Instrumentation deals with measurement and control using instruments. An instrument is a device that measures process variables like pressure, level, temperature, and flow. Pressure is force per unit area and can be measured using instruments like barometers, manometers, and bourdon gauges. Level is important to measure in storage containers and can be done directly using sight glasses or floats, or indirectly using pressure-based methods. Temperature is a measure of hotness/coldness and instruments like thermocouples, thermistors, RTDs, and infrared thermometers are used. Flow rate is measured using ultrasonic flowmeters, paddlewheel sensors, vortex meters, pitot tubes, and turbine flow meters.

2.  Instrumentation is the branch of engineering that deals with
measurement and control.
 According to ISA (International Society of Automation,
Instrumentation Society of America): Instrumentation is a
collection of Instruments and their application for the purpose
of Observation, Measurement and Control.
 An instrument is a device that measures process physical
variables such as pressure, level, temperature, flow etc.

3.  Introduction of Pressure
 Units of Pressure
 Pressure Measuring Instruments

4.  Pressure is the force per unit area.
 OR
 Pressure is the action of one force against to the other
force. In other words we can say Pressure is a force
applied to surface.
 P= F/A

5.  Pressure is divided into following tow parts:
1. Static Pressure: When the force in a system under
constant pressure is called static pressure (i.e
unvarying).
1. Dynamic Pressure: If the force is varying the
pressure is said to be dynamic pressure (i.e
Varying).

6. Some units of pressure is given below:
 Psi
 bar
 mbar
 Pascal
 kPa

7. 1. Barometer
2. Piezometer or Pressure Tube
3. Manometer
4. Bellows
5. Bourdon Gauge
6. Diaphragm Pressure Gauge

8.  The barometer is a device that used for measuring the
local atmospheric pressure.

9. The Piezometer is used to
measure the static pressure
head of a liquid flowing at any
section of a pipe.

10. Manometers are pressure gauging devices using columns of
different liquids. The fluid whose pressure is to be determined
is called the metered fluid while the other fluid is called the
manometer fluid. The manometer fluid may be of higher
density or lower density than that of the metered fluid. These
devices can be used to gauge pressures of liquids as well as
gases. Manometers have connecting U-shaped tubes
containing different fluids.

11. Bellows are thin-walled metallic cylinders, with deep
convolutions, of which one end is sealed and the other
end remains open. The closed end can move freely
while the open end is fixed. When pressure is applied to
the closed end the bellows will be compressed

12. This device consists of a metallic tube of elliptical
section closed at one end A, the other end B being
fitted to the gauge point where the pressure is to be
measured. As the fluid enters the tube, the tube tends
to straighten.

13. A diaphragm pressure gauge is a device, that uses a
diaphragm with a known pressure to measure
pressure in a fluid.

14.  Most industrial process use liquid such as water,
chemical and fuels.
 These materials are stored in containers ready for on
demand use.
 It’s very important to know the level and remaining
volume of these materials.

15.  There are two methods for measuring level,
1. Direct Method
2. Indirect Method

16.  This is the simplest for measuring the liquid level. In
this method, the level of liquid is measured by
directly means of the following level indicters.
1. Sight Glass or Gauge Glass
2. Float Type or Float-Operated Level Gauge

17.  Sight glass is used for the continuous indication of
liquid level with in tank or vessel.

18.  One common form of level measuring system uses a
tape which is connected to a float. The height can be
read as the float moves with liquid level.

19.  Following are the Indirect methods of liquid level
measurement generally used in industries.
1. Hydrostatic Pressure Type
2. Ultrasonic Level Sensor

20.  Hydrostatic Pressure methods used for liquid level
measurement are listed below.
1. Pressure Gauge Method
2. Air Purge System
3. Diaphragm Box Type

21.  A simple pressure gauge can be used for level
measurement if its scale is properly calibrated for the
actual level, inside the tank or vessel.

22.  Air purge (bubbler tube) is one of the most popular
hydrostatic pressure types of liquid measuring system
which is suitable for any liquid.

23.  The diaphragm box level meter is used to measure
the level of the open tank. The box contains a large
amount of air, which is kept within a
flexible diaphragm. A tube connects the diaphragm
box to a pressure gauge.

24.  Temperature is the degree of hotness OR coldness of
object.
 Temperature is measured in following units
1. Kelvin
2. Celsius
3. Fahrenheit

25. 1. Thermocouples
2. Thermistors
3. Resistance Temperature Detector (RTD)
4. Infrared Thermometer
5. Thermometer

26.  Thermocouples are voltage devices that indicate
temperature measurement with a change in voltage.
As temperature goes up, the output voltage of the
thermocouple rises - not necessarily linearly.
 Thermocouple Types
1. Iron-Constantan
2. Chromel Alumel
3. Copper-Constantan

27.  A thermistor is defined as a type of resistor whose
electrical resistance varies with changes in
temperature.
 There are two types of thermistors:
1. Negative Temperature Co-efficient (NTC)
thermistors
2. Positive Temperature Co-efficient (PTC)
thermistors

28.  Resistance Temperature Detectors (RTDs), also called
Resistance Thermometers, An RTD is a type of
temperature sensor that changes resistance as it is
exposed to changes in temperature. It is made from a
length of platinum wire.

29.  An infrared thermometer is the device which has
ability to measure temperature from a distance. We
can say sometimes called laser thermometers as
a laser is used to help aim the thermometer, or non-
contact thermometers or temperature gun.

30.  A thermometer is a device that
measures temperature.
Thermometers are widely used
in technology and industry to
monitor processes, in medicine,
and in scientific research.

31.  A flow meter (or flow sensor) is an instrument used
to measure linear, nonlinear, mass or volumetric flow
rate of a liquid or a gas.

32.  The common types of flowmeters with industrial
applications are listed below
1. Ultrasonic Flowmeter
2. Paddlewheel Sensors
3. Vortex Meters
4. Pitot Tubes
5. Anemometers for Air Flow Measurement
6. Turbine Flow Meters

33. The ultrasonic doppler flow meters are commonly
used in dirty applications such as wastewater and
other dirty fluids.

34.  Paddlewheel flowmeters use the mechanical energy
of the fluid to rotate a paddlewheel in the flow
stream. Paddles on the rotor are inserted into the flow
to transform energy from the flow stream into
rotational energy.

35.  The main advantages of vortex meters are their low
sensitivity to variations in process conditions and low
wear relative to orifices or turbine meters. Also,
initial and maintenance costs are low.

36.  The pitot tubes offer the following advantages, low-
cost installation, much lower permanent pressure
loss, low maintenance and good resistance to wear.

37.  Hot wire anemometers are probes with no moving
parts. Air flow can be measured in pipes and ducts
with a hand held or permanent mount style.

38.  The turbine meter can have an accuracy of 0.5% of
the reading. It is a very accurate meter and can be
used for clean liquids and viscous liquids up to 100
centistokes.