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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi,<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 are building a new fab and the current talk is whether we use variable speed fans with dampers that sense the pressure drop due to sash position or no control.
We are looking at the projected cost savings vs the cost to install sensors, dampers, fans and control software. The control software expense is very high. Preliminary numbers are not in favor of the expense.<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">The Draper EHS also treats fab hoods like fume hoods, so the requirement is 100 fpm at the open face.<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">Rick<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>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext"> labnetwork-bounces@mtl.mit.edu [mailto:labnetwork-bounces@mtl.mit.edu]
<b>On Behalf Of </b>Joe Morgan<br>
<b>Sent:</b> Friday, April 06, 2012 10:12 AM<br>
<b>To:</b> Mac Hathaway; labnetwork@mtl.mit.edu<br>
<b>Subject:</b> Re: [labnetwork] Face Velocity for Wet benches/Fume hoods?<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Mac,<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">See ANSI/AIHA Z9.5 for laboratory ventilation systems and worker health. In the past 100 feet/per minute has been the golden rule. However, for a number of
years now fume hood manufacturers have created new designs that sometimes enable sash velocities as low as 60 feet/minute. The hood must still pass testing and certification as defined by ASHRAE 110. I’m not sure how wet process benches or laminar flow hoods
fit into these standards.<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, Joe<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>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext"> labnetwork-bounces@mtl.mit.edu [mailto:labnetwork-bounces@mtl.mit.edu]
<b>On Behalf Of </b>Mac Hathaway<br>
<b>Sent:</b> Thursday, April 05, 2012 3:09 PM<br>
<b>To:</b> Lab Network (labnetwork@mtl.mit.edu)<br>
<b>Subject:</b> [labnetwork] Face Velocity for Wet benches/Fume hoods?<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hey all,<br>
<br>
What do folks currently consider satisfactory regarding the air-flow face velocity at their fume hoods and wet benches? Do you have any ASHRAE/ANSI/SEMI-type standards or references that you draw on for this purpose?<br>
<br>
The topic came up today in the context of energy savings, lab make-up air, and this sort of thing...<br>
<br>
<br>
Thanks,<br>
<br>
Mac Hathaway<br>
Harvard Center for Nanoscale Systems<o:p></o:p></p>
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