Air over hydraulic brake systems are subject to the following requirements and limitations:

(1) Supply system.

(a) The air compressor for an air over hydraulic brake system must cut in at not less than 85 pounds per square inch and must cut out at not more than 105 pounds per square inch.

(b) Air compressor buildup time must not be more than one minute to increase the air pressure from 60 pounds per square inch to 90 pounds per square inch. Engine speed will not exceed 1500 RPM to meet this requirement.

(c) Air loss from the air system must not exceed:

(i) 3 pounds per square inch per minute for a single vehicle.

(ii) 4 pounds per square inch per minute for a two vehicle combination.

(iii) 5 pounds per square inch per minute for a three or more vehicle combination. Air losses will be measured by the air gauge in the vehicle.

(d) The air system must contain no more than one quart of contaminants. Water and oil must be considered contaminants.

(e) Hydraulic fluid must be maintained in excess of 50 percent of the brake master cylinder capacity.

(2) Brake assembly.

(a) Adjustment of all brakes must comply with the manufacturer's recommended specifications.

(b) Brake system components must meet all the requirements of RCW 46.37.360, and brake drums will not be cracked or broken to the extent that such crack or break appears on the outside of the drum.

(c) Brake lining, pad friction surface, or braking surface of the brake drum or rotor must not be contaminated with grease, oil, or brake fluid.