This model has a specific purpose; to shut off the flow of fuel to a pre-set maximum in response to a signal from the float control ofa fuel-water filter/separator. it is a hydraulically operated pilot controlled, diaphragm type globe valve. The valve will close drip tight in case of diaphragm failure providing fail safe operation.
The interface float pilot is down with little or no water in the sump of the filter separator. The float pilot routes vessel pressure to the bonnet of the three-way auxiliary pilot. This position the three-port auxiliary pilot to connect the bonnet to the main valve down stream, allowing the valve to open.