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The Practical Pumping Handbook =- .... --- ....... = --- = ~ ~ .......

The tapered bore is a through bore design with a taper bore in the
chamber opening out towards the impeller at an angle of approximately
4 degrees. It is designed to encourage the migration of the heavier
particles away from the seal faces and to encourage self-draining and
self-venting.
Other seal chamber designs incorporate various devices and
modifications that change the flow pattern to encourage active
circulation of the liquid and to eliminate abrasive particles from the seal
chambers, thus providing a cleaner environment for the seal faces.

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