Assembly clearance of the power seal pair impeller in centrifugal pumps
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This post was last edited by foam_ZPTK on 2018-1-7 at 17:12. A beginner’s question: Regarding the assembly of the centrifugal dynamic seal impeller, what is the appropriate clearance?
I typed it wrong. A beginner is asking: The assembly of the dynamic seal pair in centrifugal pumps is related to that aspect – what is the appropriate gap?
A dynamically sealed secondary impeller? Is it that type of vertical, seal-less pipeline pump that uses an auxiliary impeller to achieve sealing?
This gap is determined through calculation: if the gap is greater than 3 mm, the K value ranges from 0.75 to 0.85; if it is less than 3 mm, the K value ranges from 0.85 to 0.9. The value of K directly determines the sealing pressure generated by the auxiliary impeller. There is no fixed value for this gap, as it depends on the size of the medium particles and the pressure produced by the impeller
Are you referring to that type of pump which has an open impeller behind the main impeller, along with a secondary impeller that operates in the opposite direction to the flow channel of the main impeller? It is the above-mentioned unsealed vertical pump. It ensures the perpendicularity between the shaft and the housing; the smaller the clearance of the auxiliary impeller, the better, and this value can be set based on factors such as the medium’s temperature, viscosity, and pressure. The pumps we use here are at room temperature; the setting is usually between 0.2-0.3 mm. If this value is too high, air leakage occurs and the pump is unable to draw in liquid. The clearance can be adjusted by modifying the bearing housing, making it easy to operate. The key point lies in the perpendicularity between the shaft and the pump casing; if there is an inclination, the clearance on one side will be very large, resulting in the pump failing to deliver fluid.
The clearance value between the auxiliary impeller and the corresponding pump casing partition is determined by the pressure generated by the main impeller; is it true that the smaller the clearance, the better? Could you explain in detail how this gap value is calculated using which parameters? Thank you!
One more question: what exactly is the K value you mentioned?