In this Schedule—

• “pressure vessel” means a tank container or the carrying tank of a road tanker which is—

  1. a

     used or intended to be used for the carriage of dangerous goods—

     1. i

        at a pressure of more than 500 millibar above or below atmospheric pressure; or

     2. ii

        at a pressure of 500 millibar or less above atmospheric pressure if that pressure is maintained by artificial means and would rise above it if such means were no longer employed; or

  2. b

     loaded or discharged at a pressure of more than 500 millibar above or below atmospheric pressure;

• “tube container” means a group of transportable pressure receptacles connected with a total capacity greater than 3 cubic metres, fitted into a framework suitable for lifting on or off a vehicle and intended to be used for the carriage of compressed gases;

• “tube trailer” means a trailer which has more than one transportable pressure receptacle structurally attached to, or forming part of, the trailer and which is intended to be used for the carriage of compressed gases.