Mechanical seal is a device which helps join systems or mechanisms together by preventing leakage. mechanical seal or mechanical dam is one of safest industrial companents which its purpose is to control fluids, solids or gases leakage to the outside of their sorrounding system which has two flat surfaces, one is stationary which has installed on the pumo vessel, and one is moving which has installed on the pump rotation shaft. the pressure of pumped component and capillary force, make a thin layer of fluid on tthe surface of seal which results in lubricating surfaces. working of seal in dry conditions will result in damages to its surfaces