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  1. #1
    Forum Member Fireguyminn's Avatar
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    Default Fires in Restaurant Exhaust Hoods & Ducts Water-Wash Systems

    Does anyone have any information or case studies on fires in restaurants or commercial kitchens where the fire spread into the hood and duct? More specifically, I am looking for failures involving water-wash/continuous water-wash type hoods where the water-wash feature was non-operational or disabled at the time of the fire, or a falure altogether allowing a cooking appliance fire (fryer, grill, etc.) to spread into the hood and duct.

    Our jurisdiction is fighting a disagreement on the importance of proper maintenance of Water-Wash hoods. We have a few Water-Wash Hoods in our jurisdiction that have NEVER work properly since new due to poor installation, compounded by years of neglect and poor/no maintenance. They're claiming that we are "over-reacting" and they want us to show where water-wash hood failures led to large loss fires in these types of systems.
    To explain a little more, we are a Federal Agency on a Military Installation, so those politics come into play.
    A long search of Google didn't yield any results.
    Last edited by Fireguyminn; 12-11-2012 at 06:08 PM.


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    Forum Member FWDbuff's Avatar
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    Quote Originally Posted by Fireguyminn View Post
    Does anyone have any information or case studies on fires in restaurants or commercial kitchens where the fire spread into the hood and duct? More specifically, I am looking for failures involving water-wash/continuous water-wash type hoods where the water-wash feature was non-operational or disabled at the time of the fire, or a falure altogether allowing a cooking appliance fire (fryer, grill, etc.) to spread into the hood and duct.

    Our jurisdiction is fighting a disagreement on the importance of proper maintenance of Water-Wash hoods. We have a few Water-Wash Hoods in our jurisdiction that have NEVER work properly since new due to poor installation, compounded by years of neglect and poor/no maintenance. They're claiming that we are "over-reacting" and they want us to show where water-wash hood failures led to large loss fires in these types of systems.
    To explain a little more, we are a Federal Agency on a Military Installation, so those politics come into play.
    A long search of Google didn't yield any results.
    What the heck is a water-wash system? I looked in the ICC mechanical code and couldnt even find it.....???? By the way I am a medically-retired Federal FF turned municipal fire marshal/code enforcement official. Who the heck on a military installation is fighting the Fire Department??? Every base I worked at (2 Navy, 1 Army) our word was as good as God- we told a Building Occupant to do something, it got done, period!!! Civilian DOD employee, Civilian Contractors, or Military Occupants- they didnt dare question our fire inspections. I'm curious to hear more about this.
    "Loyalty Above all Else. Except Honor."

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    Forum Member FWDbuff's Avatar
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    OK I just googled Water Wash systems, they appear to be self-cleaning hood systems. Never heard of one before much less seen one (I am in the suburbs of Philadelphia.) Doesnt make one difference- the hoods, filters, agent nozzles, etc. over cooking appliances which collect steam and airborne by-products of cooking (especially grease-laden vapors) are required to be clean and free of grease at all times, period- no IFFS ANDS OR BUTS about it- whether that is accomplished by hand cleaning or by some system doesnt matter.

    These systems do not appear to be any kind of a fire-extinguishing system, merely an auxiliary cleaning method- and as such in my opinion you have no authority or jurisdiction mandating that they operate properly or at all for that matter. Now if they were a fire suppression system, then yes you have the utmost authority to require their proper operation.
    "Loyalty Above all Else. Except Honor."

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    Forum Member bcjack's Avatar
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    In 38 years of fire service time, 25 as Fire Marshal, I have never seen a water wash system.
    everyonegoeshome.com

  5. #5
    Forum Member Fireguyminn's Avatar
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    Here is some information about Water-Wash Hoods as taken from the Phil Ackland Commercial Kitchen System Manual:

