You are most welcome, Guy. Let us know how it goes. Joyce had some good info on the seals etc.

From: Guy Ramsey <[log in to unmask]>
Sent: Wednesday, February 16, 2022 7:00 AM
To: Stadem, Richard D <[log in to unmask]>
Cc: TechNet E-Mail Forum <[log in to unmask]>; Kris Meacham <[log in to unmask]>
Subject: Re: [TN] Nitrogen flow rate for desiccator box

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Perfect, thank you.
I have always used desiccating boxes too. With the exception of the EMPF lab in Philadelphia. We had N2 dry boxes there. But, I was not responsible for maintenance, and never set one up.
This factory in Allentown is all plumbed, has the N2 tank and many boxes. But, my HIC cards are turning pink in some boxes.
Your process makes sense, and is the kind of guidance I need.
Thanks again.

On Wed, Feb 16, 2022 at 7:32 AM [log in to unmask]<mailto:[log in to unmask]> <[log in to unmask]<mailto:[log in to unmask]>> wrote:
You would place an oxygen sensor/meter inside the box. You purge the box with nitrogen, then turn down the nitrogen pressure until the oxygen level drops to whatever level you feel comfortable with (generally less than 5%). Then you open the door for about 30 seconds (which is a long time if you think about it) and close the door and monitor the recovery time to get back down to less than 5%. Then adjust the nitrogen flow rate upwards depending on how often the doors might be opened. The idea is to keep the overall average oxygen at less than 5%. Most people actually use less than 1%.
DR Storage boxes begin around $5K and have proven to be extremely reliable in the places where I have installed them. The first ones I purchased more than 17 years ago, and they still work perfectly. After maybe 7-10 years you may have to replace the desiccant package, but they are relatively cheap and you can do it yourself whereas other drybox brands they are not modular and you need to send the entire box back to the manufacture.
DR Storage boxes have proven to be a really good value for me. No issues with them whatsoever.
I purchase mine through https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fwww.salesjw.com%2f.&c=E,1,sImGHQ63zZ6nqtoxUBptnqsivK1sjINq0ZWDj6IUI0Hj48wEQjbpu_w4zxOFHD6bQrkrrTBBBsMofcseBJ4hh61f84ItW4MCr8S7e49XUxU2D0o5hg,,&typo=1 You can contact Kris Meacham directly, Kris Meacham <[log in to unmask]<mailto:[log in to unmask]>>.
DR Storage has options for adding nitrogen capability, heated dryboxes with/without nitrogen, etc. They also have options for out-of-tolerance alarms, datalogging, etc.
I highly recommend them. Much cheaper than having to run plumbing or handle nitrogen tanks. I also don't like the plastic boxes which are a huge ESD risk. DR Storage boxes are completely dissipative with respect to electrical ground.

Odin

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From: TechNet <[log in to unmask]<mailto:[log in to unmask]>> On Behalf Of Guy Ramsey
Sent: Tuesday, February 15, 2022 2:03 PM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: [TN] Nitrogen flow rate for desiccator box

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Any one using N2 to keep parts and boards dry?
How do you determine the flow rate for say a 40cu.ft. box?