The vacuum leak testing procedure is as follows: positive pressure leak testing → leak sealing → negative pressure leak testing... until the equipment's airtightness meets the standard. Positive pressure leak testing involves filling the equipment with a certain pressure of nitrogen and using soap water to inspect each copper pipe, weld seam, etc., for any leakage points. Any leakage must be sealed until it is no longer present. After positive pressure leak testing and leak sealing have been passed, it does not necessarily mean the equipment is not leaking. A negative pressure leak test must also be conducted. The high vacuum negative pressure leak test results are the standard for determining the equipment's airtightness. The pressure should be less than 10mmHg, with a continuous pressure rise of 0.2mmHg or less within 24 hours to be considered passable. If these standards are not met, a retest is required.