The Cobham Satellite Propulsion Regulator (part number B40351-1) is used to pressurize the bipropellant tanks of communications satellite propulsion systems. 

The regulator is arranged in a series redundant configuration to ensure continued system function should either of the redundant regulator pair fail open.

This arrangement is dictated by the application for which high operational reliability is required. This regulator is configured with metal to metal seats in both stages in order to tolerate upstream migration of N2O4 or N2H4 vapors. In the absence of such vapors, a metal to Vespel seat can be used in the upstream regulator to improve internal leakage performance.

Extremely good external leakage performance is achieved by employing welded closures throughout the gas flow path.  The low weight of the regulator stems from the use of a
lightweight composite spring system and a machined titanium housing.