Testing of Underground Piping
“We have a looped main severing several buildings and hydrants. Are we supposed to have a calculated flow test (Static, Residual, and Pitot) or an annual flow test? Is a flow test just opening the hydrants to flow water or the measured flow capacity? Since we are a state-owned university campus, are the hydrants considered public or private?” We have reviewed the 2014 edition of NFPA 25 you indicated as the applicable standard.Our informal interpretation is shown below since there are multiple questions. First off, although it is a state owned facility, the mains and hydrants are considered private. As you mentioned, it is your responsibility to maintain it and more it is there for the sole use of your facility. Actually, you are both somewhat right (except for the reference to calculate). Hydrants are required to be tested annually. That’s where you verify that they will operate by fully opening and closing. As such, you simply flow water without taking any measurements. This also constitutes flushing the mains (another annual requirement). Now every five years, you are required to perform a water flow test. This test requires identifying the available water supply (Static and Residual) while using a measuring device such as a pitot gauge. This is identified by: 25:7.3.1 Underground and exposed piping serving hydrants shall be flow tested at minimum five year intervals. The fact that it is a measured flow test is indicated by the annex saying perform the test in accordance with NFPA 291. Additionally, the actions required if the tests show the water supply has deteriorated confirms we have to measure the flow and pressures. This is stated in: 25:7.3.1.1 Any flow test results that indicate deterioration of available water flow and pressure shall be investigated to the complete satisfaction of the Authority Having Jurisdiction (AHJ) to ensure that the required flow and pressure are available for fire protection. The text from the old 2011 edition was in many ways better, at least from the perspective of what was required. It stated that the flow test was to determine the internal condition of the pipe and that flows should represent those expected during a fire. The effort to attempt to identify the equivalent C-factor was determined to be excessive. The intent is to determine if the water supply still meets the system demand. Another item worth noting is that the 2014 edition modified 25:7.3.1 so that the requirement applies only to mains serving hydrants. A literal interpretation (such as that used by attorneys) would be that this does not apply if the main is serving a single hydrant but that’s not the intent. There’s also the problem that the criteria for addressing individual systems without hydrants was retained. As it turns out, the 2017 edition reversed the 2014 decision and deleted the reference to hydrants. In closing, this is a measured flow test. In areas with drought conditions, it presents a problem since a calculated supply cannot identify partially or fully closed valves nor extreme tuberculation of the pipe. There is a valid argument that these conditions are flagged for individual systems by other required tests and should be restricted to just the high-volume fire flow associated with hydrants. A discussion with the AHJ is warranted. ------------ Technical Update is prepared by the Technical Services Dept. of the AFSA: Roland Huggins, a PE registered in fire protection engineering, Vice President of Engineering and Technical Services; and Tom Wellen, a PE registered in fire protection engineering. This is provided with the understanding that the AFSA assumes no liability for this opinion or actions taken on it and they are not to be considered the official position of the NFPA or its technical committees. Copyright 2016, American Fire Sprinkler Association. All Rights Reserved. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.firesprinkler.org/private.cgi/sprinklernotes-firesprinkler.org/attachments/20161212/e92ca1fd/attachment.htm>
