[labnetwork] HEPA/ULPA Filter Experience?

Wed Feb 16 16:35:57 EST 2022

Depending on your air handler design, you may be able to track HEPA life by monitoring amperage draw from the VFD's if you have it set at a closed loop ACPH setup. All acronyms aside, if you require something like 200 air changes per hour, you could baseline the air handler fan current and check it periodically.
Some older clean rooms simply use the fan speed determined at the design phase, and let the HEPA's do their thing. This simple setup is easy to baseline and monitor as well. Our facility has a closed loop Variable frequency drive system coupled with particle counters in every chase to allow the room's particle count to dictate how much air is pushed through the filters. Our system would be difficult to monitor if we didn't have speed vs. amperage data since the speeds are constantly changing depending on the activity in the clean room.
Makeup air amounts are not part of this equation since the makeup air is mixed with the circulated air and gets filtered with it. The amperage draw will tell if the filters are starting to load up. Most fabs have a HEPA life of decades is the pre-filters are changed often and the system is sealed as Deon Collins has mentioned.
Equipment Dood

Steve Paolini
Principal Equipment Engineer
Harvard University Center for Nanoscale Systems
11 Oxford St.
Cambridge, MA 02138
617- 496- 9816
spaolini at cns.fas.harvard.edu
www.cns.fas.harvard.edu

From: labnetwork <labnetwork-bounces at mtl.mit.edu> On Behalf Of Collins, Deon
Sent: Wednesday, February 16, 2022 2:45 PM
To: Reger, Ronald K <rreger at purdue.edu>; labnetwork at mtl.mit.edu
Subject: Re: [labnetwork] HEPA/ULPA Filter Experience?

Deon Collins from Holonyak lab University of Illinois

Our facility has replaced HEPA filters lab independent as well as the entire cleanroom once. Our HEPA's filter are molded into the supply side(ceiling) with no temporary seals. The filters are bolted into the ceiling as well as caulked into the structure itself, so replacement is labor intensive.

Do you have any particle count trends to go by? Do you have any Magnehelic trends to go by? If you are seeing a high delta between the two in conjunction with high particle counts it is time.

If your maintenance group has done a good job of maintaining the pre filters HEPA filters will see prolonged life. If the pre filters have been ignored the HEPA filters will suffer.

As mentioned below your ductwork integrity has a profound effect on your system. You could see an individual lab with excellent results while the lab adjacent is suspect.

Deon D. Collins

FACILITY MANAGER
Holonyak Lab
University of Illinois at Urbana-Champaign
208 N Wright St Rm. 248 | 2250
Urbana, IL 61801
217-300-7531 | deonc69 at illinois.edu<mailto:deonc69 at illinois.edu>

[https://webtools.illinois.edu/webservices/js/ds/signature_logo.png]<https://urldefense.proofpoint.com/v2/url?u=http-3A__illinois.edu_&d=DwMFAg&c=WO-RGvefibhHBZq3fL85hQ&r=-H4Z_jeDfTYjnKPXor15vLwzBllmg8gFrb9m_k9OGks&m=-RHm3HKnxd6ImetSeUzpIQlNl_jbT3aGspPMKfITwjmnVh-Yrkb0gSpgGcFkv_pn&s=_NhNKAtnOJx23DzwGAr8LXXbG6r9uuTMvXNak2vgrIk&e=>

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 is not about watching other people live it. It's about you living your own!

From: labnetwork <labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu>> On Behalf Of Reger, Ronald K
Sent: Tuesday, January 25, 2022 2:30 PM
To: labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>
Subject: [labnetwork] HEPA/ULPA Filter Experience?

Dear Colleagues,

The cleanroom here at the Purdue Birck Nanotechnology Center is in its 17th year, and we're starting to see increased frequency on some typical and expected maintenance items.  And while we haven't had any catastrophic failures yet in our HEPA & UPLA filters we are wondering when they may need some serious attention/replacement.  All along we've had to replace an occasional filter panel due to some deterioration of a seal or maybe an inadvertent puncture, but we haven't had any wholesale replacement of complete banks or bays yet.

We're wondering what other nanofabs have experienced in terms of HEPA/ULPA filter replacements?  Is there a target date (~ 20 years, 25 years?) at which filters fail and entire bays are replaced?  Are seals degrading at a certain time as shown with increasing particle counts?  Have different nanofabs experienced vastly different durations for the quality of filtration?

Any insight into filter degradation & replacement experience would be greatly appreciated as we plan for the next few years of maintenance items in our fab.

Thanks very much for your information.

Ron

Ron Reger
Engineering Manager
Birck Nanotechnology Center | Room 2289 |
Office:  765.494.6667 | Email: rreger at purdue.edu<mailto:rreger at purdue.edu>
Wiki:  https://wiki.itap.purdue.edu/display/BNCWiki<https://urldefense.com/v3/__https:/wiki.itap.purdue.edu/display/BNCWiki__;!!DZ3fjg!tb4iR8LU2kJlfRYxlQU2GDoyqa8qNXp4qL2wUDjm03kOYCsscAsB6w3yW8Gyi-BBzBY$>
iLabs:  https://purdue.ilabsolutions.com/homepage/<https://urldefense.com/v3/__https:/purdue.ilabsolutions.com/homepage/__;!!DZ3fjg!tb4iR8LU2kJlfRYxlQU2GDoyqa8qNXp4qL2wUDjm03kOYCsscAsB6w3yW8Gypg92QoA$>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20220216/6f6f95f5/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 2602 bytes
Desc: image001.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20220216/6f6f95f5/attachment.png>