The use of the 20 to 30 pounds of air is to look for "gross leaks" like a joint that wasn't glued, etc. If the pressure does not hold at all then you can walk the system and find the offending fitting. Much better than finding the same gross leak with water pouring out of a fitting and potentially damaging things under it, especially a refit job in or above a finished space.
Kevin Law, PE Bechtel National, Inc. Waste Treatment Project Fire Protection Engineering Work (509) 371-3280 Cell (509) 531-5715 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Chris Cahill Sent: Wednesday, October 28, 2009 7:52 AM To: [email protected] Subject: RE: Homeowner needs advice I don't know what they have so can't comment specifically. >From the do's and don'ts from Blazemaster: In bold face - WARNING: AIR OR COMPRESSED GAS MUST NEVER BE USED FOR PRESSURE TESTING And normal text - Fill lines slowly and bleed the air from the system prior to pressure testing. And - After cut-in cure times are met, the system must be slowly filled with water and the air bled from the furthest and highest sprinkler heads before test pressure is applied (refer to manufacturer's installation instructions regarding Hydrostatic Testing). And - After cut-in cure times are met and the air is bled from the system, it is recommended that portion of the sprinkler system containing the cut-in tee be pressure tested. Prior to pressure testing, the system must be sectioned off to its smallest area using floor valves, etc., to isolate the cut-in area. It is further recommended that the test pressure applied should not exceed 50 psi over the system pressure. This approach will minimize the potential for water damage should a leak occur. That's rather clear to me TESTING! I don't see anything related to normal return to service after whatever. 13 would not normally require a new test for some add and relocates as I'm guessing was the scope of work. So not testing would be code compliant in this case. Again I would bet fitters in the field rarely if ever bleed the air for testing on new systems. Wrong? Technically. Sure they don't fill and pressurize with air they know to use water. Although I do know some fitters will put 20-30psi of air on the system to make sure it's holding before they fill with water. Of course I asked what good knowing it was leaking did them if they couldn't see air leaks and most likely could hear them either. Yeah, well ummmmmm.....ya see.... Chris Cahill, P.E. Fire Protection Engineer Sentry Fire Protection, Inc. 763-658-4483 763-658-4921 fax Email: [email protected] Mail: P.O. Box 69 Waverly, MN 55390 Location: 4439 Hwy 12 SW Waverly, MN 55390 -----Original Message----- From: Bill Brooks [mailto:[email protected]] Sent: Wednesday, October 28, 2009 8:32 AM To: [email protected] Subject: RE: Homeowner needs advice Chris, I like your response but could you discuss (via the forum) the product spec sheet issue raised by the homeowner. If removing the air doesn't matter, why does the spec sheet highlight it? Is this only applicable to the initial hydrostatic test? I think this would close the loop for the homeowner. Bill Brooks William N. Brooks, P.E. Brooks Fire Protection Engineering Inc. 372 Wilett Drive Severna Park, MD 21146-1904 410-544-3620 410-544-3032 FAX 412-400-6528 Cell -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Chris Cahill Sent: Wednesday, October 28, 2009 9:21 AM To: [email protected] Subject: RE: Homeowner needs advice I think Ed confused the issue. He's not wrong but I don't see it as applicable. Hydrostatic testing is not the question. The bleeding of air for test purposes is recommended because yes it will create a serious hazard if it ruptures. I'd venture though this bleeding is not actually done in the field. This testing is done at 200 psi. Your system most likely does not have this kind of pressure on it. And even if it did most of what is in the system is water not air. Air is compressible, water is not for these purposes. This is why air at pressure is dangerous and water not as much. The volume of the air is also a critical factor. A little air at very high pressure is not as big an issue as a lot of air at a lower pressure. Think when air is compressed energy is retained. The more volume of air, the higher the pressure the more retained energy. When the pipe breaks this energy is released. The water not being compressible does not retain as much energy. There is no reason really to bleed the air in the situation described. Actually some air in the system is a good thing. Because it is compressible is "absorbs" temperature changes and pressure surges much, much better than water. Think of it like a spring. If there was no air in the system and the temperature rose just a few degrees the pipe would break. This is the ratio of Pressure = Temperature from basic science. Taking an empty system at 0 pressure and filling it with water at street pressure leaves the air in the system, true. But after it's compressed to street pressure (much <200 psi, probably in the 80 range) there is very little volume left. Recall the ratio of Pressure * Volume = a steady value with no changes to Temperature from basic science. Double the pressure = 1/2 the volume. With average street pressure you are doubling the pressure many, many times. If one suspects trapped air is causing false alarms like George suggested the real problem is a leaking check valve. Each time the system surges from the city supply the new high pressure should be locked in. This could take a couple hours to a couple days to stabilize at the highest pressure. But at least in these parts surges in the street are not that common on scale or duration to cause false alarms. Again there is no reason to bleed the air in your situation. Chris Cahill, P.E. Fire Protection Engineer Sentry Fire Protection, Inc. 763-658-4483 763-658-4921 fax Email: [email protected] Mail: P.O. Box 69 Waverly, MN 55390 Location: 4439 Hwy 12 SW Waverly, MN 55390 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Tuesday, October 27, 2009 6:41 PM To: [email protected] Subject: Homeowner needs advice I'm not sure how this email forum works. I'm sending this out blind hoping one of you pros has some advice for me. I am a homeowner in a three-story townhouse. Recently, a company did some minor modification to our fire sprinkler system - moving a couple of heads for a basement remodel. When they were done with the pipe and heads, they simply re-pressurized the system without bleeding out the air trapped in the lines. From what little I know about it, I thought this step was very important to eliminate any pressurize air in the system and preventing dangerous surge pressures. It says so in big bold type on the product spec sheet for the CPVC pipe. When I asked the installer he said they don't need to bleed it, but couldn't explain why not. Before I go raising a stink about it, I want to know if your forum agrees that it's not necessary; or do I need to pester them into doing it correctly. Thanks. _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.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 [email protected] http://fireball.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 [email protected] http://fireball.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 [email protected] http://fireball.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)
