9.—(1) No person may stun a pig by exposure to gas unless—
(a)the gas stunner provided for that purpose, including any equipment used for conveying a pig through the gas mixture, is designed, constructed and maintained so as to enable each pig—
(i)to remain upright until it loses consciousness; and
(ii)to see other pigs as it is conveyed into the chamber;
(b)adequate lighting is provided in the gas stunner and conveying mechanism to allow pigs to see other pigs or their surroundings;
(c)the gas stunner is equipped to maintain the required gas concentration (in accordance with Table 3 of Chapter I of Annex I) in the gas stunner;
(d)there is a means of flushing the gas stunner with atmospheric air with the minimum of delay; and
(e)there is a means of access to any pig with the minimum of delay.
(2) The business operator of a slaughterhouse and any person engaged in the stunning of pigs by exposure to gas must ensure that—
(a)no pig enters the gas chamber if the displayed concentration by volume of carbon dioxide falls below the required gas concentration; and
(b)no pig is allowed to pass through or allowed to remain in the chamber at any time when the visible and audible warning signals have been activated or when there is any defect in the operation of the chamber.