I would be very greatful if I could get the name of some suppliers of air knives. I am specifically looking for an all plastic unit because of the corrosive environment it will be in.
Try Dezurik for a starting point (dezurik.com). We had good luck with their v-type knife for controlling compressible flow. The sales team even went so far as to send me software for my own sizing, but that might be on their website. They have coated internals but I don't know about all plastic construction...