The primary and mating seal faces are lapped to a maximum of 3-helium light bands flatness to provide effective sealing and leakage protection.是什么意思_The primary and mating seal faces are lapped to a maximum of 3-helium light bands flatness to provide effective sealing and leakage protection.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句