NOTE: A tank which fully complies with the requirements of Chapter 6.8 is not considered to be a
"vacuum-operated waste tank".
The term "protected area" means the areas located as follows:
(a) The lower part of the tank in a zone which extends over a 60o angle on either side of the lower
(b) The top part of the tank in a zone which extends over a 30° angle on either side of the top
(c) On the end front of the tank on motor vehicles;
(d) On the rear end of the tank inside the protection volume formed by the device stipulated in
The special requirements of 6.10.2 to 6.10.4 complete or modify Chapter 6.8 and are applied to
vacuum-operated waste tanks.
Vacuum-operated waste tanks may be equipped with openable ends, if the requirements of Chapter
4.3 allow bottom discharge of the substances to be carried (indicated by letters "A" or "B" in Part 3 of
the tank code given in Column (12) of Table A of Chapter 3.2, in accordance with 184.108.40.206.1).
Vacuum-operated waste tanks shall comply with all requirements of Chapter 6.8, with the exception
of requirements overtaken by a special provision in this Chapter. However the requirements of
220.127.116.11.19, 18.104.22.168.20, and 22.214.171.124.21 shall not apply.
Tanks shall be designed for a calculation pressure equal to 1.3 times the filling or discharge pressure
but not less than 400 kPa (4 bar) (gauge pressure). For the carriage of substances for which a higher
calculation pressure of the tank is specified in Chapter 6.8, this higher pressure shall apply.
Tanks shall be designed to withstand a negative internal pressure of 100 kPa (1 bar).
Items of equipment
The items of equipment shall be so arranged as to be protected against the risk of being wrenched off
or damaged during carriage or handling. This requirement can be fulfilled by placing the items of
equipment in a so called "protected area" (see 126.96.36.199.1).
The bottom discharge of shells may be constituted by external piping with a stop-valve fitted as close
to the shell as practicable and a second closure which may be a blank flange or other equivalent
The position and closing direction of the stop-valve(s) connected to the shell, or to any compartment
in the case of compartmented shells, shall be unambiguous, and be able to be checked from the
In order to avoid any loss of contents in the event of damage to the external filling and discharge
fittings (pipes, lateral shut-off devices), the internal stop-valve, or the first external stop-valve (where
applicable), and its seatings shall be protected against the danger of being wrenched off by external
stresses or shall be so designed as to withstand them. The filling and discharge devices (including
flanges or threaded plugs) and protective caps (if any) shall be capable of being secured against any
The tanks may be equipped with openable ends. Openable ends shall comply with the following
(a) The ends shall be designed to be secured leaktight when closed;
(b) Unintentional opening shall not be possible;
(c) Where the opening mechanism is power operated the end shall remain securely closed in the
event of a power failure;
(d) A safety or breakseal device shall be incorporated to ensure that the openable end cannot be
opened when there is still a residual over pressure in the tank. This requirement does not apply
to openable ends which are power-operated, where the movement is positively controlled. In
this case the controls shall be of the dead-man type and be so positioned that the operator can
observe the movement of the openable end at all times and is not endangered during opening
and closing of the openable end; and
(e) Provisions shall be made to protect the openable end and prevent it from being forced open
during a roll-over of the vehicle, tank-container or tank swap body.
Vacuum-operated waste tanks which are fitted with an internal piston to assist in the cleaning of the
tank or discharging shall be provided with stop-devices to prevent the piston in every operational
position being ejected from the tank when a force equivalent to the maximum working pressure of the
tank is applied to the piston. The maximum working pressure for tanks or compartments with
pneumatic operated piston shall not exceed 100 kPa (1.0 bar). The internal piston shall be constructed
in a manner and of materials which will not cause an ignition source when the piston is moved.
The internal piston may be used as a compartment provided it is secured in position. Where any of the
means by which the internal piston is secured is external to the tank, it shall be placed in a position not
liable to accidental damage.