Abstract: An on/off sprinkler has a body defining an extinguishant inlet and outlet and is divided internally by a diaphragm defining with the body an intermediate chamber and normally isolating the inlet from the outlet. The diaphragm has a drain orifice allowing an extinguishant pressure balance on both sides of the diaphragm. There is an exhaust port from the intermediate chamber which is normally closed by a valve controlled by a heat sensitive device serving upon attainment of a predetermined temperature value to open the valve thus causing extinguishant exhaustion from the intermediate chamber which results in diaphragm movement to place the inlet in communication with the outlet and sprinkler operation.

Abstract: An installation control valve, for example for use in a fire fighting sprinkler installation, comprises a pivotal butterfly valve disc co-operable with a movable stop, which in one position abuts the valve disc to retain the valve closed against pressure forces acting thereon. A retaining mechanism is releasably held to resist stop movement and so prevent valve disc opening but is operable under a predetermined condition to permit stop movement from said one position to a second position. When the stop is in the second position, unequal pressure forces on either side of the valve disc cause same to move thereby opening the valve.

Abstract: A heat sensitive release device, for example a sprinkler, comprises two relatively movable components, for example a yoke and valve member. A collapsible strut system is located between the relatively movable components. The collapsible strut system includes a catch element having opposed wings between which is held a heat sensitive element, for example a double ended heat sensitive cartridge. The collapsible strut system also includes a lever fulcrummed on one of the components and a strut engaged between the other component and the lever adjacent the fulcrum. The lever bears against the heat sensitive element while the strut is connected to or integral with the catch element. In addition, an impediment is joined to the strut system and disposed between the lever and the catch element so that removal of the heat sensitive cartridge from the catch element is prevented.

Abstract: A method of detecting the presence of a foreign gas in a gaseous medium of known combustion properties uses the fact that the percentage lower or upper explosive limits (LEL or UEL) of mixtures of any flammable gas in any other gas all have approximately the same varying relationship to the percentage LEL or UEL of the mixture as a whole when a known percentage of a reference gas of known combustion properties is added to the mixture. The method comprises the steps of mixing a sample of a possibly contaminated gaseous medium with known combustion properties in a fire-safe container (12), actuating ignition means (17) in an attempt to ignite the gaseous mixture in the container (12), and using detection means (18) to detect ignition or otherwise of the gaseous mixture to enable the presence of a foreign gas above a predetermined concentration in the gaseous medium to be detected.

Abstract: An installation control valve preferably for use in a fire fighting installation has a pivotal valve disc with an axis spindle to which is connected a lever. A lever retaining mechanism co-operates with the lever and is releasably held to resist lever and so valve disc movement. An actuating means is operable under predetermined condition to release the lever retaining mechanism to permit lever and valve disc movement to effect valve opening.

Abstract: A sprinkler arrangement comprises a sprinkler head connected via a first valve to one end of a length of connection pipework adapted for attachment to a main pipework system containing fire extinguishant. A second valve is arranged at the other end of the connection pipework and comprises an inert plug which is maintained in a valve closed position by a strut which contacts the first valve. On opening of the first valve, for example when a predetermined temperature is reached, the strut is caused to move and thereby permit movement of the inert plugs to allow a flow of extinguishant into and through the connection pipework to the sprinkler head when the arrangement is attached to the main pipework system.

Abstract: A heat sensitive release device, for example a sprinkler, comprises two relatively movable components, for example a yoke and valve member. A collapsible strut system is located between the relatively movable components. The collapsible strut system includes a catch element having opposed wings between which is held a heat sensitive element, for example a double ended heat sensitive cartridge. The collapsible strut system also includes a lever fulcrummed on one of the components and a strut engaged between the other component and the lever adjacent the fulcrum. The strut or the lever bears against the heat sensitive element while the lever or strut is connected to or integral with the catch element.