①Special open type vortex impeller permits foreign matter passing the inlet port to be freely discharged.②As the passage size is uniform from the inlet port to the discharge port, the size of passed foreign matter can be as large as the port diameter.③4 pole induction motor runs with high torque to enhance foreign matter passing.④Built-in motor protector (automatic cut-off for model below 7.5kW and thermal protector over 11kW) protects the motor from overload or open phase.⑤Optional quick discharge connector facilitates easy installation and maintenance.⑥DVA model permits automatic operation. Parallel alternate operation possible with DVA and DVJ model.