Manual reset hydraulic valve latch for a hydraulically controlled valve

A reset latch comprising:

• a body having an input port, a control port, and a drain port, the ports being in fluid communications 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 latch 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 operationally exposed to pressure within the actuator chamber and a sealing surface, such that while in the closed position the pressure within the latch chamber urges the drain seal to the closed position;
• 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;
• and,
• a variable flow restrictor disposed outside the latch body the variable flow restrictor being operational to limit fluid flow from the inlet port into the latch chamber, the flow restrictor being coupled 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 plunger is in the standby state.

A manual reset latch comprising:

• a body having an outlet port, a control output port, and a drain port, the ports being in fluid communication 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 latch chamber and the drain port, and an open position wherein the drain seal allows fluid flow between the latch chamber and the drain port;
• a drain seal opener operative to urge the drain seal to the open position;
• a variable flow restrictor disposed to limit fluid flow from an inlet to a fire fighting system valve control chamber, the variable flow restrictor being operationally coupled to the plunger, such that moving the plunger to the reset state causes the drain seal to be urged to the closed position and the flow restrictor to lower fluid flow resistance between the inlet and a control mechanism of a valve;
• wherein the drain seal is urged to the open position by the drain seal opener when the pressure in the latch chamber falls below a predetermined level, and wherein the valve control chamber is in fluid communications with the latch chamber.