摘要 |
A pump has a large upper chamber containing an outlet, a smaller lower chamber containing an inlet, a flared transition portion between the lower and upper chambers, a driven vertical impeller extending within the chambers and the transition portion, and an aeration device in the transition portion, the aeration device being a projection into the transition portion with an upward slope facing the movement of the impeller therepast and an edge in the direction of rotation of the impeller, and an air valve controlling air flow through a channel leading into the pump at the edge of the projection.
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