BS EN 13922-2020 Tanks for transport of dangerous goods — Service equipment for tanks — Overfill prevention systems for liquid fuels.
4 Functions
4.1 To prevent overfilling of the tank-vehicle’s compartment by providing a fail-safe output to a gantry control system.
4.2 To provide a failsafe monitored earthing connection from the gantry to the tank-vehicle’s shell via
a bonding connection to the tank-vehicle’s chassis.
4.3 To provide visual indication of the status of the overfill prevention system.
5 Major components
5.1 Tank-vehicle mounted equipment
The following equipment shall be installed on the tank-vehicle as a minimum:
— one sensor or sensor circuit per compartment;
— one 10 pin socket;
— wiring to the sensors;
— earthing provision.
5.2 Equipment fitted at the gantry
The overfill prevention equipment mounted on the tank truck is operable when the following equipment is installed at a loading gantry:
— overfill prevention controller;
— one 10 pin plug and cable for connection to tank-vehicle socket.
5.3 Optional equipment
The overfill prevention system can provide the vapour collection detection safety interlock which prevents loading unless the vapour collection hose is connected to the tank-vehicle and the vapour transfer valve(s) is (are) open.
6 Characteristics
6.1 Overfill prevention system working characteristics
6.1.1 Overfill
The overfill prevention system shall be an electronic system, gantry based and gantry operated. The interface wiring shall be suitable for a two-wire or a five-wire overfill prevention system and the gantry based controller shall automatically detect the difference between either overfill prevention system through a standardized 10 pin plug and socket — see Figures A.2 and A.3 — and perform its functions.
Electrical specifications for the interface are included in Annex A.
The overfill prevention controller shall only provide a permissive signal to permit loading if, once connected, there is no system fault and no sensor is wet.
Upon an overfill condition or the detection of any overfill prevention system or controller fault, the controller shall switch to nonpermissive state.BS EN 13922 pdf download.