1. Regular Guest
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## 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?

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what formula i should use?

3. Professional Member
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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.

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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.

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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.

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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?

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Size of room?
Type of Facilty?
Size of system?
Type of System?
etc.
So many unlisted factors

Respectfully,
d

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