[labnetwork] Using CDA, rather than N2, as pump purge in Bosch-like processes?

[Vicky Diadiuk]

Hi John,
 If your CDA compressors are anything like ours, don't go there!
We've been switching anything we can to N2 simply because the compressors are totally unreliable.
Next yr we'll connect to the main co-gen plant compressors & we may learn to trust them more in due course.
Our tools only call for N2 when running, so our consumption, while high, is not terrible.
 We stil blow off a lot of N2 from our 11k gal LN2 tank.

Hope this helps,
 Vicky



On Apr 11, 2013, at 11:47 AM, John Shott wrote:

> Labnetwork Community:
> 
> Like many of you, I suspect, nitrogen is the single largest non-salary expense associated with running our facility.
> 
> Much of our nitrogen is used for pump purges in dry pumps.  Our average dry pump seems to use about 1 CFM (sorry, 25-30 SLM ...) which, at our pricing is about $4k per year.  For virtually all deposition processes using reactive gases and etch processes using corrosive gases, using nitrogen as a pump purge seems to be a firm requirement.  It is not as obvious, to me at least, that nitrogen is required in something like a SF6/fluorocarbon-based etch process like the switched Bosch processes that many of us run.  While I know that CDA isn't "free", in our case, the LN2 bill definitely comes out of our pocket whereas as CDA is a University supplied and supported building utility.
> 
> What experience, recommendations, or cautions can you offer related to switching our Bosch process tools from nitrogen to CDA pump purges?  If it matters, the dew point of our CDA is believed to be less than -40 C, but is not monitored continuously (and maybe not even monitored periodically ...).
> 
> Thanks for your consideration,
> 
> John
> 
> 
> 
> 
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