Why is it important to comply with the minimum flow velocity of disk check valves?

VAG SKR

When disk check valves are used, the minimum flow velocity is frequently not reached: This causes the valve to lose more pressure than in the case of a fully open position. As soon as the disk is not completely open, a relatively high amount of energy must be used to guarantee a supply of water.

In addition to a rise in the consumption of energy, an insufficient flow velocity can also increase wear on the valve. When the velocity is appropriate, the disk in the valve is constantly pushed open. If the velocity is insufficient, the disk in the medium will begin to vibrate, which in turn will result in repeated slams on the body. This slamming can damage the valve and increase wear on the shaft bearing, so that unscheduled maintenance work may need to be carried out, or it may even be necessary to replace the valve.

The VAG RETO-STOP Non-Return Valve and the VAG SKR Slanted Seat Tilting Disk Check Valve require very low minimum flow velocities of 2.0 m/s and  1.5 m/s respectively, thus effectively preventing this danger. The special convex shape of the disk in the VAG SKR Slanted Seat Tilting Disk Check Valve means that the valve requires far less energy than customary non-return valves. 

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