- Valve Monitor ("VM")
An valve monitor (VM) or monitored valve (MV) is an electromechanical device that forms part of the fire safety systems of a building. A valve monitor is used to monitor the normal state or position of the valve (either or open or closed) by a fire detection and alarm system. Where the normal state of the valve is changed, it's corresponding state or condition of the valve is indicated at the fire detection and alarm system.
In most circumstances a valve used in an automatic fire sprinkler system or fire hydrant system is in the normally open state, allowing the free flow of water throughout the system. In this case, the fire detection and alarm system would indicate a normal condition (neither alarm or fault).
In the aforementioned example, where a valve is normally open and is then closed, a change in state at the fire detection and alarm system is recorded as an alarm condition.