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Hermetic Motors and Compressors: The Pros and Cons

Hermetic Motors | KB Delta

A hermetic motor or compressor works just like any other unit. The primary difference is based on how the system is structured and compartmentalized. Hermetic compressors have a completely sealed structure, which makes them completely air-tight. The compressor and motor pieces are contained within a sealed compartment that cannot be accessed without breaking the seal and shielding. This prevents dirt, grime, and fluids from accessing the components, but also impacts the owner’s access to system components.

Since the entire unit is contained in a completely sealed system, certain tasks relating to maintenance and repair differ from those of traditional, non-sealed systems. To better understand the benefits and drawbacks of hermetic motors or compressors, review the points below.


Unit Shielding and Lubrication Requirements

Most hermetic motors and compressors are contained within steel shielding. This means there is an additional layer of protection surrounding both the motor and compressor components. Often, there is a lesser need to be concerned about whether the motor will drive the compressor, and the risk of physical damage caused by unexpected impacts may also be lower than traditional models.

Traditional compressors require lubrication to maintain proper function and avoid safety issues. This helps keep the rubber, leather, or other belt materials soft. When left exposed during long periods of non-use, the lubricants dissolve. This means certain components will need to be replaced before the compressor can be used again.

A hermetic motor and compressor unit does not require additional lubricants. The system is entirely sealed and does not require belts for full operation. This means a hermetic motor can be left sitting for months or even years without having startup or component issues. For those who only require the use of the compressor from time to time, this can be a more convenient and cost-effective solution.


System Size and Portability

Hermetically sealed systems are often smaller than their traditional counterparts. Often, this has to do with how the motor and compressor are fit together. A hermetic motor and compressor unit is therefore more mobile and easier to handle. Both the motor and compressor are contained within a single shielded unit, regardless of whether the hermetic motor is of the single speed variety or a multi-speed unit.

Aside from the size difference, a hermetic motor and compressor are easier to relocate within a space. Traditional compressors might need to be partially disassembled from the motor during transport. This includes uncoupling the units, and managing the belts and pulleys that connect the pieces together.

A hermetic motor and compressor system remains one unit during transport. There are no belts involved, and uncoupling is not required.


Compressor Types

Most hermetic motors and compressor units are of the reciprocating variety, but the rotary vane compressor form has also gained popularity. Rotary compressors often require less electricity to run and make less noise while being used. They can also be less expensive than reciprocating variants. Centrifugal versions are only present in large hermetic motor and compressor units based on their operation.

Traditional compressors show more variety in how they are constructed, as they are not limited by the size of the casings like hermetic units.


Repair Procedures and Warranty Issues

A regular compressor is fairly open, so the components are highly accessible. This means repairs and maintenance can be performed whenever they are required. There is also a lower risk that working on the unit will result in more harm being done to the mechanisms. But, they are also more prone to leakage. Seals degrade more quickly and must be replaced on a regular basis.

To help make managing maintenance simpler, most traditional compressors have built-in sensors and warning systems to inform the user that repair or other procedures are required. This limits the amount of personal tracking that must be completed, but failing to be prepared to perform maintenance procedures means you might not be able to complete your original task, until you are prepared to complete the repairs.

In contrast, hermetic motors or compressors can’t be simply opened for required repairs. In fact, opening the unit can cause severe damage. The steel shielding, if compromised, must be replaced and the hermetic sealing process must be repeated. This means it is normally cheaper to replace a hermetic motor or compressor instead of attempting repairs.

Generally, hermetic motor and compressor units have very long lives. With that in mind, many companies offer fairly generous warranties for their products. The longer warranties may mitigate any concerns about handling the unit should a repair be required not long after it was purchased.

Regular compressors also come with warranties, but they might not offer as many years of coverage as hermetic counterparts. However, the easier access to components can make completing repairs on your own more manageable, so you might be more comfortable with less protection.


Semi-Hermetic Variants

Some compressors come in semi-hermetic varieties. What this means is that the motor and compressor still function as one unit, and are contained like hermetic motor and compressor options. They are also protected by a steel casing.

The main difference is that semi-hermetic motor and compressor units can actually be opened when necessary. Often, the steel casing is held closed by a series of heavy bolts, which can be undone if required. Both options keep gas from escaping to the outside world, but only semi-hermetic units can be opened should the occasion necessitate access to the inner workings.


Choosing the Right Option

Both traditional and hermetic motors and compressors have their place in the world. The right option for you depends on your intended purpose for the unit, your comfort with regular maintenance requirements, your ability to maintain an inventory of replacement parts, and the frequency at which the system will be used. Your budget may also be a factor, depending on the current price of variants in the local area.

Ultimately, there is no right or wrong answer, so users need to determine what suits their needs and personal work style to come to a decision. Then, be prepared to handle the replacement of parts or the entire system once the time arrives.


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