[labnetwork] High Humidity Issues in Coastal Areas?

[Kamal Yadav]

Dear All,

Thanks for the responses from Noah, Jack, Paul, Thomas.

Looks like more maintenance gets critical in such ambiance, but its
possible.

Thanks a lot!



On Fri, Jul 24, 2015 at 1:46 AM, Noah Clay <nclay at upenn.edu> wrote:

> Kamal,
>
> A few things to consider:
>
> 1. Ensure that your incoming chilled water temperature/flow is adequate.
> We average 43F.
>
> 2. Ensure that your chilled water coils are clean.  Ours are inspected
> quarterly; prefilters are changed quarterly; coils cleaned annually & box
> filters are changed annually.  Final discharge HEPAs are changed every
> three years
>
> 3. Ensure that your reheat system is operating properly with clean coils
> for further drying.
>
> 4. Ensure that any downstream humidification valves are not
> passing/defective.
>
> 5. Calibrate any sensors in the air handlers.  We calibrate annually.
>
> I can send a screen shot of the air handler from the BAS?
>
> Good luck,
> Noah Clay
>
> Quattrone Nanofabrication Facility
> University of Pennsylvania
> Philadelphia, PA
>
> Sent from my iPhone
>
> On Jul 23, 2015, at 12:53, Paul, Jack <Jack.Paul at hdrinc.com> wrote:
>
>  Hello Kamal,
>
> In general terms, there are only a couple of methods for removing moisture
> from large volumes of air as required for the cleanroom make-up air.  You
> can cool the air enough to condense the water vapor out, or you can absorb
> the water vapor with a dessicant dryer.
>
>
>
> Of the two, the most common is to cool the air, since you need to do that
> anyway. However, to get good condensation the water temperature must be
> pretty low, and the air velocity through the air handler and over the
> cooling coils must be relatively slow.  So my best guess is that your
> infrastructure may be “under designed” to squeeze enough moisture out of
> the air to reduce the humidity to acceptable levels around 43% or so.
> In-line duct dehumidifiers just can’t keep up with the large volumes of air
> and large quantities of moisture to be taken out of such wet air.
>
>
>
> Optimally, you would have one or two large make-up air handlers with large
> cooling coils (maybe even dual coils in sequence) that would run chilled
> water provided from your chiller plant (in the building or remote on
> campus?).  The water temp is low enough (typical design range would be
> around 5 to 7 deg C) that it would cool the incoming outside air (design
> conditions maybe 32-37 deg C and 75-100% RH?) to around 13 deg C.  The 13
> deg air cannot hold as much water and it condenses out.  This low
> temperature make-up air is then mixed with recirculated air either in your
> recirculating air handlers or perhaps within the cleanroom volume if you
> are using fan-filter units, further reducing the RH as the temperature
> rises to internal cleanroom design conditions about 20 deg C.  (Since the
> humidity is “relative” to the capacity of the air to hold water vapor, if
> the water vapor content remains constant as the temperature rises, the
> relative humidity decreases as a percentage of capacity).
>
>
>
> The other option is dessicant drying, but it consumes very large
> quantities of energy and actually heats the incoming air, which is in
> contrast to what you want to accomplish.
>
>
>
> Suggest checking your
>
> -        chilled water capacity (how many tons of cooling are available)
> and the water flow rate
>
> -        chilled water temperature (can it be set lower?)
>
> -        coil size in the make-up air handler- can the air handler be
> retrofit with a better coil design or in-line dual coils
>
>
>
> Hope this helps as a starting point.
>
> Regards,
>
> Jack
>
>
>
>
>
> *From:* labnetwork-bounces at mtl.mit.edu [
> mailto:labnetwork-bounces at mtl.mit.edu <labnetwork-bounces at mtl.mit.edu>] *On
> Behalf Of *Kamal Yadav
> *Sent:* Thursday, July 23, 2015 6:42 AM
> *To:* labnetwork at mtl.mit.edu
> *Subject:* [labnetwork] High Humidity Issues in Coastal Areas?
>
>
>
> Dear All,
>
>
>
> During Monsoon time in India, and specially in Mumbai where it rains
> heavily from June to September, we observe high humidity in the lab ~65%.
> We have de-humidifiers as well as other HVAC infrastructure. But more
> control is required. Is it possible or our infrastructure is not good
> enough?
>
>
>
> Are there any other known humidity control solutions known to you. Is it
> the case with others as well, who are in heavy rains/humid area. This
> certainly is not the case with Intel in Portland, OR, where it rains a lot
> too.
>
>
>
> --
>
> Thanks,
>
> Kamal Yadav
>
> Sr. Process Technologist
>
> Electrical Engineering
>
> IIT Bombay
>
> Mobile: 7506144798
>
> _______________________________________________
> labnetwork mailing list
> labnetwork at mtl.mit.edu
> https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork
>
>


-- 
Thanks,
Kamal Yadav
Sr. Process Technologist
Electrical Engineering
IIT Bombay
Mobile: 7506144798
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20150727/4ef11188/attachment.html>