Chris: Just out of curiosity, I took some calcs I did on various buildings to see the differences. These were not AF systems, but just a couple I had on my computer. I used a density of 1.07 and a viscosity of 190 cps (based on 50% propylene glycol at -20F).
The pressure swings ranged from 40-100 psi compared to HW calcs. I will admit that it was quite an eye-opener. I would be interested in hearing what others of you may find as well. You can find viscosities for PG at http://www.lyondell.com/lyondell/techlit/techlit/2514.pdf The temps to use can be found in NFPA 13, 2007 A10.5.1. Again, there are variables that would come into play. How do you deal with solutions that are in heated areas, compared to unheated areas, when the program (HydraCalc) only allows you to input a single density and viscosity? What is the clearance time of the AF solution? Should we not allow QR reductions for AF solutions? Anyway, just stuff to ponder on a Friday. Thanks for all of the help to everyone. This has been a unique learning experience. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Chris Cahill Sent: Friday, September 19, 2008 2:05 PM To: [email protected] Subject: RE: viscosities Well slow down there partner. Isn't the code as it stands today about right on for what we know? Travis points out a big surprise, to me anyway. What, he had a 100 psi difference in the demands pressure. That ain't fly... in these part. Even if DW is academically more pure what does it matter if HW is 90 or 110 psi differences. That is still significant. And we know HW is based on a certain density of liquid and temperature. -30 and anti-freeze ain't it. DW is a fairly easy tool today. Sure in 1950 perhaps it was a bit more cumbersome thus the development of HW and the '60 where it entered the code. The 40 gallons was the annex section on a should keep them below for maintenance reasons. Who cares where it comes from really it's a made up code number at this point. Like 52,000 sq.ft. or 12" down. Nothing magical just a made up limit based on judgment. And we know judgment is loosely defined in our field. Seems to me until there is testing that actually shows what is happening at -30 and how fast the anti-freeze clears given testing volumes in the path of travel we should leave it as is. If you want to go big (over the arbitrary 40 gallons) here's the penalty. It's just like the 500 and 750 gallon limits to dry system. None of us are old enough to recall if these are tested number but I bet they are nice round places to cut some things off based on judgment. Chris Cahill, P.E. Fire Protection Engineer Sentry Fire Protection, Inc. 763-658-4483 763-658-4921 fax Email: [EMAIL PROTECTED] Mail: P.O. Box 69 Waverly, MN 55390 Location: 4439 Hwy 12 SW Waverly, MN 55390 -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Roland Huggins Sent: Friday, September 19, 2008 2:09 PM To: [email protected] Subject: Re: viscosities I have also challenged using 40 gal as the trigger point. The substantiation said that value was piked because it was where special calculation were required (remember this was for changing the 07 where there were NO other calculations thus that was BS). The old 40 gal was a trigger for ECONOMICAL considerations between AF and dry pipe which was no longer valid so deleted. We need to see at what point it takes too long before the AF is discharged and we are getting just water out in making the decision on what size requires the DW. 40 gal is just too bloody small. We shall see. Any one smell tar in the air? Roland On Sep 19, 2008, at 11:43 AM, Travis Mack, SET wrote: > > I think that I will just use this diagram in the future until there is > more clarification on the issue from NFPA 13 officials. This will > really impact those of you in the northern part of the country with > respect to AF systems40 gallons. The viscosities get way out of hand > real quick at those lower temps. _______________________________________________ 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) _______________________________________________ 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) __________ NOD32 3457 (20080919) Information __________ This message was checked by NOD32 antivirus system. http://www.eset.com _______________________________________________ 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)
