I am working on capacitive sensor to measure diesel level change by varying dielectric. as diesel rises dielectric changes.

I would like to measure diesel level in a tank of depth 6 inches with every 0.5 mm change.

I am trying to make a cylindrical capacitive sensors but the changes in capacitance are very minute. Also the main problem is capacitance is not stable. There are variations in which range the capacitance varies with the level. The changes of capacitances due to level change are around 0.01 pF.

My question is how I can make the capacitance stable to remove the parastic capacitance. and the unstability?

Plus how the sensitivity can be increase? like parallel plate design or cylindrical one.I found some multi terminal capacitance design but I am unable to understand how to design the multi terminal capacitor.

Please help me.
Thanks

 

hi

in industrial instrumentation, normally
I wouldn't select capacitance for such application. Are you sure your DK will be ALWAYS the same?...what about temperature influences or varyng fluid quality or contamination?. This is from the physics point of view. Then you have to deal with electronic issues.

I know about diesel level capacitance in more high thanks, and not .5 mm expectations. (e.g. in diesel locomotors)

My personal thinking is it will be difficult. Why not another method?

let me heard your advances!

regards
DM

 

The easiest way to measure diesel tank level is head pressure. If the tank is vented then a low cost ($200) pressure transmitter will give you a good level indication (4-20mA). If the tank is not vented then you'll have to spend a little more money and use a differential pressure transmitter.

If you like capacitive technology then use a guided wave radar level monitor. We use them to give accurate and reliable level monitoring for liquids and powders.

 

Buy a sensor from Paccar and make one just like it. Paccar's been using capacitance and magnetorestrictive sensors in diesel fuel tank measurements on the truck for well over 15 years, and the last I heard, the manufacturing cost was less than $50. The specifications include -40 to +160 F, rapid fill, slow drain, frothing on fill... Stuff like that.

Good luck,

Walt

Walt Boyes
Life Fellow, the International Society of Automation
Editor in Chief
Control and ControlGlobal.com
555 W. Pierce Rd Suite 301
Itasca, IL 60143

[email protected]
www.controlglobal.com

 

Yes, it isn't the best way to choose capacitance for such application. For tank level measurement, specially you need build-in sensor, I recommend you try magnetostictive sensor, non-contact,absolutely output (digital or analog). iTarget sensors have over 10 years experience in the industry, you can know more about the magnetostrictive technology from the website

www.itargetsensors.com
iTarget Sensors Co., Ltd

Jessica