Measurement techniques for atmospheric, absolute, gauge and vacuum pressure
1. ARHAM VEERAYATAN INSTITUTE
OF ENGINEERING, TECHNOLOGY & RESEARCH
PRESENTED BY
KOTADIYA URVISH(150920106001)
KATHIRIYA VISHAL(15092010603)
VYAS KEYUR (150920106004)
MEASUREMENT OF
PRESSURE
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2. TOPIC
1. Units of Pressure Measurements
2. Pascal’s Law
3. Atmospheric ,Absolute ,Gage Pressure and Vaccum Pressure
4. Measurement of Atmospheric Pressure
5. Manometers
6. Micro manometer
7. Mechanical gage
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Pressure is define as force divided by area. (exerts on solid, gas,
liquid)
The unit of pressure is in Pa, psi, atm, bar, torr
F = force in newton/ lb
A = area in m2/ in2
P = F/A
1 psi = 6895 pa
1 bar = 105 Pa
1 atm = 101325 Pa
1 torr = 133.3 Pa
1. Units of Pressure Measurements
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System Length Force Mass Time Pressure
MKS Meter Newton Kg Sec N/M2 =
Pascal
CGS CM Dyne Gram Sec D/CM2
English Inch Pound Slug Sec PSI
Continue…….
7. 3.Atmospheric,Absolute,Gage,Vaccum Pressure
1. Atmospheric pressure :- the local atmospheric air exerts a normal pressure upon all
surfaces which is known as Atmospheric pressure.
2. Absolute pressure :- when pressure is measured above absolute zero as datum it is called
Absolute pressure.
3. Gage pressure :- when it is above the Atmospheric pressure as a datum it is called Gage
pressure.
4. Vaccum Pressure :- when it is below Atmospheric pressure as datum it is called Vaccum
Pressure.
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9. 4.Measurement of Atmospheric Pressure
There are three types of Atmospheric Pressure
1. Mercury Barometer
2. Aneroid Barometer
3. Barograph
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17. 6. Micro manometer
Definition :- A micro manometer is a special type of manometer designed
to measure extremely small difference in pressure.
There are two type of micro manometer
1. prandtal manometer
2. Air type centrifugal micro manometer
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I. Bourdon Gage:
Principles: change in curvature of the tube is proportional to difference of
pressure inside from that outside the tube
Applications: tire pressure, pressure at the top or along the walls of tanks or
vessels
7. Mechanical gage
19. Diaphragm (Ancient, mechanical)
If each element is sealed
with a known, fixed internal
pressure, flex will depend
on pressure change on
outside. Stacking amplifies
effect!