--- title: HOW TO AVOID CAVITATION OF DIAPHRAGM PUMPS description: Cavitation can result in a critical outcome for the operation of a diaphragm pump. Find out how to avoid it and to solve the most common diaphragm pump problems. Download our trubleshooting manual. image: https://blog.comet-spa.com/hubfs/cavitazione_diaphragm%20pump-2.jpg --- - [EN](https://blog.comet-spa.com/cleaning-en) - [IT](https://blog.comet-spa.com/cleaning-it) - [B2B](http://webup.comet.re.it/) - [Job and Careers](https://joinus.emakgroup.net/areapubblica/Registrati.aspx) [YouTube](http://www.youtube.com/channel/UCef353b7MfpEv6dCix0o2lw)[Facebook](https://www.facebook.com/Cometgroupspa)[LinkedIn](https://www.linkedin.com/company/comet-s-p-a-) [![logo](https://blog.comet-spa.com/hs-fs/hubfs/Loghi/logo.png?width=248&name=logo.png)](https://comet-cleaning.com/en) - [BLOG](https://blog.comet-spa.com/cleaning-en) - [PRESSURE WASHER](https://comet-cleaning.com/en/pressure-washers) - [FLOOR CARE](https://comet-cleaning.com/en/floorcare) - [CONTACT](https://comet-cleaning.com/en/contact) Search for: # HOW TO AVOID CAVITATION OF DIAPHRAGM PUMPS By [Comet](https://blog.comet-spa.com/diaphragm-pumps/author/comet) | April 1st, 2019 | Categories: Diaphragm Pumps, Agricultural Pumps, Diaphragm Pump Problems | [3 Comments](https://blog.comet-spa.com/diaphragm-pumps/how-to-avoid-the-cavitation-of-diaphragm-pumps-in-a-spraying-machine#comments-listing) [![HOW TO AVOID CAVITATION OF DIAPHRAGM PUMPS](https://blog.comet-spa.com/hubfs/cavitazione_diaphragm%20pump-2.jpg)](https://blog.comet-spa.com/diaphragm-pumps/how-to-avoid-the-cavitation-of-diaphragm-pumps-in-a-spraying-machine) [Cavitation is a physical phenomenon](http://www.physics.org/article-questions.asp?id=134) which consists in the formation of areas of vapour inside a fluid.   ![cavitazione\_img1\_IT EN](https://blog.comet-spa.com/hs-fs/hubfs/cavitazione_img1_IT%20EN.png?width=300&name=cavitazione_img1_IT%20EN.png) *The liquid is transformed into vapour bubbles, which once in the delivery line where the pressure is positive, return to liquid state and implode due to compression, generating an intense shock wave which attacks the diaphragms, the valves and the heads with serious damage.* The phenomenon of cavitation is of great importance and **possible critical outcome** for the operation of a **spraying machine**. Let us find out why. ## **When does cavitation occur**? When pressure drops, the fluid tends to expand in volume. This is the basic principle of any pumping system, so **a fluid placed in two environments at different pressures tends by its very nature to expand to compensate for this Δ,** moving from the higher-pressure environment to the lower-pressure environment. In practice, the Δ pressure generates a downward movement of the fluid, then a rise, and in short, pumping. However, when the pressure is lowered beyond a certain threshold, **the fluid expands so much that it passes from the liquid to the gaseous state,** in the form of bubbles (real cavities) containing vapour. This can have very negative consequences on both the pump and the machine. [![Scarica la Guida | Pompe a membrana: Installazione Diagnostica e Risoluzione dei Problemi](https://hubspot-no-cache-eu1-prod.s3.amazonaws.com/cta/default/5415755/983b7a7e-694c-433c-8766-cb081fb0df30.png)](https://hubspot-cta-redirect-eu1-prod.s3.amazonaws.com/cta/redirect/5415755/983b7a7e-694c-433c-8766-cb081fb0df30) In a pumping system, the causes of cavitation can vary:  - **bottlenecks in the suction pipe** - **excessive length of the pipe itself** - **excessive difference in level between** **the supply basin and the pump**, i.e. greater than the pump's head capacity. **Head** means the ability of a pump to raise a certain volume of liquid to a certain height. In other words, it is the maximum lifting height difference that can be achieved with a given pump. In case of cavitation, the vapour bubbles rise from the suction pipe towards the diaphragm pump, where they undergo a drastic increase in pressure (in practice they are crushed violently) and this causes a violent implosion, recognizable by a characteristic noise, i.e. as if gravel was passing through the pump.  These violent shocks lead to a significant erosion of the components of the diaphragm pump, which can cause valve rupture, diaphragm tearing, and even real head fractures. ## **Can cavitation be avoided?** Yes, to prevent cavitation it is necessary to ensure that the negative pressure on the suction line never exceeds the limits set by the pump. This is achieved: - by avoiding sucking in water from excessive depths (maximum 4 metres); - by avoiding bottlenecks on the suction line: the pipes must be reinforced (spiralled) to prevent the walls from sticking to each other, blocking the passage towards the pump; - by cleaning the suction filters daily; - by reducing to a minimum the curvatures of the circuit and the use of ball valves on the suction line; - by using pipes with dimensions equal to or greater than the diameter of the suction connection of the pump. It is better to avoid using smaller pipes. - By avoiding the use of reducers and possibly elbow fittings. - By checking with a vacuum gauge that the negative pressure on the suction line of the installed pump **never exceeds -0.3 bar**. [Regular maintenance](https://www.comet-spa.com/agricultural/#manutenzione) is always highly recommended to avoid problems and malfunctions, and to extend the life of your diaphragm pumps. ![cavitazione\_img2\_EN](https://blog.comet-spa.com/hs-fs/hubfs/cavitazione_img2_EN.png?width=803&name=cavitazione_img2_EN.png) [![Scarica la Guida | Pompe a membrana: Installazione Diagnostica e Risoluzione dei Problemi](https://hubspot-no-cache-eu1-prod.s3.amazonaws.com/cta/default/5415755/983b7a7e-694c-433c-8766-cb081fb0df30.png)](https://hubspot-cta-redirect-eu1-prod.s3.amazonaws.com/cta/redirect/5415755/983b7a7e-694c-433c-8766-cb081fb0df30) #### Share This Post! 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