Why five years or ten years? There is always the potential that an aux valve could remain partially closed and forgotten any time work is done on the system. NFPA 291 recommends five years. AWWA-M17 suggests ten years. It is good practice to conduct flow tests on all parts of the distribution system, periodically and on demand, to identify the service areas affected by significant changes in the distribution system. In addition, this test requires less manpower, which makes it less expensive to perform and therefore more likely to be performed. It is from the hydrant that the firefighters count on getting water to extinguish fires. It verifies that the system works from the water source all the way to the hydrant. A test could be done on as described in either NFPA 291 or AWWA M17and an auxiliary valve that was left 95% closed would not be detected.įor the purposes of determining and indicating the available fire service water and identifying possible deficiencies in the hydrant system the Hydrant Capacity Fire Flow Test is most appropriate. The Fire Main Capacity test does not verify the functionality of the connection between the underground main and the hydrant because the Test Hydrant never flows water.
The Test Hydrant in this test never flows water. The Fire Main Capacity flow test does not verify the functionality of the Test Hydrant because the only use of the Test Hydrant is to measure static and residual pressures. The Main Capacity flow test overstates the flow-rate capacity that firefighters will encounter when they connect to the hydrant because this test does not hydraulically measure friction loss in the piping between the underground main and the test hydrant. What is the difference? Limitations of the Fire Main Capacity Flow Test If a firefighter needs to know that the hydrant works and the capacity of that fire hydrant, then the Hydrant Capacity Fire Flow Test is correct. If a fire sprinkler contractor needs to know the capacity of the water supply to hydraulically calculate a sprinkler system the Fire Main Capacity Flow Test is the correct test. The hydrant capacity flow test is not included in either NFPA 291, Recommended Practice for Fire Flow Testing and Marking of Hydrants, or AWWA M17, Installation, Field Testing, and Maintenance of Fire Hydrants.īoth tests are valuable, and correct or incorrect depending on the purpose of the test. The information derived from this test can be used by the fire service to plan for fighting fires. This procedure also determines whether the hydrant is mechanically functioning properly or not. The Hydrant Capacity Fire Flow Test determines the value of the water supply at the hydrant nozzle where firefighters are going to connect their suction hose. This test determines the value of the water supply of the underground fire main at the location of the fire hydrant. The Fire Main Capacity Flow Test is the test recommended by both NFPA 291 and AWWA M17. The Hydrant Capacity Fire Flow Test, which more accurately predicts water available from a hydrant and is more economical to perform. There is another test that is better designed for this purpose. The NFPA 291 recommends a flow test that partially addresses this issue the Fire Main Capacity Flow Test. How can it be known that a hydrant will open when needed and has the flow-rate capacity to fight a fire? The answer is to operate every hydrant and evaluate the water supply at the hydrant nozzle where the fire department is going to connect. When firefighters respond to an alarm they expect the hydrants to work.
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