Abstract: A fluid flow fuse has a body, which includes an inlet and an outlet with a valve seat therebetween. A valve stem having a valve member thereon is mounted in the body, and the valve member is operably connected to a diaphragm, which separates a region within the body into a pair of separate pressure chambers. Fluid passages are formed in the body communicating the separate pressure chambers with downstream pressure from the outlet and upstream pressure from the inlet. The pressure differential between the chambers is minimized so that at least one spring will normally hold the valve member in an open position, until the pressure differential reaches a predetermined amount, whereby the valve member is slowly and smoothly closed until fluid flow through the fuse is stopped.

Abstract: A fluid flow device has a body which includes an inlet and an outlet with a valve seat therebetween. A valve stem having a valve member thereon is mounted in the body, and the valve member is operably connected to a diaphragm which separates a region within the body into a pair of separate pressure chambers. A fluid passage is formed in the body communicating one pressure chamber with upstream pressure in the inlet, while the other pressure chamber communicates with downstream pressure in the outlet. A pressure differential between the chambers will normally hold the valve member in an open position against the action of a biasing means, until the pressure differential reaches a predetermined amount, whereby the valve member is slowly closed until fluid flow through the device is stopped.