Dave,

As others have mentioned, there are different classes based on particle
quantity and particle size.  They typically range from (cleanest) Class 1 or
10 for  Semiconductor manufacturing to Class 10,000 for hi rel
microelectronic assembly to Class 100,000 (dirtiest, less than 100,000
particles .5 micron or larger and less than 700 particles 5 micron and
larger per cubic foot) for general high rel electronics as a general
guideline.  A typical air conditioned office area would run about
200,000-400,000 particles .5 micron and larger per cubic foot.

All Clean Rooms require positive air pressure and Class 100,000 can be
accomplished with a good air handler with primary and secondary filters,
proper uniflow air flow design and some makeup air (about 20% pulled from
else where in the building) to maintain positive pressure.  Class 10,000
would also require HEPA filter supplies. Class 1,000 or better requires
specialized professional Clean Room design. Humidity control are end use
driven. See also FED-STD-209. Contact me off line if you have more specific
questions.

Bruce Misner

> ----------
> From:         Dave Blevins[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;Dave Blevins
> Sent:         Wednesday, September 27, 2000 4:44 PM
> To:   [log in to unmask]
> Subject:      [TN] Clean Room
>
>    Hi Everybody
>  I have a question, in the real world, when constructing a clean room what
> type of air handling system is used?
>
> 1. A regular air conditioning unit with a 90% dust spot filter?
>                         -or-
> 2. Something like a Liebert Environmental Control System that maintains
> temperature as well as humidity with positive
>     pressure?
>
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