While most people think of labyrinth seals as a type of rotary seal, they also have applications for non-rotating sealing.
An excellent example of a non-rotary application is to provide a non-contact seal against high pressure while sealing in oil during compression strokes in reciprocating compressors. The first reciprocating compressor with a labyrinth seal was built in 1935, and this type of reciprocating compressor is known as a labyrinth compressor. Although the technology has been modernized and improved over time, some things remain the same including the benefits.
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The use of a labyrinth seal in this context has a robust and straightforward design. It offers oil-free compression, and prevents the gas from being contaminated by particulate matter resulting from abrasion of the piston rings. There is no rubbing contact between the surface of the piston and the surface of the encasing cylinder, which means no hot spots due to friction. One of its most outstanding benefits is the long mean time between overhaul (MTBO).
This type of reciprocating compressor is used in numerous applications. For example, they have been used with non-toxic gases that need to maintain extremely high purity, gases like oxygen that involve a significant fire hazard, corrosive or explosive gases. Labyrinth compressors are used for contaminated gases, and have wide application in the polymer production process. They are commonly used in connection with gas transport and storage, and the handling of industrial gases. The use of polymeric labyrinth seals opens up the labyrinth compressor to food, beverage, and drug applications, because seals can be made of FDA approved materials like PTFE. They can also be found in refrigerated and cryogenic systems. They are even used in fertilizer production pipelines.
Polymeric Labyrinth Seals
Polymeric labyrinth seals, as already mentioned, can be made of an FDA approved polymers like PTFE. They can operate within a wide range of temperatures, all the way down to cryogenic applications. They are more lightweight than their all-metal counterparts, which aids in improving overall system efficiency. Finally, there are many polymeric options that are highly resistant to corrosive chemicals. In fact, PTFE is compatible with more chemicals than any other polymer.
In short, labyrinth seals arent just for rotating applications. The use of polymer labyrinth seals in reciprocating compressors is an excellent example of the diversity of their application, and brings with it a variety of benefits.
For troubleshooting polymer seals check out the complete guide on Sealing Solutions from Advanced EMC Technologies.