Automatic sprinkler systems for fire protection of buildings such as offices, warehouses, hotels, schools, apartments and the like are often required when there is a significant amount of combustible matter present in the building. The combustible matter may be found in the materials from which the building itself is constructed, as well as in the building contents, such as furnishings or stored goods.
Of the various types of automatic sprinkler systems available, the pre-action systems find widespread use. Pre-action systems use an actuator which responds to a combination of signals from different detectors to trip a valve which allows water to flow from a pressurized water source to the sprinkler piping network. The water is then distributed onto the fire from the sprinkler heads. Similar to the so-called “dry-pipe” systems, the piping network in the pre-action system is normally filled with air or nitrogen (and not water) prior to actuation. The pre-action system can thus be used in unheated environments which are subject to below freezing temperatures without fear of pipes bursting due to water within the pipes expanding upon freezing.
When sufficiently pressurized, the behavior of the gas within the piping network may be used to indicate a fire condition and trigger actuation of the pre-action system. Heat from the fire will cause sprinkler heads to open, allowing pressurized gas to escape from the piping network and result in a pressure drop within the system. Actuation of the system may be effectively triggered by this pressure drop through the aforementioned actuator.
For effective system operation, it is desired that the valve controlling the flow of water from the pressurized source to the piping network be able to conduct a significant volume of water at a relatively high flow rate with low pressure loss. These characteristics ensure that the sprinkler system has adequate water flow and pressure to fight the fire, and a short reaction time in order to prevent the spread of the fire. The reaction time is the duration measured between the time at which the valve is opened and the time at which water begins to flow from the sprinkler heads. Reaction times and pressure loss both increase in significance as the size of the piping network increases.
A valve that provides high flow rate with low pressure loss is desired for use in pre-action, as well as dry-pipe fire suppression sprinkler systems.