Question 18 3AE02 - Third Assistant Engineer (Alt)

The Correct Answer is A **Why Option A is Correct:** Option A, "activated alumina or silica gel desiccant beads," describes the primary and standard materials used inside modern refrigeration filter/driers. These substances are powerful desiccants—materials designed specifically to adsorb (attract and hold onto) moisture and acid from the refrigerant and lubricating oil circulating within the system. Moisture removal is the main function of the drier component of a filter/drier, making these desiccant beads the essential substance contained within. **Why Other Options Are Incorrect:** * **B) activated charcoal:** While activated charcoal is an excellent adsorbent, particularly for odors and contaminants (and is sometimes used in specialized "cleanup" driers after a severe motor burnout), it is generally **not** the standard substance used in new or routinely serviced commercial refrigeration filter/driers. Standard driers focus on moisture and acid removal, which are best handled by activated alumina or silica gel. * **C) alcohol based liquid drying agents:** Liquid drying agents, such as methanol or specialized solvents, are occasionally added directly into a system to address severe moisture problems, but they are generally discouraged because they can react with system components (like motor windings) or additives. Crucially, they are never the substance contained **inside** the physical filter/drier canister itself, which relies on solid adsorbents. * **D) any of the above may be used:** This is incorrect because Options B and C do not represent the standard contents of a typical filter/drier used in routine commercial refrigeration applications. The core component must be the moisture-absorbing desiccant described in A.