Pump cavitation is one of the most prevalent and damaging issues for fluid-handling systems. Cavitation may quickly make pumps less effective and cause expensive downtime in industrial operations, chemical processing units, water treatment plants, and agricultural irrigation systems. To make sure that pumps work well, last a long time, and are reliable, you need to know what cavitation is, why it happens, and how to stop it.
What is pump cavitation?
- When the pressure of a liquid drops below its vapor pressure, vapor bubbles form within the pump. This is called cavitation. These small bubbles move with the fluid and break apart forcefully when they reach areas of higher pressure, such as near the impeller blades. This collapse sends forth shockwaves that are powerful enough to harm metal surfaces and change the way water flows.
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- Cavitation occurs when vapor bubbles develop and then break apart in a pump. This happens when there isn't enough pressure, which is an unpleasant "boiling" effect.
What are the signs of cavitation?
Once you know what to look for, cavitation is typically simple to see. Common signs are:- Inside the pump, you may hear loud, cracking, or rattling noises that are often compared to the sound of "marbles" or "gravel" being churned.
- Too much shaking
- Lowered discharge pressure or flow rate
- Seal or bearing problems happen a lot.
- The pump is becoming too hot
- Erosion or pitting markings on the impeller
Causes of Pump Cavitation:
There are several problems with the system that might cause cavitation. Some frequent reasons are1). Not enough Net Positive Suction Head (NPSH):
- If the NPSH that is available is less than the NPSH that the pump needs, vapor bubbles will occur. Generally, incorrect placement of the pump, excessive suction lift, or long suction lines cause this issue.
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2). High Temperature of the Fluid:
- Higher fluid temperatures raise vapor pressure, which makes cavitation more probable.
3). Air Leaks in the Suction Line:
- Air may get into the suction line via leaks or bad seals, which can cause bubbles and stop the flow.
4). Suction filters that are blocked or clogged:
- Partially clogged strainers or suction filters cut down on the flow of fluid and raise the pressure drop.
5). Pump speed that is not right:
- Running the pump faster than its design limit makes the suction pressure drop more and makes cavitation more likely.
6). Designing the system wrong:
- Pressure loss and flow problems may happen when pipes are the wrong size, have abrupt bends, or have suction lines set up poorly.
Ways to Stop Pump Cavitation:
To stop cavitation, you need to take a methodical strategy that looks at the root causes. The best solutions are
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1. Make the conditions for suction better:
- Put the pump closer to the fluid source to lower the suction lift.
- To reduce the pressure drop, make the suction pipe bigger.
- Make sure that suction lines are as straight and short as feasible.
- Get rid of abrupt bends, elbows, or other things that produce turbulence.
2. Make sure there is enough NPSH:
- Make sure the available NPSH is greater than what the pump needs.
- Increase the amount of liquid in the suction tank.
- Slow down the pump, particularly if it is running too fast.
- If you can, lower the temperature of the fluid.
3. Remove rid of air that becomes stuck:
- Check the seals and joints on the suction line.
- Fix leaks and put in new gaskets where they are worn out.
- To stop air pockets from forming, keep the suction pipe completely filled.
4. Keep suction filters clean and in good shape:
- It is important to clean suction strainers, filters, and screens on a regular basis.
- To keep the flow constant, change blocked filters right away.
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5. Keep an eye on the discharge conditions:
- Don't close the discharge valve all the way while the pump is operating.
- Take away any extra limits on the discharge line.
- Keep the system pressure at the right level.
6. Pick the Right Type of Pump:
- Choose pumps that can manage the flow, pressure, and characteristics of the fluid you need.
- If you need to move fluids with a lot of vapor pressure, look into pumps that are made just for it.
7. Stay within the recommended flow range:
- Every pump has a Best Efficiency Point (BEP) that is best for it.
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- Don't operate pumps at very low or very high flow rates since this makes the water within the pump circulate more.
