PTFE Piston Ring Types

Traight Joint;Scarf Joint;Overlapped Joint;Gas-tight Joint

Traight Joint
Piston rings with straight joints are used for sealing pressure differences above 15 bar.

With this gap, the leakage is slightly higher than with piston rings that have a scarf joint. Because of the high compressor speeds (rpm) typically achieved today, the loss of gas from leakage has only a minor impact on compressor performance.

The amount of gas leakage is negligible.

Scarf Joint
Piston rings with scarf joints are used for sealing pressure differences above 15 bar. During the run-in period, the sealing effect of scarf joints is slightly better than that of piston rings with a straight joint.

Overlapped Joint
The overlapped joint achieves a favorable sealing effect.

For this reason, it is primarily used for sealing gases with a specific light weight. Because of bending stress and the resulting  risk of breakage in the overlapping areas, piston sealing rings with overlapped joints should only be used in compressors operating with pressure differences of max. 15  bar.

Gas-tight Joint
Our gas-tight piston rings achieve the best sealing effect.

The special design of the joint reduces leakage to a minimum. The differential pressure is limited to a maximum of 15 bar. During assembly, please note that the piston ring achieves a good sealing effect in one direction of pressure only.

Source:https://www.sukoptfe.com/ptfe-piston-ring-types