We have been asked to supply FDC signage for an existing building with combined sprinkler/standpipe system.
The AHJ has requested that both minimum and maximum operating pressure be included on the sign.
Can we use existing hydraulic data information or should it be recalculated including friction loss from the fire hose to pumper truck?
Also, what would constitute the maximum pressure in a combined sprinkler / Class III system?
Would it be max 175 psi at all 2-1/2” hose connections if there are pressure regulations devices on the 1-1/2” hose valves?
Thanks in advance in helping us sort this out.
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3/18/2022 08:06:34 am
I have never heard of an AHJ requesting this....FFs are taught across the board to pump into FDC's at 150psi. I imagine using the existing hydraulic information would be sufficient. Good luck!
3/18/2022 08:19:10 am
If its a manual system the minimum should be 150 psi at 1000 gpm per NFPA 14 - 2016 A.220.127.116.11
3/18/2022 08:23:31 am
3/18/2022 08:25:06 am
Clarification on the 350 PSI. This value requires PRVs off of the standpipe contingent on elevation loss. Ensure you review the entire system before providing the maximum pressure.
3/18/2022 08:28:45 am
The signage should be the requirement at the FDC inlet only. Let the Truck Engineer do the math on losses for the connections between the truck and the FDC (could be a run 2-2.5"x50' hoses or 1-4"x50' to a wye and 2-2.5"x50' hoses depending on how far away they park or available hoses). They have the potential of pumping far greater than 175PSI into a system.
3/18/2022 08:43:24 am
3/18/2022 08:45:08 am
I believe the AHJ is after the sign required by NFPA 13 2016 18.104.22.168.7.2. However it is probable that they are mistaken on the need, and proper use of the sign like our local AHJ's who often require this. The sign is required on systems that have a demand greater than 150 PSI. If the original calculation data is available, I would say that is safe to use, since the system was designed to that data, and the original sign (if needed) would have been off of that information also. Essentially when our AHJ's require this they are looking for what the inlet pressure should be at the FDC when the pressure is greater then the normal 150 psi starting pressure. I'm not sure what the minimum operating pressure they are looking for could be, and it is the fire department responsibility to calculate friction loss to the FDC. With the various types of FDC's, size fire hoses, and lengths of hose, it would be difficult to calculate the friction loss from the pumper to the FDC unless the fire department was very involved in the process.
3/18/2022 08:52:26 am
We do this a lot.
3/18/2022 09:14:41 am
- Personnel opinion -
3/18/2022 10:01:27 am
Maybe the signs they are looking for are as per NFPA 14 6.8 Hydraulic design info
3/18/2022 02:58:58 pm
Wow! Thanks for all the great replies. I agree the AHJ in this case might not be aware of the 150 psi clause as per NFPA 14.
3/18/2022 04:53:31 pm
It completely depends on the situation. What if your building is 50 stories 15 ft. elevation each? If the fire is in the penthouse, 175 psi will get the water a little more than halfway there.
3/18/2022 04:58:38 pm
Agree. If it was a high building there would likely be pressure reducing valves on the sprinkler zones and pressure restricting hose valves on the lower floors to accommodate a higher maximum pressure. In this case we had a 5 story building.
4/13/2022 10:39:44 pm
From a firefighter's perspective, we want to be prepared for the unexpected while maintaining simple, consistent procedures throughout the membership. Before I explain, a few bullet points:
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