Lubricant Selection & Management Flashcards

A high-speed spindle bearing operates at 25,000 RPM with a light radial load. Which grease consistency grade is most appropriate?

Answer: NLGI 0

Lighter NLGI grades (0 or 1) are preferred for high-speed applications because they offer lower churning resistance and better flow to the bearing.

Which base oil property most directly determines the suitability of a lubricant for low-temperature start-up conditions?

Answer: Pour Point

Pour point is the lowest temperature at which an oil flows, making it the key indicator for cold-start lubricant selection.

A food-processing facility requires a lubricant for incidental food contact. Which lubricant designation is required by USDA/NSF?

Answer: H1

NSF H1 lubricants are approved for incidental food contact and are required wherever accidental contact with food is possible.

When selecting a compressor oil for a reciprocating air compressor, which property is critical to prevent deposit formation and fire risk?

Answer: Low Carbon Residue

Low carbon residue (Conradson or Ramsbottom test) minimizes deposit buildup in hot discharge zones, reducing fire and explosion risk.

A lubricant's 'R&O' designation indicates it contains which additive package?

Answer: Rust inhibitors and oxidation inhibitors only

R&O oils contain rust inhibitors and oxidation inhibitors, making them suitable for circulating systems and turbines without EP additives.

Which lubrication regime is characterized by the lubricant film completely separating the mating surfaces with no asperity contact?

Answer: Hydrodynamic lubrication

In full hydrodynamic lubrication, a continuous pressurized film separates surfaces entirely, resulting in very low friction and wear.

An engineer selects a gear oil with an ISO VG 320 viscosity grade. At 40°C, the kinematic viscosity will be closest to:

Answer: 320 cSt

ISO VG grades define the nominal kinematic viscosity in cSt at 40°C, so ISO VG 320 oil has approximately 320 cSt at 40°C.