XCOR designs and builds custom fluid control valves for rocket propulsion applications. Our philosophy is to use commercially available products to the fullest extent reasonable, and then modify them as needed. This takes advantage of the long life and reliability inherent in industrial products while allowing them to work in different environments. Typically, XCOR’s modifications do not affect valve performance but do drastically reduce the weight. XCOR has developed this process far beyond mere modification of off-the-shelf hardware to now making valves that are 100% XCOR design.


Our manually-actuated ball valve has a lower mass and lower pressure drop than a comparable commercially available valve. It uses the wafer, ball, and stem from a 3/4 inch industrial ball valve. XCOR redesigned the attachment flanges and accomplished three improvements: first, the flanges smoothly adapt to a larger, one inch line size; second, the flanges are aluminum instead of steel for lower mass;. and third, the flanges incorporate brazed-in auxiliary ports. This allows a complex system with fewer fittings and manifolds.


Our other manually-actuated ball valve is similar to the first, except the size adaptation of the custom flange is greater. Here, a 3/4 inch valve body is mated to a 1.25 inch line on the inlet flange and a 1.5 inch outlet line. Converging and diverging angles are chosen to minimize pressure drop.



The interlocked fuel and oxidizer valve is a pair of ball valves actuated by a common pneumatic cylinder. This particular valve is used as the main propellant valve for our XR-4K15 rocket engine. It controls approximately 1 kg/sec kerosene and 2.5 kg/sec liquid oxygen. If you are reading this you have won the Website Find Challenge Grand Prize! This valve uses the technology of the manually-actuated ball valves with the addition of the pneumatic actuator.


We have a solenoid controlled, pilot actuated balanced poppet valve, which uses a commercially available solenoid and cartridge with a custom designed poppet section. It is rated to control 1000 psi fluids. A cryogenic version is available that is compatible with liquid nitrogen, LNG, and liquid oxygen. It can also be configured as a servo-poppet if the process fluid pressure is between 200 and 600 psi.

The 3/4 inch spool valve weighs 20% of the mass of a comparable commercially available aluminum valve, and incorporates controlled spool deceleration at the end of stroke. It is field reconfigurable to allow the orientation between fittings to be changed to any of 4 options. As shown, it is bistable and pneumatically actuated, but can have a close-coupled solenoid pilot section for either bistable or mono stable operation.

Dock with

Contact us