Chris, Now that makes sense. I didn't think about the vertical drop of the spray pattern. If the full spray pattern is developed in the first 18", there should not be much of a shadow effect. Good point.
Thanks, Gregg Fontes Cen-Cal Fire Systems, Inc. 11780 North Hwy. 99 Lodi, CA 95240 Phone (209) 334-9119 Fax (209) 334-2923 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Chris Cahill Sent: Wednesday, February 10, 2010 12:25 PM To: [email protected] Subject: RE: Floor Mount Vertical Obstructions Two more thoughts. First, where does NFPA 13 say head 5'6" above walls or other obstructions are an issue in any occupancy including HPS of flammable liquids? We don't put head in each aisle in HPS with over 3' from storage to head. Lesser hazards it's 18", IMHO. If LH you even have options less than 18" Second, after a bit the droplets have changed from nearly horizontal movement to nearly vertical. By the time you are 5'6" down I'm sure all movement is nearly vertical. You can't have shadows from walls without horizontal movement. I believe most of this transition from horizontal to vertical takes place in the first 18" but don't quote me on that. 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 Chad Sent: Wednesday, February 10, 2010 2:00 PM To: [email protected]; [email protected] Subject: RE: Floor Mount Vertical Obstructions Bob, That is what I getting at. If you can ignore the partition for spacing the sprinklers, you are going to have individual cubicals that are going to get a shadowing effect that will not allow the floor space to get adequate coverage. Also, theoretically, you could have a cubical that will have floor coverage greater than 130 sq. ft. using the s x l rules. If you had to take the partitions into account, you could not have the sprinkler exceed 130 sq. ft. using the s x l. My concern is that a fire marshal will come back with this argument and NFPA will not have a definitive response or am I thinking to much? Thanks, Gregg Fontes Cen-Cal Fire Systems, Inc. 11780 North Hwy. 99 Lodi, CA 95240 Phone (209) 334-9119 Fax (209) 334-2923 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Bob Knight Sent: Wednesday, February 10, 2010 11:08 AM To: [email protected] Subject: RE: Floor Mount Vertical Obstructions Greg said, "So regardless of light or ordinary hazard". The obstruction criteria for Vertical Obstructions can only be applied to Light Hazard. Therefore, I don't believe that you can apply it to the storage compartments. Maybe what you are saying is that if you position a sprinkler directly over top of a partition wall than it could be 7' either direction to the next wall and not be affected? Otherwise, the shadowing created by the vertical obstruction would be huge and the ability of the sprinkler to adequately control the fire would be greatly reduced due to the potential fuel load in any given storage compartment. Anyway, just my two cents for the day, Bob Knight -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Chad Sent: Wednesday, February 10, 2010 11:45 AM To: [email protected] Subject: RE: Floor Mount Vertical Obstructions So the chart for Light Hazard occupancy shows that if the vertical distance is 18", than the sprinkler has to be 30" or more from the vertical obstruction. So regardless of light or ordinary hazard, you can ignore the vertical obstructions if they are greater than 18" down? So If you can ignore the vertical partitions due to them being greater than 18" below, you can also ignore any horizontal spacing to the partitions. You could end up with a sprinkler horizontally 7' off of two walls of the individual cubical. Therefore, the s x l would not apply to each individual cubical, since theoretically, there are no partitions. Correct? Thanks, Gregg Fontes Cen-Cal Fire Systems, Inc. 11780 North Hwy. 99 Lodi, CA 95240 Phone (209) 334-9119 Fax (209) 334-2923 No virus found in this outgoing message. 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