Volume expansion in an Underground storage tank

[vadlamanisrikar]

I want to measure the expanion of a liquid in underground storage tank.

I have a magnetostrictive sensor in the tank, which has 5 temperature sensors equally spaced, which means the whole tank is divided into 6 zones, and i know temperature in each zone. So you guys have any suggestion as how should i apply temperature compensation,

1) apply temperature compensation for each zone i.e. for the liquid in that zone, since i know temperature in that zone, and add them together?

2) find avergae temperatue of the liquid, by seeing how many temperature sensors are inside the liquid, average the temperature, and apply temperature compensation in zones for the liquid using the avg temperature calculated.

3) find the average temperature for the entire liquid and apply temperature compensation as a whole.

any suggestions would be greately appreciated.

srikar

 

[dcasto]

Depends on density function being assume linear or no linear and if tank is linear in each zone. The average applied to a linear function is still linear. the average applied to a non linear is non linear.

At some point you get my law of measurement, measure it with a micrometer, mark it with a piece of chalk, cut it with an axe, is that an acurate enough cut?

I'd just average themps and find the 1 factor. number 3. I'd also throw out any temp you find more than 5% or 10% different as a spect reading.


If you wanted to be more acurate (and waste more time), you'd adjust the density for the pressure, the deeper it is the more dense it is. Then you should also adjust the capacity of the tank by is change in volume due to temperatur expansion.

 

[vadlamanisrikar]

mm sort of makes sense, so you say step number 3 makes sense.
BUT...........
for example, we have diesel in zones 1,2 and 3.

and temperature in zone 1=62, zone 2=67, and zone 3 = 75,

so the average would be 68, it wouldnt make sense to assume liquid in zone 1, to expand to the volume at 68, since it is at 62.

similarly all others, does that make sense?
any comments?,

As you said density of the liquid also effects the volume expansion, where can i find information on this? any leads would be appreciated.


I am triyng to calculate the leak rate for a underground storage tank.
I have decided to neglect tank expansion.

 

[CarlB]

The method you're describing to check for a leak, adjusting for fuel volume changes, is the system used by a leak testing company I learned about maybe 15 years ago, don't know if they're still around. It was an approved(?) integrity test. Not sure if making your own test methods will stand up to scrutiny. The method used 3 sensors, placed at geometric locations so each represented 1/3 of the cross-section area (or maybe 1/4 -1/2 - 1/4). There are API charts that give bulk modulus of expansion for different fuels at different temperatures. Fuel level was precisely measured in the tanks standpipe, with a bubbler. Fuel was added or subtracted to maintain the same level. Tank/soil expansion was eliminated by allowing the full tank to sit for about a day. Test was run for a few hours (don't recall), volume change calcs were made to determine leak rate.

 

[vadlamanisrikar]

where do you think i can get these API charts that give bulk modulus of expansion for different fuels at different temperatures.

I searched a lot but couldnt find any.

 

[dcasto]

You didn't say compartments, you said zones. Now if you want to track volumes in compartments, apply the corr3ection factor to each one as measured. The API tables are in API MPMS 11.1 to 11.2 I believe.

 

[vadlamanisrikar]

It is zones, not compartments, does the same arguement not hold?

The API MPMS 11.1, do you guys know a place to download this for free, or for a nominal cost, beacuse its too expensive.

 

[dcasto]

Nope no freebies, you can go to the library and follow copyright laws for personal use from there.