BENDIX TCH-008-041 Manuale Utente

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TCH-008-041

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© 2006 Bendix Commercial Vehicle Systems LLC All rights reserved.  6/2006 Printed in U.S.A.

When servicing your AD-9

™

 dryer with a purge valve replacement kit, you will need to identify the type of 

purge valve being replaced.  Removal of the purge valve from the dryer body is necessary to identify the 
correct maintenance kit.

First, identify whether the purge valve is a DLU style.  The DLU type can easily be distinguished from the 
others, because the DLU type have only two o-rings on the outside of the purge valve body, rather than 
the standard three o-rings.  For DLU purge valves, the middle o-ring seat has been removed.  Additionally,        
AD-9

™

 air dryers with a DLU purge valve have the letter “U” stamped on the side of the purge valve housing.  

Because the letter “U” is not always visible, it is best to use the number of o-ring grooves for identifi cation.  
See fi gure 2.

If the purge valve is a standard style (not a DLU), look through the upper oval hole in the purge valve 
housing to view the piston.  If a black band encircling the piston is visible, then the purge valve is a soft 
seat type.  If the piston is all metal, then the purge valve is a hard seat.  See fi gure 1 for hard and soft seat 
purge valves.

After the purge valve type has been identifi ed, the next step is to identify the heater size; voltage and wattage.  
The electrical connector on the purge valve is color coded as shown in the Purge Valve Replacement Kits 
table on the following page.

Once the correct maintenance kit is identifi ed, service the purge valve following the instructions provided in 
the kit for proper replacement.

Electrical Connector 

Figure 3 - Voltage and Wattage

DLU Style Purge Valve

Standard Style Purge 

Valve

Letter “U” stamped into 

the body

2 o-rings

3 o-rings

Figure 2 - Standard and DLU  Purge Valves