Question 24 UFIV02 - Assistant Engineer - UFIV

The Correct Answer is D ### Explanation of Why Option D is Correct: **D) Wire-mesh filter element.** Wire-mesh filter elements, often constructed of heavy-gauge metal screen or woven wires that may be wetted with oil (oil-bath type), are inherently durable and reusable. Because the filtering medium is metal, it can withstand physical cleaning processes. To restore efficiency, the element is periodically removed, washed thoroughly with a solvent or degreaser to remove trapped dust and oil, allowed to dry, and then often re-oiled before being reinstalled. This process is standard practice for heavy-duty, cleanable air filter elements used in high-vibration, demanding environments like marine diesel engine applications. ### Explanation of Why Options A, B, and C are Incorrect: **A) Multi-tube filter element.** This element typically consists of numerous pleated paper or synthetic cartridges bundled together for high capacity. Paper and synthetic filter media are designed to trap particles deep within their microscopic structure. Attempting to clean these elements (e.g., by washing or using high-pressure air) generally damages the fine fibers, reducing the filter's efficiency, creating pathways for contaminants to pass through, and shortening its operational life. Therefore, multi-tube elements are almost always periodically replaced. **B) Panel-type filter element.** Panel filters used in heavy-duty applications generally utilize pleated paper or synthetic fiber media contained within a rigid frame. Like multi-tube elements, these media are highly sensitive to aggressive cleaning methods. They are considered disposable and are replaced once they reach their maximum restriction limit. **C) Spiral-rotor filter element.** A spiral-rotor device is typically a pre-cleaner system that uses centrifugal force to spin large dirt particles and debris out of the airstream before it reaches the main filter element. While this system requires periodic maintenance (usually emptying a collection bowl), the rotor itself is a mechanical component and not a traditional filter *element* that is periodically cleaned and reinstalled like a media-based filter. The actual subsequent filter element (which does the heavy lifting of fine particle removal) is typically a paper cartridge and is replaced, not cleaned.