pressure gauge
A pressure gauge is an instrument that measures the pressure in a vessel, a line, or whatever the pressure gauge is connected to.
A Bourdon gauge consists of a C-shaped pipe with one end closed and the other end attached to a chamber whose pressure is being measured. When there is a pressure difference between the inside of the pipe and the outside, there will be a net force acting on the C-shaped pipe which will either try to curl the pipe into a tighter C shape (if the pressure in the pipe is less than the ambient air pressure), or the force will tend to straighten out the pipe (if the pressure is higher inside). This force can be measured, and from the measurement of this force, the gauge pressure within the pipe can be calculated.
There are many different kinds of gauges used to measure pressure including: Instruments hydrostatic - These measure pressure according the height of a liquid in a column. The height of the liquid is proportional to the pressure. Common types of hydrostatic gauges include: manometers, McLeod gauges, and piston gauges.
Pressure gauges come in at least two different types: differential pressure gauges, and absolute pressure gauges. Differential pressure gauges measure - surprise - DIFFERENCES in pressure. Pressure gauges that read "zero" when not attached to anything would actually be differential gauges that measure the difference between atmospheric pressure and the pressure of whatever they are attached to. Vacuum gauges are differential gauges that measure how far BELOW atmospheric pressure the pressure is in a vessel or pipe. Gauges that measure "gauge pressure" are just differential gauges that are calibrated to measure zero at atmospheric pressure. Absolute pressure gauges would only read "zero" if they were attached to an absolute vacuum. A common type of absolute pressure gauge is a barometer. Strictly speaking, a mercury barometer is really a differential gauge that measures the difference between the vapor pressure of the
A Bourdon gauge consists of a C-shaped pipe with one end closed and the other end attached to a chamber whose pressure is being measured. When there is a pressure difference between the inside of the pipe and the outside, there will be a net force acting on the C-shaped pipe which will either try to curl the pipe into a tighter C shape (if the pressure in the pipe is less than the ambient air pressure), or the force will tend to straighten out the pipe (if the pressure is higher inside). This force can be measured, and from the measurement of this force, the gauge pressure within the pipe can be calculated.
There are many different kinds of gauges used to measure pressure including: Instruments hydrostatic - These measure pressure according the height of a liquid in a column. The height of the liquid is proportional to the pressure. Common types of hydrostatic gauges include: manometers, McLeod gauges, and piston gauges.
Pressure gauges come in at least two different types: differential pressure gauges, and absolute pressure gauges. Differential pressure gauges measure - surprise - DIFFERENCES in pressure. Pressure gauges that read "zero" when not attached to anything would actually be differential gauges that measure the difference between atmospheric pressure and the pressure of whatever they are attached to. Vacuum gauges are differential gauges that measure how far BELOW atmospheric pressure the pressure is in a vessel or pipe. Gauges that measure "gauge pressure" are just differential gauges that are calibrated to measure zero at atmospheric pressure. Absolute pressure gauges would only read "zero" if they were attached to an absolute vacuum. A common type of absolute pressure gauge is a barometer. Strictly speaking, a mercury barometer is really a differential gauge that measures the difference between the vapor pressure of the