True oil tank capacity

Dave_61

Hello,

We have a typical 275 gallon vertical oil tank in our basement. I installed a Smart Oil gauge which detects the level ultrasonically. Our oil company was having a busy week, and unfortunately we got down to about 25 gallons on the WiFi gauge. When they filled it today, they put in 226 gallons. I’m just trying to figure out the accuracy. If there truly were 25 gallons in the tank, it would mean we now have 251. But both the oil company and the gauge manufacturer say 235 is the usable capacity, which would mean we were down to 9 gallons or so. I’m just trying to figure this out for my own interest. Thanks

pecmsg

I would trust the gauge on the delivery truck over the ultrasonic.

techforlife

275 is tank capacity not fill level. The vent alarm, which signals the deliverer as to when to stop pumping, is several inches down from the top of the tank, the variable of which was determined by the original tank installer. 230 to 255 would be typical working capacity. Of course everything has a margin of error.

HVACNUT

264 is max on a steel vertical 275 with the full whistle. It could have been a fast fill and it foamed to the whistle.

The fun is to let it show empty on the app, then go measure.

EBEBRATT-Ed

Most of the 275s I worked on would hold 225-235 from full to run out but that was when the oil line came out of the end of the tank.

I would suspect the more modern tanks with the bottom outlet hold about 10 gallons more so around 235-245 from full.

As others have stated the vent whistle sits down in the tank a few inches to maintain some air space.

Any gauge on the tank is only approximate.

The meter on the truck is tested every year and sealed by the weights and measures inspectors and is accurate.

EdTheHeaterMan

@Dave_61 said: "We have a typical 275 gallon vertical oil tank in our basement. I installed a Smart Oil gauge which detects the level ultrasonically. Our oil company was having a busy week, and unfortunately we got down to about 25 gallons on the WiFi gauge. When they filled it today, they put in 226 gallons. I’m just trying to figure out the accuracy. If there truly were 25 gallons in the tank, it would mean we now have 251. But both the oil company and the gauge manufacturer say 235 is the usable capacity, which would mean we were down to 9 gallons or so. I’m just trying to figure this out for my own interest.

Thanks"

That makes perfect sense. 251, is just about how much you should have in a 275 tank. The vent alarm that signals the driver to stop pumping oil into the tank will leave a safety margin at the top. That is just in case the fuel in the delivery truck is very cold and the tank is in a heated basement. 251 gallons of -3°F oil will expand when it is heated to a room temperature of 70°. and sometimes delivery trucks do deliver oil when it is below zero. It seem that they deliver a lot more oil when it gets that cold for some reason. I wonder why?

If you had a full tank of say 265 gallons of -3° oil in your basement tank and the room temperature where the tank is located is 70°, in about 3 hours from the time of delivery, you would be having to clean up a few gallons of 70° oil off of the basement floor. and that may continue thru the night as all the oil expanded and became 70° Those gauge toppers don't seal very tight sometimes. And if all the pipes and gauge fittings were absolutely liquid proof, then the oil would leak out of the vent pipe outside the building. That is still a messy proposition.

Dave Carpentier

An online calculator says that 265 gallons of diesel at -3f , then warming up to 70f, would become 274 gallons.

I get the idea of expansion due to heating it, but having a hard time considering how it relates to using it in your boiler/burner. So, a nozzle spraying 0.80 gallons per hour would have different btu outputs depending on the oil's temperature ? That energy is still in the fuel , its just more compressed when it's cold.

Or am I off my rocker here.. lol.

EBEBRATT-Ed

as far as the temperature of the air affecting the burner combustion it will.

But with a small burner the difference will be very small.

@EdTheHeaterMan

If I remember right the term we used to use was "shrinkage" and it was real

We use to have (2) 20,000 gallon underground tanks at the oil co I worked for. They filled them with cold oil and when the weather got hot we had oil at the vent pipe

EdTheHeaterMan

At some point in the life and times of fuel deliver driver, there were Temperature compensating meters that would actually adjust the gallons based on the fuel temperature. I actually remember a salesman that pitched the system to my father and his brothers, the idea was that all the refineries were selling us the oil at 70°F temperature compensated. When we sold it at 30° or lower we were loosing gallons due to shrinkage. It is a real thing, as @EBEBRATT-Ed said.