[labnetwork] Specification for clean dry air (CDA)

[Gregory Cibuzar]

Bob,
At Minnesota we rely on the campus compressed air plant to provide the
"raw" CA.  We have desiccant dryers on the feeds to our two cleanrooms.
The dewpoint settings for the dryers are different (-70F/-30F), pressure is
generally 90 psi.  The flow is around 50 cfm for each.  Our campus
facilities people maintain the central plant and our dryers.  This works
provided for us, but we do closely monitor our CA parameters and call for
service when needed.

Regards,
Greg

Greg Cibuzar
Manager, Minnesota Nano Center
www.mnc.umn.edu
University of Minnesota
612-625-8079

On Thu, Jun 9, 2016 at 4:42 PM, Robert M. HAMILTON <bob at eecs.berkeley.edu>
wrote:

> Labnetwork Colleagues,
>
> I recently contacted Dennis Grimard eho is helping design and build MIT's
> new lab to learn their specification for their compressed dry air (CDA).
> Dennis is terrific with numbers and engineering data. Dennis suggested it
> might be useful to broaden my query to the labnetwork. This begs the
> questions, how do other facilities specify their CDA and who supports their
> systems?
>
> At the outset I’ll comment many university labs use their campus
> engineering maintenance support to service utilities and specs may not be
> at one’s finger tips. And, some universities have central plants for
> utilities which serve a broad number of facilities. In the case of the
> Marvell NanoLab we have virtually all our utilities contained within our
> sub-fab and we have chosen to maintain most utilities e.g. our acid waste
> neutralization system, air handlers CDA, DI water, LN and process cooling
> water system because we are so dependent on them.
>
> My question is what are reasonable specifications for CDA? I realize this
> is a difficult question to answer because CDA usage will be based on an
> equipment load.  Perhaps adding a labs square footage helps to scale an
> answer?
>
> The UC Berkeley Marvell NanoFabrication lab’s CDA is derived from two
> Atlas Copco 117 cfm (3,32M^3/min) screw compressors operating in a lead/lag
> configuration which deliver to a 200 gallon storage vessel, then to an
> Air-Tak brand dryer and Zander particle filters before delivery to the lab.
> Our CDA delivery specification is 90 psi at a dewpoint of -70F (~16 ppm
> H2O). We began with a dewpoint spec of -90F; however, we relaxed this spec.
> to reduce the work of the air dryer with wearable, moving parts. As backup,
> to facilitate the orderly shutdown of equipment and for brief periods to do
> CDA system maintenance our delivery is configured to automatically cross
> over to the lab’s cryogenically derived process N2 when the pressure falls
> below 70 psi. Such a crossover can support the lab for several hours using
> N2; however, the associated LN vessel vaporizers do not have sufficient
> capacity to run on cryogenically-derived N2 for extended periods of time –
> they ice over.
>
> As has been previously noted, a few years ago we substituted CDA for N2
> purging on a select number of dry pumps to reduce our N2 costs. The pumps
> switched to CDA were pumps which service equipment that does not pump
> acid-gases, flammables or pyrophorics. This has been a great success. The
> downside; however, is we are now peaking our CDA demands to greater than a
> single compressor can sustain. This makes us vulnerable should we lose a
> compressor.
>
> Comparing how various research fabs spec CDA has value.
>
> Regards,
> Bob Hamilton
>
>
> Robert Hamilton
> University of CA, Berkeley
> Marvell NanoLab Equipment Manager
> Rm 520 Sutardja Dai Hall, MC 1754
> Berkeley, CA 94720
> Phone 510-809-8618 (desk - preferred)
> Mobile 510-325-7557 (my personal mobile)
> E-mail preferred: bob at eecs.berkeley.edu
> http://nanolab.berkeley.edu/
>
>
>
> _______________________________________________
> labnetwork mailing list
> labnetwork at mtl.mit.edu
> https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20160610/acddc9e4/attachment.html>