BENDIX TCH-008-013 User Manual

Technical Bulletin

Bulletin No.: PRO-08-13 Effective Date: 4/1/89 Cancels: PRO-08-13 dated 11/15/85 Page: 1 of 1

Subject: Air Dryer Installati ons w ith Tur bocharged Compressors

Part no. 103976 is a special PR-4 Pressure Protection Valve with ½” pipe thread porting,
metal inlet valve and seat, and high temperature O-ring. The flat metal surface next to
the delivery port bears the valve’s stamped part number.

This valve is designed for systems that use an air dryer and a turbocharged compressor
inlet. Installation in the compressor discharge line prevents turbocharged pressure loss
through the open purge valve of the air dryer or aftercooler when the compressor is
unloaded.

Mount the valve four to five feet from the compressor discharge, with its spring retainer
(cap) directed away from the road. The discharge line must have a continuous slope
downward from the compressor to the air dryer. If there are any upward or downward
deviations, the line can trap water. (See sketch below)

When installing the special PR-4, use brass fittings instead of steel.
Frame or bracket mount the valve rigidly. The valve should not be installed in an

unsupported manner. Mount the valve with ¼” cap screws. Make sure the screws are
long enough to accommodate the 1.88” width of the PR-4 valve, as well as the mounting
surface width and any lockwashers that may be used.

Record this special PR-4 part number on catalog pages 03-A-12, 08-A-1, 08-A-3 and
08-A-5. Note that this valve does not use all of the common service parts listed on
03-A-12.