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Oil Tank Pressures

How Much Pressure is there on a home heating oil tank during an oil delivery and what causes overpressure conditions in home heating oil tanks above ground or underground?­­­

Residential above ground steel heating oil tanks are typically factory tested to 5 psi to 7 psi by the manufacturer, (the pressure at which oil is pumped into the oil tank from the home heating oil delivery truck). If the condition of the oil tank vent piping on the home heating oil tank receiving the oil is faulty, not vented at all, or if not vented properly, the pressures to which the oil tank are subjected can be substantial. Normal oil tank fill pressure is less than 5 psi on a properly vented heating oil tank (the presumed tank pressurization must be less than the manufacturer's factory tested tank pressure). Totally-blocked or missing oil tank venting: pressures up to 280 psi - this would be an unusual condition such as an oil tank vent that has not only become totally blocked, but the vent blockage is not "blown out" by pressures created during the tank filling operation. The pressure required depends on the solidity and adhesion of the blocking oil tank vent line debris. Considering the range of possible oil tank pressures, between 0 psi and over 200 psi (with a totally obstructed vent), it should be quite easy for an oil tank pressure to exceed the manufacturer's factory-test pressure of 5 to 7 psi. Some of these causes can be: A restricted oil tank vent pipe diameter, Oil vent pipe clogged by a slug of oil or water, Oil vent pipe cap clogged by insects or debris. Oil tanks themselves should be checked seasonally to prevent any potentially dangerous situations.


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