Most satellites, space probes, and launch vehicle upper stages utilize chemical liquid propellants for propulsion. These propulsion systems typically use pressurant subsystems, including pressure regulators, to control the delivery of the chemical propellants to the vehicle engines and sometimes to deliver gas to cold gas attitude and reaction control systems. The rationale for using regulators is that controlling the pressure at which the propellants are fed into the main engine combustion chamber significantly enhances the efficiency of the engine and produces a constant thrust value.