Pressure Gauge
A Gauge to measure and indicate pressure greater than ambient using ambient pressure as the datum point
Pressure Switch
A pressure switch is a form of switch that closes an electrical contact when a certain set pressure has been reached on its input. The switch may be designed to make contact either on pressure rise or on pressure fall.
Ambient Pressure
Ambient pressure is the pressure surrounding the measuring element.
Gauge Pressure
Gauge pressure is zero reference at ambient pressure which is equal to absolute pressure minus atmospheric pressure.
Absolute Pressure
Absolute pressure is zero reference against a perfect vacuum. It is equal to gauge pressure+ atmospheric pressure.
Differential Pressure
It is the difference in pressure between two points.
Vacuum Gauge
A gauge to measure and indicate pressure less than ambient using ambient pressure as the datum point
Compound Gauge
A gauge to measure and indicate pressure greater than and less than ambient using ambient pressure as datum point.
Differential Gauge
A gauge having two connections and a means to measure and indicate the difference between the two pressures.
Barometer
A gauge to measure and indicate Atmospheric pressure.
Pressure Transducer
Converts the measured pressure into analog electrical signal proportional to the applied pressure.
Pressure Transmitter
Pressure transmitter is a unit that consists of a pressure transducer and a module for conditioning and amplifying the transducer signal.
Digital Pressure Gauge or Manometer
It is a complete measuring instrument that measures and indicates the unit of pressure
proportional to the applied pressure.
Dead Weight Pressure Tester
(Also called as Dead weight piston gauge or Pressure balance)
One of the fundamental method – Force/ unit area of the piston. Consists of an accurately machined piston of known weight which is inserted into a closed fitting cylinder (clearance between the piston and cylinder will be few microns), both of known cross sectional area.
Weights of known mass loaded on one end the piston and the fluid pressure applied to the other end of the piston until enough force is developed to lift the piston-weight combination, When piston is floating freely within the cylinder (between limit stops), piston is in equilibrium with the unknown system pressure.
So the applied pressure is equal to the ratio of force due to the weight-piston and the area of cross section of the piston cylinder.
Effective Area
The area determined for a given piston-cylinder assembly which is used in conversion equation for the calculation of the measured pressure.
Free Rotation Time of the Piston
The time during which the piston rotates freely after spinning to a specified rotation rate, until it stops
Rate of fall of Piston
The speed of fall of the piston at its operating level at 100% pressure value by loading related quantity of masses.
Datum Levels
Operating level of the piston: level of the piston, with respect to a clearly defined part of the support column or the base of a pressure balance.
Pressure reference level: The vertical level, with respect to a clearly defined part of the support column or the base of the pressure balance, to which a measured pressure is related when the piston is at a specific operating level