Water hammer is the sudden change in velocity of a fluid between high and low pressures in a pipeline. This pressure increase can be caused by power outages in electric pumps, leaks, poor valve installation or sudden closure of valves due to the effect of gravity
It is also caused by the opening of a valve (usually rotary: opening and closing at 90°), as the water flows into a lower pressure system (or dry, if only air is present), where the incoming liquid, at higher pressure, will produce the thrust and pressure surge resulting from the closing of a valve.
This will cause the water to compress tenuously, whose volume will decrease and dilate the pipe or hose. Likewise, when the flow is stopped, the compression momentum is zero, so it expands and the enlarged pipe returns to its original length.
This result occurs regularly in pipes that circulate water from one point to another in gravity dams, so the abrupt closure of a valve causes a high pressure at the end of the pipe. However, if the valve or pipe has the capacity to tolerate the pressure, it will not crack; otherwise, the pressure will burst and it will not be able to control the liquid.
It must be taken into account that water hammer also causes ruptures in connections (elbows, tees), as well as other devices involved in the process.
Measures against water hammer
- Gradual closing in valves.
- Application of linear valves (diaphragm, globe, safety, relief) due to their gradual opening and closing.
- Decrease velocity in pipelines.
- Design pipes based on the directions where water hammer may occur.
- Use pipes with increased thickness, according to the admitted overpressure.
- Use compressed air chambers in the required places.
- Revision of equipment (valves and piping).
In order to avoid water hammer, remember to reduce the flow rate of the pipe slowly, not to throttle it as it is usually done. For this we can use poppet valves, with the necessary caution, in longer pipelines with a very high gravity pressure.
If you have any of these situations or mishaps, contact the experts in our communication channels and we will assist you.