Psig
Pounds per square in gauge, or psig, is a measure of pressure, specifically it is a gauge pressure. This means that it is measured with respect to the atmospheric pressure.[1] Psig is used in contrast to psia, which is pounds per square inch absolute, measured with respect to vacuum. This can all be visualized in Figure 1.
For example, a bike tire may be 65 psi above atmospheric pressure which is its psig value, and if the atmospheric pressure is 14.7 psi, then its psia value would be 65 + 14.7 = 79.7 psia.
Figure 1: Possible pressure measurements of a system.[2]
References
- ↑ Measurement Unit Converter. (May 7, 2015). Psig [Online]. Available: http://www.convertunits.com/info/psig
- ↑ Created internally by a member of the Energy Education team.