01
Pg: definition and engineering context
Gauge pressure. Pressure referenced to local atmospheric pressure.
The term belongs to the pressure & safety context. Its exact limits can depend on the cited standard, catalog convention, unit system, reference state, and component configuration.
02
Why Pg affects pneumatic selection
Do not mix gauge and absolute values in one formula.
- Cracking pressure: It affects low-pressure operation and retained pressure.
- Proof pressure: It is not the normal operating-pressure rating.
- Burst pressure: Never use it as a working-pressure target.
- MAWP: Use the lowest rating of every component in the circuit.
03
How to evaluate Pg in a catalog or replacement project
Read the value together with its unit, test basis, operating pressure, temperature, circuit state, and manufacturer definition.
For replacement work, compare the complete datasheet and drawing. A matching abbreviation or nominal size does not by itself prove functional or dimensional interchangeability.
- Initial opening pressure: Differential pressure at which a check or relief element begins to open.
- Proof test pressure: Pressure used to verify integrity without permanent deformation under stated conditions.
- Failure pressure: Pressure at which a component may rupture or lose containment.
- Maximum allowable working pressure: Highest permitted working pressure under specified conditions.
Selection checklist
What to verify before selection
- 01
Do not mix gauge and absolute values in one formula.
- 02
It affects low-pressure operation and retained pressure.
- 03
It is not the normal operating-pressure rating.
- 04
Never use it as a working-pressure target.
Application caution
Common mistakes
- Treating Pg as a universal definition without checking the manufacturer or standard context
- Mixing gauge and absolute values, incompatible units, or different reference conditions in one comparison
- Selecting a component from the term or nominal value alone without checking the complete operating point and drawing
FAQ