What Is A Hermetic Compressor? All You Need To Know

by Anna

In the world of refrigeration and air conditioning, hermetic compressors play a crucial role in maintaining our modern lifestyle. Whether it’s the cold storage of perishable goods, the comfort of air conditioning, or the preservation of vaccines and pharmaceuticals, hermetic compressors are the unsung heroes that make it all possible. This article aims to shed light on what a hermetic compressor is, how it works, its various applications, and the key advantages it offers in these industries.


What Is a Hermetic Compressor?

A hermetic compressor, often referred to as a sealed or “hermetically sealed” compressor, is a key component in refrigeration and air conditioning systems. It is a type of rotary or reciprocating compressor enclosed within a welded or soldered housing, which makes it airtight and impervious to external environmental factors. This sealed design is in stark contrast to open-type compressors, which rely on external seals and gaskets to prevent leakage.


The hermetic compressor consists of a motor and a compressor unit, both of which are enclosed within a single housing. The motor drives the compressor, creating a closed system where the refrigerant can be compressed and circulated through the refrigeration cycle. The design is so named because it is “hermetically sealed” or closed off from the surrounding atmosphere.

How Does a Hermetic Compressor Work?

The fundamental operation of a hermetic compressor revolves around the principles of thermodynamics and fluid mechanics. To understand its working mechanism, let’s break it down into a few key steps:

Suction: The process begins with the compressor drawing in low-pressure, low-temperature refrigerant vapor from the evaporator coil, which is part of the refrigeration system. This vapor enters the compressor through an intake port.

Compression: Once inside the compressor, the refrigerant vapor is compressed by the action of the motor. This compression process increases the temperature and pressure of the refrigerant, converting it from a vapor to a high-pressure, high-temperature gas.

Discharge: The high-pressure gas is then pushed out of the compressor through a discharge port, and it travels to the condenser coil, which is another part of the refrigeration system. Here, the hot, high-pressure gas releases heat and condenses into a high-pressure liquid.

Expansion: The high-pressure liquid is then sent to an expansion device, such as an expansion valve or capillary tube. This device lowers the pressure of the refrigerant, causing it to evaporate and return to a low-pressure, low-temperature vapor state.

Return: The low-pressure vapor re-enters the evaporator coil, and the cycle repeats, ensuring a continuous flow of refrigerant through the system.

Applications of Hermetic Compressors

Hermetic compressors are used in a wide range of applications across various industries due to their reliability, efficiency, and compact design. Some of the most common applications include:

Refrigeration Systems: Hermetic compressors are found in household refrigerators, freezers, and commercial refrigeration units. They are responsible for maintaining low temperatures inside the refrigeration compartments by compressing and circulating the refrigerant.

Air Conditioning: Central air conditioning systems, window units, and split air conditioners all utilize hermetic compressors to cool indoor spaces. These compressors play a crucial role in removing heat from the air and maintaining comfortable indoor temperatures.

Automotive Air Conditioning: Hermetic compressors are commonly used in automotive air conditioning systems to cool the interior of vehicles. Their compact size and efficiency make them an ideal choice for this application.

Medical and Pharmaceutical Refrigeration: The strict temperature control required for storing vaccines, blood products, and pharmaceuticals is achieved with the help of hermetic compressors. These compressors ensure precise temperature maintenance in medical and pharmaceutical refrigeration units.

Commercial Refrigeration: Supermarkets, convenience stores, and restaurants rely on hermetic compressors in their refrigeration systems to keep food and beverages at the desired temperatures.

Beverage Dispensers: Soft drink machines and beer dispensers use hermetic compressors to maintain the desired serving temperatures.

Advantages of Hermetic Compressors

Hermetic compressors offer several key advantages, which explain their widespread use in various applications:

Compact Design: The sealed, compact design of hermetic compressors allows for easy integration into different systems, making them ideal for applications with limited space.

Reliability: The hermetically sealed construction ensures airtightness, preventing refrigerant leaks and external contamination. This enhances the reliability and durability of the compressor.

Energy Efficiency: Hermetic compressors are known for their high energy efficiency, which translates to lower operating costs and reduced environmental impact.

Low Maintenance: Due to their sealed design, hermetic compressors require minimal maintenance. There are no external seals or gaskets to wear out or replace, reducing the need for regular servicing.

Noise Reduction: Hermetic compressors are quieter compared to open-type compressors, making them suitable for applications where noise levels need to be minimized.

Cost-Effective: Their mass production and simple design contribute to lower manufacturing costs, which often results in cost-effective solutions for consumers and businesses.

Challenges and Considerations

While hermetic compressors offer numerous advantages, they are not without challenges. It’s important to consider these factors when selecting and using hermetic compressors in various applications:

Limited Capacity: Hermetic compressors have a limited capacity, which may not be suitable for large-scale industrial refrigeration needs. In such cases, open-type compressors or other compressor types may be more appropriate.

Overheating: Hermetic compressors can overheat if not properly cooled, leading to reduced efficiency and potential damage. Proper ventilation and cooling measures must be in place to prevent overheating.

Irreparable: If a hermetic compressor fails, it is often more cost-effective to replace the entire unit rather than attempting repairs, as opening the sealed housing can be challenging and costly.

Compatibility: Hermetic compressors are typically designed for specific refrigerants and applications. Ensuring compatibility with the intended refrigeration system is crucial to avoid performance issues and potential breakdowns.


Hermetic compressors are the unsung heroes of modern refrigeration and air conditioning systems. Their sealed design, energy efficiency, compactness, and reliability make them the preferred choice for a wide range of applications, from household refrigerators to commercial air conditioning units. Understanding the working principles and advantages of hermetic compressors is essential for engineers, technicians, and consumers to make informed choices and maintain these systems effectively. With their continued development and adaptation to emerging technologies, hermetic compressors are likely to remain a crucial component of our daily lives for years to come.


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