CPC Main Group G01M 3/00 Investigating fluid-tightness of structures 6 direct subcodes Child Classifications Navigate with arrow keys, Enter to open G01M 3/002 G01M 3/005 G01M 3/007 G01M 3/02 by using fluid or vacuum G01M 3/38 by using light (G01M3/02 takes precedence) G01M 3/40 by using electric means, e.g. by observing electric discharges