When Table 1 requires a cargo's containment system to have a restricted gauge, the containment system must have:

1. (a) A closed gauging system; or

2. (b) A system that has:

   1. (1) A restricted gauge (e.g., a sounding tube) with an orifice diameter not exceeding 20 cm (approx. 7.8 in.);
   2. (2) A permanently attached gauge cover that is vapor tight when in place; and

   3. (3) A venting system that has either:

      1. (i) Lock open PV valves; or
      2. (ii) Valved bypasses around the PV valves.