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<p class="MsoPlainText"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D">Hi John,<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D">I'm glad that you found the source of the leak. Any time a system is compromised it causes huge issues with down time and cost of repair. As you are probably aware,
your gas line is most likely trashed to the tool and needs to be replaced to the tool. Don't just replace the panel and run the gas again, as corrosion spreads once it starts. Your gas cabinet vendor should be able to get you a new panel, hopefully quickly,
so you're not down for an excessive time.<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D">In reading what you wrote about leak checking after install, this shouldn't be necessary. The major Fabs don't do this as the downtime and cost would be enormous. The
initial installation by your mechanical contactor includes a helium leak check through the cabinet to the tool, and if you're performing a cylinder leak check after every bottle change, you should be fine from a leak check perspective. Instead focus on keeping
the gas dry. It is well documented that HCL, and most other corrosives, in the gaseous form, can run for years in stainless steel lines with no issues, but as soon as there is the slightest trace of moisture, game over. It's my guess, that when you send this
panel back to the gas cabinet supplier, you're probably going to hear that the valve corroded through where you found the leak.
<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D">The major points for using any corrosive gas are:<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoPlainText" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:6.0pt;margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1">
<![if !supportLists]><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D"><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D">Helium leak check the connection after every cylinder change prior to the introduction of process gas. We advise using a "He/Inert Gas" blend for your purge gas,
as you can use the purge gas to helium leak test the connection.<o:p></o:p></span></p>
<p class="MsoPlainText" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:6.0pt;margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1">
<![if !supportLists]><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D"><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D">Always use DISS fittings for both the process gas and the purge gas. Not only do they provide a higher level of leak integrity and purity over a CGA, but one
is less likely to introduce a lower purity purge gas by mistake than if the connection has a standard 580 CGA on it.<o:p></o:p></span></p>
<p class="MsoPlainText" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:6.0pt;margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1">
<![if !supportLists]><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D"><span style="mso-list:Ignore">3.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D">Purge Gas Purifier - We highly recommend a purge gas purifier for all mineral acid gases. Granted, your cylinder costs $1200, but it's cheap insurance and it
will last a very long time.<o:p></o:p></span></p>
<p class="MsoPlainText" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:6.0pt;margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1">
<![if !supportLists]><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D"><span style="mso-list:Ignore">4.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D">Trickle Purge Valve - check to make you have a Trickle Purge Valve in your purge line and that it's open during bottle changes. This does a good job of keeping
atmosphere from getting into the gas line during the physical changing of the bottle.<o:p></o:p></span></p>
<p class="MsoPlainText" style="margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1">
<![if !supportLists]><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D"><span style="mso-list:Ignore">5.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D">Cycle Purges - 30 is not enough. Set your purge cycles at 60 for both pre and post purge. The pre-purge is for the safety of the operators, and does a better
job of scrubbing the inside of the tubing and components of the HCl, so any atmospheric moisture that gets past the trickle purge doesn't react. The post purge is to dry the inside of the gas line of the tube and components before the HCl is reintroduced into
the system. Any less and there is a chance that residual moisture will remain, and once the HCl gas hits it, the corrosion will start and it's a matter of time before you see the effects.<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D">I was talking with Troy on this and he ran his HCl at ON Semi for over 10 years using the above practice, and some of their systems sat idle for quite some time between
