[labnetwork] final filter on makeup air units

[Mark Heiden]

Iulian,

We have a similar configuration at UC Riverside to the one that you
described. Our experience was that the HEPA filters on the output of our MAU
were problematic. Our system injects deionized steam into the air stream for
humidity control which saturated the HEPA filters at the end of the MAU.
FYI.. wet HEPA filters do not pass air. I suspect in very high humidity
climates (we are in So. Cal. so that was not supposed to be an issue) even
without steam injection, HEPA filters may collect too much moisture to flow.
If your MAU system and the inlet air is dry and stays dry it may work. We
"over" humidify coming out of the MAU so by the time that air is mixed with
the less humid return air in the space it comes back through the
re-circulation units at exactly 45%.  

Hope this helps,


Mark Heiden
UC Riverside
Center for Nanoscale Science and Engineering
NanoFab Cleanroom Manager
(951) 827-2551
mheiden at engr.ucr.edu



-----Original Message-----
From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu]
On Behalf Of Iulian Codreanu
Sent: Tuesday, June 04, 2013 6:25 AM
To: Fab Network
Subject: [labnetwork] final filter on makeup air units

Dear Colleagues,

I am trying to convince some folks that having filters placed on the
discharge side of a cleanroom makeup air unit (MAU) is not only a good 
idea but a must.    I only have a MERV 8 and a MERV 14 on the intake 
side and I am pushing for HEPA filtration on the discharge side; your input
carries a lot of weight and I hope you can help.

My cleanroom is "two stories tall"; the makeup air discharges into the
mechanical space (it houses the recirculating air units that push the air
into the bay plenum boxes) that is above the the bay and chase cleanroom (no
raised floor, sidewall air return).

Can you please share your MAU filter configuration; it would be helpful to
list all the filters in the unit and where they are located.

Thank you very much.

Iulian

--
iulian Codreanu, Ph.D.
Director of Operations, UD Nanofab
149 Evans Hall
Newark, DE 19716
302-831-2784


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