ENGINE AR-COMPLETE 3318449 - Caterpillar

Illustration 1 g02544620
Pleated Media Element (old design)
In the past, most Caterpillar air filters were cellulose based axial or radial seal air filters. Both the primary elements and secondary elements consisted of pleated media with depth filtration (pleated media element). See Illustration 1.
Illustration 2 g02544684
Wrapped Media Element (new design)
The new air cleaner configurations utilize a different type of secondary air filter element. This secondary air filter element is not a pleated media. The media is wrapped in a single layer (wrapped media element). See Illustration 2. This media tends to surface load contaminate, making any particles that reach the secondary element highly visible.Air filtration housings are designed as a system. Primary air filters are not 100% efficient. The primary element needs to build up a surface load to reach maximum efficiency. During the early hours of operation of a new primary air filter, particles will reach the secondary element and be captured. In fact, the practice of regularly opening an air filter housing to clean a primary element removes the surface load that allows the primary element to operate at maximum efficiency. This allows additional contaminates to reach the secondary element after each time the primary element is handled. The wrapped media secondary elements tend to surface load particles, so any contaminates that get to the secondary element will be visible. Even small particles that are not normally visible (individually) will show up when present in larger quantities. Air systems that utilize the pleated media secondary elements would capture this debris across the pleat depth, making contaminates less visible. Caterpillar would like to make clear that secondary air filter elements that utilize the wrapped media tend to show any contaminates that are captured. All indications are that the air filter systems are operating as intended. SOS analysis and machine performance show that the air filters are protecting the air intake system as designed. Caterpillar continues to recommend that these wrapped media secondary elements be changed every third change of the primary air filter elements.