Can I drink when wearing my respirator?

Yes, with the exception of Avon PC50 respirator variants, which are not fitted with a drinking system. Canteen caps with Avon drink couplers are available that fit to standard water canteens. These allow fail safe connection to the integral hydration tube on the respirator (a variety of caps are available for in-service canteens).
Avon Protection also offer the CBR50i Chem Bio Reservoir as an additional accessory which is engineered to integrate with suitable Avon Protection respirators without the need for cumbersome adaptors. The CBR50i provides up to 3 litres of safe drinking water enabling the wearer to operate for long periods of time whilst wearing full CBRN protection clothing.