Coach Air Suspension Allowable Leak Down

I was going through some old Monaco Inc. Files and found this information that was sent to me by Bill D. years ago and thought it might be of interest to the Group as this question of what is the allowable leak down rate on a coach is often discussed here on the Forum.

D.O.T. Standard Allowable Leak Down. Rev. 06-03-2004

The Department of Transportation (D.O.T.) standard for allowable leak down in the air systems is as follows.

1. A 4 PSI drop in the front air system in a 2 minute time period is allowed.

2. A 4 PSI drop in the rear air system in a 2 minute time period is allowed.

This translates into a 120 PSI drop in a one hour time period. In other words, both needles would be allowed to go to zero PSI in one hour. All of the control valves, relay valves, check valves, etc., have allowable leak rates, even for new components. It is not within the Scope of Monaco Inc., or any Manufacturer, to completely eliminate air leaks. Therefore, the D.O.T. sets the standard for allowable leak down rules in the interest of safety. However, Monaco, Inc.'s leak down rate is set as follows:

Monaco, Inc. Allowable Leak Down

1. A 6 PSI drop in the front air system in a one hour time period.

2. A 6 PSI drop in the rear air system in a one hour time period.

This translates into an approximate 60 PSI allowable leak down rate, for each air system, in the overnight park mode(10 Hours). This is an extremely small air leak. The Monaco, Inc. and other Manufactures standard is 20 times more stringent than the D.O.T. required safety standards, which allows 120 PSI per hour.