Pressure reducing valve in sprinkler

[morgan.z]

Hi, I have a pressure reducing valve in sprinkler issue, my issue is when to install them in sprinkler system .
NFPA13 8.16.1.2.1 In portions of systems where all components arenot listed for pressure greater than 175 psi (12 bar) and the potential exists for normal (nonfire condition) water pressure in excess of 175 psi (12 bar), a listed pressure-reducing valve shall be installed and set for an outlet pressure not exceeding 165 psi (11 bar) at the maximum inlet pressure .
NFPA13 calls for it where it is overpressured.
Can i say , for PRV instalation of NFPA13, is it only allowed to be installed in such said case?
Other than that, is non-compliant? like, to reduce the pressure to desired level(The max pressure is not over 12bar or its rating pressure) . It seems a little vague.
Please share your view of this! we can lean .
FM has specifically specified this ,FM 0311 2.1.3 Do not use pressure reducing valves on sprinkler systems and hose connections where the static inlet
pressure is 175 psi (12.1 bar) (1210 kPa) or less.
To reduce /regulate the pressure , we have pressure-reduced deluge valve available, it is ok, if we have one ,or two deluge valves, we can use pressure -reduced deluge valve. While in Some case ,when there are more deluge valves (up to 10~20) in oil,chemical industres, to have one pressure-reducing valve at header would be cost effectly.
Thanks in advance!

 

[TravisMack]

We use the pressure regulating deluge valves to balance pressures in things like foam deluge systems. A single pressure reducing valve, while less costly would not allow the same issues of regulating / balancing pressure in those settings.

I have had to use PRVs when working with existing systems and needing to combine things like overhead and in-rack systems. If I need to balance and can't get it with reasonable pipe sizing, we may use a PRV to help balance the scenario. Again, these are very specific situations where it is used with pressures <175 psi.

Travis Mack, SET, RME-G,
Ferguson Fire & Fab, dba MFP Design

http://www.mfpdesign.com

 

[morgan.z]

Thanks, Travismack!
You are right, pressure regulating deluge valves can make adjustment individually. These are very specific situations where it is used with pressures <175 psi.
if someone uses ONE pressure -reduced valve before 7 deluge valves to lower pressure( just to avoid too much flowrate, the pressure is only 130psig at riser bottom ), can I say it is not NFPA -compliant? I currenly run into such situation.