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Old 20th December 2007, 01:10   #16
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To have a accurate fuel measurement device fitted in car has got some technical problems.

1. To measure the weight of the fuel in the tank, the tank itself has to be mounted on some kind of measuring device (springs, strain gauges etc). Keeping them working for long time in highly demanding environment (like Indian roads) is a difficult job.
2. The flowmeter can be used, but then it will be affected by initial flow of air into (the flowmeter) before fuel actually starts flowing through it.

Companies are desperately trying to find economical solutions to these problems. They have the expensive ones available with short life-span but then people are not going to like it.

Last edited by jat : 20th December 2007 at 01:11. Reason: typos
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Old 20th December 2007, 09:05   #17
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Won't a simple sensor array placed at certain heights(lets say every 500ml increase) in the fuel tank do. This will give an approximate idea.

Anyways I think volume measurement is useless because nowadays adding naptha or Kerosene is more popular
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Old 20th December 2007, 09:53   #18
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Quote:
Originally Posted by rohan_fonseca View Post
Does that mean that we can get more fuel in cooler temperatures?
Yes, Shan is right, fuel expands when heated & since we use volume rather than weight as a measure, you get lesser as temperature rises. It follows that the worst times to fill are late afternoon, or in the evenings when the ground temperature has risen to it's maximum. In the same way, the best times to fill would be early mornings, I guess.

The funny thing is, there was an article regarding this very same thing in one of the auto magazines. Apparently, the oil companies buy, & ship fuel with a temperature correction. Because they deal with millions, if not billions, of liters - they correct volume for temperature, since even a 1 degree rise in temperature could alter the volume of their stock considerably. I think the standard temperature used is 15 degrees C.

However, when the common man pulls up at the pumps, no temperature correction is applied. In fact, the article alleged that the oil companies & dealers make a lot of money this way !
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Old 20th December 2007, 09:58   #19
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sorry to digress but what kind of sensor's does the skoda and sonata use to calculate how much fuel is in it's tanks, since it gives out a digital reading of how many kilometers before having to fill up?
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Old 20th December 2007, 10:13   #20
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Sirs....I feel something like this is most crucial. People like me use low end cars like tata indigo & the fule indicators are quite scary. I only pray that the damn thing was more accurate.
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Old 20th December 2007, 15:26   #21
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tak1979, perhaps you can shed more light about the skodas, et all?
That is a very good question, and frankly I'm at a loss to guess what they use!

Last edited by anupmathur : 20th December 2007 at 15:28.
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Old 20th December 2007, 15:43   #22
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I think the best soln is that govt should bring rules to mandate unmanned fuel stations (like developed) and control the pumps.
There is technology available but no body is really interested.
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Old 20th December 2007, 16:19   #23
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Quote:
Originally Posted by anupmathur View Post
tak1979, perhaps you can shed more light about the skodas, et all?
That is a very good question, and frankly I'm at a loss to guess what they use!
None of these cars have very accurate sensors. For example when they say 400kms range left its an approximate. When you want to check cheating, approximate won't do, since they normally cheat about 2-3% on volume, and sometimes even less.
To create an accurate sensor, you would need to have some kind of precision fuel flow meter, which will measure how much fuel went through it.
They exist, and this is what petrol pumps use(after recalibration of course )
If you manage to fit one in fuel tank there would be issues
1. Most of these require recalibration
2. Due to heat, shocks etc., frequent services would be required
3. They will not be able to catch adulteration, which is more common than meter fixing, since meter fixing can be easily caught by asking to fill in a 5 liter can. By law you are entitled to ask the fuel station guy to prove that when meter says "x" liters, its actually "x" liters
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Old 20th December 2007, 16:46   #24
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Quote:
Originally Posted by tsk1979 View Post
3. They will not be able to catch adulteration, which is more common than meter fixing, since meter fixing can be easily caught by asking to fill in a 5 liter can. By law you are entitled to ask the fuel station guy to prove that when meter says "x" liters, its actually "x" liters
This seems to be the solution. But after making sure that they fill exact 5 litre in the can and the same is reflected in the dispensing machine , we have to ensure that they fill the car tank with auto shut mode only which will prevent any malpractice if filiing is done manually.
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Old 20th December 2007, 17:15   #25
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Quote:
Originally Posted by ancer View Post
sorry to digress but what kind of sensor's does the skoda and sonata use to calculate how much fuel is in it's tanks, since it gives out a digital reading of how many kilometers before having to fill up?
Actually might estimate in other way around . Rather than seeing level of tank and take some fixed-km-per-litre-value, they will measure how much fuel is being consumed dynamically(which fairly accuratly can be measured from fuel-quantity-meters which could be connected ECU/MCU -- eg. petrol-pump's meters).

So they will get instantaeneous fuel-consumption by kms-moved-in-unit-time/fuel-consumed-in-unit-time.


From current tanks level, ECU(or some other MCU) can know how much fuel is left from tank-level(though there is chance of error), then they will tell us how-many kms the car can go(approximately)
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Old 20th December 2007, 19:32   #26
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Quote:
Originally Posted by tsk1979 View Post
None of these cars have very accurate sensors.
So that about sums it up - there is no viable device available that can serve to check mal-practice at fuel bunks. Everything is 'approximate'.
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Old 20th December 2007, 23:58   #27
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Quote:
Originally Posted by anupmathur View Post
So that about sums it up - there is no viable device available that can serve to check mal-practice at fuel bunks. Everything is 'approximate'.
There is a device. Its called a 5 liter can. Very very accurate
They supply a caliberated measuring jar at the oil pumps too
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Old 21st December 2007, 08:45   #28
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Quote:
Originally Posted by tsk1979 View Post
There is a device. Its called a 5 liter can. Very very accurate
They supply a caliberated measuring jar at the oil pumps too
The calibrated measuring jar!! Calibrated by the fuel station owners or some reliable Govt authority?
It is better we carry the 5 litre can ourselves. Also we may have carry a funnel to pour the petrol from the can to the car fuel tank!!
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Old 21st December 2007, 11:09   #29
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Actually I wonder why you are so bothered about volume. Most fuel pumps have stopped going volume based cheating. Nowdays its mostly additive based cheating, and stuff like "Not resetting the meter".
If you are alert you won't get cheated on volume front.
For example last night I filled up the tank and the bill was 639.78
I asked the guy to punch in the exact amount in the machine, instead of 640. He made a face(for losing 22p), but then why should you give out even 22p
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Old 21st December 2007, 11:22   #30
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I was filling petrol last week. The tank was filled to the brim. I saw the meter reading at some where close to 40litres. Before I could note it down, that fellow reset the meter. he said that I have to pay Rs2183/- and swiped my card also for the same. When I caluclated, 2183/51.59 = 42.3litres. I was shocked and argued with him that it was well under 40 litres. He agreed finally and refunded the excess he charged on my card.
We have to be careful with these guys.....
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