Which statement is true about the Saybolt Universal Seconds (SUS) unit?

Which statement is true about the Saybolt Universal Seconds (SUS) unit?

• A. It measures temperature
• B. It measures viscosity
• C. It measures pressure
• D. It measures mass

Answer: (B)

Viscosity is the measure of a fluid’s resistance to flow. Saybolt Universal Seconds (SUS) quantifies that resistance by timing how long a fixed amount of liquid takes to flow through a standardized capillary in a Saybolt viscometer at a set temperature. Because SUS is a time-based flow measurement under defined conditions, it directly expresses how thick or thin a liquid is. A higher SUS means a thicker, more viscous fluid that flows slowly; a lower SUS means a thinner fluid that flows quickly. It’s not a temperature, pressure, or mass measurement—the instrument and the SUS value are all about viscosity, with temperature used only as the defined condition under which the viscosity is measured. In practice, SUS is widely used for petroleum products and lubricants to gauge performance in pumping and filtration.

Viscosity is the measure of a fluid’s resistance to flow. Saybolt Universal Seconds (SUS) quantifies that resistance by timing how long a fixed amount of liquid takes to flow through a standardized capillary in a Saybolt viscometer at a set temperature. Because SUS is a time-based flow measurement under defined conditions, it directly expresses how thick or thin a liquid is. A higher SUS means a thicker, more viscous fluid that flows slowly; a lower SUS means a thinner fluid that flows quickly. It’s not a temperature, pressure, or mass measurement—the instrument and the SUS value are all about viscosity, with temperature used only as the defined condition under which the viscosity is measured. In practice, SUS is widely used for petroleum products and lubricants to gauge performance in pumping and filtration.