Air Tightness

Air tightness refers to the sealing performance of a product in preventing gas leakage or permeation. It is a key indicator for evaluating the sealing quality of packaging, containers, valves, pipes, and other products. In foreign trade, this term is commonly found in contract quality clauses, product specifications, inspection standards (such as ISO, ASTM), and customer complaint handling. Usage scenarios include: when exporting food, pharmaceuticals, and electronic products, packaging air tightness must be ensured to prevent moisture and oxidation; mechanical parts such as cylinders and tires must meet air tightness testing requirements. Precautions: test methods (such as pressure drop method, bubble method), test pressure, leakage rate standards, and acceptance criteria must be specified to avoid disputes caused by differences in standards. The difference from 'water tightness' lies in the medium: air tightness targets gas, while water tightness targets liquid; air tightness requirements are usually higher because gas molecules are smaller and more prone to leakage. Compared with 'sealing performance,' air tightness is more specific and quantifiable. Foreign trade practitioners should specify air tightness grades and testing standards in contracts and retain test reports as evidence.