How can a technician determine when a filter drier is stopped up and needs changing?

How can a technician determine when a filter drier is stopped up and needs changing?

• A. The pressure drop will exceed 2 psig
• B. The temperature across the drier drops
• C. There is no change in performance
• D. The system automatically alarms

Answer: (A)

A filter drier becomes clogged when its internal media restricts flow, so the most reliable clue is a higher pressure drop across the drier. As liquid refrigerant passes through, trapped moisture and debris build up a restriction, causing the inlet pressure to push through a narrowed path and the outlet pressure to rise differently, creating a larger differential. Measuring the pressure on each side with gauges will show this delta; a drop across the drier that exceeds about 2 psi is a practical threshold indicating it’s time to replace the unit. Temperature changes across the drier aren’t a consistent indicator, and a lack of performance change or an automatic alarm isn’t a universal sign that the drier is clogged. In short, a rising differential pressure across the drier is the best telltale sign of blockage.

A filter drier becomes clogged when its internal media restricts flow, so the most reliable clue is a higher pressure drop across the drier. As liquid refrigerant passes through, trapped moisture and debris build up a restriction, causing the inlet pressure to push through a narrowed path and the outlet pressure to rise differently, creating a larger differential. Measuring the pressure on each side with gauges will show this delta; a drop across the drier that exceeds about 2 psi is a practical threshold indicating it’s time to replace the unit. Temperature changes across the drier aren’t a consistent indicator, and a lack of performance change or an automatic alarm isn’t a universal sign that the drier is clogged. In short, a rising differential pressure across the drier is the best telltale sign of blockage.