When storing different types of fuels, fuel storage tanks must be designed to accommodate the characteristics of that fuel to ensure safe storage.
Diesel fuel acts and reacts differently than gasoline does, but it is still a combustible liquid requiring specific storage tank qualities to prevent accidental combustion or burning.
As such, fuel storage tank services must install those designed specifically for storing bulk diesel fuel based on these important factors.
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Combustible Classification / Flash Point - Bulk fuel storage tank requirements are based on whether a liquid is considered combustible or flammable. Conventional diesel fuel is considered a combustible fuel as its flash point is between 126F and 204F (52.2C and 95.5C). Yet when mixed with ethanol the flash point reduces to 68F (20C), when it is then considered a flammable fuel.
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Diesel Tank Design Standards - When storing conventional diesel, fuel storage tanks must be atmospheric tanks that meet API Standard 650 requirements. These tanks must be vented and operated at a gauge pressure of 1.0 psi (6.9 kPa). Tanks may also be designed to API Standard 620 for larger tanks, as well.
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Tank Installation - Bulk diesel fuel storage tanks may be installed above ground and above ground within a vault, both with relief ventilation, within a storage building with 2-hour or more fire-resistance rating, or underground made from non-corrosive material or with cathodic corrosion protection.
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Day Tank Installation - A day tank should be installed to facilitate fuel flow from bulk fuel storage tanks to an engine-driven fuel pump when elevation or distance makes direct pumping impossible, and to serve as a heat sink to prevent unused hot fuel from the engine from returning into the bulk tank.
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Gear Pumps - To draw fuel from the bulk fuel storage tank to the day tank, diesel fuel should be pumped with a positive displacement gear pump installed over the bulk tank.
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Tank Venting - Bulk diesel fuel storage tanks must be equipped with a vent line of 1.25” diameter or more according to API Standard 2000 to prevent the formation of a vacuum as the contents of the tank are drawn down.
As with all other types of fuel storage dilemmas, storing conventional diesel fuel requires the use of only those tanks suitably designed for this fuel, with the components required to pump, vent, and store it safely.
Diesel mixed with ethanol must be stored in tanks designed for fuels with a lower flash point.