Required Hydrostatic Test Pressure 1

[stookeyfpe]

This question is based on the 2007 edition of NFPA 14 but feel free to use the current edition because the requirement hasn't changed.

I have a 32 story high-rise I'm currently reviewing for compliance. The maximum churn pressure for the fire pump is 287 PSIG. The standpipe is constructed using Allied Tube & Conduit Schedule 10 pipe which is listed for pressures to 300 PSIG. It will be assembled using Victaulic Style 005 Firelock grooved couplings which for 6-inch pipe is listed for pressures to 300 PSIG.

NFPA 14 Section 11.4.1 states:

All new systems, including yard piping and fire department connections, shall be tested hydrostatically at not less than 200 psi (13.8 bar) of pressure for 2 hours, or at 50 psi (3.5 bar) in excess of the maximum pressure where the maximum pressure is in excess of 150 psi (10.3 bar).

As the AHJ I can require a hydrostatic pressure test of 350 PSIG to the standpipe and fittings based on the referenced section. I would like confirmation if you agree or disagree with my interpretation. I know it's a simple question but I haven't done a high-rise in over a year but in the next 6 months I'll be doing at least 5 standpipe/sprinkler plan reviews on high-rise buildings so I'm asking for guidance.

Thank you.

 

[cdafd]

sounds like your call is correct.

What does the pipe maker say???

And your test gage will be at the lower level??


Never tested that high!!! Should be interesting.



A.7.2 The system pressure limits have been implemented to replace the former height units. Because the issue addressed by the height limits has always been maximum pressure, pressure limitations are a more direct method of regulation and allow flexibility in height units where pumps are used, because a pump curve with less excess pressure at churn yields lower maximum system pressures while achieving the required system demand.
The maximum system pressure normally is at pump churn. The measurement should include both the pump boost and city static pressures. The 350 psi (24 bar) limit was selected because it is the maximum pressure at which most system components are available, and it recognizes the need for a reasonable pressure unit.

 

[skdesigner]

I believe "maximum pressure" refers to the highest pressure the system will see, as opposed to the pressure rating of the components. If 287 psig is the max system pressure, the required hydrostatic test pressure would be 287 + 50 = 337 psig measured at the low elevation of the standpipe zone.

Does 287 psig represent the fire pump churn pressure + maximum city static adjusted for elevation, or is it the fire pump only? If fire pump only, 300 psig will likely not be high enough once the city pressure is added in, but I can't see a 32 storey with 6" standpipes needing that much boost.


R M Arsenault Engineering Inc.

http://www.rmae.ca

 

[stookeyfpe]

Thank you all for your help. I set the test pressure at 337 PSIG.

The static pressure of the water supply is 100 PSIG and 187 PSIG is the churn pressure based on curve submitted by the FP contractor. With this and accounting for elevation & friction we get about 103 PSIG at the roof manifold.

CDA the pipe is listed to 300 PSIG and the fittings are listed at 300 PSIG. Victaulic includes a clause in its data sheet for a one time only pressure increase of 50 PSIG above the fitting's rated pressure. I've talked with the FP contractor and they'll perform a leak check at a lower pressure before taking the system to 337 PSIG.

I do appreciate the assistance I get from this forum.