How does a Fire Hydrant Work

What is a Fire Hydrant? 

 

 

A fire hydrant is a pipe with a nozzle that takes water from a water main. It is used to put out fire. Water is the best way to fight with fire as it is cost effective and available in abundance. The water that is used in fire hydrant is the same water which is used in homes, offices and institutions etc.; however, the pressure is not more than 50-80 pounds per square inch (PSI). This pressure is not sufficient to fight fire, that's why pumps on the fire engines are used. These pumps increase the pressure and fire fighters hold small hoses to pour water on fire.

Freezing weather can be a huge problem in relatively colder states. Water freezes at very low temperatures and it makes it impossible to fight fires as ice clogs the hydrant system. Water expands when it coverts into ice, so it could cause the fire hydrant to crack, thus adding to problems in case of a fire situation. Dry Barrel fire hydrants are used in very cold states. In this type of fire hydrant water doesn't stay in the upper section when the hydrant is not in use. There is a valve that controls the water flow which is buried deep enough. This valve is connected to the stem nut through a long rod. Wet hydrants always have water in the barrel. Pressurised water is supplied to the fire engine just by opening the valve.

What do Colour Codes on Fire Hydrants mean?

Fire fighters arrive at the scene in a fire situation and they are required to get into action immediately. They need to know where is the nearby water source, how much water is available as well as capacity of the hydrants available in the vicinity. Since they don't have a lot of time, colour codes of hydrant tops and caps help them determine whether that hydrant is appropriate to fight with the fire at scene.

 

  • RED- Flow rate under 500 gallons per minute
  • Yellow- Flow rate between 500-999 gallons per minute
  • Green- Flow rate between 1000-1499 gallons per minute
  • Blue- Flow rate 1500 gallons per minute or higher

Maintenance of Fire Hydrants:- 

Maintenance of fire hydrants is of utmost importance. Ignoring the maintenance could result in loss of several valuable lives and insurance claims worth millions of dollars. Regular inspection and maintenance work should be carried out to ensure that the fire hydrants are in working condition at all times. Nozzles, Upper and lower barrels, stem nut, seat valve etc. should be thoroughly checked and replaced if necessary. Water flow testing should be checked frequently to ensure that water supply meets the demands. Quality of water is equally important as presence of sediment in the water can make the hydrant dysfunctional. It is very important to not ignore these factors as replacement of a hydrant can cost approximately 15 times more than the inspection and replacement of its  parts. 

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