Suppose we have a vessel which is closed inside. We have water now Here I am considering water is at atmospheric pressure, then we are heating this water inside a closed container by supplying heat externally. When we are adding heat to this water it will evaporate and since it is at atmospheric pressure so the temperature required for evaporation would be a hundred degrees Celsius. Now when the temperature reaches 1000C at that time water molecules will be converted into vapor and this vapor will exert a pressure on this liquid water and hence this pressure would be called as “vapor pressure”. So here we have defined vapor pressure is the pressure exerted by the vapor on a liquid.
Now, this vapor pressure can change the vapor pressure for the atmospheric condition. We know that water will boil at 1000C but if we go on decreasing the pressure then water will boil at a temperature less than 1000C. so this vapor pressure value can change so this concept of vapor pressure it takes place even when the water is flowing and it is subjected to a difference in temperature.
See cavitations mean that if we have a pipeline and the water is flowing through that pipeline. When the water flows through the pipeline then suppose we have a low-pressure region. at this location suppose we have low pressure because of the low-pressure here the water would be converted into a vapor that is where we would be having air bubbles at the low-pressure region. These air bubbles which are formed in the low-pressure region when it goes to the high-pressure region these bubbles they would be collapsing.
When the bubble collapse there is a tremendous rise of pressure so because of that the walls of the pipe they get fitted. There would be we can say that pitting action on the pipeline cavitations. It is a phenomenon when the liquid passes from the low-pressure region to the high-pressure region. so cavitations it is a phenomenon when the liquid passes from low-pressure region to high-pressure region there is collapsing of the bubbles and because of this collapsing there is pitting action or we can say there would be small holes produced on the walls. So cavitations need to be avoided it means there should not be a region where air bubbles are formed. in simple terms when the water is flowing in the pipeline we try to avoid air bubble formation because of that air bubbles when they collapse suddenly there is tremendous rising pressure and because of that the walls of the pipeline will get pitted or it looks like it is corroded. There is corrosion taking place so this forces the cavitations phenomenon.
Hence in this article, we have seen what was Concept of Vapor Pressure and Cavitations (Cavitation in Pipeline). I hope everything is clear