Operation
A hose is attached to the fire hydrant, then the valve is opened to provide a powerful flow of water, on the order of 350 kPa (50 lbf/in²) (this pressure varies according to region and depends on various factors including the size and location of the attached water main). This hose can be further attached to a fire engine, which can then use a powerful pump to boost the water pressure and possibly split it into multiple streams. The hose may be connected with a threaded connection, instantaneous "quick" connector or a Storz connector. Care should be taken not to open or close a fire hydrant too quickly, as this can create a water hammer which can damage nearby pipes and equipment. The water inside a charged hoseline causes it to be very heavy and high water pressure causes it to be stiff and unable to make a tight turn while pressurized. When a fire hydrant is unobstructed, this is not a problem, as there is enough room to adequately position the hose.
Most fire hydrant valves are not designed to throttle the water flow; they are designed to be operated full-on or full-off. The valving arrangement of most dry-barrel hydrants is for the drain valve to be open at anything other than full operation. Usage at partial-opening can consequently result in considerable flow directly into the soil surrounding the hydrant, which, over time, can cause severe scouring. A hose with a closed nozzle valve, or fire truck connection, or closed gate valve is always attached to the hydrant before opening the hydrant's main valve.
When a firefighter is operating a hydrant, appropriate personal protective equipment, such as gloves and a helmet with face shield, are typically worn. High-pressure water coursing through a potentially aging and corroding hydrant could cause a failure, injuring the firefighter operating the hydrant or bystanders.
In most jurisdictions it is illegal to park a car within a certain distance of a fire hydrant. In North America the distances are commonly 3 to 5 m or 10 to 15 ft, often indicated by yellow or red paint on the curb. In the UK, yellow lines are used to keep cars from parking over underground hydrants. Parking restrictions are sometimes ignored (especially in cities where available street parking is scarce), however these laws are usually enforced. The rationale is that hydrants need to be visible and accessible in an emergency.
Read more about this topic: Fire Hydrant
Famous quotes containing the word operation:
“An absolute can only be given in an intuition, while all the rest has to do with analysis. We call intuition here the sympathy by which one is transported into the interior of an object in order to coincide with what there is unique and consequently inexpressible in it. Analysis, on the contrary, is the operation which reduces the object to elements already known.”
—Henri Bergson (1859–1941)
“Waiting for the race to become official, he began to feel as if he had as much effect on the final outcome of the operation as a single piece of a jumbo jigsaw puzzle has to its predetermined final design. Only the addition of the missing fragments of the puzzle would reveal if the picture was as he guessed it would be.”
—Stanley Kubrick (b. 1928)