(s) Refiner. A person is a refiner if such person or a related person (as defined in paragraph (m)(1) of this section) engages in the refining of crude oil (whether or not owned by such person or related person) and if the total refinery runs of such person and any related persons exceed 50,000 barrels on any day during the taxable year. A refinery run is the volume of inputs of crude oil (excluding any product derived from oil) into the refining stream. For purposes of this paragraph, crude oil refined outside the United States shall be taken into account. Refining is any operation by which the physical or chemical characteristics of crude oil are changed, exclusive of such operations as passing crude oil through separators to remove gas, placing crude oil in settling tanks to recover basic sediment and water, dehydrating crude oil, and blending of crude oil products.