7.Differences between Resistance Type and Pressure-Relief Type Lubrication Systems

Differences between Resistance Type and Pressure-Relief Type Lubrication Systems

Resistance type lubrication system is also known as Single Line Resistance (SLR) lubrication system. Pressure-relief type lubrication system is also known as Positive Displacement Injector (PDI) lubrication system. Please refer to the below comparison chart for the differences between the two.

Lubrication System Type	Resistance Type Lubrication System	Pressure-Relief Type Lubrication System
Description	The amount of lubricant discharged is determined by the resistance level of the lubricator, the number of lubricating points, and the length and size of oil pipes: the higher the resistance level, the lower the lubricant discharges; the lower the resistance level, the higher the oil discharges. Therefore, the lubricant discharge amount cannot be precise as required.	A pressure-relief type system is a volumetric type or a metered distributed type. When the operating pressure of the lubricator reaches the preset value, the distributors deliver a metered amount of lubricant to the lubricating points. Pressure relief type, also known as volume type or quantitative type. The lubricator has a pressure relief device, the so-called pressure relief type. The lubricant is accumulated first in the pipes before discharging, the so-called volume type. The fixed volume of lubricant flows out to each lubricating point to have a precise discharge volume.
Operating Principle	The pump supplies lubricant to the main pipe and the open-straight type distributors when the lubricator operates. The distributors continue discharging lubricant until the operation time runs out.	The pump supplies lubricant to the main pipe and the volume/piston distributors until they are full. Then the distributors discharge excess lubricant from the outlets to the lubricating points. The lubricator's oil drain valve releases the excess lubricant into the tank.
Drive Method	Manual, electric, and pneumatic types.	Manual, electric, and pneumatic types.