Performing a 5-Year Flow Test

As part of NFPA 25 (and NFPA 25 California Edition, for those in the Golden State), the five-year test requires a number of inspection, test and maintenance steps, but we’re focusing specifically on your work with our team on the testing of the standpipe itself.

Dry Standpipes. An air test at 25 PSI is to be conducted prior to flowing the system with water. (NFPA 25 6.3).  Pressure over 25 PSI is not recommended due to the the potential for damage should any components of the plumbing fail.  (Wet systems do not require this, as any leaks are evident by the presence of water.  Note that NFPA 25 does not have an established allowable leakage rate, rather, it is subject to the judgement and experience of the fire protection contractor to determine if leakage should halt further testing until repairs are made.

INTENT: Verify the plumbing integrity before introducing water (and at high pressures) and posing water damage risk within the building.

Flow Test. All systems require a flow test every five years (NFPA 25 at the hydraulically most remote hose connection of each zone. This is typically the roof header or manifold on the top floor of the structure.  The test is conducted pursuant to the standard in effect at the time of the property’s construction.  (From the 1950s, 50 PSI was the design standard; from the early 1970s to 1993 were generally built to a 65 PSI standard at the the most remote connection, and 1993 and newer to 100 PSI.)  This may require a review of what version of NFPA 14 was used at the time of the original construction and occupancy. Regardless of pressure, the flow is based on a 500 GPM for the most demanding riser, and 250 GPM for each additional riser, to a maximum of 1250 GPM (partially or non-sprinkled buildings) or 1000 GPM (fully sprinklered), or 750 GPM (horizontal standpipe systems).

INTENT: Verify the system still provides the designed flow and pressure, and that any installed pressure reducing valves or devices are functioning properly.

If you cannot reach the most remote hose connection, the local fire authority having jurisdiction is to be consulted as to alternate arrangements. (NFPA 25  

INTENT: Conforming to NFPA 25 needs to be done in a practical manner; heroic measures to obtain a test are not expected.

Take note: NFPA 25 reiterates the flow and pressure requirements for five-year tests are to be conducted in accordance with the design criteria in effect at the time of installation. This becomes essential when we’re ready to flow, as the design, pipe size or configuration of, say, a 1950 structure may not be able to deliver water against the 100 PSI standard of today.  

INTENT: Directing us to pressurize a system beyond its design may stress the system and introduce damage, but may be in excess of the need to consider the test a success in any event. As the experts on the system being tested, we rely upon the fire protection contractor to know (and communicate to us) the appropriate maximum pressure for the building.  

Pressure-Reducing Valves. If the standpipe has pressure-reducing valves in place, these should be inspected per Chapter 13 of NFPA 25 (  We’d suggest completing this prior to the flow test, of course.

INTENT: By design, these valves reduce pressure as provided at the FDC and the standpipe header; a faulty or incorrectly set valve may erroneously appear to ‘fail’ a test and system that is otherwise sound.

Hydrostatic Test. There’s been a variety of approaches to meet this standard (NFPA 25 A hydro test at no less than 200 PSI (and held for two hours), or at 50 PSI in excess of the maximum system pressure where maximum pressure is less than 150 PSI, is part of the five-year test steps for both manual and semiautomatic dry. (NFPA 25; automatic dry systems do not require this testing – this requirement was removed in the 2011 edition).

INTENT: Sustained flow operations during fire operations are essential to the system meeting the functional need of the standpipe. If the system cannot maintain operating pressure for more than the few minutes of the flow test, it certainly will fail in the event of a fire emergency.

In instances where we have worked with contractors to perform this aspect of the test, we typically have conducted this after the completion of the flow test has been conducted.  (In a progression of successes, holding air pressure suggests the flow test will succeed.  Following a successful flow test, which involves flowing water into the FDC typically at or in excess of 100 PSI will then suggest the system can safely sustain a hydro test.)

In practice, by using the fire engine, we will be conducting the hydro with water — a fire engine cannot effectively pressurize a system with air.  At the conclusion of the flow test, the standpipe is already wet, so we begin by closing the valve at the test header or end-point from which we flowed water. We will then slowly throttle up the fire engine pressure until we reach the required PSI For the specific system design. Once we reach that pressure, a ball or gated valve at the FDC is closed. A pressure gauge at either (or both) the header or FDC is monitored during the two hour test to observe any pressure loss.

Before you hit the road…

  • If you notified the local fire department of the test being conducted, be sure to let them know it’s complete
  • Similarly, if flow or fire alarms were bypassed, disabled or put into a Test state, return them to a normal operating state
  • If this test was on a dry Standpipe, don’t forget to drain it!  At the end of the test, in order to leave with a “dry” system, obviously, the water needs to be drained out of the system.  We carry a contraption — and have seen others make similar devices — to help push back any swing or spring clappers to allow water to drain back down.  (Depending on local requirements, the drained water may be drained to the storm strains (via hoses – we carry plenty), captured into a tank for de-clorination, or even — once the water is flowing free of debris — can be re-captured back into the fire engine’s booster tank.)


Sources: NFPA 25 (2017) Handbook; NFPA 25 (2013) California Edition

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