Common household sources of ethanol resistant rubbers? 1

[sugarandfat]

Hi all.
I'm prototyping an open source solar energy device, which can be made from scrap and recycled parts.
It mainly works off the boiling of ethanol to provide motion for the tracker.

As a result I need to seal the system. I've been using bike inner-tube rubber which I understand is almost certainly butyl rubber, and therefor probably won't stand up to prolonged exposure to hot eths.

After a little research it looks like my most likely options are latex, nitrile, EPDM or CSM.

So, what are some easy sources of any of these? I'm thinking stuff that can bought in a supermarket or found at a scrap yard. It needs to be thick and spongy enough to make a proper seal. Like innertube rubber.

Are all my above suppositions correct? Are there any of these I shouldn't be using, or any others that I can?

cheers,

Daniel.

 

[GrahamBennett]

First of all, bicycle innertubes could quite easily be made from natural rubber as well as butyl. If the packs they come in say butyl then you have a butyl-based rubber compound.According to my information NR, NBR, EPDM, CR (Neoprene), SBR, butyl, silicone and flouro-silcone are all resistant to ethanol to a "satisfactory" extent. CSM is difficult to get hold of, as much of the global manufacturing capacity has been shutdown and/or mothballed.

As for using recycled products I would start by looking at regular automotive cooling hoses, which are usually based on EPDM compounds.

 

[btrueblood]

Ah, good call Graham.

 

[sugarandfat]

Thanks for the good info.

Ok, once and for all, how corrosive is ethanol to natural rubber and butyl? Looking into it I've read so much conflicting information, some say it's practically instant death, others that there's a bit of damage over time but not really to worry about it.

I've used bike inner tube rubber on my prototype just to see what will happen, same for aluminium. But in doing the tutorials for this device I don't want to tell people to use something they're going to have to replace in a couple months.

Cheers

Daniel.

 

[btrueblood]

Then go with EDPM (coolant hoses).

 

[GrahamBennett]

I agree with bttrueblood - use EPDM coolant hoses from scrap cars/vans/trucks.

 

[sugarandfat]

Yup. That does seem the way forward. Pretty easy to get hold of.

 

[sugarandfat]

Another option I thought of is a double layer; nitrile rubber from a non-latex rubber glove for its resistance to ethanol and temperature, backed by a layer of innertube rubber for its sponginess, so as to give a decent seal.