One thing to consider if the ITV is at the flowswitch instead of at a remote location is trapped air. If there isn't a vent or remote valve that can be opened when filling, then all of the air that is in the empty system has no where to go when you begin filling. This air will compress as the water enters, building up system pressure until the Back Flow Preventor closes even though the system is only partially filled with water. This trapped compressed air can cause multiple problems including increased oxygen corrosion, cycling of the flowswitch when testing and/or delayed operation of the flowswitch. When the ITV is opened the compressed air pushes system water out of the test valve. When the pressure drops enough the BFP will open allowing supply water to flow in and start the flowswitch retard. Since the system is not full of water, more water is flowing in than what can flow out of the ITV. This compresses the air again building up pressure until the BFP closes. Supply water stops flowing in allowing the flowswitch to reset. The compressed air pushes system water out of the ITV until the pressure drops and the whole cycle starts over again. There will be a steady stream of water flowing out of the ITV but there is not a steady stream of supply water flowing past the flowswitch. The flowswitch cycles back and forth. The flowswitch will either go in and out of alarm or may not go into alarm at all depending on the length of cycles and retard time. Leaving the ITV open for a long time doesn't help much because most of the air works towards the top of the system. Setting the retard for a shorter time delay doesn't help because opening the ITV bled of any excess pressure that may have built up and a prolonged increase in supply pressure such as the city turning on pumps early in the morning to meet the demands of the day can create a surge long enough to overcome the retard and cause a false alarm.
I'm not saying the ITV shouldn't be installed at the flowswitch, I know it saves time and money for installation & testing. I'm just saying that there should also be a vent, either manual or automatic to vent off the air as the system is being filled to aid in the reduction of oxygen corrosion and cycling or delayed flowswitch operation. Sorry to be so wordy but we receive calls about this on a regular basis. Regards, mike Mike Henke CET Sprinkler Product Manager 1-800-325-3936 314-595-6740 Direct www.pottersignal.com -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Steve Leyton Sent: Friday, January 14, 2011 2:40 PM To: [email protected] Subject: RE: Code reference for replacing remote end inspectors test withalisted Test N' Drain Valve.... True, but the latest editions are very clear that it is not required nor even recommended to locate the ITV at the most remote portion of the system: NFPA 13, 2010 8.17.4.4 The alarm test connection shall be permitted to be installed in any location on the fire sprinkler system downstream of the waterflow alarm. A.8.17.4.2 (Partial second paragraph) "... Putting the test connection at the most remote portion of the system causes the introduction of fresh oxygen into a large part of the system each time the alarm is tested and increases the corrosion that will occur in the piping." The prevailing attitude has changed significantly since the 2002 edition. On top of that, here in Southern California (as in other areas of this state, and some areas in other states) we have to contend with stormwater pollution prevention regulations that now strictly preclude and prohibit sprinkler discharge onto hard surfaces that will run toward, or directly into storm drain systems. It is much easier to coordinate a floor sink or hub drain at the base of the riser, into which we can dump both alarm test and main drain discharges, than to deal with the routing and accessory sanitary sewer connections that come with remote test locations. Steve -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Tony Liddic Sent: Friday, January 14, 2011 11:16 AM To: [email protected] Subject: RE: Code reference for replacing remote end inspectors test with alisted Test N' Drain Valve.... Sean, The 2002 Handbook says the following after 8.16.4.2.3: "Ideally the inspector's test connection is located at the end of the most remote branch line in the upper story. Such a location is not, however, required. For a wet pipe system, the exclusive purpose of the inspector's test is to verify operation of the alarm attachment, which is the reason that the test connection is not mandated at the remote portion of the system. The test connection is only required to be located downstream of the alarm device." Tony Liddic, CET MRH Sprinkler Design LLC 356 Laurel Glen Dr. Springboro, OHÂ 45066 937-369-7926 http://www.mrhsprinklerdesign.com [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Sean Lockyer Sent: Friday, January 14, 2011 1:44 PM To: [email protected] Subject: Code reference for replacing remote end inspectors test with a listed Test N' Drain Valve.... Does anyone know the specific code reference from NFPA 13, 2002 Edition, that allows for the deletion of the remote end inspectors test when you use a test and drain valve on the riser (Such as an AGF). I found it once but I'm having a heck of a time finding it again... Any help would be great appreciated as I would be in your debt... -- Sean Lockyer Project Designer Delta Fire Sprinklers (407) 328-3000, ext 139 _______________________________________________ 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)
