With the development of vacuum industry, water ring vacuum pump has been widely used. In use, the most troublesome problem for users is to detect the leakage rate of water ring vacuum pump. And its internal leakage and external leakage, external leakage is better detection, internal leakage is more difficult to do.

1. The internal leakage mostly occurs on the equipment with water-cooled jacket, and no doubt is found in the external leakage inspection. However, the following phenomena are found: the pumping speed of mechanical pump is obviously low, the indication value of vacuum gauge is low, the oil of mechanical pump is quickly emulsified, and the iron-based parts in vacuum chamber are obviously rusted. If the above conditions are met, internal leakage can be determined. First clean up the inner wall, and then pass on cooling water to see if there are wet points. The wet part is the leakage point.

2. Small leakage and micro leakage are more difficult to check. The common method is to use the ionization tube sensitive to some gases under high vacuum state to detect leakage, such as acetone or ethanol. Use a medical syringe to spray acetone or ethanol to suspicious places. When spraying to the leakage point, the pointer of the ionization meter will swing obviously. In this way, it is necessary to be patient and wait until the indication value of the ionization meter is stable, that is, the suction capacity and leakage rate of the vacuum unit are balanced, and then spray. It is best to repeat several times to confirm the leakage.

3. For larger leakage points, flame method can be used. Based on the principle that air flow can make flame deviate, vacuum is pumped first. For example, if a candle or a lighter is used to search the suspicious point step by step, and the flame will be found to shift to the leakage point, then the leakage point can be found.