22.06 What is important about foot valves and extractors?

Foot valves are vertical check valves installed into a tank to maintain the prime in the suction piping to a pump. Foot valves are either single or double poppet designed and double poppet designs are preferred.

Expansion relief in fuel piping systems is an important consideration when foot valves are used. Many pumps have internal relief valves that relieve downstream fuel pressure back to the suction side of the pump. When foot valves are used, the pump internal relief is still valid for pump protection, however, the suction pipe will be blocked by the foot valve from relieving downstream pipe pressure. An independent path needs to be provided.

He extractor valve mounts on the top of the tank to allow removal and inspection / maintenance of the foot valve from the fuel tank. Note that a foot valve extractor is different from a vent valve extractor that is sometimes used on underground tanks for ball float vent restrictors.