Owners of air coolers — and any ammonia refrigeration system — should perform periodic mechanical-integrity inspections to ensure the continued reliability of the unit and to minimize the risk of an accidental ammonia release. When performing mechanical-integrity inspections of a typical air cooler, there are 10 key inspection points to help identify potential problems with the air cooler. Look for signs of out-of-design-specification conditions such as:
Inspect all air coolers for material buildup on the fins and drain pans. Dust or packaging-material fibers are common sources for this buildup. Inspect the air coolers operating in areas below freezing for excessive ice buildup on the fins and drain pans. Excessive ice and material buildup could interfere with airflow and reduce the coil capacity. Excessive ice buildup between the bottom of the coil tubes and the drain pan could cause mechanical damage to the coil tubes and drain pan.
Remember that hot-gas-defrosted air coolers commonly have an array of heating tubes attached to the drain pan. Any damage to these tubes — or to the tubes in the coil core — could result in an ammonia leak. Follow the manufacturer’s guidelines for defrosting air coolers, which might include adjusting the number of defrosts and their duration. The pressure setting on the defrost regulator also may need to be adjusted to ensure complete defrosting.