Excess flow control valve

Claim 1

A valve that closes to shut-off flow in response to a predetermined drop in downstream pressure comprising an elongated valve body having a longitudinal axis, one end of the body being the upstream and inlet end and the other end of the body being the downstream and outlet end, said body having an aperture extending from the inlet end to the outlet end along said longitudinal axis, said aperture having a first section at the upstream end of said body and the upstream end of said first section being threaded for attachment to a conduit that supplies liquid to the valve, said aperture having a second section adjacent to and communicating with the first section and smaller in diameter than the first section, the upstream end portion of said second section being threaded, a valve positioner threadably mounted in the threaded upstream end portion of said second section and being removable from the valve body through the first section of the aperture, a valve member in said second section adapted to engage said positioner and be positioned by it, said positioner having openings in it providing for continuous relatively unrestricted liquid flow from said first section to said second section even when the positioner is engaged by the valve member, said aperture having a third section adjacent to and communicating with the second section and with said outlet end, said body having a radial valve seat at the interface of the second and third aperture sections, said valve member being adapted to seat on said valve seat on a liquid sealing engagement whereby said valve seat and valve member control liquid flow from the second section to the third section, said third section having a threaded portion, an apertured adjustment nut threadably mounted in said threaded portion of said third section, a coil spring based at its downstream end against said adjustment nut and at its upstream end against the valve member to act with downstream liquid pressure to resiliently urge the valve member to engage the valve positioner, said adjustment nut providing means to control compression of the coil spring and the pressure applied by it to hold the valve member off the valve seat and against the valve positioner, whereby the spring pressure on the valve member may be adjusted to produce seating of the valve member on the valve seat by upstream liquid pressure when downstream liquid pressure has dropped below a predetermined level.