Are you calling your insurance company before, or after, your attorney? (trick question- the insurance company hires the lawyer, so you could be placed in the position of Chris the building owner suing Chris the sprinkler installer in your own building, if your "protected" building burnt down. If you were deemed negligent as the PE reviewing the plans, and did so as a LLC you may have set up for plan review work, you could be subrogating yourself, just to add to the confusion. And since you'd likely have your building in a real estate LLC, Chris Building LLC's insurance could subrogate/sue Chris the Spkr installer corp who subrogates/sues Chris the PE, LLC).
glc -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Chris Cahill Sent: Monday, December 01, 2008 11:14 AM To: [email protected] Subject: RE: variable public water supply Just to play devils advocate where does the code say you need to consider anything else but the hypothetical .3/2000 for 600 gpm? The code also says you have to include the hose demands. And if you do this exercise for less than the total heads what does the area look like? Do you start with one head and add heads on the BL until you reach the number prescribed by the 2000 sq.ft. then add from the next line? If you try .3/1500 the heads per line would be different. The full heads on the BL would be the most demanding pressure wise usually, but what about the same number of heads across several lines. What about rings starting with 1, 4, 9 then 16? You get into an almost infinite number of permutations all falling on different points on the curve with an infinite number of hose steam possibilities. And which curve anyway, the 500 year drought and theoretical peak demands assuming the sustained growth of the city for said 500 years. Infinite defined by the realistic time I have to run all these calcs. There is no reason a curve can't have a step up in it at the gpm the pumps kick on. In theory your LH demand could have a lower pressure available than a higher demand. I don't see a problem. This is definitely an interesting discussion but may be academic. Consider the failure rates of sprinklers and the causes. Also consider I suggest 95% of flow tests are done wrong and not on the conservative side. And yet we don't have a lot of failures from this. If the valve is open and no one shut it early the failure rates get really, really small (true not 0). Take out the wrong design for the hazard and we're even closer to 0. Also consider for many operations nowhere near the designed number goes off. Further consider the local FD supplement. Out in the middle of nowhere it may be more important. Really bad sprinklers designs and installations put out a lot of fire. This paragraph is not an excuse to design bad systems but a suggestion there is a point of diminishing returns as we tweak the code and our engineering capabilities. Show me attics burning with the <99' code and I can go along with changing the attic requirements, but I Duross. But if I'm the one I don't care about the statistics when I call my insurance company because one of my protected building burned down. 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 Thom McMahon Sent: Saturday, November 29, 2008 3:01 PM To: [email protected] Subject: RE: variable public water supply It sounds like more study for the actual system demand is required, otherwise your just guessing at the 15 vs. 20 flowing. You'll need to verify all start stop settings with the civil engineer for the water purveyor, and then look at the system demand, from the flow recorders. What time will the system supply/demand be the greatest? This is when your pump will kick in fastest. When is the supply/demand the lowest? This is when the pump will take longest to kick in, possibly even over the 660 Gpm your system demands if when you did your flow test the domestic demand on the system exceeded 160 Gpm, and your lowest demand is less than 10 Gpm, then it's possible your system will never kick the pump in. 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 Todd Williams Sent: Saturday, November 29, 2008 1:46 PM To: [email protected] Subject: RE: variable public water supply In this case, the new pump is variable speed and is designed to maintain a constant pressure. At the hydrant we were reading the pressures on, it kicked in at 45 psi and boosted it to maintain 65 psi out to the capacity of the pump. My thought is that ignoring the pump at sprinkler flows up to where the pump kicked in (approx 500 gpm in this case) is correct. If the system demand was over the 500 gpm, what would be the effectiveness of the sprinkler system at the flow goes from 0 to whatever the demand is when the curve is not 1.85 linear? From the time of first sprinkler opening, up to the 500 gpm, we will be operating on a different flow curve than what we will over the 500 gpm. Our designs are usually based on a maximum flow requirement only and assumes the linearity of the flow curve. Say you have a demand of .30/2000 (ignore hose streams in this case), or roughly 660 gpm. The sprinklers require 33gpm each. The design says that we have to calculate 20 sprinklers flowing. Should the design for the first 15 sprinklers (.30/1500) be based on the lesser curve and the .30/2000 be based on the curve with the pump? Two sets of calcs? How do you justify this to the septic system engineer that speced out the sprinkler system? _______________________________________________ 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) _______________________________________________ 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)
