[Al Skierkiewicz]

Chuck,
Without talking with the safety person, I am unsure why he/she would disapprove. The defining documents are Section 3-At The Events and the First Safety Manual. Neither specifically address compressors but both make a reference to local venue restrictions which may be enforced by the safety personnel.
On a similar note, high current battery chargers are not allowed. So whether I see one or the safety people see one, you will be asked to remove it from your pit for safety reasons.
I think it might be appropriate to tell you that I have witnessed 3/4 HP compressors with 5 and 10 gallon tanks, and 50 amp battery chargers as well as team built power distribution panels in pits over the years. I have also witnessed, open flames and steel grinding (shower of sparks) in the pits as well.