Oilers/Plant Tenders (HHC) Civil Service Practice Exam

What property of a lubricant does a Saybolt viscosimeter measure?

1. Degree of fluidity

2. Viscosity index

3. Flash point

4. Pour point

The correct answer is: Degree of fluidity

A Saybolt viscosimeter measures the degree of fluidity of a lubricant. This instrument specifically evaluates how easily a fluid flows under specified conditions, typically at a set temperature. The fluidity is determined by timing how long it takes for a designated volume of the fluid to flow through a standardized orifice. This measurement is crucial in assessing the lubricant's performance, as a lubricant's flow characteristics under varying temperatures directly impact the efficiency and effectiveness of machinery. The other options involve different properties of lubricants. The viscosity index measures the change in viscosity with temperature, but it is not directly determined by a Saybolt viscosimeter. Flash point refers to the temperature at which a lubricant vapors can ignite, which is unrelated to fluid flow characteristics. The pour point denotes the lowest temperature at which a lubricant can still flow, but this is more about the temperature sensitivity of the lubricant rather than its fluidity at a specific temperature. Thus, the correct answer focuses specifically on the ease of flow, which is what the Saybolt viscosimeter assesses.