A carbon canister as utilized relative to underground fuel storage tank vapor recovery, including for the capture and purging of hydrocarbon vapors as air is introduced into and released from an underground storage tank, and wherein, in one form intended primarily for use in Stage II Vapor Recovery systems, the carbon canister includes a valve activated by weight of saturated carbon and wherein, in another form intended primarily for use in Stage I Vapor Recovery systems, the carbon canister is a free breathing carbon canister with a surge protection device.