What type of filter is used as the pre-cleaner in a dual element filter?

In a dual element filter system, the pre-cleaner is typically made of foam material. This foam pre-cleaner serves an important function by capturing larger particles and debris before the air enters the main filter element. This initial filtration helps to extend the life of the more delicate primary filter, which is often made of paper or another material designed for fine filtration.

Foam filters are effective because they have a large surface area and can trap dirt and dust while still allowing sufficient airflow into the engine. They are also easy to clean and can be reused, making them a practical choice for pre-cleaning applications.

The other options, while they serve various roles in air filtration, do not provide the same combination of durability and ease of maintenance as foam in the context of a pre-cleaner. For instance, paper filters are designed for fine filtration and tend to clog more quickly when exposed to larger particles. Mesh filters may let through more dirt than desired, and cotton doesn’t typically perform as well in the pre-cleaner role due to its absorbent nature.