# Measure fuel level in closed tank ?

Discussion in 'Homework Help' started by ArFa, Sep 30, 2013.

1. ### ArFa Thread Starter New Member

Apr 24, 2011
9
0
Hi all,
Please can you give me any idea about how to measure fuel level in a closed tank ?
Please, remind that we can't make any hole in that tank!

2. ### Sensacell Well-Known Member

Jun 19, 2012
1,183
276
Please provide more information:

Define "fuel"
is the tank pressurized or vented?
What is the tank made out of?
how big is it?

Context is everything.

3. ### ArFa Thread Starter New Member

Apr 24, 2011
9
0
thanks for your reply.
what you mean: define "fuel" ?
I want to measure genset fuel level, I don't know that what is the tank made out of.
I know that his weight may be up to 3 ton.

4. ### tubeguy Well-Known Member

Nov 3, 2012
1,157
197
You could put the tank on a scale. Weigh the tank when empty, then weigh it when full. Calculate the fuel level based on the weight difference.

In a real world application, the connections to the tank must be flexible so they don't affect the weight readings. The empty weight can be tared (zeroed), to then read the fuel weight directly. The readout could be calibrated to display gallons, liters, etc.

Last edited: Sep 30, 2013
5. ### sirch2 Well-Known Member

Jan 21, 2013
1,008
351
You could possibly use a flow meter on the fuel line? I.e. measure how much you have taken out of the tank rather than how much is in it.

Or, just a thought, is the filler cap directly on top of the tank? If so you could presumably modify the filler cap to include an ultrasonic transducer

6. ### Metalmann Active Member

Dec 8, 2012
700
223

The tank weighs 3 tons?

Full, or empty?

There has to be an opening where they fill it.
Use a stick gauge.

7. ### wayneh Expert

Sep 9, 2010
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3,224
The normal solution in industrial settings would be load cells with the info communicated to the control room. Without that, you need to stick the tank once in a while and keep track of in and out. Level sensors are not uncommon either. For instance you could use a sight glass connected to the outlet. It all depends on how much you can spend, how timely and precise the reading needs to be, the importance of the data and so on. There is no single answer.

If this is a trick question and no access to the inside is possible, and the tare weight is unknown, the answer may involve trying to sense the liquid level from the outside, like by rapping your knuckles on the tank.

8. ### ArFa Thread Starter New Member

Apr 24, 2011
9
0
Thank you for your replies,
the most common I received is to measure the weight of the tank and calibrate the measurements for fuel level, but do you think it's precise?
The issue is to measure fuel level of genset or power generator. Do you have any other idea ?

9. ### sirch2 Well-Known Member

Jan 21, 2013
1,008
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I suggested two other ideas above, how many do you want?

10. ### Alec_t AAC Fanatic!

Sep 17, 2013
5,956
1,131
If the fuel is a liquid you could perhaps mount an audio transducer and mic on the outside of the tank, drive the transducer with a frequency sweep and detect tank resonances for known fuel contents in a calibration run.

11. ### wayneh Expert

Sep 9, 2010
12,368
3,224
Weight is by far more precise when you want to know how much of something is in the tank. If you really want to know the volume, then you need calibration of the vessel, and you need to know the temperature and composition of what's in the tank so that you can calculate density and then volume from the weight. So if you really want volume, or percent full, another method might be simpler.

FWIW, even though you supposedly buy gasoline by volume at the pump, it's temperature is measured and an adjustment is applied (in the pump's computer) to correct back to a standard temperature, I think it's 60°F in the U.S. So you're really buying it by mass. Twenty gallons of gas delivered at the pump is not really 20 gallons, it's 20 standard gallons at 60°F. If you live in a hot region, it might be delivered at 70°F and it would actually be more than 20 gallons.