sprinkler systems in grease ducts

[kmjt1021]

I made my gazillionth (did I spell that right) trip to national airport to help them clear up some of their inaccessibility issues. I met with a lady from a company I have never dealt with before but they apparently do a ton of work for Host Marriot, (the Management Company for all the rental space in the airport). I was supposed to get with her and she would arrange to have things moved that are currently blocking access to the ducts. (Good luck).
She seemed preoccupied with getting access to sprinkler heads in the duct, because the nozzle need to be changed yearly, and that obviously has never been done. I have never seen this kind of sprinkler system in a grease duct. She said it sprayed water???? and that they are required in grease ducts that elbow. These are water pipes that run along the duct and at various points branch off and go through the duct wall where there is a spray head. She did not seem to impressed when I told her that I have been into a ton of places with elbowing ducts and have never seen this kind of sprinkler system. Does anyone know what she is talking about?
Oh, she introduced me to a revolutionary new access panel, it requires no welding, and they install them for only $650.00 per hole. Wow what a deal!!!! She gave me some literature for this great new panel, and guess what? On the top of the page it said DUCTMATE hahahahahahahaha I think I can buy those for about $70 bucks. She also suggested that they could install a panel on the bottom of the duct. At that point I had had enough and pulled out my copy of NFPA 96 and said I live by this. She said so do we, with a big smile.
I didn't say much, I wanted to check some facts before start anything, I will have to work with this company to get the major obstacles to the ductwork move before any panel can be installed.

this is the company
http://www.hitt-gc.com/home/main/index.html

as you can see by this website, this is no fly by nighter

 

[Douglas Hicks]

Well Mr DeLayn, it seems you have met your match. She is convinced she knows more than you do. You did ask how many ducts she has been in didn't you? Ask her nicely and give her a pair of coveralls, she may go on the job with you.
1. The Ductmate panel comes in different configurations for different applications. If you try real hard, you might be able to bid $600.00 to install the panel. I know this is low-blling, but sometimes you just have to do it. Duct mate is the best, just make sure the lady installs the high temp model and not the one w/a rubber seal. While you and I know not to install an access panel on the bottom of the duct, (NFPA 96- 2001 7.3.1) the International Mechanical Code is silent on this. I do not know the code in your part of the USA

2. Now the biggie. NFPA 13-1999, Installation of Sprinklers 4-9.3 exhaust ducts shall have 1 sprinkler or automatic spray nozzle located at the top of each verticle riser and at the midpoint of each offset. The first sprinkler or automatic spray nozzle in a horizontal duct shall be installed at the duct entrance. Horizontal exhaust ducts shall have such devices located on 10 - foot centers beginning no more than 5 feet from the duct entrance. A sprinkler or an automatic spray nozzle in exhaust ducts subject to freezing shall be properly protected aganst freezing by approved means. (this means an antifreeze loop or a dry head)
exception No. 2: unless suppression system meets UL 300

go to A 4-9.2 for a sketch of an exhaust system protected by a water system.

4-9.12 Sprinklers and automatic spray nozzles used for protecting commercial -type cooking eqipment and ventilating systems shall be replaced annually.
Exception, where automatic bulb-type sprinklers or spray nozzles are used (this means glass bulb, not fusible link) and annual examination shows no buildup of grease or other material on the sprinklers or spray nozzles.

Water based sprinkler systems can be used in exhaust systems if approved by the AHJ, or installed prior to UL 300, which went into effect in Feb of 1994. The real problem w/water based systems is that they do not meet the requirements for fryers. The only head UL listed for fryers was the EA-1 Grinnell ( I still have a couple ) The Grinnell Co delisted the head when the code was changed. Other appliances, the hood and duct use hi-temp (325 degree and up to 500 degree heads) for portection.

If this exhaust system is protected by a UL300 compliant system, the water sprinkler system will just dilute the fire suppression chemical. The heads should be removed if this is the case.
in fact, the water sprinkler system should be removed and a UL 300 system installed.
Bryan, I could fax a picture of the sprinkler system in a duct if you want.

Douglas Hicks
General Fire Equipment Co of Eastern Oregon, Inc

 

[kmjt1021]

Thanks Douglas I figured you would know. Funny I haven't run into more of these

That picture would be helpful
304-274-9370 fax

 

[karen]

But ya know what's really neat about the glass bulb sprinkler heads? If you break one with a spinner, 65 gallons of water a minute will pour out onto the guys working water containment downstairs!

Karen
(who doesn't actually go out and get dirty)

 

[kmjt1021]

This almost makes sense to me now, after reading the info Douglas sent to me, the accesses at the airport are installed to service the sprinkler heads, not for cleaning, even though some of them are up against a wall and are useless.
I had a look at the blue prints for these systems and they all say according to NFPA 96. My copy of that version does mention sprinkler systems in the duct. When was that introduced?

 

[Lou hoods&more]

Lil dust on it but good info.

 

[Ron Musgraves]

Great Post !!!