Thanks Don – yes, my ref is to current edition. But the intent is that only when multiple hose connections are influence is it required to furnish redundancy, which begets the bypass.
SML From: Sprinklerforum [mailto:[email protected]] On Behalf Of Don Casey Sent: Wednesday, September 06, 2017 12:01 PM To: [email protected] Subject: RE: PRV By-pass Steve is referencing the 2013 and / or the 2016 editions of the standard. Regardless, look at Item (3) which specifically addresses scenarios when two hose connections are downstream of a PRV. Cheers Don From: Sprinklerforum [mailto:[email protected]] On Behalf Of Tony Silva Sent: 2017/09/06 2:45 PM To: [email protected]<mailto:[email protected]> Subject: Re: PRV By-pass 7.2.4 in entirety is as follows: 7.2.4* When system pressure-regulating devices are used in lieu of providing separate pumps, multiple zones shall be permitted to be supplied by a single pump and pressure-regulating device( s) under the following conditions: (1) Pressure-regulating device(s) shall be permitted to control pressure in the lower zone(s). (2) A method to isolate the pressure-regulating device(s) shall be provided for maintenance and repair. (3) Regulating devices shall be arranged so that the failure of any single device does not allow pressure in excess of 175 psi (12.1 bar) to more than two hose connections. (4) An equally sized bypass around the pressure-regulating device(s), with a normally closed control valve, shall be installed. (5) Pressure-regulating device(s) shall be installed not more than 7 ft 6 in. (2.31 m) above the floor. (6) The pressure-regulating device shall be provided with inlet and outlet pressure gauges. (7) The fire department connection(s) shall be connected to the system side of the outlet isolation valve. (8) The pressure-regulating device shall be provided with a pressure relief valve in accordance with the manufacturer’s recommendations. (9) Remote monitoring and supervision for detecting high pressure failure of the pressure-regulating device shall be provided in accordance with NFPA 72, National Fire Alarm and Signaling Code. I may be reading it wrong, but I don't see this section as being applicable only when two hose connections are used. Tony On Wed, Sep 6, 2017 at 12:34 PM, Steve Leyton <[email protected]<mailto:[email protected]>> wrote: Read 7.2.4 closely: “Where more than two hose connections are used downstream of a pressure-regulating device …” A floor control assembly or a single hose connection with integral PR device does not require redundancy or a bypass because that section of the standard only applies to multiple hose connections influenced by a single PR device. My opinion only, but the standard clearly says what is says … SL From: Sprinklerforum [mailto:[email protected]<mailto:[email protected]>] On Behalf Of Tony Silva Sent: Wednesday, September 06, 2017 11:27 AM To: [email protected]<mailto:[email protected]> Subject: PRV By-pass NFPA 14, 2010, 7.2.4 (4) requires a bypass across a prv. Is it only when multiple smaller prv's are used instead of a larger prv, or whenever any prv is used? My application is there is a prv at the floor control stations supplying combined sprinkler/standpipe. Would this prv need a by-pass? The other question is will every prv need control valves upstream and downstream? I know it is good engineering practice to have the valves and by-pass, but very often there is not much space inside the stairs. What is the general industry practice? Thanks, Tony _______________________________________________ Sprinklerforum mailing list [email protected]<mailto:[email protected]> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
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