Artifact: Flow Control Valve, Primary Cabin Temperature, Apollo Command Module, Block II

A Block II Apollo Command Service Module Environmental Control System (ECS) Primary Cabin Temperature Flow Control Valve and Manual Crew Selector Knob assembly manufactured circa 1968 by AiResearch under CSM contract NAS 9-150. This assembly regulated the primary glycol loop in the Apollo Command Module and was normally positioned automatically by the cabin temperature control or manually by means of an override control on the face of the valve. The valve was located on the CSM panel 303 (a diagram of the panel is viewable to the left of this narrative)

The motor-operated valve is manually controlled by the back-up mode control knob. Rotational movement from H to C is approximately a ½ turn with the dual valve on a single shaft permitting water-glycol flow to route to the heat exchanger. Rotation toward H (heat) position results in proportional increase in cabin temperature by directing warm water-glycol to the cabin heat-exchanger. Rotation towards C (cool) position results in proportional decrease in cabin temperature by directing cool water-glycol to the cabin heat exchanger.