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FIRE FIGHTING SYSTEM WORKS


 

A fire fighting system is probably the most important of the building services, as its aim is to protect human life and property, strictly in that order.

A fire hydrant is a vertical steel pipe with an outlet, close to which two fire hoses are stored (A fire hydrant is called a standpipe in America). During a fire, firefighters will go to the outlet, break open the hoses, attach one to the outlet, and manually open it so that water rushes out of the nozzle of the hose. The quantity and speed of the water is so great that it can knock over the firefighter holding the hose if he is not standing in the correct way. As soon as the fire fighter opens the hydrant, water will gush out, and sensors will detect a drop in pressure in the system. This drop in pressure will trigger the fire pumps to turn on and start pumping water at a tremendous flowrate.

A sprinkler is a nozzle attached to a network of pipes, and installed just below the ceiling of a room. Every sprinkler has a small glass bulb with a liquid in it. This bulb normally blocks the flow of water. In a fire, the liquid in the bulb will become hot. It will then expand, and shatter the glass bulb, removing the obstacle and causing water to spray from the sprinkler.

Simply stated, firefighting foam is a stable mass of small, air-filled bubbles with a lower density than oil, gasoline, or water. Foam is made up of three ingredients…water, a foam concentrate, and air. Water is mixed with a foam concentrate (proportioned) to form a foam solution. This solution is then mixed with air (aspirated) to produce a foam which readily flows over fuel surfaces.Balanced pressure proportioning is the most common method used for foam system applications. The foam concentrate pressure is balanced with the water pressure at the proportioner inlets allowing the proper amount of foam concentrate to be metered into the water stream.