With the halocarbons, it is essential to reduce the water content of the refrigerant circuit to a minimum by careful drying of components and the fitting of drying agents in the system. The common form of drier is a capsule charged with a solid desiccant such as activated alumina or zeolite (molecular sieve), and located in the liquid line ahead of the expansion valve. These capsules must have strainers to prevent loss of the drying agent into the circuit, and so form an effective filter-drier to also protect the valve orifice from damage by fine debris, Figure 9.10.
Figure 9.10 Filter drier (Henry)
Large driers are made so they can be opened, and the spent drying agent removed and replaced with new. Small sizes are throwaway. Driers may also be used in the suction line.
Suction line filter-driers are a temporary installation to clean up a system after repairs, and should be removed if the pressure drop becomes 1K greater than when new.
Posted in Refrigeration and Air Conditioning