    Water wash hoods utilize a system of removable cartridges or baffles and metal angles or fixed angles to pull the grease out of the air. As the grease and dirt particles from the air stream pass through the angles at high speed, the grease is thrown out of the air stream by centrifugal force. The extracted grease is collected in the lower troughs of the hood and remains out of the air stream until removed by a daily wash cycle. The wash cycle can be operated manually or programmed for automatic self-washing during certain times of the day and for specific durations of time. Most models allow for adjustment of the flow rate for the detergent. The wash controls, pumps, plumbing assemblies, timer, cycle controls, and detergent injectors are usually housed within a control cabinet, or panel located inside the kitchen. Information on the model and mechanical servicing that has taken place will be located there as well. Water wash assemblies must be provided with inspection covers or doors so the interior of the ventilator can periodically be checked for grease accumulation. If the wash function is not working properly, these systems will accumulate dangerously large amounts of grease in the trough. This is serious because potential flare-ups on the cooking equipment can ignite this grease buildup.
    Note: Many water wash hoods do not receive regular mechanical servicing. Over heavy grease producing cooking, these systems may not function as designed. If a water wash hood is involved in a fire, consult an expert or the manufacturer of that specific unit and obtain the operational manual. By pushing the “start wash” button on the command center (or as programmed, if equipped with optional time clock) the water wash system is activated, and the exhaust fan stopped. Hot water and detergent is then sprayed into the ventilator. A water/detergent mixture is sprayed from a series of nozzles for a pre-set time period to remove accumulated grease and grime, which flows out through the drain. At the end of the wash cycle, the water automatically shuts off. Hot water should be between 130 and 180 Degrees and pressure must be to the manufacturer’s specifications. The duration of the wash down cycle is adjustable and will vary depending on the length of cooking cycle, type of cooking equipment used, concentration of detergent, water pressure and temperature, among other considerations. Some water wash hoods utilize water mist, waterfall, and water bath techniques to create a barrier that entraps grease particles through centrifugal force. Water mist hoods will also have a “wash-down” cycle, where the hood goes through the same standard mechanical water wash procedures as a normal water wash hood.
    Dampers in Water Wash Hoods: If the surface fire-extinguishing system fails to extinguish the fire, the water wash hood dampering system then acts as a backup to protect the hood interior and prevent the fire from extending into the ductwork. One of the major benefits of a listed water wash type hood is that it is designed to offer a degree of protection in case of a fire. However, if all components of the system are not mechanically maintained these systems are prone to malfunction, particularly the dampers and wash system. A service frequency of 6 months is required for listed hoods with fire-actuated water systems, mechanical or electrical detectors, actuators, and fire-actuated dampers. These hoods should be checked according to the manufacturers listed procedures and specific inspection requirements of applicable NFPA 96 Standards. Fire Suppression in Water Wash Hoods Specifically listed water wash hoods are designed to both control and contain fire. Whereas the fire-extinguishing system is always the first line of defense. Some water wash hoods are listed to activate a “constant or fire-actuated” process to control the fire. Note: NFPA 96 also requires a fire-extinguishing system in water wash hoods. Attention Inspectors: Many water wash hoods are not receiving mechanical maintenance to ensure the wash cycle and dampers will function as designed. Regular maintenance is required according to the manufacturer’s listing. Check the control panel for dates of last mechanical service. Water Wash Hoods and Fire-Extinguishing Systems Editorial Note: NFPA 96, Section 10.2.8.1: Grease removal devices, hood exhaust plenums, and exhaust ducts requiring protection in accordance with 10.1.1 shall be permitted to be protected by a listed fixed baffle hood containing a constant or fire-actuated water wash system that is listed in compliance with ANSI/UL 300 or other equivalent standards and shall be installed in accordance with the requirements of their listing. Water wash hoods were not originally designed as a fire suppression replacement; thus trade name “water wash hood”. The intent was cleaning. As with any technology advancement water has been used for fire suppressant in new ways, such as Ansul’s water enhancement of agent system. It is my understanding from hood manufacturers that they are testing water in hoods as a fire suppressant system intended to meet approval for fire safety, but only within the hood (plenum).
    The end user must check with hood manufacturers for listed approval meeting fire protection and confirm with local AHJ that they accept this system as meeting local fire protection over the appliance they intend to operate under the hood. Fire protection is required over grease producing appliances; a water wash hood does not provide this protection. A hood water system is plenum protection only. Noncompliant Water Wash Hoods As stated earlier in this manual, water wash hoods in general suffer from lack of mechanical maintenance, this is the responsibility of the owner of the unit. These units can only function properly if they are professionally maintained. The interior of most systems is not easily visible for inspection by the kitchen staff. Ensure that there is a mechanical maintenance contract in place. This does not mean a cleaning or fire-extinguishing system contract. All three of these services are totally different.
    Last edited by Fireguyminn; 12-11-2012 at 09:34 PM.

