DGMDC Direct Check Valves
These valves allow free flow in one direction in the line in which the check valve element(s) is (are) located; flow in the opposite direction is not possible.
DGMPC Pilot Operated Check Valves
These valves provide pilot operated check functions in one or both service lines (A or B), the operating pilot supply coming from the opposite service line. Thus with pressure in one service line the check valve in the other service line will be open (subject to system/actuator pressures being correct for the valve area ratios). A 3:1 area ratio of pilot piston to check valve seat is supplemented by an optional 10:1 decompression feature.