NFPA 13 (2016 Section 7.1.2 or 2019 Section 30.3.1) requires a relief valve on all wet pipe systems. The only exemption is where air reservoirs are installed to absorb pressure increases, then a relief valve isn't required.
This seems straightforward but I don't recall seeing independent relief valves on the far majority of the wet pipe systems I've come across. How is this requirement typically met from a design standpoint? Am I missing something or looking in the wrong place? Posted anonymously for discussion. Discuss This | Submit a Question | Subscribe
10 Comments
Wayne Ammons
5/3/2019 06:54:19 am
Prior to the 2010 edition of NFPA 13, only gridded wet pipe systems were required to have this relief valve. Tree systems typically have more trapped air than gridded but with air venting becoming more popular for mitigating corrosion (also required with the 2016 edition of NFPA 13), there should be less trapped air in all wet pipe systems. This can cause increased pressures within the system due to water fluctuations, solar heating, etc.
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6/4/2019 11:55:59 am
Hi Wayne,
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TJ Jones III
5/3/2019 10:16:39 am
Your Ready Risers can come with a Relief valve on the Test and Drain. You can also order them in an assortment of settings. 175 PSI is the standard for them so you have to plug them during testing.
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Franck
5/3/2019 10:23:57 am
As indicated above, this is quite a new requirement (less than 10 years) and is not retroactive. So many systems are installed without this piece of equipment.
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Ivonn
5/3/2019 10:29:30 am
Relief Valve are require in a wet system agree with section 8.1.2 NFPA 13 Ed.2019 in each system except where have an air reservoirs like you said, typically the inspector, test and drain have a 1/2" relief valve and you comply with that point.
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StephenJ
5/3/2019 11:18:13 am
I just wanted to point out that the requirement you pointed out are different. Section 30.3.1 in the 2019 version of NFPA 13 is a requirement specific to merchant vessel systems. Chapter 30 is titled marine systems.
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5/6/2019 11:24:57 am
Before this change in the Code we were the A/E firm on a project fairly near a city water system pump station, the pressure pulsations from the pump station would gradually build in the sprinkler system until the heads would blow. In the end the system check valve was drilled with a small hole to relieve pressure (and the City checked how it was operating their pumps). (Back in the day we only provided a single check valve on the water service connection).
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Jon Paton
5/17/2020 10:22:28 pm
My system was poorly designed. Static fire water pressure is constantly at or above the relief valve rating. This causes the valves to constantly leak. I can't rebuild the fire system. Can I put two valves in parallel or in series to reduce pressure? Would that invalidate the system?
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5/18/2020 07:39:42 am
Hi Jon,
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Tom Molnar
2/15/2022 12:04:10 pm
In the previous conversations, it appears that the two separate requirements for "Relief Valves" (Sect 7.1.2 in NFPA 13 2016, which first appeared in the 2010 edition) and " Air Venting" (Sect 7.1.5 in NFPA 13 2016, which first appeared in the 2016 edition) have been used interchangeably as the same item, but are two separate requirements - one for pressure relief (7.1.2) and one for air relief (7.1.5) requiring both items at each sprinkler floor control valve assembly. Please let me know if I am wrong.
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