Carbon canister with valve activated by weight of saturated carbon

A device to remove hydrocarbon vapors from air discharged from a hydrocarbon source under ambient atmospheric pressure conditions while retaining control by a pressure relief valve during lower ambient pressure, comprising:

• a casing containing a substance adapted to remove hydrocarbon vapors from air wherein the inflow of air into said casing purges said substance of hydrocarbons and the outflow of air from said casing draws vapors from the hydrocarbon source through said casing for adsorption by said substance, wherein the repetitive inflow of air through said casing regenerates said substance;
• said casing having a screened bottom and an opposite screened top, and a rod extending through the centers of said screened bottom and said screened top;
• a weight actuated valve locating beneath said casing, said valve closing when said casing attains a predetermined weight of said substance including adsorbed hydrocarbons;
• an assembly locating within said casing and opposite said weight actuated valve locating outside said casing and in fluid communication with said casing, said assembly drawing air into said casing when said weight actuated valve has opened and the hydrocarbon source has attained a low pressure or when said weight actuated valve has closed and said casing has attained a lower pressure than atmospheric pressure;
• a secondary purge valve locating proximate said weight actuated valve, said secondary purge valve opening upon detecting pressure in the hydrocarbon source below approximately −1.75 inches of water then admitting air when said weight actuated valve is closed, and directing purged hydrocarbon vapors through said weight actuated valve into said hydrocarbon source wherein said weight actuated valve reopens upon said casing falling below the predetermined weight;
• and,
• a canister containing said casing, said weight actuated valve, and said secondary purge valve, said canister being in fluid communication with said hydrocarbon source and allowing said assembly fluid communication to the atmosphere, and said casing having a diaphragm seal to said canister opposite said hydrocarbon source;
• wherein said assembly prevents flow through the inlet for pressures in the hydrocarbon source in the range of approximately +0.25 inches of water to approximately −1.5 inches of water.