Wow. Five pages, an expert, a lot of discussion, but not a clear answer to my original question, unless I missed it. If I measure the proper amount of iodophor into a five gallon keg, seal it, then push it out with CO2 into another keg, there will be no air drying involved. I'm OK with having a small amount of dilute liquid under the dip tube and I feel that that first corny keg is sanitized and ready to fill with beer.
Now what if I leave the other keg full of sanitizer until the next time I have beer ready to keg? It's in the dark without oxygen in the head space. It may be a couple of weeks before I push out the solution with CO2 into another keg.
From what I have read here, the answer is that this probably works, but since it is so cheap, why am I doing it? Because I have lots of kegs and it's nice to clean and sanitize them at one time.
This weekend I think I will pull out a sample from a keg with three week old iodophor and check for amber color. Will that be as definitive as a test strip?
I apologize for not providing a clear answer to the original post on this thread.
Your method will work just fine, and will achieve the desired outcomes of clean and sanitized kegs in an efficient manner. The fact that the kegs are pressurized, in the dark, and clean of organic material will ensure that the BTF Iodophor solution is viable for the job. As long as the kegs you sanitize and purge in this fashion remain pressure rated, they will stay in a sanitized state until use. Exposure to outside air through a. Leak would compromise this.
I would welcome your input regarding a test of the solution in storage with a test paper at the end of the process, but if kept pressurized and sealed, in the dark, I would imagine this solution would be viable for quite a while - it’s just difficult to give you an exact length of time.
In addition, small amounts of properly measured, 12.5 PPM BTF Iodophor, such as barely a tablespoon, will dilute out into such extremely small concentrations in your finished beer that it will be undetectable. I refer again to the PDF I linked in an earlier post for a good experiment:https://www.bayareamashers.org/wp-content/uploads/2015/02/Iodophor.pdf
I sincerely hope this helps and please contact me if there are unanswered questions.