9.—(1) Any filling connector for the refuelling of the vehicle must be of a type which is used exclusively for natural gas filling and which is compatible with the filling nozzle without the use of an adapter fitting.
(2) Gas must be prevented from flowing back from the gas container to the filling connector.
(3) Any filling connector must be covered with a dust cap, which is secured permanently to the vehicle.
(4) Where a filling connector is placed on the outside of the vehicle, it must be protected against unauthorised interference.
(5) The filling connector must be located outside the driver or passenger compartment in a suitably protected, well-ventilated and readily accessible position, away from any openings in the driver, passenger or living compartment.