REQUIREMENTS FOR THE CONSTRUCTION, EQUIPMENT, TYPE APPROVAL, INSPECTION AND MARKING OF VACUUM-OPERATED WASTE TANKS

NOTE 1: For portable tanks and UN multiple-element gas containers (MEGCs) see Chapter 6.7; for fixed
tanks (tank-vehicles), demountable tanks and tank containers and tank swap bodies, with shells made
of metallic materials, and battery-vehicles and multiple element gas containers (MEGCs) other than
UN MEGCs see Chapter 6.8; for fibre-reinforced plastic tanks see Chapter 6.9.
NOTE 2: This Chapter applies to fixed tanks, demountable tanks, tank-containers and tank swap bodies.

General

Definition

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
generating line;
(b) The top part of the tank in a zone which extends over a 30° angle on either side of the top
generating line;
(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
9.7.6.

Scope

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 4.3.4.1.1).
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
6.8.2.1.19, 6.8.2.1.20, and 6.8.2.1.21 shall not apply.

Construction

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 6.10.1.1.1).

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
device.

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
ground.

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
unintended opening.

The tanks may be equipped with openable ends. Openable ends shall comply with the following
conditions:
(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.
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