Belite Fuel Probes

[PaulSS]

Hello again all

Having solved the fuel flow problem, we're now looking at the fuel contents problem. The RV8 has capacitance plates fitted and, to be honest, we're truly underwhelmed by the accuracy of them. We've calibrated them a few times and have even plotted graphs of the voltage outputs to 6 decimal places and then adjusted the calibration voltages to attempt give us more accurate indications but all to no avail.

So, now we're looking at the Belite fuel probes (link below). These will chuck out between 0-5V (empty to full) and we're hoping that voltage will come directly from the probes, instead of coming for the computer normally installed between the probe and the fuel gauge. If this is true (I've asked the company) then the probe's signal wire could replace that of the capacitance plate signal wire to the Skyview.....I think.

What I would like to know is if I would just then calibrate these probes as if they were capacitance plates i.e tell the Skyview it's got an 80 litre tank and then just add 10 litres at a time until full. The probe, I think, should just send the voltage associated with the tank level and all should be well......or should it???

I know they've been asked about before ('cos I did a search) but there were no replies, so hopefully someone will be able to share their thoughts and/or experiences with such a set up.

Thank you

http://www.beliteaircraftstore.com/liquid-level-fuel-probe-system-with-1-8npt-probe/

 

[Garrett]

If you can get access to the bottom of the tanks use a 4-20 ma or 0-5 Volt signal from a pressure transmitter. Use appropriate scaling for the height of the tank which will correspond with maximum pressure. Some pressure transmitters are programmable. Then use the Dynon calibration procedure. In the field of industrial controls I found this an easy way to measure level. Although, not sure if this would be the best way if tank selector switch is set to both and/or if you have that option.

 

[PaulSS]

Thanks for your thought, Garrett. I believe these things are the type of device you're talking about. As fas as I can see they measure the head of fuel (pressure) and then output a signal between 0-5V accordingly. If access to the tank is possible that will certainly be the way to go. If not then it might have to be a 'T' into the fuel supply line each side (which will still measure the pressure).

The RV is L/R/off, no both.

 

[Garrett]

I have had some installation where I could not tap the tank and had to tap a line and the head pressure was affected by flow and/or suction from pumps. If you tee in you will know immediately when you turn the pump on I.E. the reading won't make logical sense. Like a sudden drop in tank level.