Double Shaft Seal

A shaft seal is a small part of the compressor, but it plays the important role in the refrigeration process. Shortly, it keeps the dangerous refrigerant inside the compressor. When the shaft seal starts leaking the production must stop.

Take a look on the refrigeration process.

1. Refrigerant (e.g. ammonia gas) vapour in the COMPRESSOR is compressed, causing a rise in its temperature approximately 10 degrees celsius above outside ambient. The High-pressure High-temperature vapour flows into the condenser.

2. CONDENSER. The refrigerant vapour, being hotter than its surroundings gives up its heat. The vapour condenses and becomes a liquid.

3. Liquid refrigerant is stored in the RECEIVER as a reservoir before being metered into the evaporator by a flow expansion device.

4. The refrigerant liquid expands resulting in a fall in temperature to approximately 10 degrees celsius below process requirements, and flows into the evaporator.

5. The EVAPORATOR. Here the low temperature liquid absorbs heat from the surroundings and evaporates (boils) becoming a liquid-vapour mixture at low temperature, evaporating totally before returning to the COMPRESSOR to begin the cycle again.

The shaft seal is located on the shaft of the compressor which goes into the atmosphere to the driver (E-motor) and protects refrigerant vapour from leaking to the atmosphere. The operating system and location of the shaft seal is the same for both, reciprocating and screw compressors.

Do you know that 85% of mechanical seals fail prematurely and unexpected?

A shaft seal is the most vulnerable part of the industrial refrigeration system. When the shaft seal fails the compressor needs to be stopped and immediately isolated from the installation. This creates unexpected work and reduces plant capacity.

RM Support offers a double shaft seal with a pre-warning system. Click here to read about a double shaft seal and to read about the reason of the shaft seal failure.