Water and Wastewater Terms Beginning O

A B C D E F G H I J K L M N O P Q R S T U V W Y Z

orifice (OR-uh-fiss)

An opening (hole) in a plate, wall, or partition. An orifice flange or plate placed in a pipe consists of a slot or a calibrated circular hole smaller than the pipe diameter. The difference in pressure in the pipe above and at the orifice may be used to determine the flow in the pipe. In a trickling filter distributor, the wastewater passes through an orifice to the surface of the filter media.