The vacuum pump starts the winding and transpiration system respectively to investigate whether the reading of the vacuum gauge climbs after a short decline, which can preliminarily judge the direction of the internal leakage point. The internal leakage mostly occurs on the equipment with water cooling points. No doubt is found in the external leakage inspection, but there are the following phenomena: the pumping speed of the mechanical pump is significantly low, the indication value of the vacuum gauge is low, and the mechanical pump oil emulsifies quickly. The iron-based parts in the vacuum chamber are significantly rusted. With the above conditions, it is basically possible to guess the internal leakage. First clean the cavity, then pass the cooling water, and carefully check whether the water pipeline has wet points. The wet points are the leakage points. The ionization tube can be used to detect the leakage by being sensitive to some gases under high vacuum, such as or ethanol, Use a medical syringe to spray or ethanol into the suspected area. Combined with the pointer vacuum gauge, the pointer of the ionization gauge will swing significantly when it is sprayed to the leakage point. In this way, you must be patient to detect the leakage. Wait until the indication of the ionization gauge is stable, that is, the extraction capacity and leakage rate of the vacuum unit are balanced, then erupt, repeat several times, recognize the leakage point, and pay attention to several links in repair, disassembly, cleaning, inspection and installation, It is important that vacuum equipment, large or small, be attributed to precision mechanical equipment.