The air we breath is 78% N2 I think you might want to check into this further. 97 or 98% N2 is about right?
Sent from my iPhone On Oct 5, 2012, at 6:52 PM, "Tom Duross" <[email protected]> wrote: > N2 Blast #250. 2 1/2" replacement main x 100' with 500' of 1" branches. > Relatively small. I2 5BRx2B bungalow. 120'x45'. > I talked about sizing these with their Engineer and got the impression they > size them for some 'expected' leakage plus the trickle you set the purge > valve to relieve. I was told it could take up to 72 hours to achieve 79% > preferred concentration. I really was impressed with the thought behind the > whole design of how it would basically ideally remove one aspect of that > corrosion triangle. This system that we posted here about had some serious > turburcles and just blew through 1"-3" sch40 in about 6 places. I was there > this afternoon taking a sample of N2, 79%. I cheaped out and got the > handheld probe but they have a remote reader that can be put at the valve or > someone's office, cabled to the purge valve. > Range is huge and 600+ systems could be pricey but with a basic 30 minute > compressor and then switched over to a nitrogen purge, I can't imagine any > issues even if the ramp up to concentration took 2 weeks or more. > The generator makes up to 70 PSI so it does need to be tamed, but even if we > left the compressor open to the system just in case the generator output > didn't keep up, it would mean a burst of raw air behind the nitrogen into > the system. I piped it from the generator to the tank, from the tank to the > AMD and to the DPV1 with a tee before the AMD taking the compressor output. > Everything is valved. Right now today, compressor is valved off and solely > on N2. I tripped it last week for the FD and it's been almost 7 days. I'd > like to keep the compressor on but have to talk to them. > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of George Church > Sent: Friday, October 05, 2012 5:21 PM > To: [email protected] > Subject: RE: Air Supply > > Mind sharing the system volume for that much generator $? > You well know the volume range is huge, and with electronic accelerators now > allowing reliably faster trip times, we've done some warehouse conversions > that were monstrous. The one I'm thinking of had FM blessing, and a high > pressure supply that got the delivery time needed, but I'm sure there are > lots of other systems, and we've seen em especially in recycled old mill > type buildings, where the Owner didn't want to pay for heat so there's a > bunch of 8" risers with 6" DPVs. Not that an 8" would make any difference in > delivery time in some low or medium pressure situations. > Tick tick tick > > George L. Church, Jr., CET > Rowe Sprinkler Systems, Inc. > PO Box 407, Middleburg, PA 17842 > 877-324-ROWE 570-837-6335 fax > [email protected] > > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Tom Duross > Sent: Friday, October 05, 2012 4:20 PM > To: [email protected] > Subject: RE: Air Supply > > George, the generator I bought with an autopurge valve for the line to the > ITV, a sensor for checking N2 concentration, storage tank, was $6800. I'm > gambling on limited data here that this 10K investment on a system will save > my customer from having to replace 50K in pipe and fittings only 30 years > old (30 years or less from now, not to mention the inconvenience, details, > etc.). Bottles are cheap but I was leery about a couple of 5000 PSI bombs > 20' from bedrooms. > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of George Church > Sent: Friday, October 05, 2012 11:22 AM > To: Charles Thurston; [email protected] > Subject: RE: Air Supply > > $ > You've got a belt and suspenders cost for a customer who, by code, only > needs one. > And it didn't have to be the more expensive N2 version. > So when presenting the idea of minimizing future corrosion, he's got the > following, grabbing $ out of the air: > 1. plant air- $600 for an AMD > 2. Compressor- $1500 > 3. Bottle and HP AMD- $3000 > 4. Generator- 15000 > 5. Gen and bottle- $18,000 > > I'm seriously just trying to illustrate order of magnitude, anyone else > doing bottles and generators now can chime in if I'm off by a factor of 5 or > 10. But costs vary with system size etc. > > > George L. Church, Jr., CET > Rowe Sprinkler Systems, Inc. > PO Box 407, Middleburg, PA 17842 > 877-324-ROWE 570-837-6335 fax > [email protected] > > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Charles > Thurston > Sent: Friday, October 05, 2012 11:07 AM > To: [email protected] > Subject: Re: Air Supply > > Hello, > > Use bottled nitrogen for the 30 minute refill time and the nitrogen > generator for the pressure maintenance of the system. > > Friday, October 5, 2012, 10:55:28 AM, you wrote: > >> Ron, > >> I requested a technical interpretation from NFPA for that exact question. > >> My question was: > >> NFPA 13, 2010, 7.2.6.2.2 states; The air supply shall have a capacity >> capable of restoring normal air pressure in the system within 30 minutes. > >> It does not state that the system shall be restored to normal system >> pressure in 30 minutes. It states that the air supply shall be capable >> of restoring the system to normal pressure in 30 minutes. > >> My question is, If you can prove through calculations that the air >> supply is capable of restoring normal pressure in 30 minutes, would it >> be acceptable to actually take longer than 30 minutes to restore >> normal > pressure? > >> The purpose for the delayed fill time would be to use a nitrogen >> generator as a pressure source instead of an air compressor. If an >> empty system was initially pressurized with nitrogen, that would >> eliminate the purging process that would be necessary if the system >> was first pressurized with air and then the air slowly replaced by >> nitrogen over time. This would help to slow any oxygen corrosion that >> might be initiated if the system was filled