7. No person may stun pigs or poultry by exposure to gas unless the gas stunner provided for that purpose, including any equipment used for conveying the pigs or poultry through the gas, is—
(a)designed, constructed and maintained so as to avoid any injury to a pig or bird; and
(b)equipped with devices to—
(i)measure and continuously display the required concentration of gas (in accordance with Table 3 of Chapter I of Annex I); and
(ii)give clearly visible and audible warning signals if the gas concentration falls below the required level (in accordance with Table 3 of Chapter I of Annex I).