The delivering of lubricant is influenced by many different factors.
One of the most important ones is the penetration (consistency). The higher the penetration NLGI-class the stiffer the lubricant. Generally spoken: stiffer lubricant (grease) can not be pumped that easy. NLGI-class 000 is the lowest class, i.e. the softest lubricant, NLGI-class 6 is the stiffest, viscousest lubricant.
Lubricants until NLGI-class 2 can normally be pumped without any problems.
Most of the used lubricants correspond with NLGI-class 2.
NLGI - Class = Rating of the lubricants, which is done by the National Lubricating Grease Institute.
NLGI - Class
Walkpenetration acc. DIN ISO 2137 Unit = 0.10 mm
000
445 up to 475
00
400 up to 430
0
355 up to 385
1
310 up to 340
2
265 up to 295
3
220 up to 250
4
175 up to 205
5
130 up to 160
6
85 up to 115
The apparent dynamical viscosity, which is indicated by certain manufacturers of lubricants, has an important meaning. If it goes beyond 5000 m Pa.s, a pumping by conventional lubricant pumps or systems is complicated or even not possible.
At the same time the surrounding temperature as well as the length of the conduits or hoses is also important. The surrounding temperature depends on the season.
Synthetic or Bio-lubricants can affect the seal materials.
If the part of solid content in the lubricant is to big, a pumping of the lubricants with conventional pumps could be impossible.
Give special attention to silicone grease. Do not confuse with silicone as a seal material (no lubricant).
