9. The following fuel oil shall be exempt from the tax established in section 7:(a) bunker fuel, crude oil and coloured fuel oil when put directly into the tank installed as standard equipment for supplying the engine of a vessel described as a commercial vessel by regulation;
(b) coloured fuel oil used to operate farm machinery except a pleasure vehicle or truck, or to operate a stationary engine, but only while the machinery or the engine was used for farm work and provided that the principal occupation of the consumer is farming;
(c) coloured fuel oil used to operate a fishing boat or a stationary engine, but only while the boat or the engine was used for fishing and provided that the principal occupation of the consumer is fishing;
(d) fuel oil intended for chemical use;
(e) bunker fuel, crude oil and coloured fuel oil used only for a purpose other than supplying an internal combustion engine;
(f) bunker fuel, crude oil and fuel oil, including coloured fuel oil, acquired or used in the circumstances, for the purposes and to the extent determined by regulation.