What is Cavitation in Hydraulic Pump & How to Prevent it

Hydraulic pumps are used in various industries to pump liquid, fluid, and gas. Although this equipment features robust construction, it may fail at times due to various issues. Cavitation is one of the serious issues faced by this equipment. Like all other technical issues, right planning as well as troubleshooting will help avoid this issue to a large extent. What is pump cavitation and how to troubleshoot these it?

Pump Cavitation

What is Pump Cavitation and How It May Affect Your Pump?

It is seen that many times, hydraulic pumps used for pumping liquids may face a partial pressure drop. This changed pressure may produce air bubbles inside the pump, which leads to a cavity creation. The liquid inside the pump is turned into vapor due to change in pressure, and they are converted back to liquid by spinning impellers. This produce air bubbles, which constantly move inside the pump. These air bubbles implode during pressure change, and they erode the surface of the impeller, thereby causing a cavity. Strong cavitation that occurs at the impeller inlet may lead to pump failure. Pump cavitation usually affects centrifugal pumps, which may experience several working troubles. At times, submersible pumps may also be affected by pump cavitation.

What Are Different Types of Cavitation?

The following are the two types of cavitation based on their effect:

  • Inertial Cavitation: In this type of cavitation, a shock wave is produced when a bubble or void present in a liquid collapses.
  • Non-inertial Cavitation: This type of cavitation is initiated when a bubble in a fluid undergoes shape alterations due to an acoustic field or some other type of energy input.

Cavitation is distinguished into two types based on different conditions:

  • Suction Cavitation: This cavitation is brought by high vacuum or low-pressure conditions that may affect the flow. These conditions will reduce the flow, and bubbles will be formed near the impeller eye. As these bubbles move towards the pump’s discharge end, they are compressed into liquid, and they will implode against the edge of the impeller.
  • Discharge Cavitation: Here, cavitation occurs when the pump’s discharge pressure becomes abnormally high, which in turn affects its efficiency. High discharge pressure will alter the flow of fluid, which leads to its recirculation inside the pump. The liquid will get stuck in a pattern between the housing, as well as the impeller, thereby creating a vacuum. This vacuum creates air bubbles, which will collapse and damage the impeller.

What Are the Common Causes of Pump Cavitation?

Pump cavitation may be brought by several factors. However, the following are a few common factors:

  • A large distance between the fluid source and the pump
  • Small diameter of the suction pipe
  • High running speed of the pump
  • Low liquid pressure
  • Too many fittings on the suction pipe

How to Recognize a Cavitation in a Hydraulic Pump?

There are several ways to recognize cavitation, and the following are a few quick symptoms to be taken care of:

  • Sound: The pump affected by cavitation will produce a marble, rock, or gravel type of sound when in motion. The sound will begin as a small disturbance and its intensity will increase as the material slowly chips away from the surface of the pump.
  • Metallic Debris: If during the maintenance, you find metallic debris on the filter of the hydraulic pump then it may be a symptom of cavitation. One of the easiest ways to confirm it is to check the filter. If any debris is found, you should clean the entire system, and thoroughly inspect the pump.
  • Damage: This is one of the most obvious symptoms of cavitation. If you already know that the pump is damaged, you need to remove its filter, open, and inspect it thoroughly. If you find a lot of metal inside the filter, then flush the entire system, and check for damages in other parts, too.

If you notice any of the above-discussed symptoms, the next step would be to identify the causes, and rectify the changes, otherwise, it may affect other components, too.

Easy-to-Follow Tips to Prevent Cavitation

Many times, cavitation becomes irreversible; however, the following tips will help you take appropriate measures and reduce its severity.

  • Avoid using suction strainers: These are designed to inhibit the ingestion of grime and dirt. However, these strainers do not succeed in their purpose, because they are not designed to entrap large particles. These large particles may get deposited in the flow path, thereby affecting the flow of fluid. The deposition also creates pressure, and produces bubbles, which may lead to cavitation.
  • Clean the reservoir: A dirty reservoir is one of the most common causes of cavitation. Various types of small and large objects may block the suction tube, and create pressure, thereby causing cavitation.
  • Use properly sized components: This is one of the important factors of cavitation prevention. If the inlet plumbing is too large, there will be too much liquid flow, which may trigger cavitation. Hence, check with the pump manufacturer to ensure that properly sized components are being used in the pump.

In addition to these preventive steps, you must source hydraulic pumps from a trusted manufacturer or supplier. J&M Industrial is one of the industry-leading provider of unused and used hydraulic pumps from industry-leading brands. These pumps can be availed at cost-effective prices.