What is an hermetic compressor?

Answer 1

a fully welded or serviceable

In hermetically sealed compressor, the compressor and the motor are enclosed in the welded steel casing and the two are connected by a common shaft. This makes the whole compressor and the motor a single compact and portable unit that can be handled easily. The hermetically sealed compressor is very different from the traditional open type of compressors in which the compressor and the motor are different entities and the compressor is connected to the motor by coupling or belt.

Construction of the Hermetically Sealed Reciprocating Compressor

In hermetically sealed compressor, in one side of the enclosed casing the various parts of the compressor like cylinder, piston, connecting rod and the crankshaft are located. If it is a multi-cylinder compressor, there are more than two cylinders inside the casing. On the other side of the casing is the electric winding inside which the shaft of the motor rotates. This motor can be single speed or multi-speed motor. In hermetically sealed compressors the crankshaft of the reciprocating compressor and the rotating shaft of the motor are common. The rotating shaft of the motor extends beyond the motor and forms the crankshaft of the hermetically sealed reciprocating compressor.

All these parts of the hermetically sealed compressor are assembled and enclosed in a strong and rigid casing made up of welded steel shell. The steel shell comprises of two half rounded steel bodies that are welded together to form the casing for the hermetically sealed compressor. In some cases the two halves of the shell can be bolted together instead of welding, which permits easy opening of the casing in case of compressor burnout.

The hermetically sealed compressors have inbuilt lubrication system for the lubrication of the piston and cylinder and crankshaft. The lubricant also acts the coolant for the piston and cylinder. Additionally, the cool suction refrigerant also offers cooling effect. Externally, the casing has refrigerant suction and discharge connections that are connected to the evaporator and condenser respectively. There is also socket for the electrical connection.

The typical condenser unit with the hermetically sealed compressor is shown in above fig. Such condenser units are called as hermetic condenser units. In the other image various parts of hermetically sealed multi-cylinder reciprocating compressor are shown.

Types of Hermetic Compressors

One of the most popular types of the hermetically sealed compressors are the reciprocating compressors. They were the first to be used as the hermetically sealed compressors are still being used widely. These days the vane type of rotary compressor has become more popular. It is considered that the rotary type of hermetically sealed compressor consumes less electricity, makes lesser noise, requires lesser maintenance, and is cheaper than the reciprocating type of hermetically sealed compressor. This is because the rotary compressors has less frictional parts and have only a rotor. The centrifugal types of hermetically sealed compressor are used for the large units.

Answer 2

it is a compressor with well-sealed welded steel body which prevent gas leachage, disadvantage that if the motor failed down then you have to replace the whole unit