Refrigeration System Accessories : Vibration Absorbers and Crankcase Heaters

 Vibration Absorbers:

• Purpose: Protect tubing or piping from vibration, preventing refrigerant leaks around mechanical joints.
• Usage: Used on semi-hermetic and open drive compressors.
• Location: Near the compressor on both the suction and discharge lines, piped parallel with the compressor crankshaft.
• Structure:
  • Inside: Thin corrugated copper tube absorbs vibrations.
  • Outside: Woven copper wire adds strength.
• Installation: Follow correct procedures to ensure proper function.

Crankcase Heaters:

• Purpose: Prevent liquid refrigerant from condensing in the oil of the crankcase, avoiding flooded starts which can damage the compressor.
• Function:
  • During the off cycle, refrigerant can migrate to the compressor oil as a vapor, condense, and sink to the bottom of the crankcase.
  • Upon startup, this liquid refrigerant can boil off explosively, causing damage such as:
    • Wiping oil from load-bearing surfaces.
    • Foaming the oil and causing it to leave the compressor.
    • Reducing oil level.
    • Slugging, which can damage valves and rods.
• Prevention: Crankcase heaters apply heat to prevent refrigerant from condensing in the oil.
• Types:
  • External Crankcase Heaters:
    • Coil type: Mounted typically under the compressor.
    • Plate type.
    • Insertion type: Inserts into a port on the compressor crankcase, heating the oil directly.
  • Strap/Belly Band Type Heaters: Used on fully hermetic compressors, installed around the circumference of the compressor to apply heat via conduction.
• Examples:
  • Semi-Hermetic Compressors: Internal or plate heaters.
  • Hermetic Compressors: Strap type (belly band) heaters for good thermal contact.

Summary:

• Vibration Absorbers: Prevent refrigerant leaks due to vibrations.
• Crankcase Heaters: Prevent flooded starts by stopping refrigerant from condensing in the oil.
• Installation: Ensure proper installation and good thermal contact for effective function.