423Glossary of Terms and Abbreviations
Surface Filtration: Filtration that primarily retains contaminant on the inuent surface.
Surface Tension: The contractile surface force of a liquid by which it tends to assume
a spherical form and to present the least possible surface. It is expressed in
dynes per centimeter, ergs per square centimeter, or newtons per meter.
Surfactant: Surface-active agent that reduces interfacial tension of a liquid. A sur-
factant used in a petroleum oil may increase the oil’s afnity for metals and
other materials.
Surge: A momentary increase of pressure in a circuit.
SUS (SSU): Saybolt Universal Seconds. A measure of lubricating oil viscosity in the
oil industry. The measuring apparatus is lled with a specic quant