The Carriage of Dangerous Goods by Road Regulations 1996

9.  The competent person shall be in charge of the storage tank for the purpose of the delivery and shall not permit delivery into that tank to commence—

(a) unless the tank has immediately before the delivery been measured with a dipstick or other suitable measuring device and the measurement has shown that the quantity of petrol proposed to be delivered can safely be received by that tank; and

(b) until—

(i) the hose (whether a single length or segmented) through which the petrol will be delivered ( “the delivery hose”) is connected to the filling point of that tank, and

(ii) (where the provisions of paragraph 7 apply to the delivery) the vapour balance hose is secured to the vapour balance pipe before the delivery hose is connected as aforesaid;

(c) (in any case where there is a separate dipping opening in the storage tank) until that dipping opening has been securely closed; and

(d) (where siphon pipes link storage tanks at the licensed premises and none of the linked tanks is fitted with a mechanical overfill prevention device) until the tank has been isolated from the other storage tanks by the closure of suitable valves,

and shall not as respects that tank sign his name on the certificate referred to in paragraph 10 until he has complied with the appropriate requirements of sub-paragraphs (a) to (d) of this paragraph.