Garth: I'm not saying that a drain would be required on an "Outside" installation, as we see on vacation to those warmer climates. We're talking installations inside of buildings. The IPC says a "Riser room" is a mechanical room, and requires a min. 2" drain in all mech rooms. Double check or RPZ the room will have a floor drain of 2" or it may be installed in a freely draining area or words to that effect.(So if it's in a room it's a mech. room and must have a drain, if it's in a warehouse or other open area it must be freely draining.
Now RPZ are their own animal for drains. Here in CO our Cross Connection Control Manual has a "Drain flow Chart" and Notes "Floor Drain capacities are established by the Floor Drain MfG's. The reason is that the air gap of a RPZ is usually not large enough to actually capture a full flow discharge from the intermediate chamber (Reduced Pressure zone) Most RPZ's have smaller air gaps than the max flow they discharge would require. Here's one of my favorites: 3/4" RPZ with 100 Psi will discharge 100 GPM from its relief. That translates into a 4" floor drain from most MFG's. OK building drain is 4" so just put a 4" floor drain in the Mech. right? Wrong! The plumber following the plumbing code only put in a 2". Think the GC is going to put in a 4" after the concrete is poured? Not likely. This is where "Relief drains" come in. You need to provide a way to allow the extra 50 Gpm that the 2" drain won't handle to drain to the outside or another approved location.(Without that relief, the room would fill with water, and eventually burst from the internal loads of the water filled area.) Now let's extend that out to a 4" RPZ @ 100 Psi. Flow chart says 650 Gpm or 7-4" floor drains in the riser room. Not too practical, since once again that may be larger than the building drain. Answer? 2" floor drain the plumber installed plus a 8" relief drain to the outside. (We typically use a Fernco Cap (rubber) without the tightened band over a piece of 8" pvc. By leaving the band off, the cap will blow off usually before it's running 1/2 full. The cap keeps out bugs mice ect. And helps keep heat in during cold weather. A little joint lube on the cap also helps ensure it will blow off.) 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 Garth W. Warren Sent: Monday, August 25, 2008 7:11 PM To: [email protected] Subject: backflow preventer drains (All rooms containing a backflow preventer are required to > have a drain and a relief drain.) Thom - Could you give a reference for this requirement? I know there are requirements for RPZ installed below ground level. I have seen three buildings that were flooded by RPZ above ground installations where the water had no place to go. Is this requirement for DCVs as well? Thanks, Garth _______________________________________________ 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) No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.138 / Virus Database: 270.6.9/1635 - Release Date: 8/26/2008 7:29 AM _______________________________________________ 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)
