Lost wax casting for high pressure, vacuum casting, such as pump body, valve, pressure test should be done, to see if there are any holes casting defects.Test will have a certain pressure of the air (or water, oil, etc.) within the casting into the sealed cavity, such as casting penetration cracks, holes, etc., can appear leakage, thus found the defect position.Test pressure is usually more than 30-50% of work stress of castings, the strength of precision casting is a kind of examination.When the casting is not easy to form sealed cavity, thus to pressure test, the inspection of castings is the penetration of kerosene method of compactness.