Section 096-120-4 - Tightness StandardA. A tank truck subject to the provisions of this Chapter may sustain a pressure change of no more than 3 inches of water over five consecutive minutes when pressurized to a gauge pressure of 18 inches of water or when evacuated to a gauge pressure of 6 inches of water when tested using the procedure specified in Section 5. B. A tank truck certified according to Section 5 must remain leak-tight for the 12 months following the certification test. To verify that this requirement is being met, spot checks with a combustible gas detector must not reveal readings equal to or greater than 100 percent LEL (measured as 2.2 percent propane or equivalent percent of another calibration gas by volume in air) when measured at a distance of one inch (2.5 cm) from potential leak sources, and no visible or audible liquid or vapor leaks must be observed.06- 096 C.M.R. ch. 120, § 4