See below. Scott
Office: (763) 425-1001 x 2 Cell: (612) 759-5556 From: David Williams <david.willi...@lhbcorp.com> Sent: Thursday, August 15, 2019 2:39 PM To: Scott Futrell <sco...@ffcdi.com>; sprinklerforum@lists.firesprinkler.org Subject: RE: Attic/Concealed space access to sprinkler heads Language camp facility. Rural area. Installing a underground water storage tank with vertical turbine pump. Originally we were to provide partial sprinkling of just the dining hall not sure if that meant the attic above it or not. The Fire Marshal and others convinced them to provide complete sprinkler of two buildings (and more as the campus get built out.) the demand is driven by the kitchen in the dining hall. (BTW the fire marshal wants us to use one of those weird MN domestic water pump as a supply for the fire protection system.. Yuck.. no local driller can drill the required 10 inch well and the risk of not having enough water at the yearly test drove us to the tank) The dining hall has a convoluted 4500 SF attic with some standard attic that is accessible, but that has a 6 foot wide flat roof section with skylights running down the middle. Of that a 1000 SF area that has been created with scissor trusses and the skylights and flat area over a dining area. There is a inaccessible dropped wood ceiling below the attic structure where we will run the wet system protecting the dining room. The gypsum above this could be marked for access points. And yes, cut holes if needed for the inspection. Writing the spec now, I have been using nitrogen for the last few system designs, I wasn't sure I should for this one due to cost as there is an adjoining building with a "normal" dry system for the attic and the 8 foot wide combustible eaves. Is a small nitrogen generator cost effective?[saf] Not really for a small system. More so for long-term though. Proper pitch, no roll grooves, no low points, all can extend life without nitrogen. The problem with the insulation is the almost 48 inch depth required at the "thick" part of the scissor truss. This architect doesn't want to do it that way, although our housing group regularly designs flat truss roofs with near 30 inch thick insulation due to past experience with burst/leaking sprinklers. What about Ron's contention that no access should be provided.[saf] I can't agree with NO access. NFPA 25 requires internal test and they have to be able observe line adjacent to ITV line. So, in five years they have to find the pipe and cut the first hole? I think you have convinced me to at least specify nitrogen and schedule 40 over the limited access area, with a prohibition on groove joint in those areas. David T Williams - Lead MEP/FP Engineer LHB, Inc. | PERFORMANCE DRIVEN DESIGN. From: Scott Futrell <sco...@ffcdi.com<mailto:sco...@ffcdi.com>> Sent: Thursday, August 15, 2019 2:08 PM To: sprinklerforum@lists.firesprinkler.org<mailto:sprinklerforum@lists.firesprinkler.org> Cc: David Williams <david.willi...@lhbcorp.com<mailto:david.willi...@lhbcorp.com>> Subject: RE: Attic/Concealed space access to sprinkler heads David, Interesting question. You haven't provided enough information for a thorough answer. How big of an attic area? So you intend to mark the location of every upright sprinkler in the concealed space on the ceiling below? No one will ever paint that gypsum? Then cut access for NFPA 25 5-year internal pipe inspection? And cut access for NFPA 25 20-year sprinkler inspection? Life expectancy of a design/build NFPA 13 dry sprinkler system, riser mounted air compressor, schedule 10, black steel pipe = 7-15 years. Is that the system you are specifying? Or, are you specifying with nitrogen and schedule 40 pipe? Other? Why not fill with insulation? As long as you avoid mold issues (see webinar) that could be a better long-term option for your current client and whoever buys it next. NFPA 25 requires limited access for internal inspection, but if anything goes wrong (e.g. corrosion) how do you work on it without taking significant pieces of the ceiling down. Can you imagine how hard it is to locate pipe and problems in that space (i.e. Confined space) without accurate as-built drawings (I'm lucky if the owner has any drawings, but as-built for those spaces aren't the norm). We've taken off the roof of structures less than two years old to locate pipe and abandoned dry systems in attics because it is too expensive to take the ceilings down just to start locating the leaks and facilitate repairs. Too many questions for a simple answer. It'll be great to hear other responses. Scott Office: (763) 425-1001 x 2 Cell: (612) 759-5556 From: Sprinklerforum <sprinklerforum-boun...@lists.firesprinkler.org<mailto:sprinklerforum-boun...@lists.firesprinkler.org>> On Behalf Of David Williams via Sprinklerforum Sent: Thursday, August 15, 2019 1:43 PM To: sprinklerforum@lists.firesprinkler.org<mailto:sprinklerforum@lists.firesprinkler.org> Cc: David Williams <david.willi...@lhbcorp.com<mailto:david.willi...@lhbcorp.com>> Subject: Attic/Concealed space access to sprinkler heads I have a project intended to be fully sprinkled with a combustible attic that tapers from 2' to 4 ' without being filled to within 2 inches of the deck with insulation. So I am planning on a dry pipe system with standard heads as the design of the attic does not allow the effective use of special application attic sprinklers. The questions are: whether inspection access is required to be provided, is it prudent to do so at the heads, or can the locations just be noted on the gypsum mounted to the bottom chord of the open web trusses. TIA David T Williams, PE - Lead MEP/FP Engineer 21 West Superior Street, Suite 500, Duluth, MN 55802 Direct 218.279.2436 | Cell 218.310.2446 LHBcorp.com<http://www.LHBcorp.com> LHB, Inc. | PERFORMANCE DRIVEN DESIGN.
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