NFPA 14 -Standpipe Acceptance Test with PRVs

[Luis Bernal]

Hello,
Just looking to see if anyone has accomplish this testing
As per NFPA-14, 2013 Edition section 7.8.1 "The hydraulically designed standpipe system shall be designed to provide the water flow rate required by section 7.10 at a minimum residual pressure of 100 psi at the outlet of the hydraulically most remote 2-1/2" hose connection and 65 psi at the outlet of the hydraulically most remote 1-1/2" hose station." and a total water demand of 500 gpm from the most remote two valves and 250 gpm from all other standpipes up to 1000 gpm for sprinklered and 1250 gpm for non sprinklered buildings. The expectation in the test is same, the standpipes should be able to supply the required total flow simultaneously and one most remote outlet should provide 100 psi pressure. Therefore all the hose valves should be flown at the same time when testing. The test methodology suggested in NFPA 25 Handbook reflects the same requirement.

Given in my scenario I have PRV valves up to 4th floor on a 10 story building.
Most of these PRV have a good 40's to 50's PSI Loss through the calculation process.

AHJ is addressing that the same test done at the roof (most remote valves) should be done at the most remote valves with PRVs
in this case
(2) valves one at the 3rd (250gpm) Floor and one at the 4th (250gpm @ 100psi) most remote standpipe
additional which will be the 4th floor (250gpm) of the additional standpipe.

I just cant seem to get this to work flowing with the additional losses and pressure provided by the PRV manufacturer.

Im open to ideas or suggestions.

THANK YOU,

 

[TravisMack]

It sounds like you didn't have the correct pressure settings for ordering of the PRV's. I've seen this many times over the years. If you are using the diaphragm valves (Zurn ZW3004 or something like that) you may have problems if it wasn't designed correctly. You may have to switch to a pilot operated valve, like a Cla-Val or something. The pilot operated take up a lot more room and can be problematic on a stair landing due to space constraints.

Travis Mack, SET, CWBSP, RME-G, CFPS
MFP Design, a Ferguson Enterprise

http://www.mfpdesign.com

 

[Luis Bernal]

Hello Travis
I am on the design stage . No valves have been ordered. Using the ZW4000 For Hose valve
Ive already done the HW and sent this to Zurn and gotten back pressures available.
I use Autosprink software where im doing the loss through the valve input
Example:
Inlet Static 180psi
Inlet Residual 165psi
Outlet Static 142psi
Outlet Residual 120psi

My input for loss is =45psi

This is more less at each PRV Valve -
Any other suggestion i should be looking into?
Thank you

 

[TravisMack]

So what is the issue then? You have your 100+ psi outlet residual. Assuming you are flowing all as required, it seems you meet the criteria with this.

Travis Mack, SET, CWBSP, RME-G, CFPS
MFP Design, a Ferguson Enterprise

http://www.mfpdesign.com

 

[Luis Bernal]

Yes i do have them providing 100+ individually flown. But when i do the 750gpm @ 100 psi gives me negative safety margin.
Increasing fire pump pressure will make increase the inlet PRV up the floors. Also this changes the outlet pressures which is almost like a circle providing almost or close losses.

Also the outlet starting pressures will be 120psi - not the minimum of 100psi
I'm just looking to see if there is anything that I'm not applying right in my input or if there is something I'm not applying right. Or even if this test requested doesnt work
considering that the lower the floors the more loss/restriction you have on these valves.

Thanks for responses

Luis

 

[TravisMack]

I think you may be doing your calcs incorrect. Since you use AutoSprink, I'd be willing to do a quick Microsoft Teams meeting with you and show you how to do these calcs.

Travis Mack, SET, CWBSP, RME-G, CFPS
MFP Design, a Ferguson Enterprise

http://www.mfpdesign.com

 

[Luis Bernal]

I would greatly appreciate that!
Let me know when you are available.

Luis
Luis@lm-fire.com