Does copper react with gasoline?


5 replies to this topic
  • msiddalingaiah

Posted 05 July 2010 - 01:32 PM

#1

I have a clear fuel line connected to a short copper tube that is soldered to a copper end cap. It was an easy way to get fuel into a pump and it was working well. Today I noticed a discoloration of the gas in the fuel line close the copper. It turned kind of reddish in less than 24 hours of exposure.

I took the cap off and didn't notice any reaction on the copper, but the gas inside was discolored. I have read mixed opinions about copper reacting with gasoline. Is this a known problem or is it something else like some residue on the copper end cap? I'm testing another end cap to see if anything happens, but it has me concerned.

  • johanssont

Posted 05 July 2010 - 01:52 PM

#2

I'm not a chemist so I would bow to someone with better knowledge but from what I have read the copper can become brittle over time and will also cause the fuel to age quickly. This is not based on any scientific data so it can be incorrect.

If I were you I would throw some gas and a copper fitting in a glass and cover it for a week and see what you come up with. Personal testing is more fun and satisfying.

Good luck

  • William1

Posted 05 July 2010 - 03:04 PM

#3

Never heard of a problem with gas and copper.
Back in olden tymes, fuel lines were made of copper.
It is possible, there is a reaction with some modern additive used these days.
But.... All the jets in your carb are brass, which is copper based so... I would not loose sleep over it.

  • msiddalingaiah

Posted 05 July 2010 - 06:33 PM

#4

If I were you I would throw some gas and a copper fitting in a glass and cover it for a week and see what you come up with. Personal testing is more fun and satisfying.


I'm with you there. I set up a test in the garage earlier today. No change so far. We shall see.

Never heard of a problem with gas and copper.
Back in olden tymes, fuel lines were made of copper.
It is possible, there is a reaction with some modern additive used these days.
But.... All the jets in your carb are brass, which is copper based so... I would not loose sleep over it.


That is a good point. Many brass alloys have twice as much copper as zinc. I'm not sure if the alloy changes the chemistry or not, but brass doesn't tarnish as much as copper.

The more I think about it, a chemical reaction doesn't make sense. I suspect something else is going on.

  • msiddalingaiah

Posted 06 July 2010 - 01:25 PM

#5

OK, I'm getting more information on this. I was going to say I'm getting to bottom of it, but it might be a bottomless pit :)

There is one other factor I neglected to mention yesterday: I had added Spectro FC fuel stabilizer to the gas tank. I regularly do this because people have said it's a good idea. I really don't know, so it is what it is.

So I called Spectro and asked them why this would happen. They told me there's red dye in the stabilizer, it doesn't do any harm. I'm almost certain that's what collected near the fuel pump. It does not look anything like a chemical reaction with copper. It reminds me of automatic transmission fluid, but not as thin or as deep red. It looks like thinned out Spectro FC.

I went further and asked if Spectro FC reacts with copper and they said no. Spectro FC has inhibitors to keep any oxidation from occurring, so it's actually a good thing. They also reiterated what William1 stated about copper fittings having been used for years in fuel systems without significant problems.

Digging deeper, I contact several major oil companies, specifically Shell, Sunoco, and Chevron. Exxon-Mobil doesn't like to answer the phone, so I didn't bother with them. Chevron is the only one that responded, and this is what they said:

Trace levels of soluble metal compounds, particularly copper, catalyze
the oxidative degradation of gasoline by promoting the formation of gums
and deposits. Metal deactivators overcome this problem by chelating the
metal and rendering it inactive.

Additives are frequently added to gasoline to address oxidative
stability and other issues; they include antioxidants, metal
deactivators, and detergents.

The only negative thing with copper might be that it might act as a
catalyst and cause oxidation.

Probably inorganic copper salts.

Maybe replace the copper fuel lines.


When I asked if copper is any worse than any other metal and if they could quantify the time required to gum up gasoline, they said:

Do not know. Suggest you search the internet.

My copper experiment has so far yielded no observable change. The gas looks like gas, the copper looks like copper. I think it's probably not a huge deal as William1 says. At the end of the day, gas is going to break down eventually no matter what you do. It's not clear to me that it happens any faster with copper.

We have all seen our share of rusty gas tanks, so I'm not sure if steel is any better than copper in this regard. I think aluminum does have the advantage in that it's oxides are tightly bound to the surface and form a protective layer.

Anyway, it's sounding more and more like analysis paralysis. I'm not losing any more sleep :banana: I'll probably change over to aluminum soon, but not today.

  • msiddalingaiah

Posted 21 July 2010 - 05:10 AM

#6

I just got this response from Shell Customer Care:

This is in response to copper inquiry.

There are some molecules that may be present in gasoline which would react with copper. This reaction process is referred to as corrosion. Refiners control/remove these molecules in the gasoline production process to protect copper components in fuel systems. All Shell gasoline is certified to meet the ASTM D130 Standard Test for Corrosiveness to Copper in order to provide assurance.





 
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