John, Our Technical Support receives calls on this topic regularly. I will not point to a specific manufacturer, however some are worse than others. The problem your are experiencing is trapped air in the sprinkler system. There are two steps to correct this. The first in regards to adjusting the retard delay, move the trip stem down manually and time the flow switch. This will give you and idea of where the flow switch is working. The next step is to drain the sprinkler system and have them fill if SLOW, painfully slow in fact. While the system is filling, open every downstream drain, test connection etc. This will help evacuate the air as the system is filling. if there are any high points bleed the air at those points or install and automatic air release system.
The phenomena that you are witnessing is an air pocket in the system contracting and relaxing. The check valves are opening as the air pocket constricts and the y close as the air pocket relaxes. The pressures are equalizing and to prevent "back flow" the RPZ is closing preventing water from entering the system. Remember a flow switch is mechanical device and that vane is reacting to waterflow from 4-10 gpm. If the system is flowing less than 4 gpm or stopped, the flow switch will reset. Kind Regards, Tm Frankenberg Tim Frankenberg, CFPS Fire/Security Product Manager Potter Electric Signal Company www.pottersignal.com 800-325-3936 >>> "John Drucker" <[EMAIL PROTECTED]> 4/30/2007 3:24 PM >>> During waterflow alarm testing on a Wet Pipe NFPA-13 System I witnessed a phenomena wherein the vane type waterflow switch fluctuated back in forth appx every 10 seconds making it impossible to set a 30 second retard. Supply Pressure is 60 psi static, 55 psi Residual at 2" Main Drain Test. The WF Switch is mounted horizontally in a straight length of 6" Sch 10 48" from closest change in direction. Inspectors test is located downstream end of a branch line 1/2" orifice in place. The sprinkler contractor suspects theres a problem with this particular BFP. Anyone had a similar problem. Thanks John Drucker Fire Protection Subcode Official (AHJ) New Jersey _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
