Impeller seat with a guide pin for a pump

A Pump for pumping liquid comprising solid matter, the pump comprising:

• an open impeller having:
• a cover plate;
• a centrally located hub;
• and
• at least two spirally swept blades connected to the cover plate and to the hub, each blade having a leading edge adjacent the hub, a trailing edge at a periphery of the impeller, and a lower edge extending from the leading edge to the trailing edge and separating a suction side of the blade from a pressure side of the blade;
• an impeller seat having:
• an axial inlet defined by an inlet wall and an upper surface located downstream of the axial inlet;
• an inlet radius (R) measured from an axially extending centre axis (A) to a circular intersection between the inlet wall and the upper surface of the impeller seats;
• a guide pin connected to and extending radially inwards from said inlet wall the guide pin having a tip radius (r) measured from the axially extending centre axis (A) to the radially innermost part of the guide pin, wherein an imaginary 15%-circle is offset radially inwards from said circular intersection fifteen percent of the difference between said inlet radius (R) and said tip radius (r);
• an imaginary 85%-circle is offset radially inwards from said circular intersection eighty-five percent of the difference between said inlet radius (R) and said tip radius (r);
• a trailing edge line defined by an axially projected straight line extending between the intersection between the 15%-circle and a trailing edge of the guide pin and the intersection between the 85%-circle and the trailing edge of the guide pin;
• and
• a trailing edge angle (a) between a first radius of the impeller seat intersecting the trailing edge of the guide pin at the 15%-circle and the trailing edge line is equal to or more than 10 degrees and equal to or less than 30 degrees;
• wherein:
• the impeller is displaceable back and forth in an axial direction in relation to the impeller seat during operation of the pump;
• the leading edge of each blade is configured to cooperate with the guide pin of the impeller seat during operation of the pump and the lower edge of each blade is located opposite the upper surface of the impeller seat;
• a cleaning angle (ε) between a projected tangent to the trailing edge of the guide pin and a projected tangent to the intersection between the leading edge of the blade and the suction side of the blade, between the 15%-circle and the 85%-circle, is equal to or more than 80 degrees and equal to or less than 120 degrees;
• and the leading edge of the blade is spirally swept from the hub of the impeller to the lower edge of the blade.