[labnetwork] Recommendations to reduce lab nitrogen usage

[Demis D. John]

Last year Our staff installed flow meters on the N2 lines going into each
bay, so that we could monitor usage, specifically to find leaks.
Then later went through the lab and shutoff various tool's N2 and looked at
∆usage, or maybe they did something like leak-down rate (I don't remember
the details),
I'm pretty sure they found numerous "bad" leaky lines etc that needed to be
replaced, I believe this reduced N2 usage a good amount (again I don't know
the numbers, I just remember the general story!).

Also during annual 1-week lab shutdown (Christmas time for us), when the
lab is quiet the staff often listen for leaks on the various lines.

-- Demis (contact info <https://wiki.nanotech.ucsb.edu/wiki/Demis_D._John>)
*Reminder*: The NanoFab has a publications policy
<https://wiki.nanotech.ucsb.edu/wiki/Frequently_Asked_Questions#Publications_acknowledging_the_Nanofab>


On Fri, Sep 19, 2025 at 9:28 AM Collins, Deon <deonc69 at illinois.edu> wrote:

> HMNTL invested in a PSA that went online in July 2024. The LN₂ portion of
> the system paid for itself within a year. Prior to that, HMNTL was spending
> about $350,000 annually on LN₂ expenses. As part of the upgrade, we also
> replaced our air compressor with a variable-speed, oil-free unit. If you
> upgrade to a PSA, you will most likely be required to use an oil-free
> compressor. The advantage of this is that it gives you the flexibility to
> run either CDA or N₂, depending on your needs.
>
> We have recently begun transitioning back to CDA on systems that were
> previously plumbed with N₂, primarily due to oil and water contamination
> concerns.
>
> Based on our experience, I strongly recommend that any facility currently
> using LN₂ as a purge gas consider investing in a PSA. Smaller units, such
> as the DB-5 or DB-10, can easily handle the demands of most small labs
> while eliminating the need for bulk deliveries.
>
> Just my two cents.
>
>
>
> *Deon D. Collins*
>
>
>
>
> *Director of Facilities*
>
> *The Grainger College Of Engineering UIUC*
> Holonyak Micro & Nanotechnology Lab
> 208 N Wright St Rm. 1114 | MC-249
> Urbana, IL 61801
> 217-300-7531 | deonc69 at illinois.edu
>
>
> <http://illinois.edu/>
>
> *Under the Illinois Freedom of Information Act any written communication
> to or from university employees regarding university business is a public
> record and may be subject to public disclosure. *
>
>
>
> *Life begins at the end of your comfort zone.  *
>
> *                                                                                      Propeck
> Amanda*
>
>
>
> *From:* labnetwork <labnetwork-bounces at mtl.mit.edu> *On Behalf Of *Danny
> Pestal
> *Sent:* Thursday, September 18, 2025 7:14 PM
> *To:* Carsen Kline <carsen at stanford.edu>
> *Cc:* Labnetwork (labnetwork at mtl.mit.edu) <labnetwork at mtl.mit.edu>;
> Schmidt, Benjamin Willis <ben.w.schmidt at vanderbilt.edu>
> *Subject:* Re: [labnetwork] Recommendations to reduce lab nitrogen usage
>
>
>
> Since Bob Hamilton wrote that entry to the Labnet, UC Berkeley decided to
> extend the replacement of the nitrogen purge on vacuum pumps to our etch
> tools as well. We felt confident doing this since we are very diligent in
> the upkeep of our CDA dryer and run it at a very low dew point such that
> the ppm of water in our CDA is lower than the moisture created in a lot of
> the etch processes. Everyone was convinced we would end up with a bunch of
> rusted out vacuum pumps and/or exhaust lines but we haven't had any issues
> at all.  In 2013, prior to adding the etch tools, this was saving us
> upwards of $50,000 a year, I'm sure it's more now.
>
>
>
> More recently we installed a nitrogen generator to provide low quality
> nitrogen (99.5% - 99.99%) in places where "process" level nitrogen wasn't
> required. I don't have any savings data from this yet as we've been overly
> busy and haven't plumbed the system out to the tools yet. We expect the
> savings to be SIGNIFICANT.
>
>
>
> Future plans are to add even more nitrogen generation, but at that point
> we'll have to look into an upgrade of our air compressors.
>
>
>
> Danny Pestal
