Just before 2300 Sherburne Fire was dispatched to a possible propane fire behind Chenango Valley Pet Foods (CVPF) in the area of a large propane storage cylinder.  280 arrived to find flames coming from a vent pipe and near by fitting that feeds the ovens for CVPF from a 10,000 gallon storage tank near the fire.  284's crew determined there was no heat impinging on the storage tank and went to work with assistance from 287's crew in isolating the fire and shutting off the fuel.  Due to the location of the leak and associated fire several valves had to be closed to prevent back feeding the flames.