The use of compressed air for cleaning purposes at pressures greater than 30 P.S.I. is permissible, if the outlet or source is fitted with a relief device that drops the pressure to less than 30 P.S.I. if the flow is dead ended, according to an OSHA letter of interpretation sent by then- Acting Director,
Federal Compliance and State Programs Bruce Hillenbrand in response to an inquiry.
“Air guns used with long pipes are acceptable, if they meet the requirements of 29 CFR 1910.242(b),” said Hillenbrand.