[labnetwork] question ...

[Mac Hathaway]

Hi Leo,

One other thing which I have not seen mentioned yet:  The only material 
I know of that we would definitely and always use a local scrubber for 
is perchloric acid, which forms crystals when its condensate dries out, 
which crystals are shock sensitive, along the lines of TNT.  (Really.)  
Perchloric is used for etching diamond, among other things...

This material calls for a local scrubber, or a "scrubber bench", which 
incorporates a wet-spray scrubber in the base of the wet-bench.  Small 
or occasional use requires at least a condensing column above the heated 
material to insure the vapors do not escape.


Mac Hathaway
Harvard CNS
617-495-9012

On 12/2/2012 12:12 PM, Rizik wrote:
> In addition, your local/regional air quality management district should have
> a limit on the quantity of toxic, highly toxic and particulate discharged
> into the atmosphere. You might want to consult with the local district about
> the maximum allowable discharge limits.
>
> I agree with Michael about the reactivity and byproducts. In case you are
> using gases with corrosive residual byproducts where some of these gases are
> released from the tool un-reacted, such gases need to be locally abated. The
> process could either be a wet scrubber, a thermal-wet abatement system or a
> dry scrub system. The cost of these systems ranges between $55K for a single
> canister dry scrub system to up to $125K for a thermal wet point of use
> scrubber. If you are abating ozone depleting gases along with other
> toxic/corrosive gases, then the cost could be as high as $150K. Each option
> brings to the table other challenges that need to be met. Depending on your
> current facility infrastructure set up you might be able to favor one over
> the other.
>
> Regards
>
> Rizik Michael, PE
> Principal
> Integrated Engineering Services
> Office: +408 261 3500, Ext. 201
> Cell:      +408 718 0927
>
>
>
> -----Original Message-----
> From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu]
> On Behalf Of Michael Khbeis
> Sent: Saturday, December 01, 2012 5:32 AM
> To: Leonidas Ocola
> Cc: labnetwork at mtl.mit.edu
> Subject: Re: [labnetwork] question ...
>
> Leonidas,
>
> I would say it is dependent on the reactivity of the byproduct.  For
> pyrophorics we "scrub" at the point of use with a gas reactor column.  For
> acids we just collect at the main scrubber.  If there was something that
> would be potentially reactive with other byproducts, you may be better off
> with the local scrubber, but these are very expensive.  You also need to
> consider the dilution factor in the exhaust stream.  If you have a large
> volume of exhaust, say from numerous wet benches, this will dilute the
> shared exhaust so consider the volume and rate of byproduct being produced
> compared to the total exhaust volume/flow.
>
> Dr. Michael Khbeis
> Associate Director
> Microfabrication Facility (MFF)
> University of Washington
> Fluke Hall, Box 352143
> (O) 206.543.5101
> (C) 443.254.5192
> khbeis at uw.edu
>
>
>
> On Nov 30, 2012, at 9:29 AM, Leonidas Ocola wrote:
>
>> Dear List,
>>
>> When does it make sense to just use a point of use scrubber for a
>> particularly noxious tool or when to install a "capture it all"
>> scrubber at the end of a facility exhaust?
>>
>> Just curious.
>>
>> Thanks
>>
>> Leo
>>
>>
>> --
>> Leonidas E Ocola, PhD
>> Center for Nanoscale Materials
>> Argonnne National Laboratory
>> Bldg 440, Rm A129
>> 9700 South Cass Avenue, Argonne, IL 60439
>> Ph: 630-252-6613
>> Fax: 630-252-5739
>>
>>
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>
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