NFPA-14 2019 Edition. There is a new section in NFPA 14 - Section 188.8.131.52.1:
The pressure required at the fire department connection for manual standpipes shall not exceed the working pressure of the system components of the standpipe system or sprinkler system when the system is a combined system.
Does anyone have any idea why this was added?
It seems to me that the maximum pressure at the FDC would be 175psi as this is what the sprinklers are rated.
Pumping at that pressure I would never get the 100psi required at the top of the most remote riser.
Or am I interpreting this section incorrectly?
Thanks in advance.
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11/23/2022 07:43:31 am
My best guess (and I've done this before using 200PSI on a 750GPM combined standpipe) and needed 180 at the base.
11/23/2022 08:31:14 am
Essentially, this means that if the standpipe is combined with a fire sprinkler system, and the required pressure to operate the standpipe is greater than 175 psi, the components of the sprinkler system that are not rated for pressures greater than 175, need to be upgraded. This is one reason that sprinklers listed to pressures greater than 175 psi were developed. The alternate is to pipe the sprinkler systems and standpipe systems separately.
11/23/2022 08:41:13 am
NFPA 14 (2019) 7.2.1 states the "maximum pressure at any point in the system at any time shall not exceed 400 psi".
11/23/2022 01:03:18 pm
If you put in PRV and have an overpressure event., you will not have fire protection. That violates fundamental precepts of code, protect life and property, noting life is first. That's why they limit source pressure to the pressure of the lowest rated pressure of any component in the system. Another way to look at it, if you need more than 175 psig, then you have designed outside of code - look at you hydraulics ( pipe size) and zone design, adjust accordingly.
11/23/2022 09:27:57 am
For a manual standpipe system the maximum floors you would exceed in height is typically 8 stories just below the 75 feet so to get a 100 psi residual pressure on the roof or top landing you can keep all components on any part of the combined system under 175 as long as the fire pumper operator does so.
11/23/2022 11:02:18 am
I haven't gone back through the committee discussions, but in AFSA Russ Bainbridge's January 7 article for "Sprinkler Age" on 2019 changes to NFPA 14, he states:
11/23/2022 11:15:08 am
And it might be below 175psi as well. If my FDC is at ground level, but my systems go below ground, I might have to have a maximum of ~150psi at the FDC.
11/23/2022 11:46:49 am
This is one of those code sections that shouldn't need to exist, but does because someone messed up a design using way to much 4" pipe, and then tried to rules lawyer their way out of the mistake by saying this very requirement wasn't explicitly stated in the code.
11/23/2022 12:17:23 pm
One reason this could have been added is for the firefighting side of the system. Depending on the jurisdiction, the FDC is either going to be a 2.5” connection, or a 4/5” stortz connection (large Diameter hose). One of the big issues with LDH is that they only have a service rating of 225 psi max. That rating is more for the actual hose. The weak point of the hose is the stortz connection to the hose. When you operate LDH at that sort of pressure, the hose normally does fine, but the hose will blow off the connection, and send the hose flying.
11/28/2022 12:37:28 pm
When I was at the FD, the LDH was never supposed to be used for anything other than supply to the truck from the hydrant. They started adding 3" intake pipe and Stortz connections to pump the hose primarily to set up a relay from distant water supplies and the pressure was always 150 psi for the maximum flow of the pump. I haven't kept up with the NFPA requirements for fire hose but I would hope the pressure tests of the 4 and 5" hose has been adjusted for increased pressures for Stortz connections at FDC's.
11/28/2022 12:39:22 pm
Sorry, "intake" should be spelled "discharge".
12/5/2022 12:18:06 pm
This one is always hilarious to me on several levels:
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