On Mon, 29 Nov 2004, Aadu Adok wrote:

> hi Nigel,
>
> I have 1500 litre tank. On 'proper Estonian winter' (with temperatures
> below -20 celsius), stove consumes about 1cm per day (which is about 10
> litres). So - 1mm of oil level in tank corresponds to 1 litre.

Use a capacitive gauge, it will be accurate enough after calibration. But 
1 liter/hour is pushing it a little imho. As to measuring oil flow speed, 
that would be worse. You are trying to measure a flow of ~0.09 cm/sec in a 
10mm pipe assuming 1 liter/hour consumption. That is hard. Maybe you can 
use a dripper and count drops optically or by pressure impulse. I don't 
think that something else will work very well at this speed.

> What is the maximum precision you can squeeze out from ultrasonic ping
> measurement? Should be well under 1mm?!

You can't probably. Express it as percentage of full scale. F.s. is 1500mm 
and you want to read 1mm/1500mm = 0.00066 so you measure 0.00033. That's 
0.033% . Very hard.

Peter
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