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  1. #1
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    Feb 2011
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    Scotland, UK
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    Pressurisation fans and Fire dampers

    Hi,

    new to this forum but thought i'd ask for some advice. Not sure if this is the best place to ask so here i go....

    basically, i'm a self employed AC / Refrigeration Engineer but i'm about to get involved with Offshore accomodation and workspace modules. A60, zone 1 + 2 Atex rated etc, fitted with split AC systems as well as pressurisation fans and Automatic fail safe fire dampers
    The AC side of this is not an issue but as far as pressurisation fans and fire dampers go my knowledge is pretty limited. Does anyone have any advice on how to balance the fans and set up fire dampers? Any literature that i could maybe look up online? Im sure it's not too difficult but I want to make sure i'm as clued up as i can be before i get stuck in.

    Any help would be very much appreciated.

    Thanks

    G.D.

  2. #2
    Join Date
    Apr 2010
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    southern california
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    Please explain in detail what you are asking. Is this a hotel, what is A60 and Atex, I am not familiar with those terms.

  3. #3
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    Sorry,
    Like I mentioned i'm not sure if this is the correct place for me to ask.

    Atex is a rating used for all mechanical and electrical equipment used in potentially explosive atmospheres, ie Offshore, and A60 is a fire rating used in the offshore sector also.
    Maybe there is a more suitable forum for these topics?

    Thanks

    G.D

  4. #4
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    Apr 2010
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    southern california
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    Gonzo1, I am familiar with fire dampers and building pressurization, but you threw me for a loop on the other. I did research the A-60 and the Atex rating. I love this site cause one can always learn. I have zero knowledge on marine hvac systems but as far as fire protection , it is all about protecting egress areas, stairwells, elevator shafts, etc. Are your structures multi-story like what would be found in a mid-rise commercial building.

  5. #5
    Join Date
    Mar 2003
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    7,326
    Fire dampers are used to isolate zones from each other in the event of a fire or smoke event. typically a fire damper would be open until an event occurs, and then may close by loss of power, or breaking of a fusible link which melted due to being exposed to a temp higher than the rating. as far as pressurization systems, thats a whole other thing. in a high rise office tower, for example, it is typical to use multiple systems for an event. for example, for smoke evac, you would use the supply fans and damper logic to pressurize the floor above and below the event, and then another damper and exhaust fan to remove the smoke via smoke evac fans. For "safe zones" such as a stairwell built for life safety with a two hour rated wall, you would use pressurization fans to keep a positive pressure in the stair tower relative to the occupied floors. generally you would use a fan with a vfd, anf control the vfd to maintain a slight pressure relative to the interior space to prevent smoke from entering the stair tower.

    for specific applications, you should consult NFPA or an engineer regularly engaged in this type of design service. when it comes to life safety, especially offshore, you dont want to mess around.

  6. #6
    Join Date
    Jan 2011
    Location
    London, England
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    Quote Originally Posted by flange View Post
    Fire dampers are used to isolate zones from each other in the event of a fire or smoke event. typically a fire damper would be open until an event occurs, and then may close by loss of power, or breaking of a fusible link which melted due to being exposed to a temp higher than the rating. as far as pressurization systems, thats a whole other thing. in a high rise office tower, for example, it is typical to use multiple systems for an event. for example, for smoke evac, you would use the supply fans and damper logic to pressurize the floor above and below the event, and then another damper and exhaust fan to remove the smoke via smoke evac fans. For "safe zones" such as a stairwell built for life safety with a two hour rated wall, you would use pressurization fans to keep a positive pressure in the stair tower relative to the occupied floors. generally you would use a fan with a vfd, anf control the vfd to maintain a slight pressure relative to the interior space to prevent smoke from entering the stair tower.

    for specific applications, you should consult NFPA or an engineer regularly engaged in this type of design service. when it comes to life safety, especially offshore, you dont want to mess around.
    Flange is right.

    Pressurisation fans are to ensure that safe zones and access to them are kept clear of smoke, they do this by supplying more clean air than the smoke extract's are removing.

    If someone dies due to a design problem that can be traced back to your error then you WILL be going to court (and probably prison). Manslaughter is not a light charge, don't risk it!

  7. #7
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    Quote Originally Posted by only1doug View Post
    Flange is right.

    Pressurisation fans are to ensure that safe zones and access to them are kept clear of smoke, they do this by supplying more clean air than the smoke extract's are removing.

    If someone dies due to a design problem that can be traced back to your error then you WILL be going to court (and probably prison). Manslaughter is not a light charge, don't risk it!
    I could not agree more. A couple of other notes. Back-up generators are a must and design of a pressurization system must insure that they do not contribute to adding oxygen to a fire. Flange pretty much summed it up.

  8. #8
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    May 2009
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    South of Heaven
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    Another angle on this issue is the " door force " requirement ( the amount of force required to open a door when entering a pressurized area ). Inspectors in my area use belt tensioning gauges ( automotive ) and pull the door handle with the device.

    This is a real hassle tuning a PID control for a VFD as to not over - pressure a stairway yet meet the pressure requirements for smoke evac. I vote for barrametric relief for these applications ( if I'm ever asked , lol ).

    So , regarding smoke dampers ( or fire ) ...as they close the pressure in the evauation area has to remain constant ( not too much , not too little ). In the end this requires a great deal of testing and adjusting ( making it a " thankless " job ). Mechanical relief is the best way to achieve the desired results with these systems IMO.

  9. #9
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    Feb 2011
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    Scotland, UK
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    Cheers for the advice guys. Like i say i'm just getting involved in this so i have time to get all the info i need, and obviously anything i'm not clear on i'll seek further advice.

    Does anyone know of any site that i could check out for this subject?

    Cheers again.

    G.D.

  10. #10
    Join Date
    Mar 2003
    Posts
    7,326
    I would look around on the web and do some reading. google thing like "stair pressurization", "smoke containment and control", "life safety systems" etc. you could also check with your local code enforcement people to see what code they have adopted, and then buy that cosdebook. when it comes to maritime though, I have no idea who regulates that internationally if anyone.

  11. #11
    Ruskin offers an A60 rated fire damper for marine applications, I would look there

  12. #12
    Join Date
    May 2011
    Location
    Doha,Qatar
    Posts
    1
    Please suggest me a good Exhaust Fans,Pressurization fans & in-line fans to market here in Doha, QATAR

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