You can leak air through the seat and out the ball drip. When you hydro it doesn't show because the clapper is up and the ball drip is closed unless you're hydroing against the clapper which is not recommended.
On Thu, Jul 9, 2009 at 8:47 AM, <[email protected]> wrote: > Maybe the leak isn't in the system piping but in the compressor piping to the > system valve? > > > > > Craig L. Prahl, CET > Fire Protection Specialist > Mechanical Department > CH2MHILL > Lockwood Greene > 1500 International Drive > PO Box 491, Spartanburg, SC 29304-0491 > Direct - 864.599.4102 > Fax - 864.599.8439 > [email protected] > http://www.ch2m.com > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Tom Duross > Sent: Thursday, July 09, 2009 11:40 AM > To: [email protected] > Subject: RE: Dry System Air Question > > Very little grooved, just repairs made in the last 10+ years. It's all Sch40 > threaded, 1"-4", threaded flanges. This is just our 3rd year here, last year > when we did a full flood we attached a pump and took it to 200 looking for > leaks but couldn't find anything. I'm thinking the leak is concealed behind > old plaster walls. It does an unheated attic, traditional piping > arrangement. I'm guessing 40 years old with a 15 year old dry valve and > compressor. I'm told the compressor runs about once a day for a few minutes. > They lost power last Friday and the valve tripped about 4 AM on the 4th, I > spent most of the morning chasing low points and resetting it. > The compressor was tripped out so I'm thinking it went out on overload from > running so long, I did mention it shouldn't and suggested rewiring it to the > generator. It's a long term care facility right near NFPA in Quincy. I'm > aware of the allowable leakage but sometimes (like this) have a hard time > applying it. I did consider a scent test but if we couldn't even find a drip > at 200, would this help? > I'm getting splinters scratching my head but I have tweezers. > TD > > > > We have done this a couple times and have always replaced the compressor. > However, a word of warning inspired by learning the hard way. Assuming this > is a grooved system, when you drop the pressure the entire thing can start > leaking like a sieve. Older couplings can be a little brittle and less > resilient. They just don't like to seal correctly under the lower pressure. > > Best of luck! > > Lori Kitchen > > _______________________________________________ > Sprinklerforum mailing list > http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > For Technical Assistance, send an email to: [email protected] > > To Unsubscribe, send an email to:[email protected] > (Put the word unsubscribe in the subject field) > _______________________________________________ > Sprinklerforum mailing list > http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > For Technical Assistance, send an email to: [email protected] > > To Unsubscribe, send an email to:[email protected] > (Put the word unsubscribe in the subject field) > -- Ron Greenman Instructor Fire Protection Engineering Bates Technical College Tacoma, WA Member: SFPE, ASCET, NFPA, AFSA, NFSA AFAA _______________________________________________ Sprinklerforum mailing list http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
