How do you pressure test a fire hydrant?
Remove the nozzle cap of the pressure hydrant and add the pressure gauge to its outlet. Open its valve completely and gather static pressure reading (Water should not be flowing). Then, open the flowing hydrant’s valve. Always be cautious of nearby obstacles and traffic.
How do you calculate gpm for a hydrant?
In other words, if your pitot pressure is 28 psi and your orifice size is 4, your theoretical discharge according to the table is 2,526 GPM. If the coefficient of your hydrant outlet is 0.9, multiplying 2,526 x 0.9 finds the actual rate of flow: 2,273.4 GPM.
What is a good hydrant pressure?
While a residual pressure of 20 psi is the general rule of thumb, NFPA allows for the available flow rate from a hydrant to be determined at residual pressures less than 20 psi in low-pressure areas.
How do you test a fire hydrant?
A fire hydrant flow test is performed for a specific area by using three fire hydrants. A pressure gauge is placed on one hydrant to record the static pressure; this is hydrant #1. The remaining two hydrants are opened to allow water to flow out as fast as possible.
What is the flow rate of fire hydrant?
A green fire hydrant is a class A hydrant and has a flow rate between 1,000 and 1,500 gallons per minute. A blue fire hydrant is a class AA hydrant and has a flow rate over 1,500 gallons per minute.
What is a fire hydrant flow test?
Hydrant flow tests are conducted to measure real world pressure and flow in the water system. Hydrant flow tests are required for fire sprinkler design and for water modeling purposes. They are generally known as fire flow tests as the highest demands on the system occur when fighting a fire.
How do you calculate fire flow?
Fire flow = length times width divided by 3. This formula is most easily applied if the estimated square footage of the entire structure is used to determine an approximate fire flow for the total structure and is then reduced accordingly for various percentages of fire involvement.