Self-priming centrifugal pump

A self-priming, centrifugal pump comprising:

• a first housing part having a front wall with an inlet for receiving liquid,
• a second housing part having an outlet for expelling the liquid, the first housing part being connected to the second housing part for enabling the liquid to flow from the first housing part and into the second housing part,
• an impeller rotatably arranged in the second housing part about a central axis for pumping the liquid from the inlet to the outlet when the impeller is rotated,
• a pump screw rotatably arranged in the first housing part about the central axis, connected to the impeller and comprising a center body around which a helical blade is arranged for feeding the impeller with any gas that is present in the liquid, wherein
• the helical blade comprises an end blade that extends in a direction towards the front wall that faces the helical blade,
• the helical blade having a first lead angle and the end blade having a second lead angle, the second lead angle being greater than the first lead angle and smaller than 90°.