Hello again Brian,

In my immediate defense I have to say that not only do we discourage the
wanton waste of natural and national resources by using too much Nitrogen
but also we offer a Reflow System that uses one-half to one-third of the
consumption rate of any oven I have seen on the market.  Ok, ok, I'll stop
with the tongue-in-cheek adverts =-)

On to the technical issues, I would say that the effect will not be quite a
linear relationship but it should be pretty close.  At the same flow rate
and all variables being constant (bar the additional oxygen molecules) I
would not see you having any problem getting under 50 ppm with a 25 - 30
ppm source - if that is indeed what they are able to get (I suggest making
sure they are correct about their numbers).  So, unless someone disagrees,
I do not think the expansion rate differentail between N2 and O2 will be
significant.  If you find out otherwise please let me know.  I may not be
telling you anything new, but there's my two-cents.  Take care.

Doug Bennett
Sales Engineer
Heraeus Amersil, Inc
Atlanta, Georgia, USA
770-623-5630 ext 4225



At 03:39 PM 4/29/98 -0700, you wrote:
>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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