Ok, I'm catching up after some time away and some time off. My recollection in the late-80's was the condensation would come down to the check and form an ice plug, which would mean no water to that section of the dry system. "Gluing" a clapper in place would be similar, but wasn't what I heard in Phila at the time.
glc -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ron Greenman Sent: Thursday, April 10, 2008 12:27 PM To: [email protected] Subject: Re: Check valves and dry systems Todd, That was what I was talking about in my last post. You cannot subdivide the dry piper with check valves. One reason I can think of is because when new and they work you have one water delivery time but as they age and leak each subdivision that does so adds time to decompression and so to water delivery also. I've seen this problem and so from this standpoint this recent (maybe 99) in 13 makes sense. The other problem I can imagine is the clapper on a swing check "glueing" itself shut due to disuse.On the one's I'm familiar with that was never a problem. Back to subdivision. 13 does not (and I admit I'm stretching this and remember that I don't like the idea but I'm not the owner, designer, layout tech or the AHJ and am merely arguing code/standard points) prohibit check valves in dry systems. It specifically prohibits using them for subdivision. Again, if water delivery time was what prompted the prohibition, then testing the system with the check valves removed and replaced by spools effectively addresses the prohibition since the now missing clappers are not there to hold air back and so you are getting a realistic picture of the entire system rather than just the riser and one floor. Would IU recommend such a scheme. Never, but not because the schema itself is without logical merit but rather because of the ridiculous costs and the tendency to "cheat" associated with IT&M. Part of the argument here revolves around committee intent. Why is this rule there in the first place (like the 52K square footage limitation)? Is it there because it's always been there and we don't remember why (Like 52K)? Is it there because a problem was discovered and this is a fix (maybe like this prohibition against subdivision by check valve in dry pipes)? Is it there because some vendor has come out with a new product that meets a need and rules for its use are needed (the section for ESFR)? Or is it there because someone can just make money? We can't know unless we religiously follow the RFPs/RFCs and the voting and have photographic memories or wish to spend hours upon hours searching old stuff that's not catalogued or indexed. Perhaps with the state of electronic filing NFPA can make access to the thousands of hours of committee stuff easily accessible. I don't think the intent is to make these deliberations opaque in any way but they are, at this time, translucent at best. We have Joe Hankins that can shed light on some of FM reasons and conclusions. Steve addresses 14 intent regularly. Bamford, Dead Bob, Roland (my neighbor that I never see) and others chime in when they know how a committee came to a decision but these guy's memory hardly make an archive. Ron Greenman ...at home _______________________________________________ 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)
