Abstract: An alarm switch for a control valve (5) is disclosed which has resilient fingers (37) extending from a casing (1) thereof. The fingers (37) are attachable to a yoke (23) of the valve (5) and resiliently deflect to accommodate for minor variations of yoke widths between different valves (5) and support the casing (1) in a position centrally across said yoke and in alignment with the central longitudinal axis of the valve shaft (3). This, in turn, can permit adjustment of the position of the casing (1) relative to an appropriate sensing initiating means carried by the valve shaft (3). Brackets (45) can be used to hold the casing (1) fixed to the yoke (23) so that when a correct position is obtained the casing (1) can be securely held in that position.

Abstract: A valve is disclosed which includes a first magnetic sensing means (71) and a closely positioned second magnetic sensing means (73). A valve shaft carries magnetic material (91) which is moved as the valve is opened or closed. The first magnetic sensing means (71) is magnetically held in one of its states when the valve is open, by the presence of the magnetic material (91). When the valve is closed the magnetic material (91) influences the second magnetic sensing means (73) and trips it into an alarm condition. The first magnetic sensing means (71) also trips into an alarm condition when the valve is closed. Thus, there is back-up sensing of the valve being closed. The second magnetic sensing means (73) also acts to provide an alarm if a person should maliciously attempt to fool the sensors by placing magnetic material near the first magnetic sensing means (71) to subsequently close the valve, without causing an alarm.

Abstract: An improved water supply valve for a fire installation where water is to be supplied through the valve in the event of fire. The valve includes a sensor external of the valve chamber which can magnetically sense the gate of the valve being closed and being useable to provide an alarm activating output signal. The sensor is connectable to a fire installation to give an alarm indication in response to the output signal when the gate is closed.