Suggestions for Veggie Oil Level monitor ??

craigcurtin

Senior Member
Guys, I run my car on Waste Vegetable oil and will soon be putting a 2nd tank (old glass lined water heater) under my car.

I intend to use a picaxe to monitor temperature at various critical points (probably using DS18B20). I would like to build a Oil level gauge to give me some indicative levels for the vegoil tank - level of say 10%, 33%, 66% - Full would be close enough.

Anyone got an idea of a good way to do this - that would be OK immersed in Vegoil on an ongoing basis. ?

I will be using an old electric hot water tank so by removing the elemnt will have an approximately 2 inch opening to insert the unit through.

In intend to use a 2 or 4 line LCD for display in the car. I am OK on the programming side, just weak on the actual electronics.

Thanks in advance

Craig
 

manuka

Senior Member
So you've 2 quests- temp. & level? Is this a street legal vehicle? Are such mods. permitted? There are of course numerous ways to measure liquid level-acoustically,electrically & mechanically espec.- but how about just grabbing a fuel level gauge from a car wrecker?
 

demonicpicaxeguy

Senior Member
using the level "sender" out of the normal fuel tank can be problematic as some of the oils that are used in the nature can destroy the plastic float

are you using anything to thin out the watse oil? turps, transfluid?plain heat?

the last level sensor i saw that was used for this type of thing, was inside a 44 gallon drum , it consisted of a aluminium "U" channel and a heap of leds glued through holes and were shining inside the U channel directly at photo diodes,eg:


i can't remember what color the ledss were but it worked perfectly, and was used primarily for used engine oil , which was burnt in a diesel

the channel has to obviously mounted vertically

as for reading it, you will require the use of the adc from there it shouldn''t be rocket sience
 
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craigcurtin

Senior Member
Answers to questions

DPG, Nope no thinners in this tank - oil will be cold filtered prior to being introduced to the tank - heating will happen in the fuel lines within the engine bay. This tank may need a pusher pump dependent on the viscosity of the oil - the plans cater for this if required.

The main tank in the car will hold a Blend (Kero/ULP/Diesel/WVO) - once the system is up to temp i will then switch over to Vegoil.

Yes this is legal as the tank is holding Vegoil only - which is not seen as a fuel per se.

So the UTube concept had the LEDS and Photo Diodes exposed to the Oil and they had no issues ?

I think the idea of the capacitive plates is a better one and am just wrapping my head around that at the moment

Thanks for the suggestions guys - any more ideas ?

Craig
 

alband

Senior Member
Would it be possible to weigh it in any way?

All other methods (excluding the capacitive one, I'm still not sure how this works either) would be accurate on the straight and level but if there is a bump or a roundabout, who knows.

If you weigh it, you will get a much more accurate reading unless you're planning driving inverted!
 

kevrus

New Member
Maybe ultrasonic transducers in the top of the tank measuring the distance between the veggy oil and thetop of the tank...not sure how the transducers would fair regarding oil contamination though.

What base car are you using?

are you going to monitor the veggy temp and only switch to veggy manually or automatically when the engine and veggy reaches temp?

Areyou going to flush through the injectors with you blended fuel at journeys end?

Sorry, I asked more questions than answered
 

slimplynth

Senior Member
Would it be possible to weigh it in any way?

All other methods (excluding the capacitive one, I'm still not sure how this works either) would be accurate on the straight and level but if there is a bump or a roundabout, who knows.

If you weigh it, you will get a much more accurate reading unless you're planning driving inverted!
surely the weight would change as you went over bumps? well i'm sure it would if you lived in the UK.. thwarted by sleeping policeman everywhere
 

slimplynth

Senior Member
found this .. bit too big to put on a dash board :) but other than a floatation meassuring system, how else could it be done? At work, we use ultrasonic transducers to measure the volume (height) of acid baths but again, bumpy roads would soon kill one.
 

KMoffett

Senior Member
I think the idea of the capacitive plates is a better one and am just wrapping my head around that at the moment.
Craig
It's the change in an oscillator frequency, due to a change in the capacitor's (sensor's) capacitance, due to the change in its dielectric constant, due to the change of the dielectric from fuel to air as the fuel level drops.

Another version, but the same principle: http://www.imagineeringezine.com/PDF-FILES/capgage.pdf

You can but commercial versions.

Ken
 

KIGX

Member
I hope you remember how to do calculus because if it is a cylindrical tank lying on its side then the height of the oil and volume of the oil will be nonlinear - rate of change of volume to height. That would be fun math with a PICaxe... The earlier post regarding the pressure sensor sounds good, there are pressure transducers out there that will put out 0-5V which sounds like a readadc command. But the transducer would need to operate in the range of oil pressure you would find at the bottom of the tank. The old fashion way for measuring fuel levels is a sight gauge. Run a clear plastic tube outside the tank from the bottom of the tank to the top. The fuel level in the tank will be visible in the tube. You could probably 'read' the tube with IR, or light sources and photodetectors or by capacitance. I assume you are using 'used' veggie oil which will be fairly opaque. It will also be somewhat acidic and corrosive unless you process it into the methyl esters.
 

