Doug,

I appreciate your input but it does not really answer my question. I am
aware that by putting high amounts of N2 in the machine the customer can
reach the same PPM level as the source Nitrogen but no customer in their
right mind is going to want to pay for that. You may ask your customers to
do that but we look for affordable N2 processing methods for our customers.
Sorry, had to put at least one plug for my company just to return the favor!
;-)

The real question is at the same flow rates how will the purity levels in
the process cavity be affected if the source is 25 - 30 ppm. Keep in mind
that ETS ovens run at approx 9 ppm throughout the process cavity when the
source is less than 5 ppm (approximately 2-3 ppm). Should the customer be
able to acheive less than 50 ppm (in other words add the inpurities in the
source to the PPM levels acheived in ETS Factory or does the expansion rate
of O2 affect this number)?

I appreciate any advise offered.

Brian




>Hi Brian,
>
>To answer your question they will be able to reach whatever
>purity level their gas is spec'ed at as long as they are willing to pay for
>it in total nitrogen consumption.
>
>Simply put, the spec residual oxygen level will be dependent on the
>internal (relative) positive pressure of the gas inside the process
>chamber.  Specific formulas for consumption depend on oven design so it is
>best to use empirical data - i.e. run experiments.  But if they crank up
>the internal pressure they will be able to reach those levels but they will
>have to pay for it, and prices of Nitrogen in Asia are quite expensive.
>
>On another note, your customer will also have fluctuating levels of
>residual oxygen along the length (and width for that matter) of the process
>chamber.  This situation depends on your configuration for feeding nitrogen
>into the process chamber.  So, if your customer has concerns about
>reliability of a steady residual oxygen level throughout the entire process
>chamber this could be a problem.
>
>Hope this helps
>
>Doug Bennett
>Sales Engineer
>Heraeus Amersil, Inc.
>Atlanta, Georgia
>770-623-5630 ext 4225
>
>
>At 04:48 PM 4/27/98 -0700, you wrote:
>>Dear Technet,
>>
>>My company builds reflow ovens that are capable of processing in a Nitrogen
>>(N2) atmosphere. We are getting ready to send an N2 machine to a customer in
>>Asia. While preparing for the installation our customer found that his
>>source N2 has 25 - 30 PPM of Oxygen (O2). At our factory we have source N2
>>that is 99.999% pure or has 1-3 PPM of O2. With this source purity level we
>>are able to acheive less than 20 PPM of O2 in the process cavity. With this
>>in mind what purity level should our Asian customer be able to acheive with
>>his source of 25 - 30 PPM?
>>
>>Is there a relationship between source N2 and process cavity purity levels
>>at constant flow rates? Does it have something to do with the expansion
>>rates of these gases during heating?
>>
>>Thanks in advance for all replies.
>>
>>Brian Stumm
>>
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