[labnetwork] burn box location

[Tom Britton]

Hello gentlemen,

John, excellent comments. Iulian, If your pumps are located in the chase and you are exhausting the pumps then you should not need to worry about them contaminating your cleanroom. The carbon-based oils in a wet pump can and would add to the possibility of build-up in the exhaust ductwork and present a fire hazard if left for many years.

As far as the gowning, we had different sets for the maintenance technicians, blue, and the process people wore white. We of course had these tested in my many years as a fab manager and even after crawling around under a subfloor the blue gowns passed inspection. The technician gowns, were rejected only for tears and stains which happened quite often.

Thanks,

Todd Erickson
Critical Systems, Inc.
Director of Operations MN
612-328-2312
www.CriticalSystemsInc.com

-----Original Message-----
From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Weaver, John R
Sent: Tuesday, September 30, 2014 6:24 AM
To: 'Iulian Codreanu'; Fab Network
Subject: Re: [labnetwork] burn box location

Iulian -

I am concerned about two things. First, are your pumps in the chase? If so, and if you are using any carbon-based oils (not dry pumps and not Fomblin), you are most likely putting paraffins into your airstream. These will pass right through a HEPA or ULPA filter and condense on cold surfaces like silicon wafers. 

If the pump issue is not a problem, the "soot" problem is of concern. It can have multiple effects, depending on the range of particle sizes. First, there are surface particles. When a person is cleaning the burn box are they wearing a cleanroom garment that will be worn elsewhere in the cleanroom, even just to enter and exit that chase? Also, cleanroom laundries are not geared to remove large percentages of contaminants, only small quantities. Garments that come in heavily soiled will not be as clean as other cleanroom garments after processing.

Second, there is the issue of aerosol particles. Any size particles can deposit on chase walls and be a constant source of particles. People going into the chase and touching the wall with their cleanroom garment can spread it around the cleanroom. Aerosol soot can plug your prefilters and also plug your HEPA filters if the particle size allows a significant quantity through the prefilter. In general, I would be very concerned with that approach.

If there is any way you can locate the burn boxes outside of your cleanroom airstream you are far better off.

John

-----Original Message-----
From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Iulian Codreanu
Sent: Monday, September 29, 2014 5:32 PM
To: Fab Network
Subject: [labnetwork] burn box location

Dear Colleagues,

I am looking at the possibility of using a burn box (using natural gas for fuel) to abate the exhaust from some CVD tools.  I would have to locate it in the chase area.  It appears that a burn box is not that clean; I can imagine "soot" spreading throughout the cleanroom during maintenance.  Does anyone have burn boxes in the chase area?  How do you keep the soot contained?

Thank you very much.

Iulian

--
iulian Codreanu, Ph.D.
Director of Operations, UD NanoFab
University of Delaware
Office: 163 ISE Lab
Mail to: 250N ISE Lab
Ship to: 165 ISE Lab
221 Academy Street
Newark, DE 19716
302-831-2784


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