i need to explain what an absolute pressure gauge measures
pressure and temperature
Bourdon's tube pressure gauge cannot be used to measure negative pressure. This is because absolute pressure must be measured and the Bourdon gauge only indicates the gauge pressure.
A compound pressure gauge measures two scales, one in positive pressure and one in negative (below atmospheric) pressure or vacuum positive pressure is measured in pounds per square inch (psi) or kilopascals or in some cases bars (1 bar = 14.35 psi) [ the average atmospheric pressure at 1000 feet above sea level] vacuum is measured in millimeters of mercury mmHg or inches of mercury inHg
Gauge pressure usually refers to the pressure difference between ambient, atmospheric pressure and the pressure in a vessel or line. A gauge pressure of zero would mean that the vessel or line was at atmospheric pressure. Normally the pressures of interest are ABOVE atmospheric so the gauge pressure is positive. Vacuum gauge pressure measures how far BELOW atmospheric pressure a vessel or line is. As such vacuum gauge pressure may be measured as a negative number - or for convenience it may be reported as a positive number with the caveat that it is "vacuum gauge pressure", meaning that the reported pressure is how far atmospheric pressure is above the pressure in the vessel or line.
44.7 psi
look at the gauge
The Compound Gauge measures above and below atmospheric pressure (in psig and inches of mercury).
A compound gauge is a pressure gauge that displays both negative and positive gauge pressure measurements. Gauge pressure is a measurement of pressure relative to ambient pressure. For example, if ambient pressure was 14.7 PSI and you were to measure absolute vaccum using a compound gauge, the gauge would indicate -14.7 PSI.
The compound gauge is an instrument to measure pressures, positive or negative.
to measure pressure
Bourdon's tube pressure gauge cannot be used to measure negative pressure. This is because absolute pressure must be measured and the Bourdon gauge only indicates the gauge pressure.
A Bourdon Tube or a Bellows gauge
to measure pressure
Pressure.
pressure and temperature
To measure pressure
Pressure gauge
To measure air pressure.