Ever wondered why your 96 hour qualified 15-25 solution goes out of spec after 2 days? Historically, water based 15-25 solutions have been qualified in a different manner than 2-8 solutions. They are not designed to control the temperature between 15-25 degrees, in fact there is very little temperature control going on inside water based 15-25 solution and the qualification process has been adapted to reflect this. If you take the time to compare the qualification reports of a 2-8 and 15-25 solution for the same payload and duration, say 96 hours, you will probably find that a different temperature profile was used in the qualification process. Yet if you have two shipments, one 2-8 and one 15-25 going to the same destination on the same day you can be pretty sure they are going to experience the same ambient temperatures, so why have they been qualified to different temperature profiles?