Disclosed is an apparatus for installing a carbon dioxide absorbent canister which comprises a body, a lifting member, and a lifting mechanism. The body comprises a breathing circuit and an adapter for connecting the carbon dioxide absorbent canister with the breathing circuit. The adapter is located at or near the bottom of the body. The lifting member comprises a base portion, a positioning portion beneath the adapter, and a connecting portion. The lifting mechanism has a force receiving portion and a force, applying portion and which actuates the lifting member. Actuating the handle in the first direction causes the canister to be connected to the breathing circuit and to close the breathing circuit bypass. Turning the handle in a second direction actuates the canister to enable replacement of the canister and to cause the breathing bypass to open. The process can be achieved simply with one hand.