American Fire Sprinkler Association 12750 Merit Dr., Suite 350, Dallas TX 75251
Ph: (214) 349-5965 Fax: (214) 276-0908 ----------------------- TECHNICAL UPDATE OCTOBER 14, 2009 ----------------------- We have a dry pipe system installed in an attic with a sloped ceiling. Near some of the attic spray sprinklers are return bends to sprinklers below the ceiling and are covered with 2 ft wide batt insulation. It looks like a small curtain next to the sprinkler. An inspector has flagged these as obstructions and indicated 8.6.5.2.2 for floor mounted obstructions apply. Considering that the ceiling is sloped, what is the appropriate evaluation as an obstruction for these items? We have reviewed the 2007 edition of NFPA 13 you indicated as the applicable standards. Our informal interpretation is the covered return bends fall under section 8.6.5.2: Obstructions to Sprinkler Discharge Pattern Development. This is actually a very interesting question because when you look down the plane along the floor of the attic, the insulation appears above the sprinkler. In actuality, though, you should be looking down the plane of the ceiling since we are evaluating the impact on the water discharge and the deflectors are required to be installed parallel to the ceiling as per 8.5.4.2. So with that plane of reference in mind, lets consider how to address the obstruction. First off, let╒s address whether it should be considered a floor mounted obstruction since the batt insulation does touch the floor. As stated in 8.6.5.2.2, it is guidance for privacy curtains, freestanding partitions, room dividers, and similar obstructions. All of these listed items are expected to obstruction a wider portion of the sprinkler discharge whereas the batt insulation is only 2 ft wide so the regular obstructions rules should be applied. As in all obstructions, one should step through the three sections to determine which one applies. Starting with 8.6.5.1, we can skip this one since it is for obstructions tight (or very close) to the ceiling. Moving to 8.6.5.2 looks right since it is for obstructions less than 18 inches below the deflector (since we are looking down the plane of the ceiling). You do still have to consider two issues. First is this a continuous obstruction (defined as affecting two or more adjacent sprinklers. It is not. The second issue is a bit more obscure but as discussed in A.8.6.5.2.1.4, you have to ensure that the obstruction is not butted up beside the sprinkler so as to obstruct close to half the water discharge. These should then been consider continuous obstructions even though it does not affect two or more sprinklers. Since this is not the case, this section applies. ----------------- Technical Update is prepared by the Technical Services Dept. of the AFSA: Vice President of Engineering and Technical Services Roland Huggins, a PE registered in fire protection engineering; Phill Brown, a NICET IV certified automatic sprinkler technician and NFPA Certified Fire Protection Specialist (CFPS); and Tom Wellen, a degreed fire protection engineering technologist. This is provided with the understanding that the AFSA assumes no liability for this opinion or actions taken on it and they are not to be considered the official position of the NFPA or its technical committees. Copyright 2009 American Fire Sprinkler Association. All rights reserved. -------------------------- If you╒d rather not receive future faxes from AFSA, fax your removal request to Amy Sweeney at Efax (214) 242-3155 or call toll free (888) 839-4830 or send e-mail request at [email protected]. Please include your company name and the specific fax numbers(s) at which you do not wish to receive faxes from us. Our failure to comply with your request may be unlawful. _______________________________________________ Sprinklernotes mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklernotes
