home heating oil change in volume due to temperature change

[Ken10]

Hello,
I hope someone can help me out. I am looking for a formula that I can use to calculate the change in volume due to temperature change in home heating oil. For example if I have 175 gallons in a 275 gallon tank on a 60 degree day and the depth of the fuel oil measures 31.2 inches, what will the depth be at 63 degrees. Thank you for any and all help.
Regards.
Ken

 

[jmw]

try using the temperature density corrections found in density08.xls at

http://www.viscoanalyser.com/xls.html

This will help you along.

JMW

http://www.ViscoAnalyser.com

 

[Ken10]

Hi jmw,
Thanks for the reply. That's a little beyond my scope. I was hoping for a formula that I could plug into a VB program I'm writing. I have two variables to work with and they are temperature and depth of fuel. Is this enough information to calculate a change in volume?
Regards,
Ken

 

[blackwed]

Nope. It isn't as easy as I'm sure you're hoping. API's most current document that covers this goes for around $500 on CD. But for a start, go to DynamicFlowComputers.com and in the download section get the manual for their SFC332 flow computer. In the back are the formulas necessary to calculate CTL, the factor for correction for effects of temperature on liquid. Be aware the calcs are for volumetric quantities and changes in volume in a home heating oil tank likely won't be linearly related to the level. If the tank doesn't have straight top, sides and bottom, i.e., if it's a cylinder, you have to then account for the tank's geometry. Once you get a handle on the math, you'll see it's not as hard as I'm making it out to be, either.

Dan

 

[Ken10]

Hi Dan and thanks,
I saw a correction factor of (.000055)-1 per degree F for kerosene in my search and I was hoping for something like that. I'm using pi*a^2/2 - a^2*arcsin(1-h/a) - (a-h)*sqrt(h(2a-h)) to calculate a partially full cylindrical. You mention CTL, what does this stand for?
Ken

 

[jmw]

You didn't say why you needed this data, especially for such a small tank. If you are concerned about over-fill protection I would expect that should already be taken care of in the tank design to account for the worst case scenario e.g. a maximum fill level.

If you want to challenge your suppliers delivery account then you probably need another approach.

Idle curiosity?

Your fuel oil supplier should be able to provide you with a facts sheet about your fuel including a material safety data sheet.

In this you will find a typical density.
If not,ask and every time you get a delivery.
Density is usually quoted as kg/m3 at 15degC.

Hence, using the spreadsheet all you do is fill in the density at 15degC and calculate the density at different temperatures.
From the density you can calculate the change in volume at any temperature.

Many home heating oils are delivered using weights and measures approved volumetric flowmeters which have automatic temperature compensation (a mechanical system in earlier systems but the newer electronic register meters are more sophisticated) and hence should provide a degree of correction for density when the fuel is delivered, some have a dial to calibrate the density into the system.
Some systems use a density meter (more usually aviation fuels where density is more critical) and some use coriolis mass flowmeters.

Incidenatlly, if you really want to be able to interpret the mass of fuel in your tank from level measurements, there is some bad news:

Heating fuel is not usually produced to a specific viscosity or density. So long as it is within limits, that is usually all you can count on. This means that unless you have segregated storage to separate your different consignments of oil you are going to be delivering new oil into a tank containing old oil. The lighter will sit on top.

This means that you may find your calculations have to reflect two different amounts of fuel in the same tank, though I guess this might be nit-picking with this size of tank.

There is a caution, the least dense of your fuels may be with you for some time as more recent more dense fuels sink to the bottom and are used first. The longer a fuel is in storage the more likely it is, over time, to break down. Of course, this is more ture of heavy fuel oils which may also suffer stability and compatibility problems and where this can be a serious problem.
One supplier of HFO reported that his 380cst fuel in storage suffered this and he found the variation in viscosity from top to bottom to be from 150cst to 420cst and no longer could he be sure that any of it was still compliant with the standards. The major suppliers keep fuels in storage homogenised using tank mixers.
Smaller suppliers may not.
This could mean your supplier. Of course, if he gets through lots of fuel, it may not be a problem, but it may mean he can't give you an exact density.

JMW

http://www.ViscoAnalyser.com

 

[blackwed]

CTL = Correction factor for effects of Temperature on Liquid.

Volume x (1 +/- (0.0005 x delta Temp)) is as good a number to use as any other for a fairly close estimate in a home heating oil tank. Use + for a temperature increase and - for a decrease. Don't plan to take anybody to court with it though.

Incidentally, for a horizontal cylindrical tank, once you get your "corrected" volume, I think you're going to find it's not a trivial effort to find the corresponding level.

Dan