F-1 Rocket Engine Main LOX Valve
This page serves as a repository for photos and diagrams of the F-1 rocket engine's main LOX valve (sometimes called the main oxidizer valve).
The F-1 rocket engine had two identical oxidizer valves that directed the flow of liquid oxygen to the thrust chamber and the flow of hydraulic control opening fluid to the gas generator control valve. The oxidizer valves were hydraulically actuated, spring-loaded closed, pressure-balanced, fail-to-the-run position, poppet-type valves having quick response and low delta-P operating characteristics. An integral part of each oxidizer valve, and mechanically opened by this valve, was a normally closed sequence valve which, in the open position, directed hydraulic control fluid to the opening port of the gas generator control valve.
The oxidizer valve was designed so that when it was in the open position, at rated engine oxidizer pressure and flowrate, it would not close if hydraulic control fluid opening pressure was lost. The oxidizer valve consisted of a housing that contained the oxidizer inlet and outlet ports and the seat for the poppet seal; a poppet with a machined Teflon seal secured by a seal retainer; a cover that attached to the valve housing and contained the two poppet-closing springs and also served as a mount for the cylinder and a guide for the piston rod; a cylinder, within which the actuating piston operated, that contained the open and closed actuator ports and supported the position indicator drive shaft; a cylinder head that contained the inlet and outlet ports of the sequence valve and also provided a mount for the sequence valve gate; and a tapered piston rod that connected the actuator to the poppet, mechanically opened the sequence valve, and actuated the position indicator.
The sequence valve was a spring-loaded gate valve that seated against, and was hinged to, the oxidizer valve cylinder head. The sequence valve was offseated by the piston rod to direct opening hydraulic control fluid to the gas generator control valve when the oxidizer valve reached 16.4 percent of its open position. The position indicator consisted of a rotary-motion variable resistor and open and closed position switches. The position indicator was mounted on the oxidizer valve cylinder and was coupled to the indicator drive shaft, which was mechanically linked to the piston rod. The position switch provided relay logic in the engine electrical control circuit, and the variable resistor provided instrumentation for recording valve poppet movement.
Each oxidizer valve incorporated an oxidizer dome purge check valve to admit gaseous nitrogen downstream of the valve poppet to purge the thrust chamber oxidizer dome. The check valve was a gate-type valve, spring loaded to the closed position, and allowed flow in one direction when the differential pressure across the valve exceeded 5.0 psi. Five types of seals were used in the oxidizer valve: machined Teflon seals, Mylar lip seals, Teflon-coated steel Naflex seals, and Buna-N O-rings.
The bulk of the descriptive text was taken, largely verbatim, from the F-1 Engine Familiarization Training Manual.