quartz cleaning steps on seldom used tools. I also talk with a lot of gas systems managers in my travels and this is a fairly common way that the production Fabs keep their corrosive systems running and the problems at bay.<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D">Hope this helps. See you on Sunday.<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D">Tom<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial Narrow","sans-serif";color:#244061">Tom Britton</span><span style="font-family:"Times New Roman","serif";color:#244061"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial Narrow","sans-serif";color:#244061">Director of Sales</span><span style="font-family:"Times New Roman","serif";color:#244061"><o:p></o:p></span></p>
<p class="MsoNormal"><i><span style="font-size:14.0pt;font-family:"Arial Narrow","sans-serif";color:#244061">Critical Systems, Inc.</span></i><span style="font-size:14.0pt;color:#244061"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial Narrow","sans-serif";color:#244061">Direct: 208-890-1417<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial Narrow","sans-serif";color:#244061">Office: 877-572-5515<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;color:#1F497D"><a href="http://www.criticalsystemsinc.com/"><i><span style="font-family:"Arial Narrow","sans-serif";color:blue">www.CriticalSystemsInc.com</span></i></a></span><i><u><span style="font-size:12.0pt;font-family:"Arial Narrow","sans-serif";color:#1F497D"><o:p></o:p></span></u></i></p>
<p class="MsoNormal"><i><u><span style="font-size:4.0pt;font-family:"Arial Narrow","sans-serif";color:#1F497D"><o:p><span style="text-decoration:none"> </span></o:p></span></u></i></p>
<p class="MsoNormal"><span style="color:#1F497D"><img border="0" width="245" height="48" id="Picture_x0020_1" src="cid:image002.png@01CF855E.C2ACFA90" alt="logo for email signature png"></span><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoPlainText"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Arial Narrow","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoPlainText">-----Original Message-----<br>
From: labnetwork-bounces@mtl.mit.edu [mailto:labnetwork-bounces@mtl.mit.edu] On Behalf Of John Shott<br>
Sent: Tuesday, June 10, 2014 2:20 PM<br>
To: Weaver, John R; labnetwork@mtl.mit.edu<br>
Subject: Re: [labnetwork] Anhydrous HCl after it escapes ...</p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">Labnetwork Community:<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">First, I'd like to thank Chung Wing Leong, Dennis Grimard, Craig Cheney, Tom Britton and John Weaver for taking the time to respond to my query.
<o:p></o:p></p>
<p class="MsoPlainText">I appreciate your collective expertise and input and am taking a number of things you suggested under careful consideration as we move forward.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">In the meantime, we have learned a bit more about this leak and I thought that I would share with you a bit more about what we have learned:<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">First, the leak seems to have occurred at the joint between the valve body and the tube stub ... not, as we had originally feared and suspected at one of the VCR connection points. Nor did it occur at one of the orbital welds between
the tube stub on the valve and a VCR gland. <o:p></o:p></p>
<p class="MsoPlainText">To me it is unusual to see a leak at that point in a valve ...
<o:p></o:p></p>
<p class="MsoPlainText">particularly one that has not been in service very long.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">Second, this failure occurred downstream (on the tool side) of the pneumatically-controlled, low-pressure outlet valve on the panel.
<o:p></o:p></p>
<p class="MsoPlainText">Certainly on our panel, and in most auto-purge panels of this type, this valve is typically closed during bottle changes and similar leak checking activities. To be candid, this has been a bit of a blind spot for me: while I told you
that we leak check the panel each time that we change a cylinder (which is true), now that I think about it more carefully, we don't have a mechanism for leak checking anything on the downstream side of this valve on a regular basis.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">In fact what we normally leak check is that portion of the panel that is upstream of the pneumatically-controlled, low-pressure outlet valve.
<o:p></o:p></p>
<p class="MsoPlainText">Since this is a manifolded cabinet that has two bottles feeding a single output line, there are actually a number of potential failure points that we do not regularly check that includes the output side of each pneumatically-controlled
output valve, the manual quarter-turn valve in series with and downstream from the pneumatically-controlled output valve and the fittings associated with the tee in the manifold. As this cabinet has not been service for an extended period of time, those downstream
fittings have likely been checked only twice: once by the cabinet manufacturer at their facility and once by us during the cabinet install. While our cabinet was helium leak checked and certified by a third-party to be less than 10^-9 SCCM leakage, is there
a chance that we missed something then? I'm certainly wondering ...<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">My guess is that I am not alone in having thought that we leak check the entire panel and all fittings each time we change a gas cylinder ...
