[labnetwork] Anhydrous HCl after it escapes ...

[Tom Britton]

Hi John,



Sorry to hear about your HCl issue. As we all know, HCl is very difficult to manage once it escapes. Neutralizing is seldom effective in a clean room environment, and replacement of metal components that have come in contact with the HCL is the proper way to keep it from spreading.  If the proper leak test procedures are in place, one thing that could be causing the leaks is residual moisture that may be present due to either  low quality purge gas or inadequate purging.



To solve the problem of how to prevent leaks with HCl and other corrosives these are the questions I would start with.

*         What is the quality of the purge gas?

*         Are you using a purifier on the purge gas?

*         Is H2O or O2  analysis done on the gas system prior to gas introduction?

*         How many purge cycles on gas line prior to gas introduction?

*         How many purge cycles post cylinder change are being done?



If you want, I can set up a conference call with Troy Reese, who was the gas systems manager at ON Semi before he came to us, and we can go over these questions. Troy is very knowledgeable in these situations and we would be happy to help wherever possible. He is also presenting with you at the Bootie Camp coming up at the UGIM conference, so we can talk about it there as well if necessary.



See you at Harvard.

Thank you!

Tom Britton
Director of Sales
Critical Systems, Inc.
Direct: 208-890-1417
Office: 877-572-5515
www.CriticalSystemsInc.com<http://www.criticalsystemsinc.com/>

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-----Original Message-----
From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of John Shott
Sent: Thursday, June 05, 2014 1:09 PM
To: labnetwork at mtl.mit.edu
Subject: [labnetwork] Anhydrous HCl after it escapes ...



Labnetwork Community:



Sooner or later, it seems, anhydrous hydrogen chloride (or a number of equally corrosive materials) is going to escape.  At least that is our experience at the Stanford Nanofabrication Facility.  Despite our best efforts to use quality components, do proper leak checking, etc., it seems as if we end up with a leak either in a gas cabinet or in a tool near a mass flow controller.  At that point, anything near the site of the original leak has been covered with now moisture-laden hydrogen chloride ... which, I believe, is far more corrosive than the original anhydrous material.



For those of you who have encountered similar situations, how do you recover or what to you replace?  Do you have effective means of neutralizing those metal surfaces?  Do your replace VCR gaskets with thicker-than-normal or grooved "super gaskets"?  Do you replace the entire assembly?  Do you leak check, put back in service, and pray?



Thanks for sharing your experience and insights,



John





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