[labnetwork] Corrosive exhaust material of construction

[Iulian Codreanu]

Many thanks to those who have provided input!

To summarize the input:
- Three sites have teflon-coated SS and two designers strongly recommend 
it. I know of at least two other sites that have it.
- Three sites have FRP
- Two sites have coated galvanized steel (one with PVC, one with Plasite?)
- One site reported polypropylene

I wonder why polypropylene is not more commonly used.  Abbie's comments 
about explosions seem to be a good reason. Any other reasons? Can anyone 
comment on its durability; in my mind "plastic" becomes brittle after a 
while although I saw decades-old polypropylene wet benches that seemed 
to be fine?

Best regards,

Iulian

iulian Codreanu, Ph.D.
Director of Operations, UD NanoFab
University of Delaware
149 Evans Hall
Newark, DE 19716
302-831-2784

On 12/21/2013 12:46 AM, Abbie Gregg wrote:
> Thanks for the lead in Julia,
> A few comments. The Teflon lined stainless steel which is flanged/gasketed/bolted or welded is especially important if you are combining potential effluents containing pyrophorics or hydrogen (eg CVD or LPCVD exhaust/purge) in the same duct as the wet hood (acid or base) effluent, because you have the risk of explosion, fire and corrosion in the same exhaust stream.
> Also we have been able to modify the Teflon lined stainless in the field at many jobs, it just takes special skills and a kit from PSP to do a tap in the field for modifications. This material is a long lead item and also quite expensive,  but it has been much safer than any other material. FM prefers it because it is "factory made" rather than wrapped or coated in the field.
> We did use Plasite coated heavy gauge galvanized ductwork in the same application at a couple of Northern CA projects but this was not preferred because the plasite is coated at the fabrication shop and there can be voids, think areas or other quality control problems that are hard to find. It is also heavier.
> If there is no risk of overheating, fire, or explosion and only corrosion resistance needed, the Fiberglass reinforced plastic "field fabricated" duct is good if made by talented fabricators, although any Fire in the facility will also destroy it,  and it makes really awful destructive and corrosive smoke when it burns. PVC has  similar characteristics, and neither of these materials meet the 25/50 flame and smoke spread requirements of some H-5 codes. (depending on IBC year, I believe).
> Best regards,
>
> Abbie Gregg
> President
> Abbie Gregg, Inc.
> 1130 East University Drive, Suite 105
> Tempe, Arizona 85281
> Phone 480 446-8000 x 107
> Cell 480-577-5083
> FAX 480-446-8001
> email agregg at abbiegregg.com
> website www.abbiegregg.com
>
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>
> -----Original Message-----
> From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Aebersold,Julia W.
> Sent: Thursday, December 19, 2013 3:57 PM
> To: Iulian Codreanu; Fab Network
> Subject: Re: [labnetwork] Corrosive exhaust material of construction
>
> Teflon lined stainless steel was designed and implemented for our acid exhaust system.  Our cleanroom has been in place since 2006 and was designed by Abbie Gregg.  She would be a great source for this type of information.
>
> Cheers!
>
> Julia Aebersold, Ph.D.
> MNTC Cleanroom Manager
> Shumaker Research Building, Room 233
> 2210 South Brook Street
> University of Louisville
> Louisville, KY  40292
>
> 502-852-1572
> http://louisville.edu/micronano/
>
> -----Original Message-----
> From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Iulian Codreanu
> Sent: Thursday, December 19, 2013 1:52 PM
> To: Fab Network
> Subject: [labnetwork] Corrosive exhaust material of construction
>
> Dear Lab Network,
>
> I, once again, seek your wisdom.  Could you please share with me the type of material used for your corrosive exhaust system, how long you had it in operation, if you had any problems with it, and what you would do differently of you were in a position to do so?
>
> Thank you very much for your help.
>
> Iulian
>
> --
> iulian Codreanu, Ph.D.
> Director of Operations, UD NanoFab
> University of Delaware
> 149 Evans Hall
> Newark, DE 19716
> 302-831-2784
>
>
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