  6. #6
    Forum Member FWDbuff's Avatar
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    I didnt read the whole thing, my eyes kinda glazed over after the third paragraph (perhaps because it is 2300 here and I am tired); however I did catch what I believe to be a contradiction- I saw in one part where it said that these systems are not intended, designed or suitable as suppression systems, however towards the end I think I saw something about being suppression systems for hoods themselves? Not sure. In any case, if they are intended as, and are part of a grease removal system as intended by the manufacturer, then you MAY have a leg to stand on- depending on your fire code. What code do you use? Being on a base you probably have some bastardized version of the IFC or some kind of a self-written one. I have also heard in recent years that some facilities and some regional chain of commands have even adopted the IFC.

    What branch of the service? I know some branches are more anal retentive about fire protection than others. Where does the fire chief and his boss stand? What is the occupancy/occ load/type of construction of the building? Is it protected? And is this a DOD/Military kictchen or a civilian contractor?

    Most codes will require that all installed systems, whether they be mechanical/HVAC/air handlers, Fire protection or other building systems are to be installed, inspected and maintained according to the Manufacturer's instructions and specifications and/or a relevant professional guideline such as ASHRAE for HVAC/air handlers or NFPA for fire protection. First thing I would do is determine if this system is truly a fire suppression system, is it truly required by code (and you have to determine if it will fall under the relevant code at the time it was installed OR will it fall under current codes?) If you figure out that its a required system, I would go down the avenue of making them repair it so as to function according to the Mfr's instructions- give them 15, 30 or 45 days to comply. If they cant get it fixed because it is so old that the Mfr no longer supports it, then have them consult with a Hood vendor to design a new suppression system- allow 120 days for that, and another 45 after that for the install. Dont forget the plan review and building permits as well as a final inspection. Oh yeah and dont forget to tie into the alarm system.
    "Loyalty Above all Else. Except Honor."

  7. #7
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    You might call Marriott fire protection, they use to use them.

    Have seen them, but have not heard about any fires associated with them

    Seems like just require, and have owner provide proof that cleaning, maintenance, and operation is done per manufacture.

    Also, check with this company:::


    http://www.philackland.com/

  8. #8
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    Fire guy

    Set up so you can get private messages

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    I am going through the same situation where I work. One of our hood systems has a water wash system, our hood inspector says we need to make sure the water wash is tied in to the suppression system and also that it needs to be maintained and run regularly. I am receiving a lot of push back from the people with the money to fix it.

    Any info found, can you send my way as well?

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    Quote Originally Posted by asner85 View Post
    I am going through the same situation where I work. One of our hood systems has a water wash system, our hood inspector says we need to make sure the water wash is tied in to the suppression system and also that it needs to be maintained and run regularly. I am receiving a lot of push back from the people with the money to fix it.

    Any info found, can you send my way as well?


    so what capacity are you in?? enorcement/inspection, owner, other??

    would get model of vent a hood and get the operating instrucitons from the maker, and have the business follow the vent a hood operation/ cleaning per manufacter.

    not sure what you mean by """water wash is tied into suppression system""" if I remember correctly the only fire protection that is needed is in the duct work, and to protect appliances.


    now I forgot what I was going to PM fireguy about

  11. #11
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    Ok the water washes I have seen had duct protection also, But:::

    http://usmma.edu/waterfront/kingspoi...ord%20Hood.pdf

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    Captive Air is a manufacture of exhaust hoods , i believe there may be some info on the wash systems on their site.

