Firomatic oil valves operate using a spring-loaded plunger. In the case of a fire in the boiler room, the handle (made of a special alloy that melts at a low temperature) melts off the shaft which shuts off the oil flow to the burner. Oil flow can also be manually shut off by turning the handle on the valve clockwise.
Firomatic valves as well as a variety of other valves can be found at www.supplyhouse.com
