$ 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 g...@rowesprinkler.com -----Original Message----- From: sprinklerforum-boun...@firesprinkler.org [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of Charles Thurston Sent: Friday, October 05, 2012 11:07 AM To: sprinklerforum@firesprinkler.org 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 §7.2.6.2.2 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 > mi...@pottersignal.com > www.pottersignal.com > > -----Original Message----- > From: sprinklerforum-boun...@firesprinkler.org > [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of Ron > Greenman > Sent: Friday, October 05, 2012 9:19 AM > To: sprinklerforum@firesprinkler.org > 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 <tduro...@comcast.net> 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: sprinklerforum-boun...@firesprinkler.org >> [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of Roland >> Huggins >> Sent: Thursday, October 04, 2012 5:44 PM >> To: sprinklerforum@firesprinkler.org >> 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 >> Sprinklerforum@firesprinkler.org >> http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum >> >> _______________________________________________ >> Sprinklerforum mailing list >> Sprinklerforum@firesprinkler.org >> http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum >> -- Best regards, Charles mailto:charl...@mbfsg.com 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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