A Diffuser pump is on in which stationary vanes called diffusers are fitted radially facing the discharge from the impeller. These vanes which gradually increase in space as the water moves outwards serve to convert the velocity of the water exiting the impeller into pressure.Diffuser pumps do not require a volute. Diffuser pumps provide a more efficient conversion of velocity input pressure. The flow is more controlled and smoother.
For large capacity pumps, the diffuser model is smaller in size than the volute design.
The diffuser design is more efficient at peak loads while the volute design is efficient at off peak loads.