Any polymer chemists out there?

Hey everyone, I'm about to embark on the fuel tanks for my RV-10 and have decided to fit them with the Van's "plate-style" capacitive sensors based on their RV-9 design. The plans call for the plates to be electrically insulated using polypropylene tubing and UHMW (polyethylene) washers. I'm having trouble sourcing the PP tubing while PE tubing seems easy to find. From what I've read, PP is more resistant to organic solvents while PE seems to be a better electrical insulator. My question is--given I do not want to crack open the tank in the future if I can avoid it--can I substitute PE tubing for the PP tubing without it degrading? If so, why would Van's plans call for PP vs. PE? Finally, am I overthinking this?

You might try Grainger.
https://www.grainger.com/category/p.../tubing/polypropylene-tubing?categoryIndex=22

Can’t help you with sourcing the materials, but if you want to install Princeton capacitance probes made for the RV-10 fuel tanks instead - I have a new set you can buy.

No converter box required and they are compatible with the GEA 24 on a G3X install. Don’t know about other avionics manufacturers.

Decided to install the CiES senders instead.

Email is better than PM - Krea dot Ellis at gmail dot com

It depends

https://www.calpaclab.com/polypropylene-chemical-compatibility-chart/

Former polymer chemist here. Actually it depends on what kind of organic solvent, or what type of gasoline which is actually a blend of lots of different chemicals.

Take a look at the chart in the link where you will see different types of gasoline and their compatibility with polypropylene.

Also, it's not just polypropylene versus polyethylene because polyethylene comes in low, medium, and high density as well as the ultra high molecular weight you mentioned.

I have been using snap in bushings (similar to rudder cable/fuselage bulkhead bushings, fuel line bushings, etc) to separate & insulate the capacitance plates in fuel tanks.
SB375-3 snapped into the sensor plate
SB500-6 or SB625-5 between plate & rib as the spacer/insulator
SB375-3 through the rib
A long #8 screw & nylock nut through the bunch to hold everything together.
Tank senders I built this way continue to work flawlessly.

PP Tubing

https://www.usplastic.com/catalog/default.aspx?catid=713&parentcatid=856&clickid=leftnav