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FDC1004 compatible for cylindrical sensing?

syed hamad
Expert 1120 points

Hello,

My application is to measure diesel level of GENSET application,   As you know GENSET tank will prone to rust, corrosive and in grease environment.

Pasting the electrode on the tank will be the challenging task.

 

Shall we use any standard cylindrical sensing electrode to measure the change in capacitance according to the change in level?

Pls share info if you have.

regards,

syed

  • 0
    TI__Expert 7400 points

    Hi Syed:

    Due to the conditions of the tank, it is probably not feasible to stick the electrodes on the side of the tank. It maybe possible to use a probe setup where you have a cylindrical tube with a rod in the center to act as a cylindrical parallel plate capacitor. We have done some studies with immersing our OOP method inside the liquid, but we have not used a cylindrical tube before.

    What kind of material is the GENSET tank made out of for it to rust and corrode?

    Thanks

    -David Wang

    Capacitive Sensing Applications

  • 0 in reply to David Wang11
    Prodigy 10 points
    Hi David,

    I am actually am trialing cylindrical plates at the moment. I seem to have some issues related to temperature. Specifically my measurements seem to drift more due to the plate metal expansion. I use the traditional method to take the measurement. CH1 - GND(plates) and I also CH2 as a REF. Ref doesnt seem to help with the temp drift. Do you think this is something the OOP might solve? My other idea is to include a temp sensor next to the plates and compensate in software.

    Let me know what you think.
    John
  • 0 in reply to John May29
    TI__Expert 7400 points
    Hi John:

    OOP will not solve the temperature variations. We are still investigating this and it is a very complex problem. There are several ways temperature variations can affect measurements:

    1) The temperature of the environment, heating and cooling the sensors
    2) The temperature of the water, heating/cooling of the water through thermal transfer to the sensors (when the sensors are directly in contact with the container)

    If you are sure that the sensors are only changing due to temperature, then it is possible to use a temp sensor to characterize the change in capacitance and use a look up table in processing. But the issue is that if temperature is drastically changing, I would expect the water temperature is changing as well. By how much, that would need to be tested.

    Thanks
    -David Wang
    Capacitive Sensing Applications