There is no such rule. But then the area where you are storing furnace oil comes under Hazardous Area classification. The Petroleum Act, 1934/The Petroleum Riles, 1976 provides some regulations, if you are maintaining the temperature of Class C petroleum (which furnace oil is)above its flash point. I will put here some of the rules.
Petroleum Class C: Means petroleum having a flash point of 65 deg C and above but below 93 deg C
Rule103: Hazardous area
ii) petroleum or any inflammable liquid having flash point above 65 deg C is likely to be refined, blended, handled or stored at or above its flash point.
Rule 104: Classification of hazardous area
A hazardous area shall be deemed to be -
- a division 0 area, if inflammable gases or vapors are expected to be continuously present in the area.
- a division 1 area, if inflammable gases or vapors are likely to be present in the area under normal operating condition if inflammable gases or vapors are likely to be present in the area only under abnormal operating conditions of failure or rupture of an equipment.
- a division 2 area, if inflammable gases or vapours likely to be present in the area only under abnormal operating conditions of failure or rupture of an equipment.
Now the area where you store the oil should comply with the rules and regulations of hazardous area and should be approved by Chief Controller of Explosives (CCE).
I suggest you to contact any Competent Person of CCE.
One more thing is considering the ambient conditions in India, it will be ok if you maintain 500C for storage and higher temperatures for pumping. This is my general practice and never had problems. Unnecessary heating would leave you with energy losses.
Note: I presume you are not an NRI (The rules are applicable only in India)
Regards,