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1. Pressure Measuring Devices
Subject: FM
Semester: 4th
Division: FX-1
Branch: Mechanical
Prepared By:
1. Akash Ambaliya (140030119003)
2. Ansari Mohammadarif (140030119005)
3. Girish Bhanderi (140030119012)
4. Ashish Parekh (140030119006)
Atmiya Institute of Technology & Science Gujarat Technological University

2. Pressure
Pressure (P) expresses the magnitude of normal force(F) per unit
area(A) applied on the surface.
SI units :- Pascal (N/m²)
Other units:- bar (=10⁵ pa), atm (=101.3kpa),
mm of hg or (torr = 0.133322kpa)

3. MECHANICAL ELECTROMECHANICAL
STATIC DYNAMIC(Force Summing
Devices)MANOMETER
U-TUBE
WELL TYPE
INCLINED
DIAPHRAM BELLOWS BOURDON-TUBE
CLASSIFICATION OF PRESSURE MEASUREMENT
FLAT CORRUGATED CAPSULE
C-TYPE HELICAL
TYPE
SPIRAL
TYPE

4. ELECTROMECHANICAL
POTENTIO
METER
PHOTOELECTRIC
TYPE
CAPACITIVE PIEZOELECTRIC
TYPE
INDUCTIVE

5. U- Tube Manometers
This manometer consist of U-shaped
tube in this manometric fluid is filled.
Water and mercury are used as a
manometric fluid.
Advantage of using these fluid is that
mass density of these fluid can be
obtained easily and they do not stick to
the tube.

6. Well Type Manometer
The well type manometer is widely used because of
inconvenience; the reading of only a single leg is required in
it.
It consist of a very large-diameter vessel (well) connected
on one side to a very small-sized tube.
Thus the zero level moves very little when pressure is
applied.

7. Calculations for manometers
to find the pressure..
Since, P = ρgh
h = (P₁ - P₂)/ρg
P₁ - P₂ = ρgh
Where, ρ - mass density of fluid
g - gravity
P₁ - unknown pressure
P₂ - atmospheric pressure

8. Inclined Manometer

9. Bourdon Tube Pressure Gauge
Principle:- The bourdon tube works on a simple principle that a bent tube
will change its shape .
As pressure is applied internally, the tube straightens and returns to its
original form when the pressure is released .
The tip of the tube moves with the internal pressure change and is easily
converted with a pointer onto a scale.
These devices should be used in air if calibrated for air and in liquid if
calibrated.

12. Bourdon Tube Pressure Gauge
ADVANTAGES
Inexpensive
Wide operating range
Fast response
Good sensitivity
Direct pressure measurements
DISADVANTAGES
Hysteresis on cycling
Sensitive to temperature
variations
Limited life when subjected to
shock and vibrations

13. Diaphragm
The diaphragm is a flexible disc, which can be either flat or with concentric
corrugations and is made from sheet metal with high tolerance dimensions.
The diaphragm can be used as a means of isolating the process fluids, or
for high pressure applications.
It is also useful in providing pressure measurement with electrical
transducers (LVDT).
It is used as primary pressure transducers in many dynamic pressure
measuring devices.

14. Diaphragm

15. Advantages of Diaphragm
Good for low pressure
Inexpensive
Wide range
Reliable and proven
Used to measure gauge, atmospheric and differential pressure.

16. Linear variable differential
transformer(LVDT)
This type of pressure measurement relies on the movement of a high
permeability core within transformer coils . the movement is
transferred from the process medium to the core by use of a diaphragm
,bellows or bourdon tube.
Working principle :-
◦ The LVDT operates on the inductance ratio between the coils. The
primary coil is located between two secondary coils and is energized
with an alternating current . Equal voltage are induce in the
secondary coil if the core is in the center when the core is moved
from the center position the result of the voltages in the secondary
winding will be different.

17. Conversion of ac to dc

18. Bellows
A bellows gauge contains an
elastic element that is a
convoluted unit that expands and
contracts axially with change in
pressure.
The pressure to be measured can
be applied to the outside or inside
of the bellows however, in
practice, most bellows measuring
devices have the pressure applied
to the outside of the bellows.

19. Thank You…