hydrostatics

How and when is a hydrostatic test conducted on standpipes and sprinkler systems

A fire protection system requires regular inspection and testing to ensure it works in an emergency, and one of the essentials is a hydrostatic test, also known as a functionality test. The National Fire Protection Association (NFPA) defines a hydrostatic test as “a test of a closed piping system and its attached appurtenances consisting of subjecting the piping to an increased internal pressure for a specified duration to verify system integrity and system leakage rates. [NFPA 24, 2016]”

Basically, a qualified fire safety inspector uses a test pump to force water into the system at a specified pressure, ensuring that there are no leaks that could cause standpipes or a sprinkler system to fail during a fire. The test ensures that piping has been put together correctly, that there are no weaknesses that have developed due to damage or corrosion, and that the Fire Department Connection (also known as the Siamese Connection) can withstand high pressure.

Performing a Hydrostatic Test

Performing a Hydrostatic Test (Image Source)

This article will examine the code requirements, conditions, and methodology of hydrostatic tests for standpipes and sprinklers according to NFPA codes 24 and 13, simplifying this guidance for contractors and building owners.

Are you looking for a test pump to conduct a hydrostatic test? If so, feel free to browse our selection of hydrostatic test pumps here.

To see an in-depth review of how to choose a hydrostatic test pump for fire sprinklers and standpipes, check out this blog.

The 5-year rule: Hydrostatic tests for standpipe systems

Standpipes are an essential apparatus in the event of a fire, basically serving as fire hydrants for the interior of a building. These systems are composed of pipes that run vertically up the floors of a building with horizontal bridges that allow professional firefighters or building occupants to access water during an emergency. They come in two main varieties: A wet standpipe (manual or automatic) is filled with water at all times, shortening the time it takes to deliver it. Dry standpipes are only filled with water when an action is taken, and they include manual dry standpipes, which require a fire department pumper to supply water through a Fire Department Connection; semi-automatic dry standpipes, which can provide pressurized water after activating an onsite fire pump or control device; and automatic dry standpipes, from which a ready supply of pressurized water can be accessed.

A Fire Department Connection

Automatic versions of both types of standpipe are pressurized (wet with water, dry with air), enabling anyone to simply turn a valve to access water, which is often already connected to an onsite hose within a pinrack unit.

The following types of standpipe systems are exempt from the five-year hydrostatic test, as they contain pressurized air or water within them at all times:

  • Manual wet standpipes that are part of a combined sprinkler/standpipe system
  • Automatic wet standpipes
  • Automatic dry standpipes

All other standpipes must comply with five-year hydrostatic testing. These include:

  • Manual wet standpipes that are not part of a combined sprinkler/standpipe system
  • Manual dry standpipes
  • Semi-automatic dry standpipes

That said, NFPA 25 also states that “The piping from the fire department connection to the fire department check valve shall be hydrostatically tested at 150 psi (10 bar) for 2 hours at least once every 5 years.” A literal interpretation of the code could mean that this particular section of piping should be hydrostatically tested in all types of standpipe systems, but that isn't necessarily the case. For an in-depth look at this issue, see this Sprinkler Age article.

From the 2017 Edition of NFPA 25

6.3.2.1* Hydrostatic tests of not less than 200 psi (13.8 bar) pressure for 2 hours, or at 50 psi (3.4 bar) in excess of the maximum pressure, where maximum pressure is in excess of 150 psi (10.3 bar), shall be conducted every 5 years on manual standpipe systems and semiautomatic dry standpipe systems, including piping in their department connection.

6.3.2.1.1 Manual wet standpipes that are part of a combined sprinkler/standpipe system shall not be required to be tested in accordance with 6.3.2.1

How is a hydrostatic test done on a standpipe system?

To conduct a hydrostatic standpipe test, a qualified fire safety professional needs to introduce water through a hose connected to both a water supply and a test pump at the lowest point in the system, which is typically from the city water supply to the fire department connection. The water must be pressurized to 200 psi or at least an additional 50 psi in systems with a maximum pressure of over 150 psi. The system must stay pressurized for two hours, during which time the inspector looks for signs of a leak.

What are the signs of a leak in a hydrostatic test of a standpipe system?

During the two-hour pressurization, the fire safety professional examines the standpipes for visible leaks in the piping, joints, and fittings, while periodically reading the pressure gauge to look for a drop in pressure.

A significant drop in pressure from 200 psi (or stipulated test pressure) indicates that there is a leak somewhere in the system. If the leak is not visible, it could mean that it is occurring in hard-to-access areas, such as underground piping. Sometimes, these leaks may show themselves after a period of time; for example, a growing wet spot on a concrete floor could indicate a problem underground.

NFPA 25 is unclear about what constitutes an acceptable drop in pressure, noting “Minimum leakage existing only under test pressure is not cause for repair.” That said, the separate NFPA 13 guidance on hydrostatically testing underground pipes in fire sprinkler systems may provide some insight:

From the 2016 Edition of NFPA 13

10.10.2.2.1* All piping and attached appurtenances subjected to system working pressure shall be hydrostatically tested at gauge pressure of 200 psi (13.8 bar) or 50 psi (3.4 bar) in excess of the system working pressure, whichever is greater, and shall maintain that pressure at gauge pressure of ±5 psi (0.34 bar) for 2 hours.

10.10.2.2.2 Acceptable test results shall be determined by indication of either a pressure loss less than gauge pressure of 5 psi or by no visual leakage.

Thus, a loss of a little over 5 psi at ground level might indicate a small leak, whereas if the 200-psi test pressure drops to the city water pressure of about 50-60 psi, it indicates that there is a catastrophic failure in the system.

