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<div>I could not agree more with Noah.</div>
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<p class="MsoNormal" style="margin: 0in 0in 0.0001pt;"><span style="background-color: rgba(255, 255, 255, 0);">My take on this:</span></p>
<p class="MsoNormal" style="margin: 0in 0in 0.0001pt;"><font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);"> </span></font></p>
<p class="MsoListParagraph" style="text-indent: 0px; margin: 0in 0in 0.0001pt 0.5in;">
<font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);">1.<span style="line-height: normal;"> </span> Lets say you have the bottle in a smallish room
say 10x10x10 or 1,000 CF.</span></font></p>
<p class="MsoNormal" style="margin: 0in 0in 0.0001pt;"><font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);"> </span></font></p>
<p class="MsoListParagraph" style="text-indent: 0px; margin: 0in 0in 0.0001pt 0.5in;">
<font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);">2.<span style="line-height: normal;"> </span> Lets say you leak 1 CF
that is a dilution of 1,000X</span></font></p>
<p class="MsoListParagraph" style="margin: 0in 0in 0.0001pt 0.5in;"><font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);"> </span></font></p>
<p class="MsoListParagraph" style="text-indent: 0px; margin: 0in 0in 0.0001pt 0.5in;">
<font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);">3.<span style="line-height: normal;"> </span>0.2 % F2 in whatever is 2,000 PPM
</span></font></p>
<p class="MsoListParagraph" style="margin: 0in 0in 0.0001pt 0.5in;"><font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);"> </span></font></p>
<p class="MsoListParagraph" style="text-indent: 0px; margin: 0in 0in 0.0001pt 0.5in;">
<font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);">4.<span style="line-height: normal;"> </span>Assuming perfect and uniform dissipation throughout the room
the room concentration would be 2 ppm.</span></font></p>
<p class="MsoListParagraph" style="margin: 0in 0in 0.0001pt 0.5in;"><font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);"> </span></font></p>
<p class="MsoListParagraph" style="text-indent: 0px; margin: 0in 0in 0.0001pt 0.5in;">
<font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);">5.<span style="line-height: normal;"> </span>That is 20X the PEL which is a legally enforceable exposure limit
independent of a non-binding CGA recommendation.</span></font></p>
<p class="MsoListParagraph" style="margin: 0in 0in 0.0001pt 0.5in;"><font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);"> </span></font></p>
<p class="MsoListParagraph" style="text-indent: 0px; margin: 0in 0in 0.0001pt 0.5in;">
<font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);">6.<span style="line-height: normal;"> </span>At 2 ppm you would be right at the odor threshold
so you would have a poor warning property to the leak</span></font></p>
<p class="MsoNormal" style="margin: 0in 0in 0.0001pt;"><font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);"> </span></font></p>
<p class="MsoNormal" style="margin: 0in 0in 0.0001pt;"><font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);"> </span></font></p>
<p class="MsoNormal" style="margin: 0in 0in 0.0001pt;"><font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);">Of course my logic could be wrong, my math could be wrong and the amount of the leak could be less
or more
you should verify
for yourself.</span></font></p>
<p class="MsoNormal" style="margin: 0in 0in 0.0001pt;"><font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);"> </span></font></p>
<p class="MsoNormal" style="margin: 0in 0in 0.0001pt;"><font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);">Finally, if you did have a leak and the people were not able to detect the leak until they began to experience the effects of
F2 exposure
what do you tell them? The CGA P-20 pamphlet said it was ok? As Noah says ... pitchforks might be the least of your worries.</span></font></p>
<p class="MsoNormal" style="margin: 0in 0in 0.0001pt;"><font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);"> </span></font></p>
<p class="MsoNormal" style="margin: 0in 0in 0.0001pt;"><font color="#000000"><span style="background-color: rgba(255, 255, 255, 0);">Put it in the gas cabinet
. Or a vented enclosure with detection. At the very, very, least, place a vent in the room with
a detection point in the vent to actively sweep up (constantly sample) a possible leak that could occur. I would smoke the room to make sure that any point in the room eventually ends up in that vent at some point in time.</span></font></p>
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D<br>
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<b>Dennis S Grimard, Ph.D.</b>
<div>Associate Director of Operations</div>
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<div><b>MIT.nano</b></div>
<div><b>School of Engineering</b></div>
<div>Massachusetts Institute of Technology</div>
<div>60 Vassar Street, Bldg 39-559</div>
<div>Cambridge, MA 02149</div>
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<div>EM: <a href="mailto:dgrimard@mit.edu">dgrimard@mit.edu</a></div>
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<div><br>
On Mar 4, 2017, at 9:04 AM, Noah Clay <<a href="mailto:nclay@upenn.edu">nclay@upenn.edu</a>> wrote:<br>
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<div>Hi Sandrine,</div>
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<div>We have a 193nm excimer laser micromachining system in our cleanroom and went through a similar exercise. </div>
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<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>
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<div>1. Housing F2 gases directly in the recirc path (no gas cabinet) was not an option.</div>
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</div>
<div>2. Shutting down the gas with with a TGMS interlock was required since</div>
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<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>
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<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>
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<div>I hope this helps.</div>
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<div>Best,</div>
<div>Noah</div>
<div><br>
<div>Noah Clay
<div>Director, Quattrone Nanofabrication Facility</div>
<div>University of Pennsylvania </div>
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<div><br>
On Mar 3, 2017, at 14:28, Sandrine Martin <<a href="mailto:sandrine@umich.edu">sandrine@umich.edu</a>> wrote:<br>
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<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>
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<div>Since the mixture is not toxic and the F2 concentration is <1%, EH&S concludes that a gas cabinet is not required.<br>
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<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>
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<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>
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<div>-- <br>
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Cell <a value="+17342772365" style="color:rgb(17,85,204)">734-277-2365</a><u></u><u></u></p>
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