The comment below stating the flow switch activation does not need to be timed for wet systems because "the water is already there" is absolutely true THEORETICALLY. The "real life" truth is that all wet systems which benefit from electronic fire alarms should be timed to ensure they will operate with 90 seconds as required by NFPA and the Life Safety Code. Anyone who has conducted inspections knows the flow switch does not activate the very instance the ITC is opened. If the sprinkler system was 100% full of water, this would be the case; however, nearly all sprinkler systems have some trapped air pockets. Real life problems exist when the trapped air pockets are relatively large. A real life problem is when the delay on the flow switch is set for 30 seconds (the switch activates at 30 seconds during functional testing) and the electronic fire alarm does not activate when the ITC is wide open for 3 minutes, 5 minutes, 10 minutes or longer. This happens when the trapped air pocket allows (causes) the flow switch to cycle repeatedly!
Rodney K. Hamm, P.E. President/Owner Falcon Fire Protection Office (478) 953-1677 Cell (478) 396-6988 Date: Mon, 9 Mar 2009 12:30:43 -0700 From: Ron Greenman <[email protected]> Subject: Re: Test/Drain at the Riser To: [email protected] Message-ID: <[email protected]> Content-Type: text/plain; charset=ISO-8859-1 Timothy, You're right about testing the single head flow but on a wet system this can be done from anywhere since the water is equal everywhere. It does not need to be timed at the most remote point because it is already there. Timing is in this case to note the time from beginning of flow to alarm. This of course is only accurate if the test line is equipped with an orifice plate of the same K factor as the smallest head orifice. This I know Steve knows so the presumption would be that he was describing this as part of his overall scheme. On Mon, Mar 9, 2009 at 8:34 AM, Timothy W Goins <[email protected]> wrote: > I respectfully disagree. > > The purpose is to test the alarm device during a one head fire flow. Since > we have to time the device, putting it at the most remote area makes more > since, since we are simulating a fire at the most remote area and timing the > activation of the alarm device. The alarm device must activate before 90 > seconds (Electric) and or 5 minutes (Water Motor Alarm) you pick. > > If you are ONLY checking that the alarm device will work at the riser okay > then, but I don't believe that that is the intent of the ITC. > > Just my opinion, > > Timothy Goins _______________________________________________ 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)
