11.—(1) Any regulator fitted must be designed so that—
(a)it has a pre-set pressure and flow rating suitable for the part of the system to which it is attached;
(b)it incorporates a means of protecting the system downstream of the regulator from the upstream pressure in the event of failure of or leakage from the regulator;
(c)it is marked clearly and permanently with the fuel type, pressure and flow direction; and
(d)if the engine cooling system is utilised within the regulator, passage of gas into the engine cooling system is prevented.
(2) Any pressure relief device on a regulator must comply with the requirements of paragraph 6(3) to (7).
(3) Any regulator must be so installed that—
(a)it is in an accessible position for inspection and maintenance;
(b)it is in a position where it is protected from heat sources;
(c)it is in a position where, as far as is practicable, any ventilation holes are prevented from being blocked; and
(d)it is securely attached to a secure mounting.
(4) Where a regulator is to be located in the driver, passenger or living compartment, or in the vehicle boot or in any other space which is not so ventilated as to prevent the accumulation of gas, it must be enclosed in order to contain any gas leakage, either by—
(a)placing the gas container and its fittings within a durable enclosure which is—
(i)sealed so that it is gas tight to the compartment, vehicle boot or space, as the case may be; and
(ii)provided with permanent direct ventilation to the outside of the vehicle; or
(b)enclosing the neck and fittings of the gas container within a durable envelope which is—
(i)gas tight to the compartment, vehicle boot or space, as the case may be; and
(ii)provided with direct permanent ventilation to the outside of the vehicle.
(5) A regulator may not be attached directly to the engine or to any part ancillary to the engine.