Troubleshooting Refrigerant Piping
Table 9-5 lists the most common operating problems associated with the refrigerant piping. For each observable symptom, a possible cause and remedy are suggested.
Filters and Dryers
Filters and dryers are devices that provide very important functions in a mechanical refrigeration system. A filter is a device used to remove particles from the liquid refrigerant and from the oil by straining the fluid. For this reason, it is also sometimes referred to as a strainer. If a filter or strainer were not used, these particles trapped in the fluid could block small passages in the thermostatic valve or capillary tube, thereby seriously affecting the operation of the cooling system, or they could eventually damage mechanical parts.
A dryer is a device designed to remove moisture from the refrigerant in a mechanical refrigeration system. It is also referred to as a dehydrator or a drier (a spelling variant used by some authorities).
A typical combination filter-dryer is shown in Figure 9-29. The desiccant surrounding the filter core is usually a silica gel and functions as a drying agent. This unit is usually installed in the liquid line (either at the liquid receiver outlet or at the expansion valve outlet).
Filters and dryers are not included with small-capacity cooling units (residential types) that are filled and hermetically sealed at the factory. Filters and dryers are usually installed in systems where the refrigerant circuit is designed for field service.