Manual reset hydraulic valve latch for a hydraulically controlled valve

A manual reset latch comprising:

• a body having an input port, an outlet port, a control port, and a drain port, the ports being in fluid coupling with a latch chamber formed at least partially within the body;
• a plunger having at least a portion thereof disposed in the body, the plunger being movable between at least a standby state and a reset state;
• a drain seal disposed to move between a closed position wherein the drain seal impedes fluid flow between the actuator chamber and the drain port, and an open position wherein the drain seal allows fluid flow between the latch chamber and the drain port, the drain seal having a top surface exposed to pressure within the actuator chamber and a sealing surface;
• the drain seal being urged to the open position by a drain seal opener, the drain seal further being disposed such that placing the plunger in a reset state will urge the drain seal to the closed position;
• a variable flow restrictor disposed to limit fluid flow from the inlet port into the latch chamber, the flow restrictor being coupled directly or indirectly to the plunger at least when the plunger is in the reset state, the flow restrictor presenting a lower fluid flow resistance when the plunger is in the reset state than when the latch is in the standby state.