EN 13922-2020 pdf download.Tanks for transport of dangerous goods – Service equipment for tanks – Overfill prevention systems for liquid fuels.
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 rns.
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 tank- vehicle 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 kfl, 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 6 1000-6-4 for emission;
— EN 61000-4-3 for immunity.
6.1.5 Circuit interlock (optional)
When included within the overfill prevention system, the circuitinterlock (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 k16.
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.
6.2 Sensors
6.2.1 General
Any of the following types of sensors may be used:
— two-wire system: negative temperature coefficient (NTC) thermistor, optic or other compatible device;
— five-wire system: optic or other compatible device;
— sensor circuit.
6.2.2 Two-wire system
Thermistor sensors shall have a NTC and shall work in the temperature range from —20 °C to +50 °C. Thermistor sensors have a warm-u p time which shall not exceed 75 s with the thermistor sensor at an ambient temperature of —20 °C.
NOTE I Optic sensors or other compatible sensors have a negligible warm-up time.
Two-wire sensors can be used on tank-vehicles with no more than 8 compartments. The overfill prevention controller shall always monitor 8 sensors and stop all loading if any sensor detects an overfill. Tank-vehicles equipped with two-wire sensors with less than 8 compartments shall employ an electronic dummy sensor for the unused channels of the controller.
These dummies shall form part of the tank-vehicle mounted equipment.
The electronic dummy sensor shall generate a permissive signal when it is connected to a controller.
The signal shall correspond to a wave form as shown in FigureA.1 with the values according to
Table A.4.
A two-wire optic or other compatible sensor shall work in the temperature range from —20 °C to +60 °C. When connected to a gantry controller, a dry sensor shall generate a permissive signal, which shall correspond to a wave form as shown in Figure A.l with the values according to Table A4.
NOTE 2 Sensor operating temperature range Is different from ambient temperature range because of the effect of direct sunlight on the tank.
6.2.3 Five-wire system
A five-wire optic sensor or other compatible sensors shall work in the temperature range from —20 °C to +60 °C. When connected to a gantry controller, a dry sensor shall generate a permissive signal, which shall correspond to a wave form as shown in Figure A.I with the values according to Table A.l.
NOTE Sensor operating temperature range is different from ambient temperature range because of the effect of direct sunlight on the tank.
6.2.4 Sensor circuit
A sensor circuit shall comply with the requirements according to 6.2.2 and 62.3 as applicable. 6.2.5 Response time
The reaction time from sensor going wet to the change of state of the signal at the interface socket shall not exceed 250 ms.EN 13922-2020 pdf download.