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CHAPTER 5 Pressure Measurement - Coggle Diagram
CHAPTER 5
Pressure Measurement
high pressure measurement
high wire pressure transducer
1.special techniques for measure the pressure above 1000 atm
2.based on electrical resistance change of a manganin(alloy of Cu, Ni, Mn) with hydrostatic pressure to accommodate a bulk compression
1.filled with kerosene(medium of transmitting pressure to the coil)
2.changes in resistance of the wire between A and B is measured like wheatstone bridge
LVDT
1.Transducer element used-Bellows
2.The pressure is applied to the Bellows
3.acts as a transducer element which converts the pressure into a displacements,x
4.x ,moved to the core and effect the voltage between primary and secondary coils.
5.the output reading is proportional to the displacement of the core(iron)
low pressure measurement
vacuum gauges
Types of vacuum gauges below 0.1 Torr range:
1.McLeod Gauge
2.Thermal Conductivity Gauge/Pirani Gauge
3.Lonisation Gauge
4.Knudsen Gauge
1.represent by unit Torr and micron
2.one Torr is pressure equivalent of 1 mm of Hg while 1 micron is 10^-3 Torr
3.manometer and elastic element gauges can be used to about 0.1 Torr.
moderate/medium pressure measurement
manometer
1.The simplest device for measuring static pressure.
2.the different in level h between the two limbs(p1-p2)
h=(p1-p2)/pg
characteristic:
1.non-corrosive
2.low viscosity
3.should have negligible
type manometer:
1.well type
2.inclined tube
3.micrometer
4.movable tube
bourdon tube
elastic type:
1.pressure applied the elastic elements will get deformed
2.will be measured mechanically or electrically
3.common used to measure pressure.
4.main elements is elastic bourdon tube
5.measured by amplified the motion of the tube end and indicated by a moving pointer on scale
elastic elements:
1.diaphragm
2.bellows
3.corrugated diaphragm
4.capsule
5.bourdon tube
6.helical tube