>
>
>
> Equipment & Facilities Manager
>
> UC Berkeley NanoLab
>
>
>
> 510-809-8600
>
>
>
> On Thu, Sep 18, 2025, 4:47 PM Carsen Kline <carsen at stanford.edu> wrote:
>
> Hi Ben,
>
>
>
> Here at Stanford we just moved to a nitrogen generator in July. We're now
> filling our 9000 gallon liquid tank every five weeks instead of every five
> days. So if you can convince the powers that be to pay for it (major
> savings in operating costs), and if your overhead dollars pay the
> electricity, it's the greatest thing ever. We've kept our tank in place to
> keep feeding our branch of purified process nitrogen, and it serves as
> automatic backup in case the generator shuts down.
>
>
>
> Before the generator, we were looking for ways to automate nitrogen cuts
> to our vacuum pumps during idle times. I inherited a control panel from a
> fab surplus sale that uses a PLC and solenoid valves to reduce N2 flow
> after x minutes using a signal tied to the NEMO interlock. I can provide
> full details or even a partially built panel if you like.
>
>
>
> We're using CDA for all of our gas cabinet headcase purges (we were able
> to justify it with our jurisdiction because there are sprinklers in the
> cabinets) and acid wet bench headcase purge.
>
>
>
> You can also get away purging some of your vacuum pumps using CDA instead
> of N2. I refer you to a thread on the labnetwork archives:
>
> https://mtl.mit.edu/pipermail/labnetwork/2013-September/001033.html
> <https://urldefense.com/v3/__https:/mtl.mit.edu/pipermail/labnetwork/2013-September/001033.html__;!!DZ3fjg!6jLgXjzxPIqtzWX5PK3es0jyTLOj5kC42yG6s3YVIu8A2zBcKUl_3JMG7vneoqmD97-dBhh6tuDm80hJluzED7ax6oQ$>
>
>
>
> Or try a search like "Show me threads about using CDA in lieu of N2" on
> nanobot.chat to go deeper into the Labnetwork archives.
>
>
>
> Happy to share more offline if you like.
>
>
>
> All the best,
>
>
>
> Carsen
>
>
>
>
>
> Carsen Kline
>
> Lab Operations Manager
>
> Stanford Nanofabrication Facility
>
> 650-724-8214
>
> snfexfab.stanford.edu
> <https://urldefense.com/v3/__http:/snfexfab.stanford.edu__;!!DZ3fjg!6jLgXjzxPIqtzWX5PK3es0jyTLOj5kC42yG6s3YVIu8A2zBcKUl_3JMG7vneoqmD97-dBhh6tuDm80hJluzEDFcqnLI$>
> ------------------------------
>
> *From:* labnetwork <labnetwork-bounces at mtl.mit.edu> on behalf of Schmidt,
> Benjamin Willis <ben.w.schmidt at Vanderbilt.Edu>
> *Sent:* Thursday, September 18, 2025 10:05 AM
> *To:* Labnetwork (labnetwork at mtl.mit.edu) <labnetwork at mtl.mit.edu>
> *Subject:* [labnetwork] Recommendations to reduce lab nitrogen usage
>
>
>
> Hello Labnetwork,
>
> In our nanofab at Vanderbilt, we are looking at ways to reduce our
> nitrogen usage, and I wanted to ask for any recommendations, success
> stories, or failures that might help in our search.
>
> For background, we use 5N “house” N2 for purging catastrophic scrubbers,
> point-of-use scrubbers, gas cabinets, VMBs, and some vacuum pumps 24/7.
> Additionally, we have on-demand usage at wet chemical hoods and various
> tools, but the most significant users are the constant-purge items listed
> above.
>
> Our N2 is supplied from a large tank next to our building that is
> periodically filled from a truck to provide 5N “house” nitrogen, and then
> we have a set of purifiers to give us 6N “process” nitrogen for specific
> tools.  This was part of an original design for flexibility with future lab
> growth.
>
> We’re already trying to cut back on the on-demand needs and only turning
> hoods on and off as needed for example, but we don’t really have the same
> options for the gas delivery and abatement systems.
>
> We’re also looking at ideas such as a hybrid approach like putting the
> scrubbers onto a nitrogen generator that may not need the same purity
> requirements, but this is a new area for us.
>
> I can provide specific usage numbers privately if it helps, but we are a
> nominally 10,000 sqft facility (half under filtration, half service areas).
>
> Thanks for any suggestions!
>
> Ben
>
>
>
>
>
> Ben W. Schmidt, Ph.D.
>
> Cleanroom Manager
> Vanderbilt Institute of Nanoscale Science and Engineering
>
> Vanderbilt University, Nashville, TN
>
>
>
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