Oil tank Level sensor?

[mpooley]

Hi
I would like to monitor my oil use on a daily basis, so I need a relatively cheap but accurate sensor that I can hook up to a computer input.

I reckon I can work out the connection ok but I just cant find a sensor?

anyone have an idea where i might get one please?

Mike

[rt29781]

Hi,  How about a laser based distance sensor?  Here is a link to a DIY sensor:
http://sites.google.com/site/todddanko/home/webcam_laser_ranger

[mpooley]

Hi,  How about a laser based distance sensor?  Here is a link to a DIY sensor:
http://sites.google.com/site/todddanko/home/webcam_laser_ranger

Thanks

I wonder if the oil would reflect the laser ok?  wouldn't it diffuse the beam?

Mike

[noelsquibb]

a reflective layer floating on the oil ?

perhaps shaped like a large washer and sliding up and down a stiff piece of wire fastened to the side of the hole you would poke the laser rangefinder down ?

[rt29781]

The system works because the laser causes a bright spot on the target (in this case the surface of the oil).  So it may work without a floating target.  The camera takes a photo and the algorithm finds the brightest pixels.  Then by some simple maths calculates the distance to the bright pixels.  My advice would be to try a mock up without a target.  If it doesn't work then float a target on the oil.  There are also ultrasonic distance sensors that bounce sound off the target.

[Greenbeast]

http://www.arduino.cc/playground/Main/InterfacingWithHardware#Input

scroll down to distance sensing

[pottsiwebber]

If you want to measure level of a liquid without any contact then ultrasonic is your best bet, its what we use in the water industry. Alternatively we use pressure transducers at the bottom of the tank if access to the top is a problem.

I see from Greenbeasts link ultrasonic is already pretty well sorted for you.

[rt29781]

The cheap ultrasonic distance sensors only have a resolution of 3-4 cm which probably isn't enough.  What sort of oil tank do you have and how big is it?  Is it white plastic?  Can you see the oil level?  How often do you want a reading?  How much oil do you use a day approx?  trying to get a handle on the resolution you might need.

[EccentricAnomaly]

http://www.sparkfun.com/commerce/product_info.php?products_id=9495

Pricey (relative to their cheap ones :-) ) but 1 cm resolution on the serial output.  Also has an analog output which you could probably get more resolution out of given the fairly narrow band of ranges to be measured.  Their cheaper ones also have an analog output for which this might also be possible.

[ericw]

A KISS solution
A float attached to a wire wrapped round a drum or pulley then just measure the rotation of the drum.

[pottsiwebber]

A KISS solution
A float attached to a wire wrapped round a drum or pulley then just measure the rotation of the drum.

That's not a bad idea, it would need a weight on the float and might get a bit "tangly" espessialy when filling back up.

How about a float with a gear running up and down a "rack" then hack an optical mouse and measure the rotation on the gear as it runs up and down.

Or maybe a ball cock float arrangement with a potentiometer on the opposite end from the float to measure the rotation? might need gearing to get the resolution but it may work.

We also used to use capacitance probes to measure levels when I started as an apprentice, dont see them much anymore but may also be worth investigating.

[Baz]

I've never used oil heating. What size is the tank and what is daily consumption? I expect it is a rather small change to measure daily by assessing the tank.
I suggest using a car solenoid type fuel pump to deliver known units. Power consumption is minimal. You can probably find an explanation of how they work on the 'net.

[rogeriko]

you should be just measuring the oil flow through the pipe I wonder if a domestic water meter would work with fuel oil and measure the litres used

[mutleybones]

rogeriko,

I agree with what you've said, providing you know the start-point / capacity of the tank.

I've been following this thread as I'm interested in attaching a sensor to my 1-wire network to monitor the rainwater cistern's depth. We use the water for irrigation and toilet flushing. One problem (if you can call it that) is I don't know quite how big the tank is. It's underground and I've tried rodding it to determine the size and it was more than 6m (length of my rods) in the x and y directions. Not fancying digging the garden up to see how big, I came to the conclusion that it was 'big enough'.

We've a meter purely to see how much of the rainwater we're using, without measuring the volume of rain going into the tank, monitoring its depth is therefore the way forward for us.

One solution I saw involved an ultrasonic rangefinder aimed down a section of waste-pipe at a ping-pong ball that rose and fell with the level.

I was also thinking of measuring the air pressure in a capped-off pipe whose open end was pushed down to the bottom of the tank. I've given up for the moment as I couldn't find a suitable sensor that was 1-wire enabled.

Steve.

[mpooley]

Thanks for all replies 

I really like the sound of the pipe with a table tennis ball in it and the ultrasonic rangefinder.
anyone found a cct diagram for one?  I cant.

I would like a flow meter even better but I can only find exspensive ones! 

thanks again

Mike