SgtB

Member
Take a brass tube and punch a few holes in it to let the oil move freely. Float a magnet in the tube and epoxy a few reed switches along the tube. You could even make it a resistor ladder so it uses one pin. It's not super accurate, but simple and rugged IMHO. Just make sure your float will always trigger at least one switch.
 

craigcurtin

Senior Member
answers to all the questions

yes it is Waste Veggie Oil - it is filtered (cold) to 1 micron, washed and dewatered - using a glass lined tank will take care of any issues with reaction to metal.

The car is a toyota surf - 93 model - currently running on an blend of Veggie oil/kerosense and ULP - depending on the time of year.

Yes it is an automated changeover with a manual override - so once the coolant comes up to temp and passes heat to the oil via a flat plate heat exchanger the system will then changeover from Startup tank to Veg oil and then either idle for a set period of time at the end of the journey to flush out all the veg oil or prior to reaching your destination perform a manual changeover - this is obviously dependant on amount of time you are stopped - if it is less than 3 hours or so the car will retain enough heat to start on straight veggie oil.

The tank will actually have baffle balls in it which are designed to fit into through a normal cleanout port and help to baffle the unwanted movement of the medium in the tank.

I think the capacitance setup is the best way to go from what i can see - is it as easy putting two plates into the tank seperated by nylon washers and then building the circuit seperately ?

I am thinking about two stainless steel plates 25 mm wide, by 3mm thick, just less in length than the total width of the tank - they would then be inserted through the element inlet and sealed

I guess the other option would be a tube with reed magnets inside it and a magnet mounted on a nylon slide on the outside ?

It does not have to be entirely accurate (as a normal fuel gauge isn't) just indicative of levels

Thanks for all the suggestions

Craig
 

jglenn

Senior Member
You might try a resonant audio sensor, some kind of oil proof speaker or piezo that sends sound in the air on top, and finds the resonant freq. This should change with tank level. Just run a cal curve from full to empty.

I would do it more easily, eliminate the sensor. You know when the tank is full, just integrate running time or miles, and decrement a value that represents fuel. Might be within 5% accurate.
 

BjBlaster

New Member
yes it is Waste Veggie Oil - it is filtered (cold) to 1 micron, washed and dewatered - using a glass lined tank will take care of any issues with reaction to metal.

The car is a toyota surf - 93 model - currently running on an blend of Veggie oil/kerosense and ULP - depending on the time of year.

Yes it is an automated changeover with a manual override - so once the coolant comes up to temp and passes heat to the oil via a flat plate heat exchanger the system will then changeover from Startup tank to Veg oil and then either idle for a set period of time at the end of the journey to flush out all the veg oil or prior to reaching your destination perform a manual changeover - this is obviously dependant on amount of time you are stopped - if it is less than 3 hours or so the car will retain enough heat to start on straight veggie oil.

The tank will actually have baffle balls in it which are designed to fit into through a normal cleanout port and help to baffle the unwanted movement of the medium in the tank.

I think the capacitance setup is the best way to go from what i can see - is it as easy putting two plates into the tank seperated by nylon washers and then building the circuit seperately ?

I am thinking about two stainless steel plates 25 mm wide, by 3mm thick, just less in length than the total width of the tank - they would then be inserted through the element inlet and sealed

I guess the other option would be a tube with reed magnets inside it and a magnet mounted on a nylon slide on the outside ?

It does not have to be entirely accurate (as a normal fuel gauge isn't) just indicative of levels

Thanks for all the suggestions

Craig
Good to see another vege oil bloke! I too run SVO in my hilux ute using a picaxe to control the electric heating and pumping. Have a look at my ute conversion here. I just used the standard car float level.

Cheers

Bj
 

craigcurtin

Senior Member
Hey BJ - funny seeing you here

I thought you only did native PICs not picaxe !

Yep have been to your site for many tips previously.

Looks like i might have a workaround for this - just found out that i can get Prado Fuel tanks when they have an LPG conversion done for nothing - including the fuel sender - which is directly compatible with my in dash gauge - theory says thrown in a switch for Veg/Startup and the gauge should be able to show me both levels.

Craig
 

demonicpicaxeguy

Senior Member
I thought you only did native PICs not picaxe !

Yep have been to your site for many tips previously.

Looks like i might have a workaround for this - just found out that i can get Prado Fuel tanks when they have an LPG conversion done for nothing - including the fuel sender - which is directly compatible with my in dash gauge - theory says thrown in a switch for Veg/Startup and the gauge should be able to show me both levels.

Craig
just don't forget that if you do thinnout the veggie oil out with anything down the track make sure the plastic float is conpatible with it, and if it's a plastic tank make sure that is as well,
 

BjBlaster

New Member
I thought you only did native PICs not picaxe !

Yep have been to your site for many tips previously.

Craig
No I like/use the native PICs like the 16f84, but have moved over to the picaxe due the the better A/D converters and ease of programming :)

LPG tank sender idea will work fine for a dual tanker, I did this for a mates 80 series Cruiser.

Cheers

Bj
 
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