4.—(1) If dangerous goods are being carried in tanks a telephone number where specialist advice concerning the dangerous goods in question can be obtained in English at any time during carriage shall be displayed—
(a)at the rear of the transport unit;
(b)on both sides of—
(i)any tank;
(ii)the frame of any tank; or
(iii)the transport unit; and
(c)in the immediate vicinity of the orange-coloured plates displaying the emergency action codes,
and shall be in black digits of not less than 30mm in height against an orange-coloured background.
(2) The phrase “consult local depot” or “contact local depot” may be substituted for the telephone number if—
(a)the name of the carrier is clearly identifiable from the marking on any tank or the transport unit;
(b)the Chief Fire and Rescue Officer (within the meaning of the Fire and Rescue Services (Northern Ireland) Order 2006(1)) has been notified in writing of the address and telephone number of the relevant local depot; and
(c)the said Chief Fire and Rescue Officer, as referred to in head (b), has indicated, in writing, satisfaction with the arrangements.