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    I am assuming that you are talking about Type I kitchen hoods that are designed to handle grease laden vapor as classified in the IMC. Type II hoods are designed to ventilate heat and moisture (as generated from dishwashers). Type I hoods are constructed from either stainless steel or galvanized steel and thicker gauge material than typical duct galvanized steel or aluminum. All Type I duct work is required to be welded and tested to ensure that there are no leaks in the duct work as well as wrapped with insulation capable of withstanding direct flame impingement for a minimum of 1.5 hours.

    The way the hood systems are designed to operate is that if the under hood suppression system were to discharge that the exhaust fan would stay in operation and draw the suppression agent through the duct work to extinguish any fire that would potentially be in the duct work.

    The IMC also calls out for there to be a no obstructions (turning vanes or dampers) in the duct work for grease to collect. While the idea of a wash system is good, in all reality everyone is looking to save money when renovating or installing equipment and wash systems are usually never installed unless the Code Official interprets the code to require it.
    Last edited by Caruso; 02-08-2013 at 12:50 PM.

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    [QUOTE=Caruso;1357064]I am assuming that you are talking about Type I kitchen hoods that are designed to handle grease laden vapor as classified in the IMC. Type II hoods are designed to ventilate heat and moisture (as generated from dishwashers). Type I hoods are constructed from either stainless steel or galvanized steel and thicker gauge material than typical duct galvanized steel or aluminum. All Type I duct work is required to be welded and tested to ensure that there are no leaks in the duct work as well as wrapped with insulation capable of withstanding direct flame impingement for a minimum of 1.5 hours.

    The way the hood systems are designed to operate is that if the under hood suppression system were to discharge that the exhaust fan would stay in operation and draw the suppression agent through the duct work to extinguish any fire that would potentially be in the duct work.

    The IMC also calls out for there to be a no obstructions (turning vanes or dampers) in the duct work for grease to collect. While the idea of a wash system is good, in all reality everyone is looking to save money when renovating or installing equipment and wash systems are usually never installed unless the Code Official interprets the code to require it.[/QUOTE



    A water wash hood is an approved system,

    A code official is not going to require it, just review it for installation

  15. #15
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    And now UV;;

    Have not seen one yet

    http://www.aps-hoods.com/blog/commer...s-of-uv-hoods/

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    Quote Originally Posted by fire49 View Post
    so what capacity are you in?? enorcement/inspection, owner, other??

    would get model of vent a hood and get the operating instrucitons from the maker, and have the business follow the vent a hood operation/ cleaning per manufacter.

    not sure what you mean by """water wash is tied into suppression system""" if I remember correctly the only fire protection that is needed is in the duct work, and to protect appliances.


    now I forgot what I was going to PM fireguy about
    I am in a bit of an owner capacity but am also in an enforcement capacity. We have an on-site contractor that operates the kitchen. I am trying to justify to those higher than me more cleaning at a minimun, but preferably replacement.

    By tied in to the suppression system, I mean that our inspector wants us to have the water wash system activate and dump water while the suppression system dumps its agent. There are no agent nozzles in the ducting of the system and supposedly activating the water wash would help protect the ductwork.

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    If you have an approved normal vent a hood installed already, I would go with a regular wet chemical system meeting UL 300.

    Have two or three extinguishing companies come in and look at what you have, and give you a price

    I do not understand this """"" There are no agent nozzles in the ducting of the system and supposedly activating the water wash would help protect the ductwork. """""

    how old is the vent a hood and fire extinguishing system??

    normally there is one nozzle at the entrnace to the duct work to the roof. This one nozzle will cover from the vent a hood to the top of the roof. Normally one is all that is required.

    sounds like someone is trying to sell you something not needed, or it is on their wish list.


    as far as cleaning, at least once a year, and depending on what you are cooking may have to be bumped up to twice a year or more.

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    I am a mechanical engineer as well as volunteer FF and I too have never come across anything pertaining to the necessity of such a system per any codes. my district has though in recent years seen an increase in hood fires in commercial kitchens due to lack of proper cleaning. the problem we are seeing is that once the film catches, the ansul system kicks in but below where the ignition occurs. and if the exhaust fan is not automatically shut off when the system kicks on, it pulls ventilation air up the stack and fuels further fire. has anyone seen or heard of a system where multiple heads are installed up the stack so that fire near the top of the stack can be extinguished?

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