Piston Rings

A piston ring always seals two surfaces. It is pressed against the cylinder wall and the groove flank by the pressure load and its inherent pre-loading force. PTFE piston rings are self-clamping. Consequently, in most cases, there is no need to back the ring by a clamping spring. For compressors with upright cylinders self-clamping piston rings up to app. 700 mm can be manufactured.

Straight Joint

kolbenringe1Piston rings with straight joints are used for sealing pressure differences above 15 bar. With this gap, leak-age is slightly higher than with piston rings that have a scarf joint. Due to the high compressor speeds (rpm) typically achieved today, the loss of gas from leakage has a minor impact on compressor performance. The amount of gas leakage is negligible.

Scarf Joint
kolbenringe2Piston rings with scarf joints are used for sealing pressure differences above 15 bar. During the run-in period the sealing effect (tightness) of scarf joints is slightly better than that of piston rings with a straight joint.
Overlapped Joint
kolbenringe3The overlapped joint achieves a favorable sealing effect. For this reason, it is primarily used for sealing gases with a specific light weight. Due to the occur-rence of bending stress and the resulting risk of breakage in the over-lapping areas, piston rings with overlapped joints should only be used in compressors operating with pressure differences of a maximum of 15 bar.
Gas-tight Joint

kolbenringe4Our gas-tight piston rings achieve the best sealing effect. The special design of the joint reduces leakage to a minimum. As with the overlapping joint the level of differential pressure is limited to a maximum of 15 bar. With regard to as-sembly please note that the piston ring achieves its good sealing effect only in one direction of pressure.


Operating Limits
Temperature –60 °C to +200 °C
Max. pressure differences to be sealed 100 bar
Median piston speed up to 6.0 m/s


Compounds
The selection of the suitable compound is largely affected by the contact surface, medium used and a number of other factors. Please contact our application engineers to discuss your requirements.