Fresh air requirements cargo-passenger

Discussion in 'Class Societies' started by powerabout, Sep 28, 2011.

  1. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    Hi Guys
    Can anyone tell me what the fresh air requirement is for a passenger vessel
    i.e. how many changes of air per hour are required

    Having worked on AHTS's I know there is clearly no rule for them but I believe DNV has one?
    Are there any rules for small craft i.e below solas requirements

    How do these rules compare to a building etc
    No rules for aircraft

  2. HReeve
    Joined: Dec 2009
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    HReeve Junior Member

    The modern standard is ISO 7547 “Air-conditioning and ventilation of accommodation spaces on board ships – Design conditions and basis of calculations”.

    The older standard is SNAME T&R Bulletin 4-16 “Calculations for merchant ship heating, ventilation and air conditioning design”

    In summary:

    ISO 7547 requires a minimum fresh air flow of 480 litres per minute (lpm) per person.

    SNAME specifies a minimum of 12 cfm = 340 lpm per fresh air per person for high occupancy spaces and 15 cfm = 435 lpm for low occupancy spaces.
  3. daiquiri
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    daiquiri Engineering and Design

    By the way, there must be something wrong in the way passenger ship air-conditioning is commonly calculated. I have to board yet on a ship which has a humanly reasonable air-temperature difference between outside and inside ambients. The usual summer situation is something like outside air = 32-35 °C, inside air around 20 °C. If one gets in and out few times, or dares to sweat just a little bit, it's almost sure he'll get sick. :eek:

    Ok sorry for this, please carry on... :)
  4. powerabout
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    powerabout Senior Member

    thanks guys

    makes me wonder I worked on a fleet of new 80m ahts's ABS class and they had no fresh air systems at all
    once the sanitary fans and galley exhaust was on the accomodation was low pressure and sucked the exhaust in everywhere it could
  5. CmbtntDzgnr
    Joined: Jun 2011
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    CmbtntDzgnr Senior Member


    In looking for useful information, while not very successful (so far), I ran across these:

    The first is a product manufacturer's site.

    The second is a 13-page or so report.

    The third is a more detailed set of rules/recommendations/etc.


    witt (3 pages, engine room ventilation):


    a medical section regarding USN ships:


    This one looks like GL's documents from 2004, on scribd:


    Ventilation Systems, US NAVY SHIPS (9 pages) Systems.pdf

    (has a GROSS photo of dust buildup in the ventilation system)

    Check out page 6: "New Design Galley Ventilation"

    Although, I don't know what is "new" about it. If you can get ahold of the science fiction/thriller/action film "Deep Rising", you'll see such an exhaust hood/grease interceptor. That DVD was out around 1999 or 2000. I bought it around that time, and then re-bought it around 2007 to replace the stolen one. (Incidentally, it seems to me the ship was real internally, though IIRC, the external was CGI. The internals looked VERy real, and that is one reason I enjoyed it very much, aside from all the craziness going on between the characters in their bid to survive.)

    The doc was created March 11, 2009, so it must be "new" for USN types, hehehehe...

    I've never heard of this before:

    "Installation of Textile Ductwork Textile ductwork (made of NOMEX fire-retardant material) has been included in new Navy ship designs to replace traditional metal supply air ductwork and air diffusing terminals. Textile ducting provides even air distribution throughout the space. The system is able to achieve this by virtue of the fact that the entire length of the duct is used for discharging the supply air into the conditioned space. Since the airflow is distributed evenly into the space, there are no hot or cold spots and noisy air diffusers in the room. This helps to eliminate unauthorized ventilation system alteration throughout the ship.

    Textile ductwork is easy to clean and maintain, which reduces cleanup costs. This type of ducting can be removed and washed in conventional clothes washers at a low labor cost. In addition, textile ductwork is lighter than metal ductwork, resulting in reduced fuel costs."

    Sounds like a neat ideal, but I hope the textile material can be removed and washed like a filter.

  6. Squidly-Diddly
    Joined: Sep 2007
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    Squidly-Diddly Senior Member

    daiquiri, why do you think that will make you sick?

    Most 'common colds' happen when inside heated air dries out your membranes and cracks/raw spots happen that let germs enter.

    I don't think coming from hot outside when sweating to cool insides is a problem.

    Are you talking about 'feeling faint' or chills from going from hot to cold when sweating?

    But of course those cruise ships are well known for outbreaks due to crowded conditions, to say nothing of a mix of foreign germs.
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