Each facility is certified and will require monthly visits by the inspection agency. During the first inspection visit to get your facility setup, you will require to view the kiln and probably perform a test or test run to be certain that your kiln can actually heat treat pallets.
Detailed answer:
First and foremost you do not need to purchase a certified kiln, since it is your facility that needs to be certified. You should however be certain that the kiln components/design or the turn-key kiln either has been certified at other facilities or meet the specifications of the inspection agency. You can actually build your own chamber based on your own design as long as it passes the inspection.
Kiln-direct kilns have passed certification by several of the inspection companies and this is usually always accomblished in one day.
The following links may be helpful in learning more: