[labnetwork] Recirculating DI water spray guns?

[Olona, Leonard E.]

Hi Mary,

I agree with Jeff.  Here at OU our DI system has a return loop.  However,
the DI guns inside our acid bench have a short run that does not return.

Simply put....  WE only use our DI water guns for general wash down or
final decontamination of the bench.  It's much better than using city
water.  And we do not encourage the students and or researchers to use the
spray guns where pure DI (18Mohm) is required.

I like to think of the DI "vegetable" sprayer as a cleanup tool.

You could do an experiment where you run the sprayer into a beaker and
check resistivity.  Letting it run for a while may clear things up.  We
also have an inline ultraviolet system bacteria unit that helps keep the
biological fishes at bay!

It really all depends on what you're trying to achieve. The level of
resistivity that is required.  Biological stuff as well. (we are not too
concerned with the latter) Etc...

I hope this helps.

Thank you,    
 
-Len

Leonard E. Olona
University Cleanroom Director and Facility Manager
University of Oklahoma
110 West Boyd Street
Norman, Oklahoma  73019

Email len.olona at ou.edu
Desk  405 325-4374
Cell  405 630-9068
Fax   405 325-7066










On 1/17/13 2:53 PM, "Kuhn, Jeffrey G" <kuhn1 at purdue.edu> wrote:

>Mary,
>
>Our circulating DI water guns return the water back to the storage tank
>via the return loop piping. Since the water is returned to the tank, it
>is not actually consumed. This configuration uses no more DI water than
>if our piping were to dead-end at the guns. The only time water is
>actually consumed is when the guns are in operation.
>
>The issues I see with using a circulating configuration are primarily
>cost driven. The UPW distribution pump needs to be sized large enough to
>accommodate the additional flow requirement. The distribution loop
>equipment (resin & membrane systems, UV, etc.) also need to be sized such
>that it can handle the additional flow. These things are usually initial
>design considerations that an existing facility should already be beyond.
>Other cost factors are that the circulating guns themselves are more
>costly, and there is additional PVDF piping required to construct the
>loops.
>
>Personally, I would never use a non-circulating DI water gun unless I was
>certain that bacteria would not be an issue. You will almost certainly
>develop bacterial growth in any stagnant DI water piping and hardware. I
>can personally attest to the ability of bacteria to grow amazingly well
>in low nutrient environments. Continuous flow is one method of combating
>bacterial growth in UPW systems; the flow helps prevent them from gaining
>a "foothold" on the pipe walls.
>
>I am a bit surprised to hear folks are using non-circulating DI water
>spray guns. I'd be interested in hearing the logic behind why that is
>being considered, especially since it doesn't really save any water.
>However, as I mentioned before if bacteria is not an issue then
>non-circulating guns may be fine.
>
>I hope this helps somewhat.
>
>Regards,
>
>Jeff Kuhn
>Facility Engineer
>Birck Nanotechnology Center
>Purdue University
>1205 W. State St.
>West Lafayette, IN 47907
>Ph:  (765) 496-8329
>Fax: (765) 496-2018
>
>
>
>-----Original Message-----
>From: labnetwork-bounces at mtl.mit.edu
>[mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Mary Tang
>Sent: Thursday, January 17, 2013 2:10 PM
>To: labnetwork at mtl.mit.edu
>Subject: [labnetwork] Recirculating DI water spray guns?
>
>Dear labnetwork members --
>
>Our wet benches have "recirculating" DI guns to avoid stagnant water
>lines.  WIth 10 wet benches, this adds up to 50K gallons of DI water each
>year.  We are in the process of replacing our wet benches.  All of the
>wet bench providers we've spoken with have said that most of their
>customers are choosing to use non-recirculating DI spray guns to save
>water.   But I wonder if this may be feasible in certain lab
>environments.  Does anyone have advice and insight to offer?
>
>Mary
>
>--
>Mary X. Tang, Ph.D.
>Stanford Nanofabrication Facility
>Paul G. Allen Room 136, Mail Code 4070
>Stanford, CA  94305
>(650)723-9980
>mtang at stanford.edu
>http://snf.stanford.edu
>
>
>
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