<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Hi Sandrine,</div><div><br></div><div>We have a 193nm excimer laser micromachining system in our cleanroom and went through a similar exercise. </div><div><br></div><div>We concluded that even though OSHA or NIOSH limits would indicate that a gas cabinet is unnecessary, that housing the ArF cylinders in an exhausted enclosure is a safer/better option. Since the laser requires frequent purges/refills, placing the cylinder near the cabinet is a must - therefore, it needed to be placed in an adjacent service chase. And so, we reasoned that:</div><div><br></div><div>1. Housing F2 gases directly in the recirc path (no gas cabinet) was not an option.</div><div><br></div><div>2. Shutting down the gas with with a TGMS interlock was required since</div><div><br></div><div>3. We perceived inherent difficulty in diluting a full cylinder release, as might be the case with a standard gas panel that could not be shut down by our TGMS.</div><div><br></div><div>4. Our researchers would be wielding pitchforks if they were exposed to high levels of F2, even if we explained it was permissible.</div><div><br></div><div>I hope this helps.</div><div><br></div><div>Best,</div><div>Noah</div><div><br><div>Noah Clay<div>Director, Quattrone Nanofabrication Facility</div><div>University of Pennsylvania </div></div></div><div><br>On Mar 3, 2017, at 14:28, Sandrine Martin <<a href="mailto:sandrine@umich.edu">sandrine@umich.edu</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr">Hello,<div><br></div><div>There are a few individual labs here at the University of Michigan that have excimer lasers and use F2 premix gases with 0.1 or 0.2% F2. So far, these gases have been installed in gas cabinets. We are now involved in a new installation and are getting some push back about the need for a gas cabinet. </div><div><br></div><div>The argument is made using the Compressed Gas Assoc Pamphlet P-20 Standard for Classification of Toxic Gas Mixtures (2009) that apparently states that, if the LC50 value is over 5,000ppm, the gas mixture is not considered toxic. </div><div>Pure F2 is listed with a LC50 (rat, 1h) at 185ppm. </div><div>At 0.2% F2, the calculated LC50 is then 92,500ppm, well above the 5,000ppm threshold and the premix is no longer considered a toxic gas. (it also has an NFPA rating of "1" in health on the MSDS)</div><div><br></div><div>Since the mixture is not toxic and the F2 concentration is <1%, EH&S concludes that a gas cabinet is not required.<br></div><div><br></div><div>However, considering that the F2 PEL is 0.1ppm and IDLH 25ppm, it still seems that a gas cabinet would be the safest option and the best solution.</div><div><br></div><div>Has anybody gone through similar discussions? </div><div>If you have a lab with a fluorine premix gas, is it in a gas cabinet? If not, what type of space is it in, and what kind of ventilation and gas detection are in place?</div><div><br></div><div>Thanks</div><div>Sandrine</div><div><br></div><div><br></div><div>-- <br></div><div><div class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><p style="margin:0px;font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">Sandrine Martin, Ph.D.</p><p style="margin:0px;font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)"><u></u></p><p style="margin:0px;font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">University of Michigan </p><p style="margin:0px;font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">LNF Managing Director<u></u><u></u></p><p style="margin:0px;font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">1246D EECS, 1301 Beal Ave<u></u><u></u></p><p style="margin:0px;font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">Ann Arbor, MI 48109<u></u><u></u></p><p style="margin:0px;font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">Cell <a value="+17342772365" style="color:rgb(17,85,204)">734-277-2365</a><u></u><u></u></p><p style="margin:0px;font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">Fax <a value="+17346471781" style="color:rgb(17,85,204)">734-647-1781</a><u></u><u></u></p><p style="margin:0px;font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)"><a href="http://www.lnf.umich.edu/" style="color:rgb(17,85,204)" target="_blank">www.LNF.umich.edu</a> </p><p style="margin:0px;font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">@LurieNanofab</p></div></div></div></div></div></div>
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