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  1. #1
    Join Date
    Feb 2011
    Location
    Malaysia
    Posts
    18

    Cool Clean room calculation

    A clean room is designed for positive pressure 0.05" w.g. There is a 2 sqft opening on the wall. Calculate the leakage velocity and leakage rate at the opening.

    If the positive pressure is changed to 0.1" w.g. What are the new leakage velocity and leakage rate?
    What is the consequence if we change the design positive pressure from 0.05"w.g to 0.1"w.g?

  2. #2
    Join Date
    Feb 2011
    Location
    Malaysia
    Posts
    18
    what formula i should use?

  3. #3
    Join Date
    Sep 2010
    Location
    FL Tampa Area
    Posts
    48
    0.05"wg would be difficult to maintain. I would almost definetly leave the room slighlty over pressureized to allow for filter loading, belt wear or any other building change.

    Calculations are great but only way to be sure is adjust while watching a monometer.

  4. #4
    Join Date
    Feb 2011
    Location
    Malaysia
    Posts
    18
    There are many consequences regarding to high and low positive pressure in the clean room or others.
    1-if the positive pressure is high like 0.1" w.g the load will be high therefor
    2- velocity also high so,
    3-high initial cost and
    4- high operation cost
    however, the opposite is correct as the positive pressure is low everything will be low as mention above.

    this word can be proof as follow:-

    leakage in CFM = (room pressure in W.G )^-1/2 X 4005
    = (0.05")^-1/2 X 4005
    = 896CFM
    leakage in cfm / sqft= 895.545 X 2 =1792 cfm
    the mean velocity is 896 fpm
    and in same method with 0.1" w.g
    leakage in CFM = (room pressure in W.G )^-1/2 X 4005
    = (0.1")^-1/2 X 4005
    = 1267 CFM
    leakage in cfm / sqft= 1267 X 2 =2533 cfm
    the mean velocity is 1266 fpm
    so, the deference is 742 cfm and 370 fpm for velocity.

    Conclusion,
    the positive pressure and velocity has a relation ship as one of the increase the other will be increased in other meaning the initial & operation cost also will be increased due to these tow reasons.finally, the high positive pressure is not recommended unless the application demand it.

  5. #5
    Join Date
    Feb 2011
    Location
    Ireland
    Posts
    1

    Clean room calculation Reply to Thread

    Hi all
    and hello snail and thanks for sharing this useful information with us. There is also one easiest way to have clean and fresh air in your room just have a air conditioning you will be glad by this.

  6. #6
    I am in need of calculating how much CFM it will take within 15 minutes to pressurize a clean room from 0" w.c. to .03" w.c.
    I'm also assuming no leakage for the space for now.
    Do you know the formula?

  7. #7
    Join Date
    Mar 2013
    Posts
    11
    Size of room?
    Type of Facilty?
    Size of system?
    Type of System?
    etc.
    So many unlisted factors

    Respectfully,
    d

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