Safety valve

A normally closed valve comprising:

• a seat that has a fluid inlet and a fluid outlet;
• a diaphragm, an external handle and an internal safety mechanism operationally coupled to the external handle and the diaphragm;
• wherein the valve is configured to allow forcing the handle in a first direction, thereby moving the internal safety mechanism through at least a first stage and subsequently a second stage;
• wherein
• during the first stage:
• the diaphragm is pressed onto the seat,
• flow of pressurized air through the internal safety mechanism is blocked, and
• air in the valve is vented,
• causing the valve to be and remain in a closed state;
• during the second stage:
• flow of pressurized air through the internal safety mechanism is allowed, the pressurized air after passing therethrough, acting against the pressing of the diaphragm onto the seat, and a venting of air is reduced,
• causing the valve to be and remain in an open state,
• wherein the valve is further configured to allow moving the internal safety mechanism through an intermediary stage, and
• wherein during the intermediary stage, the valve is in the closed state;
• the internal safety mechanism comprises:
• a pneumatic disable mechanism, a control shaft, and a series of ducts extending through the disable mechanism and the control shaft;
• wherein the moving of the internal safety mechanism comprises moving the control shaft relative to the disable mechanism;
• during the second stage, the series of ducts are aligned;
• the valve further comprising
• a threaded stopper, the stopper comprising a stopper duct and a housing chamber, the stopper duct extending through a wall of the housing chamber and being a member of the series of ducts;
• wherein the disable mechanism is situated within the housing chamber;
• the disable mechanism comprising:
• a disable shaft comprising a disable mechanism duct;
• resilient means for urging the disable mechanism against the control shaft, and
• sealing means for sealing in between the disable mechanism duct and the control shaft duct when the disable mechanism duct and the control shaft duct are aligned.