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<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>Yes, the flow restricting orifice is key, as well as an excess
flow sensor in the hydrogen lines, regardless of the source.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div>
<p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>Abbie
Gregg</span><span style='color:#1F497D'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>President</span><span
style='color:#1F497D'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>Abbie
Gregg, Inc.</span><span style='color:#1F497D'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>1130
East University Drive, Suite 105</span><span style='color:#1F497D'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>Tempe,
Arizona 85281</span><span style='color:#1F497D'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>Phone
480 446-8000 x 107</span><span style='color:#1F497D'><o:p></o:p></span></p>
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480-446-8001</span><span style='color:#1F497D'><o:p></o:p></span></p>
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style='color:#1F497D'><o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:red'><o:p> </o:p></span></p>
<p class=MsoNormal><i><span style='font-size:9.0pt;font-family:"Arial","sans-serif";
color:navy'>CONFIDENTIALITY NOTICE: All information contained in or
attached to this email constitutes confidential information belonging to Abbie
Gregg, Inc., its affiliates and subsidiaries and/or its clients. This
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attachments immediately</span></i><span style='font-size:9.0pt;font-family:
"Arial","sans-serif";color:navy'>. <o:p></o:p></span></p>
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color:blue'><o:p> </o:p></span></p>
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<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
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<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>Rizik<br>
<b>Sent:</b> Wednesday, July 18, 2012 6:11 PM<br>
<b>To:</b> 'Grimard, Dennis'; labnetwork@mtl.mit.edu<br>
<b>Subject:</b> Re: [labnetwork] H2 Generators<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span style='color:#1F497D'>The average cost runs about
$6,500 per gas sensor including hardware, programming, sensor, wiring, conduit,
functional testing, commissioning, etc. Pull Stations and horn/strobes each
runs about $1,500 installed. <o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>You really got a point there.
And yes, you will need to place gas sensors to overlap in the area of work so
that they will not miss a gas leak. Although this is quite difficult to
achieve, you try to install welded tubing from the generator to the point of
use then provide as sensor at each point. Again, cost will be an issue. In a
previous email, I mentioned that the gas monitoring system shall be interlocked
with the generator to ensure that it shuts down upon gas detection, manual
activation and fire alarm signal initiation. <o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>One more item to consider, is
installing an orifice in the tubing leaving the generator to ensure that we do
not allow more than 150% of the process gas demand to be supplied to the tools.
On past projects, we installed excess flow mechanical valves that would trip if
H2 flow rate exceeds a preset limit. This will allow us to limit H2 leakage to
a level that would not exceed 25% of the LEL concentration in the lab space.
All these parameters MUST be taken in consideration by the engineer of record.
Occasionally, these parameters are overlooked and are only discovered during
the plan review cycle by the AHJ. <o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Regards<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<div>
<p class=MsoNormal><span style='color:#1F497D'>Rizik Michael, PE<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Principal<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Integrated Engineering Services<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Office: +408 261 3500, Ext. 201<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Cell:
+408 718 0927<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
</div>
<p class=MsoNormal><span style='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>Grimard, Dennis<br>
<b>Sent:</b> Wednesday, July 18, 2012 1:37 PM<br>
<b>To:</b> labnetwork@mtl.mit.edu<br>
<b>Subject:</b> [labnetwork] H2 Generators<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>All:<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I have been watching the discussion regarding H2
generators. Although I agree with most of what has been said I worry
about being able to shut off the generator in case of a leak. The
generator does not know that it is delivering into a leak and unless the leak
is detected then the generator will continue pumping to that leak. Adding
detectors is not the solution. H2 detectors are difficult to place such
that they will pick up a leak. Do you add detectors at every possible
leak point? Add in the high velocities of the cleanroom and I hesitate to
change from bottles to generators.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>When considering the costs, you also have to consider the
cost of the added detectors … which are not cheap …<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Dennis Grimard, Ph.D.<o:p></o:p></p>
<p class=MsoNormal>Managing Director<o:p></o:p></p>
<p class=MsoNormal>Lurie Nanofabrication Facility<o:p></o:p></p>
<p class=MsoNormal>1246D EECS Blding<o:p></o:p></p>
<p class=MsoNormal>1301 Beal Avenue<o:p></o:p></p>
<p class=MsoNormal>Ann Arbor, MI 48109-2122<o:p></o:p></p>
<p class=MsoNormal>(734) 368-7172 Cell<o:p></o:p></p>
<p class=MsoNormal><a href="http://www.lnf.umich.edu">http://www.lnf.umich.edu</a><o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
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