9.—(1) Subject to sub-paragraph (2) a gauge connected to a gas container or to a pipeline shall be so constructed as to be unlikely to deteriorate under the action of the gas used or to be used and shall be so constructed and fitted that—
(a)no gas can escape into any part of the vehicle as a result of any failure of the gauge, and
(b)in the event of a failure of the gauge the supply of gas to the gauge can be readily stopped.
(2) Sub-paragraph (b) shall not apply to a gauge fitted as an integral part of a gas container.