Check valve at the outlet of centrifugal pump is used to prevent water hammer caused fluid backflow in outlet pipeline from damaging impeller inside pump. Check valve is mainly used to prevent fluid from flowing back which makes pump reverse and cause damage. And it also protects other storage tanks from being damaged by fluid backflow.
According common situation of pump, choosing check valve for outlet of centrifugal pump should follow these tips:
1. For pipeline having low dimension which is lower than 50mm, lift check valve should be used.
2. For pipeline whose dimension is higher than 50mm, swing check valve which can be installed horizontally and vertically should be used. The disc of swing check valve rotates around with spindle. And the fluid resistance is lower than that on lift check valve. Swing check valve is suitable for larger dimension pipeline. The installing position has no limitations. Swing check valve is usually installed on horizontal pipeline. According to the quantity of disc, swing check valve is classified into single-disc swing check valve, double-disc swing check valve and multi-disc swing check valve. In order to reduce pressure of water hammer, slow-close check valve is the best. Double-disc swing check valve is suitable for medium or large dimension pipeline. Wafer double-disc check valve has small structure and light weight. Double-disc swing check valve is also suitable for large dimension pipeline.
The installation of check valve
1. Swing check valve is general installed on horizontal pipeline. For check valve whose dimension is 80mm, it can be installed on vertical pipeline.
2. Straight through lift check valve is installed on horizontal pipeline. Vertical lift check valve must be installed on vertical pipeline. Media flow from bottom to top.
3. The check valve can be damaged easily. So, the check valve should be installed near to outlet of pump. Cut-off valve is (ball valve or gate valve generally) is installed upside check valve, convenient for maintenance.