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Glycerin/biodiesel sensor

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http://biodiesel.infopop.cc/eve/forums/a/tpc/f/919605551/m/279101603

November 23, 2009, 08:46 PM
Jon Heron
Glycerin/biodiesel sensor
I had an idea to make a sensor to mount on the drain of a biodiesel reactor to determine when the glycerin was done draining so I added a NC relay to Grahams Laming's Darlington pair dipstick circuit that will sound an alarm when the probes are out of the glycerin and into the biodiesel.
If it works well an automatic valve or solenoid could be controlled by the relay instead of the alarm thus automating the draining of the glycerin.
I haven't 100% decided on what to use for probes yet but I am leaning towards using 2 steel nipples isolated by a plastic coupling on the drain pipe or drilling and tapping 2 plastic bushings into a fitting to hold steel probes. The circuit is very sensitive and I used a quality trim pot for fine tuning the switch so the gap between the probes will not be too particular.
The circuit is simple to build and the parts can likely be had for under $10.00, I had most of them on the shelf already so I cant give you a real number...
I built 3 of them and sent one to fabricator and one to BioTom on trade. Hopefully they will get a chance to try them out and work out any bugs before I put mine to use next spring! Big Grin
I put up some pictures of what I built HERE for those interested.
All I did was add a NC 9VDC relay with a protection diode across the coil and an 85db siren to GL's circuit. It's certainly nothing fancy but it will work great!
This may work for draining wash water too but I have not tested the circuit on wet biodiesel, it may be too conductive for the circuit to trip...
This should be handy for those who do AE treatments that have trouble telling when your at the good stuff.

Cheers,
Jon


___________________________

Simple schematic for a pump and heater control with a high limit
Sensor for the biodiesel/glycerin layer
December 07, 2009, 04:18 PM
Jon Heron
While in Home depot today I noticed THESE water alarms for $12.00.
Just a guess but I bet it would work just as well as GL's sensor, it would alarm when in contact with glycerin and then stop when in contact with biodiesel(non conductive)...
Just a thought for those who aren't too handy with a soldering iron...

Jon


___________________________

Simple schematic for a pump and heater control with a high limit
Sensor for the biodiesel/glycerin layer