The satisfactory operation of any compressor is based on a supply of clean, cool, dry air. To aid in keeping the air supply clean, filters are fitted to compressor intakes. Unless inspected and cleaned regularly, these filters become clogged and cause a loss of capacity.

Filter elements should be removed from the intake and cleaned either with a jet of hot water or steam, or by immersion in a strong solution of sal soda. The filter body should be drained and replaced. Filter elements of the oil-wetted type should be dipped in a clean, medium viscosity oil after cleaning and the excess oil should be drained from the elements before replacing them on the filter intakes. Gasoline or kerosene should not be used for cleaning air filters because of the explosive fumes which may collect in the com-pressor or air receiver.

Dehydrators

On some ships, compressed air is used for the operation of missile system components and with automatic controls for boilers. In order to pre-vent failure of these systems, moisture and lubricants from the compressor must be kept at a minimum. Blowing down the compressor separators prevents most of this, but still some moisture is carried over. To aid in the removal of the moisture and lubricants, two types of dehydrators are generally used: type I refrigerant dehydrators and type II dehydrators using a desiccant of either silica gel or activated alumina, and containing electric heating coils for reactivating the desiccant when it becomes saturated with moisture. Type II dehydrators are normally installed in pairs so that one can always be in service while the other is be-ing reactivated.