Differences Between Oil and Grease Lubrication Systems

Oil characteristics.

Low-viscosity oil has high fluidity and relatively low oil-film adhesion.

High-viscosity oil has low fluidity and relatively high oil-film adhesion.

Lubricator pressure.

Lubricator pressure is lower, usually30 kgf/cm² or less, with low pressure in the piping.

Lubricator pressure is higher, usually30kgf/cm ² and above, reaching up to 300kgf/cm², with higher pressure in the piping.

Lubricator design.

To suit the oil’s properties, a lubricator reservoir is usually positioned below, with oil added through the upper filling port.

To suit grease characteristics, the reservoir is generally above the lubricator and contains a follower plate that presses the grease downward. Available types include high-pressure lubricators with agitators, replaceable-cartridge lubricators and units filled through a grease gun.

Applications.

Lubricators have relatively low technical and initial-cost barriers, are easy to obtain and operate, and are available in many types for a wide range of applications.

The grease grades generally used in lubrication systems are NLGI 000~2. Lubricant viscosity affects the lubricator’s pumping capability and therefore model selection. The design must also account for operating pressure. Distributors and tubing require correspondingly high pressure ratings, making the technical requirements more demanding.