Copper reaction!!!

[oscar]

Hi when getting MOT other day guy there was quite knowledgeable re Citroens etc was one of the other mechs had been into them who had worked there.He told me when said id had leak from the green life blood of citroens i said i joined pipe together with a joiner. He said don't use copper as it reacts with the fluid!!!? where's citrojim he'd know.

[Mandrake]

Never heard that one before!

Can't see how copper would possibly be affected by mineral oil. There could potentially be an electrolysis reaction between the copper and steel it is in contact with however.

[Stewart(oily)]

I hear bumspeak

[Old-Guy]

I suspect this derives from the old idea (I don't know if there was ever any truth in it) that you shouldn't use copper for petrol lines - because (supposedly) with damp fuel there can be a complex reaction between sulphur compounds, tetra-ethyl-lead and copper pipe. This sounds plausible, but lots of cars built in the 1950s had SU carburettors with copper floats (I've repaired a few leaky floats), and lots of petrol engines in the era of leaded petrol had jets, needles and other fuel system components made of brass (which is a more reactive alloy of copper and zinc).

As for any reaction with LHM, complete 80ll0cks! Not even electrolysis, unless the LHM is very old and wet - when a bit of electrolytic corrosion in the pipes would be the least of your problems! Unlike non-mineral hydraulic fluids, LHM isn't hygroscopic and contains advanced corrosion inhibitors, which is why you should replace LHM at the recommended interval.

He'd have been on sounder ground if he'd suggested that it might not be a good idea to use ordinary copper pipe on the HP side due to possible risk of the much higher (1000 p.s.i.) than conventional pressures causing soft copper pipe to swell and split.

[oscar]

But floats etc are made of brass

[kenhall1202]

Personally I would not entertain using copper pipe on a hydraulic Citroen because of the work hardening characteristic of pure copper. Once work hardening has taken place, eg through bending or shaping the tube, there is a small risk of failure through cracking, particularly if the tube is not fully supported.
Copper / nickel alloy tube (eg Kunifer) does not have this drawback.

Ken

[Old-Guy]

But floats etc are made of brass

Somehow in the editing process "brass (alloy of zinc and copper)" became "copper"