Pump Cavitation Types and Applications

The pump cavitation can be formed due to the vapor bubble implosion within a pump. These bubbles occupy space within the pump so the operating pressure, as well as the flow of the pump, can be affected. When the bubbles are extended instead of carrying more fluid into the pump, then the motor energy can be wasted at the low power regions of the pump. When the bubbles flow into high-pressure regions of the pump, the energy of the motor can be wasted because of the bubbles reduction instead of expanding the fluid from the pump. The vapor bubbles can fall down when they flow from the low-pressure region to the high-pressure region within the pump. So the fluid hits the parts of metal at the sound speed. The sound which is produced from the gas bubbles impacts into the parts of metal within the pump makes sounds like stones & pumping marbles.

What is Pump Cavitation?

The pump cavitation can be defined as it is the formation of a vapor bubble within the pump otherwise cavities in the fluid around an impeller at low pressure. When the bubbles in the pump are collapsed then activate strong shockwaves within the pump, which results in major injury to the impeller of the pump.

There are many reasons for causes of pump cavitations which include Impeller failure, extreme vibration, and decrease of the flow, superior to required power utilization, increase in temperature, an increase in liquid velocity, unwanted liquid flow conditions caused by obstacles and reduced flow or force.

Types of Pump Cavitation

There are two types of pump cavitations namely suction cavitation and discharge cavitation.

suction-cavitation-and-discharge-cavitation
suction-cavitation-and-discharge-cavitation

1). Suction Cavitation

The suction cavitation occurs when a pump is below low-pressure otherwise high-vacuum conditions. When the pump does not receive sufficient liquid flow, then cavities otherwise bubbles will form at the impeller’s eye. When the bubbles take over to the expulsion face of the pump, then the condition of fluid will change, reducing the bubble in the direction of fluid & cause it to collapse adjacent to the impeller face.

An impeller has fallen victim toward suction cavitation which will include huge chunks otherwise extremely small bits of material missing, causing it to appear similar to a sponge. This type of cavitation can cause due to some reasons which include the following.

  • Clogged filters otherwise strainers
  • Obstruction within the pipe
  • Pump runs too far exact on the curve of the pump
  • Piping design is poor
  • Suction condition is poor

2). Discharge Cavitation

The discharge cavitation occurs when the expulsion force of a pump is very high. As the expulsion pressure is high, the flow of fluid will difficult to flow out from the pump, Thus it flows within the pump among the impeller as well as the housing at extremely high velocity, that will cause a vacuum on the housing divider & the formation of the bubble.

In this type of cavitation, the collapse of bubbles will activate strong shockwaves that will cause the pumps housing and the impeller tips. Then this type of cavitation is the reason for the impeller shaft toward the break. This type of cavitation can cause due to some reasons which include the following.

  • Obstruction within the pipe at expulsion side
  • Strainers otherwise Clogged filters
  • Pump runs too far exact on the curve of the pump
  • Piping design is poor

Signs of Cavitation

Whenever any mechanical or structural issue occurs, it is very essential to maintain a reliable process for checking the act of pump to recognize the premature caution indications of cavitation. The following one or more symptoms can cause cavitation.

  • Noise
  • Reduced Flow otherwise force
  • Failure of bearing or seal
  • Unpredictable power use
  • The gradual destruction of an impeller
  • Sudden vibrations

Cavitation Prevention

When the pumps are facing cavitation problems, then the prevention can be done using the following methods.

  • Verify filters as well as strainers once because blocks on the suction, otherwise expulsion side can cause an inequity of force within the pump
  • Mention the curve of the pump by employing a pressure gauge & a flow meter for recognizing the pump working over the curve, and confirm its functionality at its finest efficiency end.
  • Re-examine the design of pipe by ensuring the lane of the liquid flow from your pump which is perfect for the working conditions of the pump.

Pump Cavitation NPSH Formula

The full form of NPSH is Net Positive Suction Head, and it can be defined as the main disparity among the inlet pressure level as well as the lowest pressure level within the pump. In the primary section of the pump, the force reduces before it enhances the expulsion face in the direction of an upper level than the intake force.

The formula for calculating Net Positive Suction Head (NPSH) is

NPSH = PT-Pv/ρg

Where,

PT = Inlet total pressure
Pv = Vapor pressure of the fluid
Ρ = density
G = acceleration of gravity.

Thus, this is all about pump cavitation. Once the prevention of cavitation can be done then the lifespan, as well as the efficiency of the pump, can be increased. The prevention of cavitation is worth a thousand treatments. So, notice a fault pump before it turns into the main problem by taking the time to maintain a pump to run a long time. Here is a question for you, what are the different types of cavitations?

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