Nominal pressure is a reference value for a piping system.
Flame arrester Device fitted to the opening of an enclosure, or to the connecting pipe work of a system of enclosures, and whose intended function is to allow flow but prevent the transmission of a flame. It is specified according to DIN, EN, ISO by the designation PN (pressure nominal) followed by a dimensionless integer indicating the design pressure Design pressure Design pressure is the maximum pressure for which the system or component was designed for continuous usage. in bar at room temperature (20 °C).