<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="Generator" content="Microsoft Word 14 (filtered medium)">
<!--[if !mso]><style>v\:* {behavior:url(#default#VML);}
o\:* {behavior:url(#default#VML);}
w\:* {behavior:url(#default#VML);}
.shape {behavior:url(#default#VML);}
</style><![endif]--><style><!--
/* Font Definitions */
@font-face
{font-family:Helvetica;
panose-1:2 11 6 4 2 2 2 2 2 4;}
@font-face
{font-family:Helvetica;
panose-1:2 11 6 4 2 2 2 2 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
@font-face
{font-family:Georgia;
panose-1:2 4 5 2 5 4 5 2 3 3;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p.MsoAcetate, li.MsoAcetate, div.MsoAcetate
{mso-style-priority:99;
mso-style-link:"Balloon Text Char";
margin:0in;
margin-bottom:.0001pt;
font-size:8.0pt;
font-family:"Tahoma","sans-serif";}
span.apple-tab-span
{mso-style-name:apple-tab-span;}
span.apple-style-span
{mso-style-name:apple-style-span;}
span.EmailStyle19
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
span.BalloonTextChar
{mso-style-name:"Balloon Text Char";
mso-style-priority:99;
mso-style-link:"Balloon Text";
font-family:"Tahoma","sans-serif";}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="blue" vlink="purple">
<div class="WordSection1">
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hello Dr. Khbeis,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">We supply a fair number of fume scrubbers and here are a few tips that should solve most of the problems with scrubbers. First, the most important part of the
pH system is the probe. They last one year no more. Always have a new probe in stock and on a regular basis replace it. If you have to continually recalibrate the system, the probe is bad. Next is to get the hysteresis set up correctly. This should
solve the problem.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Second. If you over shoot on the pH, never try to buffer it back. Send it to waste treatment and start with fresh water. It is a logarithmic calculation
and will take too much buffer to get it back and you will end up with soup.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Third. Over flow of the scrubber is critical. Min. .5 gpm and Max. 2 gpm. You should always have fresh water entering the scrubber.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hopefully this helps, but if you have any questions, please let me know.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Best Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Tom Britton<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Sales Manager<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Georgia","serif";color:#1F497D">Critical Systems, Inc.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">7000 W. Victory Road<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Boise, ID 83709<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Direct: 208-890-1417<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Shop: 877-572-5515<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><i><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><img width="365" height="49" id="Picture_x0020_1" src="cid:image003.png@01CD6A4D.D5309790"></span></i><i><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span></i></p>
<p class="MsoNormal"><span style="font-size:8.0pt;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><i><span style="color:#1F497D"><a href="http://www.criticalsystemsinc.com/"><span style="color:blue">www.criticalsystemsinc.com</span></a><o:p></o:p></span></i></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> labnetwork-bounces@mtl.mit.edu [mailto:labnetwork-bounces@mtl.mit.edu]
<b>On Behalf Of </b>Michael Khbeis<br>
<b>Sent:</b> Tuesday, July 24, 2012 11:29 AM<br>
<b>To:</b> Fab Network<br>
<b>Cc:</b> Leonard Hixson<br>
<b>Subject:</b> [labnetwork] Fume Scrubber pH Drift<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Dear Colleagues, <o:p></o:p></p>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">I was wondering if any of you had experience in pH swings on fume scrubbers. We inherited the facility and associated scrubber that is attached to all our gas cabinets, GRC, and fume hoods. We have little documentation on the PM schedule
and no Operating and Maintenance manuals. Basically, we are neutralizing or raising pH to 10, but then over the course of a few minutes up to several hours the system will drop to pH of <5. Acceptable range in our AOP is 5.5 - 11. We see this swing even when
tools are idle - there does not appear to be an operational indicator that tracks the system response. <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">System description at a high level: Age of system is 15 years. Last media change - unknown, but plastic media looks mostly normal. Manual fill/drain, system recirculates with addition of caustic soda to balance out acidification - also
manual dispense when pH is out of range. We started a bacterial kill that was recommended in the weekly PM schedule about 3 weeks ago and starting seeing this instability in pH a week later. We halted the PM schedule to see what impact there is, if any.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Remedies attempted: <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><span class="apple-tab-span"> </span>1) Added sodium bicarbonate to increase buffering of system. Minimal impact.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><span class="apple-tab-span"> </span>2) Multiple drain/flush cycles - pH was normal (7) for few minutes then dropped to 4 shortly after. <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><span class="apple-tab-span"> </span>3) pH probes were recalibrated and verified to be operational independently.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Any recommendations or anecdotal experience would be appreciated. I thank you for participating in this community. <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Gratefully,<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<div>
<div>
<p class="MsoNormal"><span style="font-size:13.5pt;font-family:"Helvetica","sans-serif";color:black">Dr. Michael Khbeis<br>
Associate Director<br>
Microfabrication Facility (MFF)<br>
University of Washington<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal" style="margin-bottom:13.5pt"><span style="font-size:13.5pt;font-family:"Helvetica","sans-serif";color:black">Fluke Hall, Box 352143<br>
(O) 206.543.5101<br>
(C) 443.254.5192<br>
<a href="mailto:khbeis@uw.edu">khbeis@uw.edu</a><br>
<br>
<o:p></o:p></span></p>
</div>
</div>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</div>
</body>
</html>