BS EN 13922-2020 pdf free download.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 non-permissive state.
The overfill prevention system shall be fail safe and shall be self-checking. The effective cycle time
between self-checks shall be less than the overfill response time.
The overfill prevention response time shall not exceed 700 ms.
The overfill prevention system shall be capable of handling up to and including the following number of
compartments for each type of installation:
— Two-wire system 8 compartments;
— Five-were system 12 compartments.
No signals other than those defined in the standard are allowed.
6.1.2 Earthing
The overfill prevention system shall provide an electrical connection from the gantry earth to the tankvehicle chassis via the cable and connection plug and socket and shall continuously verify this
connection throughout the loading operation.
To comply with the transport regulations (ADR), a good electrical connection from the tank vehicle chassis to earth shall be established before tanks are filled or emptied.
Should the electrical resistance of the connection exceed a maximum of 10 kΩ, the gantry controller shall switch to non-permissive state.
6.1.3 Severe environmental condition
Where the overfill prevention system is subjected to temperatures outside the specified temperature range all applicable temperature values shall be extended. All other requirements shall remain
unchanged.
6.1.4 Requirements for electromagnetic compatibility (EMC)
The overfill prevention system shall fulfil the requirements of:
— EN 61000-6-4 for emission;
— EN 61000-4-3 for immunity.
6.1.5 Circuit interlock (optional)
When included within the overfill prevention system, the circuit interlock (switch) shall provide the function of the vapour collection detection interlock described in 5.3 and shall be connected as shown
in Figures A.4 and A.5.
6.1.6 Electrical interface
At the plug/socket interface each sensor or sensor circuit shall be suited for controller’s intrinsically safe parameters. The electrical connections of the 10-pin-socket shall comply with Table A.16.
The cable used shall comply with Table A.9 and EN 60079-14.
6.1.7 Interoperability of sensors
Sensors connected directly to the 10-pin socket as shown in Figures A.4 and A.5, shall be interoperable,but not necessarily mechanically interchangeable.
Sensors connected indirectly (i.e. through an additional electronic device) to the 10-pin socket as shown in Figures A.4 and A.5, may not be interoperable.
6.1.8 Tank vehicle identification device (optional)
When included with the overfill prevention system, a tank vehicle identification device shall provide a unique identification number using a 1-wire protocol, as shown in Figures A.4 and A.5.BS EN 13922 pdf download.