Priming and Air Separation Accomplished Within Casing - Dual volute design primes suction with only an initial charge of liquid in the casing. During priming cycle, the lower volute functions as an intake while upper volute discharges liquid and entrained air into separation chamber. Air is separated and expelled through pump discharge while liquid recirculates into lower volute. Once air is completely removed from suction and liquid fills impeller eye, pump is fully primed, and functions as a conventional centrifugal pump with both volutes performing as discharges.

The casing is designed so that an adequate volume of liquid for repriming is always retained in pump even if liquid is allowed to drain back to source of supply from discharge and suction.