolts.

12.  Recorder or Indicator (or an end device): An
end device performs the final conversion of
measurement energy to an indication, record,
or the initiation of control. The end device
provides the means of indicating or recording
the data sensed by primary sensor and
altered by the intermediate means. The
readout may be analog or digital indication,
or reading

13.  The dynamic response of a measuring instrument
is the change in the output y caused by a change
in the input x. Both x and y are functions of time
t.
 Classes of Linear Instruments
◦ Zero Order Instruments
◦ A zero order linear instrument has an output which is
proportional to the input at all times in accordance with
the equation
◦ y(t) = Kx(t),
◦ where K is a constant called the static gain of the
instrument. The static gain is a measure of the
sensitivity of the instrument.

14.  A first order linear instrument has an output
which is given by a non-homogeneous first order
linear differential equation
◦ tau.dy(t)/dt + y(t) = K.x(t),
◦ where tau is a constant, called the time constant of the
instrument.
 In these instruments there is a time delay in their
response to changes of input. The time constant
tau is a measure of the time delay.
 Thermometers for measuring temperature are
first-order instruments. The time constant of a
measurement of temperature is determined by
the thermal capacity of the

15.  A second order linear instrument has an
output which is given by a non-homogeneous
second order linear differential equation
 d2y(t)/dt2 + 2.rho.omega.dy(t)/dt +
omega2.y(t) = K.omega2.x(t),
 where rho is a constant, called the damping
factor of the instrument, and omega is a
constant called the natural frequency of the
instrument.

16. Quiz
1. Instrumentation is about
a. the principles of operations of measuring instruments
b. Monitoring process variables
c. The design and implementation of measurement equipment.
d. All the options above
2. The standard unit for the measurement of time ia
a. hours
b. days
c. seconds
d. All the options above
3. The fundamental unit for luminous (light) intensity is
a. Watts
b. Kilowatt-hour.
c. Candelas
d. Ohms
4. Magnetic flux is measured ins of measuring instruments
a. Webers
b. Magnetics.
c. All the options above
d. Farad