HallScrew Semi-hermetic Air-Cooled Ammonia Chiller

Common issues

• Ammonia leakage at the compressor shaft seal, valves, or pipe joints
• Screw compressor slide valve/capacity control sticking
• Oil separator or oil return system fouling causing oil carryover from the compressor
• Condenser fan motor or fan blade failure reducing head pressure control
• Gasket or fitting degradation causing low-level ammonia odor/leaks
• Compressor motor overheating from low refrigerant charge or a fouled condenser
• Suction or discharge valve leakage reducing compressor capacity

Inspection checklist

• Check for ammonia odor or leaks with an appropriate detector at joints, valves, and seals
• Inspect the condenser coil/fins for fouling and clean as needed
• Check oil level and oil pressure differential across the compressor
• Verify high/low pressure and oil safety cutouts trip correctly
• Check slide valve operation and capacity control response
• Check refrigerant charge level via sight glass or level indicator
• Inspect suction line insulation for condensation or ice buildup
• Test the ammonia detection/alarm system
• Check condenser fan motors for vibration or bearing noise

Service intervals

Typical intervals for this design class, not the manufacturer’s figures for your model. The manufacturer’s manual is binding.

Typical wear limits

Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.

Critical spares

• Shaft seal kit for the screw compressor
• Solenoid/expansion valve
• Oil filter element
• Refrigerant filter-drier
• High/low pressure safety switch
• Condenser fan motor
• Refrigerant joint gasket/O-ring set

Safety

• Ammonia is toxic and, in certain concentrations, flammable - full PPE (gas-tight goggles, gloves, escape breathing apparatus) is required for any refrigerant work
• Confirm the ammonia detection and alarm system is operational before entering the compressor/chiller space
• Refrigerant piping and vessels are under pressure - isolate and recover charge before opening
• Screw compressor rotating parts and drive coupling guards must be fitted
• Ensure adequate ventilation of the machinery space per class requirements for ammonia systems

Class survey

Ammonia refrigeration plant is subject to class rules specific to toxic/flammable refrigerants (detection, ventilation, machinery space arrangement) in addition to standard refrigeration machinery survey. Class checks leak detection function, pressure vessel/piping certification, and relief discharge arrangements at survey.