(1) The opening pressure of the check valve is related to the sealing performance of the check valve when it is closed. If the sealing property is good in the closing state, the opening pressure will be high, and vice versa, it will be small.
(2) the opening pressure is generally larger than the local head loss when the flow is normal.
(3) Quick-closing silence check valve and damped slow-closing check valve both have the function of weakening the water hammer of stopping pump, but the mechanism of both is different. Quick-closing silence check valve is generally used for small-caliber water pump, and damped slow-closing check valve is generally used for large-caliber water pump.
(4) When the flow stops, the disc or spool of the check valve should be able to close by itself under the action of gravity or spring force. Generally speaking, horizontal lift check valves and damped slow-closing check valves and multi-function valves can only be installed on horizontal pipes. In addition to vertical lift check valves, other check valves can be installed on horizontal pipes or on vertical pipes with water flow direction from bottom to top. Check valves should not be installed in the top-down risers, whose discs can not be closed by themselves and can not play a check role.
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