(1) Application. This section applies to compressed air receivers, and other equipment used in providing and utilizing compressed air for performing operations such as cleaning, drilling, hoisting, and chipping. On the other hand, however, this section does not deal with the special problems created by using compressed air to convey materials nor the problems created when persons work in compressed air as in tunnels and caissons. These standards are not intended to apply to compressed air machinery and equipment used on transportation vehicles such as steam railroad cars, electric railway cars, and automotive equipment.

(2) New and existing equipment.

(a) All new air receivers installed after the effective date of these standards must be constructed in accordance with the 1968 Edition of the A.S.M.E. Boiler and Pressure Vessel Code, section VIII.

(b) All safety valves used must be constructed, installed, and maintained in accordance with the A.S.M.E. Boiler and Pressure Vessel Code, section VIII Edition 1968.

(3) Installation. Air receivers must be so installed that all drains, handholes, and manholes therein are easily accessible. Air receivers should be supported with sufficient clearance to permit a complete external inspection and to avoid corrosion of external surfaces. Under no circumstances must an air receiver be buried underground or located in an inaccessible place. The receiver should be located as close to the compressor or after-cooler as is possible in order to keep the discharge pipe short.

(4) Drains and traps. All air receivers having an internal and external operating pressure exceeding 15 psi with no limitation on size, and air receivers having an inside diameter exceeding 6 inches, with no limitation on pressure, if subject to corrosion, must be supplied with a drain pipe and valve at the lowest point in the vessel; or a pipe may be used extending inward from any other location to within 1/4 inch of the lowest point. Adequate automatic traps may be installed in addition to drain valves. The drain valve on the air receiver must be opened and the receiver completely drained frequently and at such intervals as to prevent the accumulation of oil and water in the receiver.

(5) Gages and valves.

(a) Every air receiver must be equipped with an indicating pressure gage (so located as to be readily visible) and with one or more spring-loaded safety valves. The total relieving capacity of such safety valves must be such as to prevent pressure in the receiver from exceeding the maximum allowable working pressure of the receiver by more than 10%.

(b) You must not place any valve of any type between the air receiver and its safety valve or valves.

(c) Safety appliances, such as safety valves, indicating devices and controlling devices, must be constructed, located, and installed so that they cannot be readily rendered inoperative by any means, including the elements.

(d) You must test all safety valves frequently and at regular intervals to determine whether they are in good operating condition.