What is the typical gap between the outer circle of the impeller inlet boss and the pump casing volute?
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What is the typical gap between the outer circle of the impeller inlet boss and the pump casing volute? The impeller accessories we purchased have an outer diameter that is equal to the inner diameter of the volute; there is no gap between them. The impeller won’t rotate when installed – what should we do?
The gap between the outer circumference of the impeller inlet boss and the pump casing volute is generally around 0.1mm to 0.2mm, depending on the pump’s design and requirements. If the outer diameter of the impeller accessory you purchase is equal to the inner diameter of the volute, with no clearance, it will not be able to rotate after installation; this may be because the fit between the impeller and the volute is too tight, resulting in excessive resistance. It is recommended that you contact after-sales service or professional technicians for inspection and adjustment to ensure the pump can operate properly. .
The outer diameter of the boss should be machined using a lathe; for vertical pumps, it is recommended to leave a margin of 1–3 mm