9.2.9. A person may be decompressed in 3 stages as described in section 9.2.8 at a rate not greater than twice the rate stipulated, if:(a) he has had previous experience with the hazards of compressed air;
(b) he has been subject to air pressure not exceeding 200 kPa for one-half hour or less and has not performed manual work therein; and
(c) no person is in the air lock during decompression other than the person to whom paragraphs a and b apply.