How do you make oil deliveries?
Our drivers arrive at your house; locate the tank; bring the oil hose to the tank; unscrew the cap and begin fueling. (Similar to how you fill your car with gas.)
When the driver is putting fuel into the tank, the air in the tank comes out through the second pipe (called the vent pipe). In the vent pipe is a whistle. As the driver is delivering the oil, the air coming up the vent pipe blows through the vent pipe and makes a whistle sound.
When the tank is completely full there is no more air in the tank to come out of the vent pipe and the whistle stops blowing. The driver ends the delivery.
If the driver does not stop delivery when the whistle stops in the vent pipe, he will very quickly overfill the tank. This could cause the tank to rupture or oil to spill out of the vent pipe. It is vitally important to stop the fill especially if your tank is in the basement. An overfill will leave oil in the pipes above ground and those pipes leading into the tank.
Because of gravity, oil will eventually find its way out of any crack in the tank, tank gauge or pipes.
I ordered a fill-up and after the delivery, my tank is not completely full. Why does this happen?
Your gauge may not be accurate and showing a little less reading when your tank is actually full;
Sometimes the vent line goes into the tank but is located lower than the very top of the tank. During filling when the fuel level gets to the bottom of this vent line it will seal off the bottom of the vent pipe. Because the bottom of the vent pipe is lower than the top of the tank, then the whistle stops before the fuel hits the tippy-top of the tank. This is because the fuel is touching the bottom of the vent line and now blocking the air from escaping the tank as the fuel is entering. The driver has no way to know how low your vent line goes into the top of the tank, so when the whistle stops he has to assume that he cannot put too much more into the tank without exceeding the capacity and risking a leak. When plumbers set up a new tank they intentionally place the bottom of the vent line a little lower than the top of the tank. This is to give the driver a little cushion and reaction time to shut of the delivery before the tank is full. Most of the time it is just slightly lower so the tank ends up being almost full. Sometimes it is a lot lower which causes the driver to stop when there is still a decent amount of room left in the tank;
Depending on different trucks, how fast they pump, contaminants in your tank, and/or other factors (temperature, pressure etc.) the fuel oil will actually foam up while it is being pumped into the tank. This foam can also block and vent line and stop the whistle. Then after the driver leaves and the foam settles down (similar to a carbonated beverage) your tank is no longer full and you would actually be able to put more fuel in the tank. This causes a tank to appear to be full during delivery, when in fact after the foam settles and the tank the gauge will read that the tank is no longer full.
In all these cases, the driver must to obey what the whistle is telling him in order to prevent the possibility of a spill. The driver has no way of knowing how much “cushion” is built into the tank setup, if the oil is foaming or if your gauge is inaccurate. It is dangerous to overfill a tank and our drivers should not pump any more oil into the tank once the whistle stops. An under-filled tank is a far better choice than overfilling the tank which could result in causing a leak or worse, rupture of the tank resulting in a total spill of the contents.
We at All Island Fuel always err on the side of caution for your safety. We would rather come back to top off a tank than have an oil spill in our environmentally sensitive local habitat.