Sprinklers are often equipped with vane-type flow switches fitted in riser pipes in order to detect the flow of water in the system. At times pressure switches are used to detect a significant drop in water pressure within the riser, which usually signifies water flow.
Tamper switches, which are placed on main water valves, must also be monitored in case one is closed, which means the system would not work if a fire broke out. In the past, building owners had a choice whether to electronically monitor these valves or to chain them, but not so today under ICC.
In dry-type sprinkler systems pressure switches also are used to monitor the air pressure in the sprinkler piping. Water flow in dry system sprinkler pipes is prevented by maintaining an air-to-water pressure ratio, usually 7-to-1. This is achieved using an air compressor regulated by an air pressure switch.
By monitoring this air pressure we can be assured that if a problem should occur, such as a kicked breaker on the air compressor or a leaky pipe, someone would know about it.
Notification is crucial in this regard because once the low air pressure in the sprinkler pipes falls below a certain level, water will be allowed to enter the system. Because dry systems are most often used in cold climates, it goes without saying what can happen when water is allowed to remain in these pipes for extended periods.
Code requires the installation of at least one fire pull and one notification appliance device, in addition to electronic monitoring.
Video Allows Dangers to Be Seen
Video is increasingly playing a larger role in fire detection. It can be used to detect fires in areas that have been historically difficult for traditional methods. A good example is a large warehouse where you have high ceilings and lots of racks and shelves.
Central station operators and onsite personnel also can use these video surveillance systems to verify fire alarms inside large buildings and high-rise facilities.
“Video fire alarms are also good in certain industrial applications, such as clean rooms, clean manufacturing facilities and other places where you can’t use traditional smoke detection,” says Nick Markowitz, owner of Markowitz Electric Protection in Verona, Pa. “This technology is also helpful in heavy industrial environments where there’s airborne dust, smoke and dirt. Churches with large cathedral ceilings, social halls and big, wide-open buildings are also great applications for video detection.”
By utilizing both technologies, it’s possible for the end user to obtain the best of both worlds. In a typical large church, for example, traditional fire sensors can provide the brunt of detection while video can be utilized to improve coverage in sanctuaries and large attic spaces. The central station can use the cameras to verify the presence of smoke or flames.
In most cases detection using existing cameras involves the addition of a second control console designed to analyze the images. This detection approach is one that can save a lot of time and money, particularly when working in large facilities such as a warehouse or large industrial complex where property protection is paramount.
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Fire Market Report