with air. > >> Membrane type oxygen generators work by forcing air into a membrane >> that separates the nitrogen from the oxygen. The CFM output of a >> nitrogen generator is about 50% less than the CFM of the air >> compressor supplying the nitrogen generator. The nitrogen generator >> has a bypass loop so the system could be filled directly from the >> compressor if desired. This is similar to the fill and maintain modes >> of an Air Maintenance Device. > > >> Their response was: > >> The intent of NFPA 13, 2010 edition ยง7.2.6.2.2 is to provide a >> guideline which will protect the owner of the system from someone >> installing an undersized compressor which would render systems out of >> service for elongated periods of time while increasing service costs. >> The compressor is not required to be listed, in fact - a compressor is >> not required. The compressed gas supply may be from a reliable plant >> air source or nitrogen tanks with a regulator. The committee intent >> is to have the system returned to service within the 30 minute >> timeframe - regardless of the source for compressed air or nitrogen. >> It is assumed that a nitrogen generator (or other approved compressed >> gas) will provide nitrogen over the subsequent hours of operation and >> replace the air used for initial charging. > > > >> Regards, >> >> mike >> >> Mike Henke CET >> Sprinkler Product Manager >> 314-595-6740 direct >> [email protected] >> www.pottersignal.com >> >> -----Original Message----- >> From: [email protected] >> [mailto:[email protected]] On Behalf Of Ron >> Greenman >> Sent: Friday, October 05, 2012 9:19 AM >> To: [email protected] >> Subject: Re: Air Supply > >> I'm curious where the 30 minute fill came from. Convenience to FDs? >> I'd certainly not want my highly paid and trained engine company >> hanging around for a couple of extra hours to watch the system fill. >> But if I'm likely have the service guy from the sprinkler company, or >> even my owned trained maintenance, hanging around, and I'm willing to >> pay for him to watch the paint dry, and I'm so concerned with my >> system as to have bought a nitrogen generator instead of using that >> nasty moisture holding air, why not ignore > >> that code section? Or is the 30 minute rule there just because we >> needed a > >> definitive time frame and 30 minutes sounded reasonable at the time? >> Or is > >> there another, more compelling reason? Curious minds want to know. > >> On Fri, Oct 5, 2012 at 6:07 AM, Tom Duross <[email protected]> wrote: > >>> Most generators, if not all, have a nitrogen storage tank. The one I >>> used put out 70 PSI requiring an AMD and we still had a riser mount >>> air compressor because the generator could not fill in 30 minutes. >>> They're interconnected and valved. >>> >>> -----Original Message----- >>> From: [email protected] >>> [mailto:[email protected]] On Behalf Of Roland >>> Huggins >>> Sent: Thursday, October 04, 2012 5:44 PM >>> To: [email protected] >>> Subject: Re: Air Supply >>> >>> If you use nitrogen (7.6.2.7) it now kicks you over to 7.2.6.5 >>> (Automatic Air Maintenance). Must admit, I see no reason to use an >>> air tank and plenty not to (as George already said). I'd say an air >>> cylinder would be not different than a nitrogen cylinder when it >>> comes to requiring an AMD. If you do not have a low pressure alarm, >>> the pressure gauge has to be checked weekly instead of monthly. Now >>> that dry pipe system have to have an air > >>> leakage test performed every 3 years, there shouldn't be any systems >>> (or at least as many) needing a compressor running full time to keep >>> it from tripping. >>> >>> Roland >>> >>> On Oct 4, 2012, at 12:54 PM, Cahill, Christopher wrote: >>> >>>> Looking over a job where the EOR wants to use cylinders to supply >>>> the air for a dry system. There is plenty of power to the building >>>> so that's not the issue. They are showing lab air cylinders from >>>> both air (NC) and nitrogen (NO) into an AMD into the system. I get >>>> automatic air is not required. But I'm seeing NFPA 13 >>>> '12-7.2.6.5.1 limiting air supply when AUTOMATIC to dependable shop >>>> system or a compressor. I don't see bottles being allowed. Or >>>> that is to say I don't see bottles as being a dependable shop system. >>>> >>>> I assume some of you have done bottles for the air to a dry system? >>>> As I read you can have them if someone manually opens a valve and >>>> refills the system when needed? Of course this is even confusing. >>>> Is there something on a manual fill system that requires daily >>>> checking? Or are they relying on the low pressure alarm to note >>>> when time to refill? Actually, the low pressure alarm isn't even >>>> required, > >>>> right, so are they waiting for a system trip to know when to add air? >>>> >>>> If manual is allowed isn't an AMD off a bottle a little better but >>>> not > >>>> quite the full blown compressor? Why would they restrict the >>>> middle on the order of worst to best? >>>> >>>> Who wants to straighten me out 'cuz none of us here have ever seen >>>> bottles used on a system? >>>> >>>> Chris Cahill, PE* >>>> Senior Fire Protection Engineer, Aviation & Facilities Group Burns >>>> & McDonnell >>>> >>>> http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum >>> >>> _______________________________________________ >>> Sprinklerforum mailing list >>> [email protected] >>> http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum >>> >>> _______________________________________________ >>> Sprinklerforum mailing list >>> [email protected] >>> http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > > > > > > > -- > Best regards, > Charles mailto:[email protected] > > Confidentiality Notice: This e-mail message, including any attachments, is > for the sole purpose of the intended recipients and may contain confidential > and privileged information. 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