what is cavitation in mechanical pump ?

Answer 1

When there is air in the pump allowing the impeller to bypass

Answer 2

Cavitation occurs as a result of vaporization of the pumped liquid.

What you are hearing is actually the collapsing of the bubbles that are formed, not the formation of the bubbles.

What is happening at the suction to a pump is that the pressure is dropping.

Theoretically, this drop in pressure occurs because the velocity of the liquid is increasing and "pressure energy" is being converted to "velocity energy."

A liquid that is close to it's "boiling point" will then start to boil in the suction of the pump. (Even water can boil at room temperature if you drop the pressure low enough. A well pump sucking water upwards 20-25 feet is an example of a system where there is actually a vacuum at the pump suction, and water might be boiling at room temperature.)

After the vapor passes through the pump, and the pressure increases, the vapor is no longer at it's boiling point for the pressure that exists, and the bubbles will collapse. The sound you hear is the liquid essentially hitting itself as the bubble collapses.

Believe it or not, the injection of air can actually decrease the sound of cavitation, since the air would not completely collapse. The air, however, could also "gas up" the pump and cause it not to pump at all.

You would hear the same sort of sound if you inject steam into cold water. The steam would immediately condense and collapse causing a hammer or cavitation sound. If you inject steam into cold water with a small amount of air you will near no hammer what so ever.

I have done this so I know it works.

Added Comment:
It should be noted that the damage done by cavitation is due to the hammer created by the collapse of the vapor bubbles, not by the formation of the bubbles. Impeller and pump casing damage is the typical damage and it is usually in the form of pitting and gouging of those components.

While air injection through the seal if the seal were leaking and the pump suction was operating under a vacuum would cause loss of pump performance, it by itself would not cause damage due to vapor bubble collapse.

The loss of pump performance could lead to a zero flow situation and then cause heating of the fluid in the pump which would cause the pumped fluid to vaporize.

All cavitation is an indication of a problem that requires an engineering analysis and a solution.

Answer 3

whilst the static tension of a liquid drops under the vapor tension of that liquid, most of the liquid will replace into gas and a bubble will seem. this could take place in 2 distinctive techniques - static and dynamic. Static cavitation is the place you have liquid interior a container (say, an hermetic piston), after which you strengthen the quantity of the container. The liquid will cavitate to fill the container (it can not merely be a vacuum) and the bubble will stay till you lower back decrease the quantity of the container. Dynamic cavitation occurs whilst an merchandise strikes at extreme velocity by using a liquid. the object could desire to be something from a propeller to a dolphin. because of the fact the object travels during the water, the static tension of the water drops on the 'withdrawing' area. If the object strikes speedy sufficient, the strain in specific areas will drop low sufficient to reason a cavitation bubble to look. the version with dynamic cavitation is that the bubble rapidly strikes into an stronger-tension section, and collapses very rapidly, producing a marvel wave. The marvel wave can led to harm to to the trailing edge of the object. Dolphins, tuna, and different speedy ocean creatures are limited of their precise velocity because of the fact cavitation will harm their pores and skin. Propellers can definitely have steel chipped off via the collapsing cavitation bubbles. the subject is even worse for propellers, because of the fact if it rotates speedy sufficient, one blade can enter the cavitation bubble of the previous blade, and the propeller will then spin even speedier because of to the low drag of the gas.

Answer 4

Cavitation means that cavities(bubbles) are forming in the liquid that we are pumping.
The cavities form for five basic reasons:
Vaporization
Air ingestion
Internal recirculation
Flow turbulence
The Vane Passing Syndrome
All type of cavitation is demaging to the pipes and pumps and reason for the cavitation should be eliminate.
You will fing detailed information on the referenced site.

Answer 5

It really means that the speed or the pitch of the propeller are not right. If the propeller has too much pitch for the speed, instead of pushing only water, air will be sucked in too, making the pump inefficient. You could define cavitation as sucking in air.

Answer 6

When liquid vaporizes around the impeller and you loose the prime. Or you get air sucked into the pump. The pump will only move liquids.

Answer 7

When the pump is pumping air instead of the liquid it was designed to pump

Answer 8

Cavitartion is caused when air is introduced into the intake of the pump, ie... low fluid level or air in the line.

Answer 9

The pump is not "pumping" fluid due to air in the system.

Answer 10

Bubbles are created in the water under certain conditions.