Understanding Cavitation in Diaphragm Pumps: Causes, Damage, and Prevention Strategies
Mar,17,2025
CONTENT [HIDE]
What are the Damagesof Cavitation?
Judgment of Cavitation of Diaphragm Pump
How to Improve the Anti-cavitation Ability
What is Cavitation?
During the operation of the diaphragm pump, if the absolute pressure of the pumped material in the local area of the flow part drops below the critical value for some reason, it will begin to vaporize and produce a large number of bubbles. The high-pressure material around the bubbles will cause the bubbles to shrink sharply and even burst. Cavitation is the whole process of the bubbles gathering, moving, splitting and eliminating.
Causes of Cavitation
1. The suction pipe is too long or the diameter is too small: the liquid flow rate is too fast and the pressure loss is too large.
2. The temperature is too high: the liquid temperature rises, the saturated vapor pressure rises, and vaporization is more likely to occur.
3. Too many impurities in the liquid: the liquid contains a large amount of gas or solid impurities, which will accelerate the formation of bubbles.
4. The liquid level is too low or the pump is installed too high: the pump inlet pressure is insufficient.
What are the Damages of Cavitation?
1. Corrosion of Flow Components.
When bubbles burst, high-frequency (600~25000HZ) impact is generated, and the pressure is as high as 49Mpa, causing mechanical erosion on the surface of the pump body; when the material vaporizes, heat is released, and hydrolysis occurs due to the temperature difference battery effect. The generated oxygen oxidizes the metal and chemically corrodes.
2. Component Damage and Performance Degradation.
The impact caused by bubble bursting will cause vibration and noise in the pump body. Severe cavitation will cause damage to components such as the impeller and pump casing. In addition to the destructive effect on the flow components, the diaphragm pump will also generate noise and vibration after cavitation occurs, and the performance of the pump will be reduced. In severe cases, the liquid in the pump will be interrupted and it cannot work normally.
Judgment of Cavitation of Diaphragm Pump
1. Increased noise: abnormal metal knocking sound is generated when the pump is running.
2. Intensified vibration: the pump body produces obvious vibration.
3. Reduced flow: the output flow of the pump decreases.
4. Unstable pressure: the system pressure fluctuates greatly.
5. Shortened diaphragm life: the diaphragm is frequently damaged.
How to Improve the Anti-cavitation Ability
1.When cavitation occurs in the diaphragm pump, the flow rate of the diaphragm pump should be reduced or the speed should be reduced.
2.The cross-sectional change rate of the flow section should be as small as possible, and the wall surface should be as smooth as possible.
3.Reduce the suction loss hc, so you can try to increase the pipe diameter, minimize the length of the pipeline, elbows and accessories, etc.; (In simple terms: the resistance of the suction pipe should be small, short and straight).
4.Reduce the geometric suction height hg (or increase the geometric backflow height).
5.Prevent long-term operation at a large flow rate.
6.Under the same speed and flow rate, a double-suction pump is used, because the inlet flow rate is reduced and the pump is not prone to cavitation.
7.The condition of the diaphragm pump suction pool has an important impact on the pump cavitation.
8.For pumps operating under harsh conditions, cavitation-resistant materials can be used to avoid cavitation damage. (The specific method is: epoxy resin coating is applied to the cavitation area).
The above measures can be comprehensively analyzed and appropriately applied according to the conditions such as the selection of the pump, the selection of materials and the use site of the pump.
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