∃surrounds.Impeller ⊓ ∃hasComponentPartAtAllTimes.SuctionNozzle ⊓ ∃hasComponentPartAtAllTimes.DischargeNozzle
A casing that surrounds an impeller and has integral suction and discharge nozzles forming part of its structure.
The differentia captures the three key structural characteristics: (1) spatial relationship to impeller, (2) integral suction nozzle, (3) integral discharge nozzle. The 'single wall' aspect is implicit in the casing genus. These conditions are both necessary and distinguishing from other casing types.