There are many protective measures for water hammer, but different measures need to be taken according to the possible causes of water hammer.

1.Reducing the flow rate of the water pipeline can reduce the water hammer pressure to a certain extent, but it will increase the diameter of the water pipeline and increase project investment. When laying out water pipelines, consideration should be given to avoiding humps or drastic changes in slope.

Reduce the length of the water pipeline. The longer the pipeline, the greater the water hammer value when the split case water pump is stopped. From one pumping station to two pumping stations, a water suction well is used to connect the two pumping stations.

The size of the water hammer when the pump is stopped is mainly related to the geometric head of the pump room. The higher the geometric head, the greater the water hammer value when the pump is stopped. Therefore, a reasonable pump head should be selected based on the actual local conditions.

After stopping the pump due to an accident, the pipe behind the check valve should be filled with water before starting the pump.

When starting the pump, do not fully open the split case water pump outlet valve, otherwise a large water impact will occur. Major water hammer accidents in many pumping stations often occur under such circumstances.

2. Set up a water hammer elimination device

(1) Using constant voltage control technology

The PLC automatic control system is adopted to carry out frequency conversion speed control on the pump, and implement automatic control on the operation of the entire water supply pump room system. Since the pressure of the water supply pipeline network continues to change with changes in working conditions, low pressure or overpressure often occurs during system operation, which can easily cause water hammer, leading to damage to pipelines and equipment. A PLC automatic control system is used to control the pipe network. Detection of pressure, feedback control of the start and stop of the water pump and speed adjustment, control of flow, and thus maintain the pressure at a certain level. The water supply pressure of the pump can be set by controlling the microcomputer to maintain constant pressure water supply and avoid excessive pressure fluctuations. The probability of water hammer is reduced.

(2) Install water hammer eliminator

This device mainly prevents water hammer when the pump is stopped. It is generally installed near the outlet pipe of the split case water pump. It uses the pressure of the pipe itself as power to realize low-pressure automatic action. That is, when the pressure in the pipe is lower than the set protection value, the drain port will automatically open to drain water. Pressure relief is used to balance the pressure of local pipelines and prevent the impact of water hammer on equipment and pipelines. Eliminators can generally be divided into two types: mechanical and hydraulic. Mechanical eliminators are manually restored after action, while hydraulic eliminators can be automatically reset.

(3) Install a slow-closing check valve on the large-diameter split case water pum poutlet pipe

It can effectively eliminate water hammer when the pump is stopped, but because a certain amount of water will flow back when the valve is activated, the water suction well must have an overflow pipe. There are two types of slow-closing check valves: hammer type and energy storage type. This kind of valve can adjust the valve closing time within a certain range as needed. Generally, the valve closes 70% to 80% within 3 to 7 seconds after a power outage. The remaining 20% to 30% closing time is adjusted according to the conditions of the water pump and pipeline, generally in the range of 10 to 30 seconds. It is worth noting that when there is a hump in the pipeline and water hammer occurs, the role of the slow-closing check valve is very limited.

(4) Set up a one-way pressure regulating tower

It is built near the pumping station or at an appropriate location in the pipeline, and the height of the one-way pressure regulating tower is lower than the pipeline pressure there. When the pressure in the pipeline is lower than the water level in the tower, the pressure regulating tower replenishes water to the pipeline to prevent the water column from breaking and bridge the water hammer. However, its pressure-reducing effect on water hammer other than pump-stop water hammer, such as valve-closing water hammer, is limited. In addition, the performance of the one-way valve used in the one-way pressure regulating tower must be absolutely reliable. Once the valve fails, it may cause a large water hammer.

(5) Set up a bypass pipe (valve) in the pump station

When the pump system is operating normally, the check valve is closed because the water pressure on the pressure side of the pump is higher than the water pressure on the suction side. When the accidental power outage suddenly stops the split case water pump, the pressure at the outlet of the water pump station drops sharply, while the pressure on the suction side rises sharply. Under this differential pressure, the transient high-pressure water in the water suction main pipe pushes open the check valve valve plate and flows to the transient low-pressure water in the pressure water main pipe, causing the low water pressure there to increase; on the other hand, the water pump The water hammer pressure rise on the suction side is also reduced. In this way, the water hammer rise and pressure drop on both sides of the water pump station are controlled, thereby effectively reducing and preventing water hammer hazards.

(6) Set up multi-stage check valve

In a long water pipeline, add one or more check valves, divide the water pipeline into several sections, and install a check valve on each section. When the water in the water pipe flows back during water hammer, each check valve is closed one after another to divide the backflush flow into several sections. Since the hydrostatic head in each section of the water pipe (or backflush flow section) is quite small, the water flow rate is reduced. Hammer boost. This protective measure can be effectively used in situations where the geometric water supply height difference is large; but it cannot eliminate the possibility of water column separation. Its biggest disadvantage is: increased power consumption of the water pump during normal operation and increased water supply costs.