This PPT file about Pressure and Level delver by Meer Muhammad (Electronic Engineer)

1. Pressure & Level

2. Instrumentation
 Instrumentation is the branch of engineering that deals with
measurement and control.
 According to ISA (International Standards of Automation):
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.
 Today we will study about Pressure & Level.

3. Pressure
 Introduction of Pressure
 Pressure Measuring Units
 Pressure Types
 Pressure Measuring Instruments

4. Introduction
 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 Measuring Units
Some units of pressure is given below:
 Bar
 Psi
 Pascal
 Torr

6. Types of Pressure
Absolute Pressure, Atmospheric pressure, Gauge Pressure, Vacuum
Pressure and Differential Pressure

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

8. Pressure Measuring Instruments
1. Barometer
2. Manometer
3. Bellows
4. Bourdon Gauge
5. Diaphragm Pressure Gauge

9. Barometer
 The barometer is a scientific instrument that used for
measuring the local atmospheric pressure.
 Application of Barometer:
1. Meteorologist use barometers for check changes in
the weather.
2. Atmospheric pressure
3. Altitude

10. Manometer
 A manometer is one of the most accurate devices for
measuring pressure.
 Manometer applications
1. Fluid flow measurement
2. HVAC system maintenance
3. Residential or Commercial furnace gas valve pressure
measurement
 There are three types of Manometer:
1. Manometer U-Type
2. Manometer Well Type
3. Manometer Inclined Type

11. Manometer U-Type
Both sides of the manometer open to the atmosphere,
the fluid level on one side will be the same as the level
on the other side because both sides are equal. Now
suppose one end of the U-tube manometer is
connected to an unknown pressure whose value must
be determined. The other
end is left exposed to the
atmospheric pressure.

12. Manometer Well Type
In the well type manometer, the pressure to be measured is
normally applied to the well. When pressure applied to the well
the level of liquid in the well falls by the distance ” x ” and the
level in the limb rises by the distance ” h “.
When the column of liquid (h + x) exerts a pressure equal to the
pressure applied to the well.

13. Manometer Inclined Type
 It is similar to a well type manometer in construction.
The only difference being that the vertical column
limb is inclined at an angle θ. Inclined manometers
are used for accurate measurement of small pressure.

14. Bellows
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.
Applications of Bellows
1. Compressed air systems
2. HVAC equipment
3. Pumping systems
4. Process equipment etc.

15. Bourdon Gauge
The Bourdon-tube gauge is one of the most
widely used instruments for measuring the pressure
of liquids and gases of all kinds, including steam,
water, and air up to pressures of 100,000 pounds per
square inch (70,000 Newton's per square cm).

16. Applications of Bourdon Gauge
1. Machine and plant engineering
2. Gas distribution
3. Automotive
4. Chemical Plants
5. Process equipment etc

17. Diaphragm Pressure Gauge
A diaphragm pressure gauge is a device, that uses a
diaphragm with a known pressure to measure
pressure in a fluid.
Applications
1. Chemical, petrochemical
2. Power plants, mining
3. On-/offshore
4. Environmental technology
5. Machine building and
general plant construction

18.  Introduction of Level
 Units of Level
 Level Measuring Methods
LEVEL

19.  Position of the surface of the liquid above or below a
fixed reference point or a datum line. The datum line
is the zero point from where the liquid surface is to be
measured.
 Level is measured in
Two types of tank
1. Open Tank
2. Close Tank
Introduction of Level

20.  Level is measured in any unit which can be used for
height.
For example:
1. Meter
2. Millimeter
3. Inches
4. Feet
5. Percentage (%)
Units of Level

21. Level Measuring Methods
1. Sight Glass or Gauge Glass
2. Float Local Indication
3. Dipstick
4. Displacer
5. Pressure Gauge Method
6. Air Purge System
7. Capacitance

22. Sight Glass or Gauge Glass

23. Float

24.  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.
Float Local Indication

25. Float
 Applications
1. Monitoring high value chemicals
2. Monitoring dispensed agricultural fertilizers
3. Small day tank level monitoring

26. Dipstick

27. Displacer
 Displacer don't ride on the surface of the liquid but it’s
designed to submerge in the liquid. Displacer mechanism
transfer the slight mechanical motions due to loss of
weight which can be used in instruments to indicate level.

28. Applications
 This Displacer level sensor is used in level
measurement applications such as Condensate drums,
Separators, Flash vessels, Storage vessels and tanks

29. Pressure Gauge Method
 There is a water tank that is
open at the top. A pressure
gauge at the bottom. The liquid
exerts a force on the bottom.
The force is proportional to the
depth of the liquid. Force at any
point in the tank varies with the
elevation of the liquid.

30. Air Purge System
Air purge (bubbler tube) is one of the most popular
hydrostatic pressure types of liquid measuring system
which is suitable for any liquid.
This system usually used for
the underground tanks.
Air continuously bubbling out
of the tube and the
instrumentation read back
pressure.

31. Capacitance
A capacitor is formed when a level
sensing electrode is installed in a
vessel. The metal rod of the
electrode acts as one plate of the
capacitor and the tank wall (or
reference electrode in a non-metallic
vessel) acts as the other plate. A
change in the value of the capacitor
takes place because the dielectric
between the plates has changed. RF
(radio frequency) capacitance
instruments detect this change and
convert it into a proportional output
signal.

32. Applications
 Capacitive level measuring instruments are used for
level detection in soils, tanks and bunkers, for both
limit detection and continuous measurement. These
instruments are used in all areas of industry such as
measuring liquid level as well as solid materials.