What is the material inside the filter drier called?

• A. Desiccant
• B. Adsorbent
• C. Catalyst
• D. Filtration media

Answer: (A)

The material inside a filter drier is a desiccant. A desiccant is a substance that actively absorbs water from the refrigerant and oil, which is essential because moisture in a refrigeration system can react to form acids or freeze into ice, causing corrosion, compressor damage, and blockages. By pulling water out, the desiccant keeps the system dry and protects components. Common desiccants include silica gel and molecular sieve materials, chosen for their strong affinity for water and compatibility with refrigerants and lubricating oils. An adsorbent is a broader term for moisture-collecting materials, but in this context the precise, purpose-built role is desiccation. Catalysts speed chemical reactions and aren’t used for moisture removal, and filtration media targets solid particles rather than removing moisture.