AN EXCESS-FLOW SAFETY SHUT-OFF DEVICE

摘要

A fluid flow safely device comprises a body having an inlet end for connection to a fluid supply and an inlet passageway (8, 48, 103) which leads lo a selective fluid flow sensor chamber (9, 49, 115) having a sealing means (10, 50) which encircles the outlet orifice (11, 51) of smaller cross section than that of the sensor chamber, said outlet orifice leading from the sensor chamber into a pressure chamber (12, 52) within the body leading to an outlet. Between the inlet end of the sensor chamber and the sealing means is a tapered section (13, 117), wherein the bore of the sensor chamber decreases in a diameter as it nears the sealing means. A sensor chamber shield (120) may encircle the sensor chamber by forming, defining and separating the internal length of the sensor chamber passageway from that of the inlet or any other passageway. A ball (16, 56, 119) in the sensor chamber moves between the inlet passageway end of the sensor chamber and the outlet orifice, to form a seal with the sealing means when flow through the sensor chamber is above a predetermined value. Within the pressure chamber is a movable piston (20, 60, 131) in sealing contact with it to increase or decrease the volume of the pressure chamber. Movement of the movable piston from a rest position fully towards the sensor chamber will deny a seal to be made between the ball and the sealing means. The movable piston may be a primary valve mechanism which forms a seal between the inlet and outlet passageways. The movable piston may include an indicator mark visible only when the pressure in the pressure chamber is above a predetermined value. Embodiments for LP gas include separate use of sensor chamber or movable piston with or without primary valve.