Single-Volute & Double-Volute Casings & Reverse Runaway Speed
01/22/2014
Q. What are some differences between single-volute and double-volute casings for rotodynamic centrifugal pumps? A. The discharge casing serves the following purposes:
- Collects output from the rotating impeller
- Decreases the velocity momentum of liquid leaving the impeller before it reaches the next stage impeller or pump discharge
- Transforms increased kinetic energy of liquid at the impeller outlet into pressure
![Single-volute casing](/sites/default/files/0214/Figure-1-3-3-1-Single-volute-casing.jpg)
![Double-volute casing](/sites/default/files/0214/Figure-1-3-3-2-Double-dual-volute-casing.jpg)
![Reverse runaway speed ratio versus specific speed when the head equals the pump head at BEP](/sites/default/files/0214/Figure-A-10-Reverse-runaway-speed-ratio-versus-specific-speed.jpg)
![](/sites/default/files/0214/Figure-3-1-8-2c-three-screw-double-end-pump.jpg)
![](/sites/default/files/0214/Figure-3-1-8-2b-three-screw-single-end-pump.jpg)