Hydrostatic tests for fire sprinkler systems

In contrast to standpipe systems, there is no regular hydrostatic testing schedule for sprinkler systems. Instead, sprinklers are only hydrostatically tested when they are first installed or whenever the system is modified. This “acceptance testing” must be done on both wet systems – those prefilled with water – and dry sprinkler systems – those filled with pressurized air or nitrogen – at either of those two events.

From the 2016 Edition of NFPA 13

25.2.1.1 Unless permitted by 25.2.1.2 through 25.2.1.5, all piping and attached appurtenances subjected to system working pressure shall be hydrostatically tested at 200 psi (13.8 bar) and shall maintain that pressure without loss for 2 hours.

25.2.1.2 Portions of systems normally subjected to system working pressures in excess of 150 psi (10.3 bar) shall be tested as described in 25.2.1.1, at a pressure of 50 psi (3.4 bar) in excess of system working pressure.

25.2.1.4 Modifications to existing piping systems shall require testing at system working pressure.

25.2.1.4.1 Where modification is made to an existing system affecting more than 20 sprinklers, the new portion shall be isolated and tested at not less than 200 psi (13.8 bar) for 2 hours.

25.2.1.4.2 Modifications that cannot be isolated, such as relocated drops, shall require testing at system working pressure.

25.2.1.5* The test pressure shall be read from a gauge located at the low elevation point of the system or portion being tested. The pressures in piping at higher elevations shall be permitted to be less than 200 psi (13.8 bar) when accounting for elevation losses. Systems or portions of systems that can be isolated shall be permitted to be tested separately.

 

water leak around sprinkler head and escutcheon

See the water ring? This may indicate a leaky pipe

Essentially, the entire system must be tested at (at least) 200 psi for two hours upon installation. Small, subsequent modifications to the system may be tested at normal system working pressure, whereas any larger modification of the system (involving more than 20 sprinklers) must be isolated and again tested at a higher pressure.

How is a hydrostatic test done on a sprinkler system?

Conducting a hydrostatic test on a sprinkler system is very similar to the test for a standpipe system. The water supply and a test pump are used to introduce pressurized water from the lowest access point of the system for two hours. During the testing period, an inspector examines the piping, fittings, and all appurtenances for visible leakage while periodically monitoring the gauge for a significant loss of pressure, which should ideally stay within ±5 of the target psi at the lowest elevation.

Special considerations for hydrostatically testing sprinklers and standpipes

Commercial vs. residential sprinkler systems

Commercial sprinkler systems require a pressure of at least 200 psi for acceptance testing at installation and large modifications to the system, whereas residential NFPA 13D sprinkler systems only require hydrostatically testing the system at its normal operating pressure (for systems without a fire department pumper connection). When any system has a fire department pumper connection, it must be hydrostatically tested at the higher pressure in accordance with NFPA 13.

Cold-weather testing

Testing a sprinkler system in weather where water is subject to freezing can be done on an interim basis with air pressure, but this does not permanently replace the need to test the system with water (NFPA 13: 25.2.1.3). In systems that use pendant sprinklers in a cold environment, all water must be drained from the system after hydrostatic testing, unless it is filled with an NFPA-approved antifreeze solution that has been premixed from the factory. (NFPA 13: 7.6.1.3, 7.6.1.3.1)

Testing prior to completing construction

Some pendant sprinklers heads can’t be installed until their escutcheons are in place after the ceiling is assembled, which would block visual inspection of the pipes. In these cases, hydrostatic acceptance testing can be done using plugs in place of the sprinkler heads. (NFPA 13: 25.2.1.8) In addition, plugs may be used in deluge systems to block the open sprinklers, which must, of course, be removed after the completion of the test. (NFPA 13: 25.2.1.9)

Other inspections that can be done during a hydrostatic test

While a professional performs the two-hour hydrostatic test, a general visual inspection of the system is a good idea. Items to look for in addition to leaks include obvious signs of corrosion or physical damage. Visual inspection for compliance with codes such as appropriate labeling of fire safety system components, sufficient lighting, emergency signs, and fire extinguisher placement can also be conducted while examining the piping in the building.

A quality test pump should be used during a hydrostatic test

Hydrostatic testing requires the use of test pumps that are reliable, powerful, and convenient for use in a range of settings. At QRFS, we offer a full selection of Triple R Specialty test pumps that get the job done, from lightweight electric-powered versions with easy-carry handles to heavy-duty, gas-powered models attached to a cart. Our selection of test pumps ranges from 200 to 1,200 maximum PSI and all come equipped with 10 feet of high-pressure hose.

Tru-Test Hydrostatic Test Pump

Tru-Test Hydrostatic Test Pump from Triple R – See All Test Pumps Here!

Ordering from QRFS means you get competitive pricing, fast delivery, and exceptional customer service. We stay up to date on all NFPA requirements, ensuring that we offer the right equipment to keep you both compliant and safe.

Do you have more questions about hydrostatic testing and test pumps? Add a comment below, give us a call at 888.361.6662, or fill out our contact form and we’d be happy to assist.

Additional Sources:

1.“Back to Basics: Standpipe Systems.” Firehouse.com. https://www.firehouse.com/article/10503421/back-to-basics-standpipe-systems

2.“Everything You Need to Know About the 5-Year Hydrostatic Test.” Capitol Fire Sprinkler. https://capitolfire.com/everything-you-need-to-know-about-the-hydrostatic-test/

3.“Maintenance and Testing of Fire Sprinklers.” Minnesota Department of Health. https://www.health.state.mn.us/divs/fpc/engineering/Firesprinklers2.pdf

4.Clay, Howard. “Standpipe Hydrostatic Testing.” Sprinkler Age. https://sprinklerage.com/standpipe-hydrostatic-testing/