Tom: Per NFPA 13 "A7.2.6.2.2 When a single air compressor serves multiple dry pipe systems the 30-minute fill time is based upon the largest single system."
When we trip larger systems, if we know the compressor is correctly sized, we rarely use it to refill the system. We typically rent a 125 or 185 CFM trailer mounted compressor, and use that to reset the system in a "burp" test, or to assist with blowing out the water after a full trip. And then to re-set the system. Even on a two or three system garage like we normally see here, it saves many man hours, and we feel we will have less water trapped in the system when we're done, because we've blown it out the insp. Test or drum drips at a very high velocity. Another "Down" side to using a compressor that we know is struggling to keep the system pressurized is it may fail during our testing, and then the first words out of the owners mouth will be "What did you do to my compressor?" This in spite of the fact that for the past 3 years you've listed it on inspection report as "Inadequate" "Does not meet NFPA 13 Requirements" "Needs immediate replacement" and copied the AHJ, because the system failed due to the compressor operation. We are actually looking for a used 100 CFM or larger trailer compressor of our own for just these situations. Thom McMahon, SET Firetech, Inc. 2560 Copper Ridge Dr P.O. Box 882136 Steamboat Springs, CO 80488 Tel: 970-879-7952 Fax: 970-879-7926 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Tom Duross Sent: Thursday, January 01, 2009 7:25 AM To: Sprinklerforum Subject: Dry System Valves Air Supply Happy New Year Campers, How many DPV's have you seen supplied off the same air compressor? I have a new ITM account that I'm thinking of recommending plant air compressors for. One location I just picked up, 5 levels of parking beneath Boston Common the FM guy went and bought two rotary screw compressors with big tanks and runs 80 PSI to 10 DPV's each with regulating assemblies. It seems to work real nice and he says his days of 4 AM trip calls are over. They used to have individual riser mounts that became problematic for him. They also have nice Hankinson refrigerated dryers. The buildings I have, the worst one anyway, has 6 levels of parking, 3 DPV's each level, one tank mounted 1/2 HP compressor for every two valves. They do have listed trim assemblies. The problems we had a few weeks ago were resetting the valves. We tripped both on a compressor (but only the first time) and they took an hour and a half to return the air pressure. After we did this, we only tripped one per compressor BUT our client got nuisance calls from the noise of the echoing compressors all over the garage and the Christmas shoppers thinking something was wrong. There are two stacks of rooms, one with a single DPV for 6 levels and one with 2 per level. The single stack has three compressors on each other level and the other has one in each room. These were only limited trips, I"m concerned about when we do full floods this summer. I haven't began looking into system capacities but they're all 4" Reliable D's, fed from 4" Cla-Val's set for 120-150 PSI discharge pressure and not that large. Would seamless pipe be in order? Malleable fittings? Would I size it for all connected valves or a percentage? Thanks, Tom Duross _______________________________________________ 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)
