I have a question. The limit of 10 ppm for detergents often comes up.
How is this limit establihed.
I would say 10 ppm in the next batch. ie if the next batch is 1000 kg, then 10g of deterget is allowed to be present in the next batch.
Divide this by the surface area will give g/cm2.
Now if only one piece of equipment is cleaned with detergent, which surface area do we use.