Abstract: An excess flow valve (EFV) for installation in a service line of natural gas distribution system serving an existing structure. The EFV has a cylindrical housing having a first length and a second length and a through hole therethrough for passage of gas. The EFV 11 engaged in the through hole of the first length and the second length has an expandable wall which can be expanded and fixed in said service line.

Abstract: An excess flow valve (EFV) for installation in a service line of natural gas distribution system serving an existing structure. The EFV has a cylindrical housing having a first length and a second length and a through hole therethrough for passage of gas. The EFV 11 engaged in the through hole of the first length and the second length has an expandable wall which can be expanded and fixed in said service line.

Abstract: An excess flow valve (EFV) for installation in a service line of natural gas distribution system serving an existing structure. The EFV has a cylindrical housing having a first length and a second length and a through hole therethrough for passage of gas. The EFV 11 engaged in the through hole of the first length and the second length has an expandable wall which can be expanded and fixed in said service line.

Abstract: A flow shut-off valve shuts off natural gas if there is a break in a gas line, for example, the line to a water heater toppled by an earthquake. The shut-off valve is fitted into a standard pipe nipple that is installed in a vertical position. The shut-off valve includes a plastic float having a tapered nose with a O-ring in a groove at the base of the nose, a flow-restricting orifice region, and guide fins at the lower end of the float to guide it along the bore of a plastic body having a bore and shoulders at either end to contain the float. The body includes an conical aperture at the upper end into which the float nose and the O-ring are inserted when a break occurs and the downstream pressure drops, forcing the float upward as the gas flow surges. No spring is used; the balance of gravity and gas=flow forces controls the operation of the shut-off valve. The body is spin-welded from two pieces and crimped into position in the nipple.

Abstract: A gas line limiter valve is preferably built into a stiffener used to connect gas lines. The valve includes a through-passage having a large bore and a small bore downstream from the large bore, with a conical valve seat between. A central reservoir may be disposed between the large and small bores. A movable float includes a piston disposed within the large bore, a stem disposed within the small bore, and a popper to seal against the valve seat when the float is moved downstream. A coil spring urges the float upstream. The stem and the piston are cylindrical. The piston and large bore form a first orifice, and the stem and small bore form a second orifice. With the second orifice being smaller than the first, the second orifice and the buffer gas inside the reservoir create a resistance to the valve closing during sudden temporary drops in the downstream pressure.

Abstract: A safety flow limitor of modular construction for use in gas supply lines for passing a combustible natural gas from a source to a consumer comprises a cylindrical shell defining an internal passageway in which resides an axially movable valve head member having an annular surface for mating with an annular valve-seat provided along the passageway. A coil spring having its downstream portion retained in the passageway and its upstream portion abutting the valve head member serves to bias the annular surface of the valve head member away from the annular valve-seat so as to maintain the passageway open. If there is a pressure drop downstream, then the upstream pressure acts against the force of the coil spring and moves the valve head member to a downstream position where its annular surface mates with the annular valve-seat.