Abu Dhabi Gas Liquefaction Company Ltd Job Training Mechanical Technician Course Module 9 Compressors

Carbon ring seals are seperate carbon rings located in spacers. They are in sections, 
held together by a spring. When the compressor is operating, gas pressure pushes the 
rings against the spacers, forming a seal as shown in Figure 5.26.
Carbon is a solid material with natural lubricating properties. Labyrinth seals may 
also be used to help make a good seal. A sleeve on the shaft prevents any contact 
wear on the shaft. 
Liquid film seals use oil pumped into the seal to stop gas leakage. The oil is at a 
pressure higher than the compressed gas pressure so no gas can flow into the seal.
Figure 5.27 shows a liquid film seal. 
 
 
 
 
Figure 5.26: Carbon Ring Seal 
Figure 5.27: Liquid Film Seal 
Spring 
Spacer 
Carbon 
ring 
Labyrinth 
seal 
Labyrinth 
seal 
Shaft 
sleeve 
Gas 
pressure 
side 
Atmospheric 
pressure 
side 

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Personnel & Training Division
Job Training—Mechanical Technician 
Compressors/Rev. 0.0 
Page 68 of 90
Labyrinth seals are also used to help stop the seal oil from flowing into the gas stream. 
Mechanical seals can come in many different designs. They can be supplied with 
high-pressure liquid or gas to help keep the compressed gas from escaping. A basic 
mechanical seal was described in the module on Pumps in this course. Another 
example of a simple mechanical seal is shown in Figure 5.28. 
A seal is made between the faces of the fixed and rotating rings. 
All of these seals are described in more detail in the Seals module.
Figure 5.28: Mechanical Seal 
Rotating 
shell 
Springs Rotating 
ring 
Fixed 
ring
Shaft 

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Personnel & Training Division
Job Training—Mechanical Technician 
Compressors/Rev. 0.0 
Page 69 of 90