1. What is water hammering?
Water hammer is one kind of phenomenon which is ,when the power is off suddenly or the pipe valve is closed very quick, due to the inertia of the pressure water flow, a shock wave of the water flow is generated, just like a hammer, so that phenomenon is called water hammering. The force of the back and forth shock wave of the water flow sometimes is so powerful, which can damage the valve and sump pump.
After the installation of plastic pipes, it is usually necessary to test the pressure with water. During the pressure test, an important step is to drain the air inside the pipe. Otherwise, the water pressure test will cause water hammering, which will break the pipes.
2. How water hammering happens?
When the working valve is suddenly closed, the flow of water will create a pressure on the valve and pipe wall, because the pipe wall is smooth, the subsequent water flow quickly reaches the maximum speed under the action of inertia, and produces a destructive effect. That is the“ water hammer effect” in fluid mechanics, and also called positive water hammering. That water hammering phenomenon must be considered in the construction of water supply pipelines.
On the contrary, when the closed valve is suddenly opened, which will also produce water hammering, it is also called negative water hammer, it also has a certain destructive power, but it is not as large as the former. When the electric water pump unit is suddenly powered off or started, it will also cause pressure shock and water hammer effect. The shock wave of this pressure propagates along the pipeline, which can easily lead to local over-pressure in the pipeline, resulting in rupture in pipeline and damage to equipment. Therefore, how to prevent the water hammering has become one of the key technologies in water supply engineering.
3. Why water hammering happens and how to prevent the happening of water hammering:
①. the air in the pipeline is not exhausted, which is easy to cause water hammering.
The pipeline has ups and downs parts. The higher position of the pipeline is easy to accumulate air. After the air is pressurized, its volume will be compressed and become smaller, but its internal pressure will increase significantly, and water hammering will happen.
How to stop the water hammering:
An “automatic exhaust valve” should be installed at the higher position of the pipeline, and there is a floating ball above the automatic exhaust valve. When the water is not full or there is no water, the floating ball will automatically drop, and the air can be discharged from this hole. When there is water in the pipe, the floating ball will float up, when the pipe is full with water, the floating ball will float up to block the round hole above. This function mentioned above can discharge the air left in the high part of the pipe to prevent the occurrence of water hammering.
②. when the water is passed through, the valve is opened too large, the exhaust is not enough, which is easy to produce water hammering.
When the pipeline is completed and the water is to going to pass through, the water valve is opened too fast and too large, which results in insufficient exhaust, a large amount of air is left in the pipe, and plus the impact of excessive water flow will cause water hammering.
How to stop that water hammering:
The exhaust valves must be opened before the water comes to facilitate the exhaust. When the water is coming, the water valve should not be opened too fast and too large, so that the air inside can be discharged successfully. When water flows out of the exhaust valve, which means the pipeline is full of water, it should be closed.
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