Having a problem with Salicylic acid paddles running low on paddles in one
vessel? You are deaerating properly, and are sure of the standard, because
all the other vessels passed middle of the range. The vessels are brand new.
The mechanical parameters are perfect. Baskets pass as well. What would you
suggest?
First of all, you can eliminate the tablets, if all other vessels are passing
mid range. Usually this is my first suggestion because of the subliming of
salicylic acid. However, if all other vessels are passing and all tablets are
from the same bottle. Then I would suspect the vessel. If it were not one
vessel but all, then I would suspect the media pH. But, this is not the case
here.
Take it out and look at it. It may have a ridge, dent, or other defect. No
matter how perfect, all are hand made and have subtle flaws. Because
salicylic is non-disintegrating, it is sensitive to vessels flaws under
paddle conditions. You won't have this with baskets, because they are not in
contact with the vessel. If you haven't already, make note of the vessel
positions and replace the suspect vessel and keep all other vessels in the
same position.
A few years back, the PHRMA study claimed that Salicylic Acid was not
sensitive to mechanical parameters. However, they forgot about vessel
imperfections.