7. Glossary

These definitions are taken from NF EN ISO 4126-1 (07/04) "Safety devices for protection against excessive pressure, Part 1: Safety valves", NF EN 14071 "Safety valves for liquefied petroleum gas (LPG) tanks. Auxiliary equipment, and NF EN ISO 23251 "Petroleum, petrochemical and natural gas industries. Depressurization and overpressure protection systems".

Pressure drop on re-closing; blow down

Difference between opening pressure and reclosing pressure, generally expressed as a percentage of opening pressure, except for pressures below 3 bar, when it is expressed in bar.

Coefficient of discharge; Coefficient de débit

Actual flow rate (from tests) divided by calculated theoretical flow rate.

Built-up back pressure

Pressure downstream of the...