Which one of the following statements is not correct?
- ACavitation forms where the local pressure drops up to the vapour pressure condition due to increase in local velocity.
- BCavitation takes place in turbines, runners of pumps and spillways where local velocity increases considerably.
- CCavitation may be prevented by maintaining the ambient pressure relatively higher at probable points of occurrence by raising their levels.Correct
- DBoundaries likely to be affected by cavitation can be prevented against pitting by covering it with tough materials like stainless steel or rubber
Solution
Concept
Cavitation control
Step-by-step solution
1. Cavitation can be prevented by raising the local pressure, e.g. by lowering the machine. 2. "Raising their levels" reduces the pressure.
Explanation
Statement C is incorrect because raising the level lowers the ambient pressure.
Why the other options are wrong
A, B and D are correct statements.
Shortcut
Lower the machine to avoid cavitation.
Correct answer: C) Cavitation may be prevented by maintaining the ambient pressure relatively higher at probable points of occurrence by raising their levels.