Mechanical safety shut-down valve

A mechanical shut-down valve assembly comprising:

• a valve body having a bore extending from an inlet to an outlet through which fluid may flow;
• a main valve located in the bore, the main valve comprising a valve wall defining a valve seat and a valve member, the valve member moveable between a closed position in engagement with the valve seat and preventing flow through the bore and an open position in disengagement with the valve seat and permitting flow through the bore;
• a reservoir chamber provided in the valve body and being partially defined by the valve member;
• a thermostatic motor assembly coupled to the valve body, the thermostatic motor assembly including a motor housing defining a sensing chamber and a thermostatic motor located in the sensing chamber, the sensing chamber being in fluid communication with the reservoir chamber and the thermostatic motor being configured to axially change in length in response to temperature changes in the sensing chamber;
• a pilot valve defining a variable-size orifice in a fluid pathway communicating the reservoir chamber with the bore, the pilot valve being moveable between defining a fully closed position and a fully open position of the variable-sized orifice, the pilot valve being operative coupled to the thermostatic motor whereby the variable-size orifice is varied in size in response to temperature changes in the sensing chamber;
• and
• wherein when the variable-size orifice is in the fully closed position an increase in fluid pressure is effectuated in the reservoir chamber causing movement of the valve member into the closed position.