To reduce friction and corrosion, lubrication is absolutely necessary in compressors with metal piston rings. In this type of compressors some problems are unavoidable as it is impossible to prevent leakage into the system. Especially in oxygen compressors even a drop of lubricant may cause danger of inflammation and explosion. For this reason, instead of metal piston rings, piston rings that function without lubrication have been considered as a good choice and carbon piston rings have been used with this aim. The fact that carbon piston rings are fragile, have a short life and can be operated only at low pressures and velocities have prevented their wide range application. Later on, Efalon^® (PTFE) piston rings have begun to replace carbon piston rings.

The fact that friction resistance of Efalon^® (PTFE) piston rings is high and operating life is long depends on may factors such as design, production method, selection of appropriate piston ring type, cylinder material, cleanliness of surface, pressure, velocity and heat. While designing Efalon^® (PTFE) piston rings, high thermal expansion coefficient of PTFE should be taken into consideration. Polikim produces with a special process, pre-tensioned PTFE in order to increase the springiness of piston rings.

• Piston rings are long-lasting. They do not break.

• Are self-lubricated.

• Provide absolute sealing.

• The fact that they are flexible enables them to be fixed into piston rings of even smallest diameters.

• Enable using simple and economic pistons.

• Friction that is observed with other piston rings in the first running period is very little in Efalon^® (PTFE) piston rings. In first running period a thin layer of PTFE tape is formed on surface of cylinder. In this way low PTFE-PTFE friction is obtained. Surface of cylinder is not worn out.

• Are used in all temperatures and environments starting from liquidated gases at -190°C to corrosive gases at +250°C.

• The fact that they can be used without lubrication eliminates danger of inflammation and explosion. For this reason they are used safely in oxygen compressors.

• Are hygienic, they don’t give way to oxidation when cylinders are not in motion.

• Do not contaminate their working environment. They are used without hesitation in food and pharma industries.

• Have a very high wear resistance in iron casts and stainless steel cylinders. In corrosive environments, they give good results with cylinders lined with hard chrome.

• Are used successfully with aluminum cylinders.

• Absorb solid particles in the environment and prevent surface of cylinder from being scratched.

• Virgin Efalon^® (PTFE) piston rings are used in cases that require very high chemical resistance and generally in low velocity and low pressure applications.

• Carbon-filled Efalon^® (PTFE) piston rings are most commonly used. They have very high resistance to wear and deformation under load and perfect wear resistance in dry and wet environments. They do not wear off the surface in contact even at high velocities. They have very high heat conductivity. Compared to types with other fillers, their resistance to alkalies is better, but their resistance to oxidizers is less than glass-filled.

• Glass-filled Efalon^® (PTFE) piston rings are recommended where chemical resistance is important. Their resistance is low only against alkalies. They can wear off surface in contact at high PV values if surface in contact is not hard enough. Compared to virgin PTFE piston rings, they have higher wear resistance and deformation resistance under load.

• Bronze-filled Efalon^® (PTFE) piston rings have highest heat conductivity, but their chemical resistance is not good. Generally speaking chemical environments that affect bronze have an effect also on bronze-filled PTFE. Their resistance to deformation and wear under load is good. They can be used at low and high PV values where chemical resistance is not necessary. If surface in contact is not too hard, they are also appropriate at high speeds in dry conditions.

• Gas compressors such as air, oxygen, hydrogen, carbon dioxide, ammoniac etc.
• Liquidated gas compressors such as butane, propane etc.
• Hydraulic and pneumatic cylinders
• Liquid oxygen pumps
• Corrosive liquid and gas carrying pumps with pistons
• Liquid pumps with high fluidity
• Dosage pumps

• Bearing load should not be applied to piston rings.
• Intake air should be cleaned by filters as much as possible.
• Cylinder should be protected from water, steam and dust.
• On the condition that it is not harmful, little lubrication lengthens life of piston rings.
• In cylinders with cooling jackets, temperature of cooler should be kept very low to prevent densification on cylinder wall.
• Maximum average piston velocity at which Efalon^® (PTFE) piston rings can be used in a dry environment is 5m/s and maximum pressure is 200kg/cm². This performance can be increased up to 500kg/cm² with a special design and with lubrication.