Anaesthesia Anaesthetic equipments 820d98b2 Pin code index of N2O is A 1,6 B 2,5 C 2,6 D 3,5 High-Yield Explanation PIn index provides prevention of wrong attachments of cylinders . N20 - 3 ,5 O2 - 2 , 5 C02 (Gas) - 1 ,6 . ( Liquid below 88F ) 2 , 6 ; Cyclopropane 3 , 6 .