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Measures against Solid Noise (Noise) of Outdoor Air-Conditioning Units

Category
  • Type of equipment/device
    • Air conditioning/Sanitary equipment
    • Electrical equipment
    • Buildings/Structures
    • Precision equipment
    • Vibration-sensitive equipment
  • Vibration obstacle phenomena
    • Vibration
    • Noise
    • Magnetic fields
  • Type of usage environment
    • Living environments
    • Office buildings
    • General facilities
    • Factories
    • Research facilities
  • Building type
    • Hotels/Accommodations
    • Hospitals/Welfare facilities
    • Office/Meeting rooms
    • Store/Commercial buildings
    • University Labs/Schools
    • Condominiums/Houses
    • Plants/Factories
Tag
Solid noise is generated when the outdoor unit of an air conditioner is defrosted
When the air conditioner outdoor unit installed on the rooftop of the office building was defrosted, solid noise was generated on the floor directly below.

Countermeasure points: Failure occurs when special driving is performed

Depending on the equipment, even if there is no problem during normal operation, a failure may occur during special operation.

Cause: A solid noise is generated when the defrosting operation is performed because the rotation speed of the compressor built into the outdoor unit increases.

Both the vibration and noise peak components appear at 30Hz during normal operation of the rooftop air conditioner outdoor unit, but a peak appears at 95Hz during defrosting operation, and the sound pressure level in the 125Hz band immediately below is NC-20 to NC-35. Increased to the level of. It is considered that this is because the rotation speed of the compressor built into the outdoor unit rises during defrosting operation, the frequency of the outdoor unit fluctuates from 30 Hz to 95 Hz, and the excitation force also increases.

  • Air conditioner outdoor unit

  • Noise on the floor directly below

  • Vibration spectrum on outdoor unit base

  • Sound pressure spectrum of the lower floor

Measures: Replace with spring anti-vibration device

Although the outdoor unit of the air conditioner was vibration-isolated by the rubber pad, the vibration-damping performance of the rubber pad was small, and the vibration of the outdoor unit propagated to the skeleton, producing solid noise on the floor directly below. Therefore, as a countermeasure, we proposed replacement with a spring anti-vibration device.

  • Outdoor unit equipped with anti-vibration device

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