Top questions about hermetic compressors

Tuesday, Jun 07
engineer pointing to a hermetic compressor on a table

Hermetic compressors are used in various applications for refrigeration, in particular domestic refrigeration. Air conditioners and refrigerators are examples of equipment that use this type of compressor.

This text answers the main questions on the subject, according to Google: how it works, what are its applications, its advantages and the differences to other types of compressor.

What are the differences between hermetic compressors and semi-hermetic compressors?

This is the top question about hermetic compressors on Google. Basically, the difference is in the construction of the system.

A hermetic compressor has a motor and compressor sealed in the same housing. Thus, it is impossible to access the components in isolation.

In semi-hermetic compressor, motor and compressor are also in the same housing, but the system can be opened.

To understand better, let’s see how the hermetic compressor works in practice.

How does a hermetic compressor work?

As a hermetic system uses the same housing for the compressor and motor, the unit is compact and easy to transport and handle.

The frame is made up of welded steel parts. This is done to protect the components and isolate the motor and compressor from possible damage, such as infiltration or dust.

For the same reason, there is no leakage of refrigerant to the outside.

The main parts of a hermetic compressor are:

  • Motor;
  • suction muffle
  • Discharge line;
  • head;
  • Piston;
  • Cylinder;
  • Axle.

Because of the welded steel parts of the hermetic compressor, if any of these components presents a problem, the entire system needs to be replaced. After all, as the compressor is hermetically sealed, it is impossible to access them individually.

Where are hermetic compressors used?

In general, hermetic compressors are used in domestic refrigeration, in air conditioners or refrigerators up to about 30 kW in power.

Some practical examples of application are:

  • Household refrigerators;
  • Window air conditioners;
  • Split air conditioners;
  • Household freezers;
  • Air conditioning units or small-capacity refrigerators in general.

What are the advantages of hermetic compressors?

The main advantages of hermetic compressors are:

  1. Easy handling. As the components are inside a sealed housing, it is not necessary (and not possible) to disassemble the equipment to transport it.
  2. Leak immunity. There is no space for gas or liquid leakage.
  3. Does not require external lubrication.
  4. Installation is simple, as it is a single component. In addition, suction muffle and discharge line are provided externally.
  5. Long lifespan. As the main components are fully protected by the housing, they last a long time – around 5 to 7 years. It depends on how the compressor is used, so it’s worth confirming the validity with the manufacturer before purchasing.
  6. Low noise and vibration levels.


What are the downsides?

The main disadvantages of hermetic compressors are two:

  1. When a component fails, it is necessary to replace the entire compressor. If the engine, cylinder or piston has a problem, it is not possible to replace them, because of the sealed housing.
    2. General difficulty of maintenance. Moving parts are difficult to access, making it necessary to break the welds or replace the entire compressor. That’s why there are cases where it’s cheaper to just change everything.

Despite these disadvantages, hermetic compressors are widely used in domestic refrigeration around the world. Therefore, Vibroacustica contributes to several projects to make them more efficient, especially with regard to noise reduction.

If you want to know more about this type of service provided by our specialists, feel free to contact us!

NVH specialists

Vibroacustica is specialized in NVH analysis and simulations in several areas, in addition to having expertise in compressor projects for national and international customers.

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