<o:p></o:p></p>
<p class="MsoPlainText">whereas there are likely several fittings and connection points that are not actually checked each time. I will certainly think about this in a new light ...<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">Thanks,<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">John<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">On 6/9/2014 5:43 AM, Weaver, John R wrote:<o:p></o:p></p>
<p class="MsoPlainText">> John -<o:p></o:p></p>
<p class="MsoPlainText">> I've had experiences (certainly plural :)) with both external and internal leaks. For an internal leak, where moisture has gained access to the piping, I have always replaced the piping components up to the point where the leak was
blocked - a valve, etc. I use valves with Hastelloy wetted surfaces (sometimes called Hastelloy trim), which is not impervious to HCl corrosion but certainly holds up better.<o:p></o:p></p>
<p class="MsoPlainText">> For external leaks, the key is to neutralize the surfaces as quickly as possible. In one instance we had to replace many components because we didn't neutralize the surfaces more quickly. A mild base works well for neutralization -
something with a pH in the 9 range. Then a thorough rinse to remove any salts is necessary.<o:p></o:p></p>
<p class="MsoPlainText">> We run all of the gas cabinet exhausts for chloride gas cabinets through our plastic exhaust system, so we don't have to worry about exhaust. If you use a metal exhaust on the gas cabinet where the leak occurred, I'd carefully inspect
the exhaust for a month or two after the incident.<o:p></o:p></p>
<p class="MsoPlainText">> I hope this helps.<o:p></o:p></p>
<p class="MsoPlainText">> John<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">> John R. Weaver<o:p></o:p></p>
<p class="MsoPlainText">> Facility Manager<o:p></o:p></p>
<p class="MsoPlainText">> Birck Nanotechnology Center<o:p></o:p></p>
<p class="MsoPlainText">> Purdue University<o:p></o:p></p>
<p class="MsoPlainText">> <a href="mailto:jrweaver@purdue.edu"><span style="color:windowtext;text-decoration:none">jrweaver@purdue.edu</span></a><o:p></o:p></p>
<p class="MsoPlainText">> nano.purdue.edu<o:p></o:p></p>
<p class="MsoPlainText">> ________________________________________<o:p></o:p></p>
<p class="MsoPlainText">> From: <a href="mailto:labnetwork-bounces@mtl.mit.edu"><span style="color:windowtext;text-decoration:none">labnetwork-bounces@mtl.mit.edu</span></a> [labnetwork-bounces@mtl.mit.edu]
<o:p></o:p></p>
<p class="MsoPlainText">> on behalf of John Shott [shott@stanford.edu]<o:p></o:p></p>
<p class="MsoPlainText">> Sent: Thursday, June 05, 2014 3:08 PM<o:p></o:p></p>
<p class="MsoPlainText">> To: <a href="mailto:labnetwork@mtl.mit.edu"><span style="color:windowtext;text-decoration:none">labnetwork@mtl.mit.edu</span></a><o:p></o:p></p>
<p class="MsoPlainText">> Subject: [labnetwork] Anhydrous HCl after it escapes ...<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">> Labnetwork Community:<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">> Sooner or later, it seems, anhydrous hydrogen chloride (or a number of
<o:p></o:p></p>
<p class="MsoPlainText">> equally corrosive materials) is going to escape. At least that is our
<o:p></o:p></p>
<p class="MsoPlainText">> experience at the Stanford Nanofabrication Facility. Despite our best
<o:p></o:p></p>
<p class="MsoPlainText">> efforts to use quality components, do proper leak checking, etc., it
<o:p></o:p></p>
<p class="MsoPlainText">> seems as if we end up with a leak either in a gas cabinet or in a tool
<o:p></o:p></p>
<p class="MsoPlainText">> near a mass flow controller. At that point, anything near the site of
<o:p></o:p></p>
<p class="MsoPlainText">> the original leak has been covered with now moisture-laden hydrogen
<o:p></o:p></p>
<p class="MsoPlainText">> chloride ... which, I believe, is far more corrosive than the original
<o:p></o:p></p>
<p class="MsoPlainText">> anhydrous material.<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">> For those of you who have encountered similar situations, how do you
<o:p></o:p></p>
<p class="MsoPlainText">> recover or what to you replace? Do you have effective means of
<o:p></o:p></p>
<p class="MsoPlainText">> neutralizing those metal surfaces? Do your replace VCR gaskets with
<o:p></o:p></p>
<p class="MsoPlainText">> thicker-than-normal or grooved "super gaskets"? Do you replace the
<o:p></o:p></p>
<p class="MsoPlainText">> entire assembly? Do you leak check, put back in service, and pray?<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">> Thanks for sharing your experience and insights,<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">> John<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">> _______________________________________________<o:p></o:p></p>
<p class="MsoPlainText">> labnetwork mailing list<o:p></o:p></p>
<p class="MsoPlainText">> <a href="mailto:labnetwork@mtl.mit.edu"><span style="color:windowtext;text-decoration:none">labnetwork@mtl.mit.edu</span></a><o:p></o:p></p>
<p class="MsoPlainText">> <a href="https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork">
<span style="color:windowtext;text-decoration:none">https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork</span></a><o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
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