Heres a challenge. I need to find a way to activate a solenoid valve based on the colour of a liquid.?

I want to convert my car to run on cooking oil. I need to be able to activate a 12v solenoid depending on whether there is diesel or oil in the line. I was thinking about putting an LED on one side of a clear line and a LDR on the other side. The LDR will pick up the difference and activate the selenoid. This is how i would do it in theory but i have no idea how one would go about this. Heres a challenge. I need to find a way to activate a solenoid valve based on the colour of a liquid.?
I would ask on these forums.


http://www.biofuelsforum.com/svo_users/3鈥?/a>


http://www.biofuelsforum.com/svo_users/3鈥?/a>Heres a challenge. I need to find a way to activate a solenoid valve based on the colour of a liquid.?
You could, but why would you want to. Cooking oil ($12/gal) is much more expensive in the US than diesel ($4.50).





If you use waste oil, it is necessary to filter it to remove food particles, even tiny ones, so that the oil is clear. Otherwise your engine is likely to clog.





To implement this you need to know how much of the LED light is absorbed the the oil (filtered if waste oil) or diesel. You will have to determine this experimentally and select the LED color for the maximum difference.





For the actual device, you will need a transparent tube that you can insert in the fuel line. The LED is on one side and the detector on the other. the entire unit will have to be enclose to prevent stray light. The output of the detector will probably have to be amplified to activate the solenoid.





To reiterate, filtering is essential to prevent clogging. That is filtering before the oil is put in the tank: the internal fuel line filter is not sufficient. Waste oil does not have a consistent color so it must be filtered until the color is consistent, otherwise the detector will probably be unreliable.





Also you should be aware the cooling oil becomes solid at temperatures much higher than diesel. Thank and fuel line heaters may be necessary.