Wear comparison of different metals

[mhow]

Which will last the longest,a housing made from copper or brass with a brass rod working with a reciprocating action inside the housing.The whole caboodle immersed permanently in water.

[kellys_eye]

What kind of water? Pure unadulterated water and there wouldn't be much in it assuming no 'loading' on surface-to-surface contact but otherwise brass is harder and less prone to corrosion caused by impurities.

[aeromech3]

mhow, most plain bearings are best made up from metals of differing hardness hence you get steel running within brass, brass on brass is a no go if I recall correctly; in marine use, the bearing might be a nitrile rubber shell and metal moving parts immersed in water.

[Someone-Else]

Only a thought, why not have them both the same metal. That way they should both wear at the same rate.

[mhow]

The question raised by "SOMEONE-ELSE"is a good one and the original housing was made of brass but due to being unable to obtain brass pipe of 10mm internal diameter I have had to make one out of copper to keep the blasted thing working,which it is working fine but I am concerned about the durability of the copper housing.The type of water environment it is working in is ordinary domestic soft water off the Pennines.

[aeromech3]

mhow, think I explained same same not good, yes to S-E they will wear same rate = 'accelerated rate' and at worst bind together.
Having replaced the big end bearing in my 1st motor bike in 1965 (BSA 250 C11G) I have gained a bit of experience in this field.

[Hitch]

mhow, think I explained same same not good, yes to S-E they will wear same rate = 'accelerated rate' and at worst bind together.
Having replaced the big end bearing in my 1st motor bike in 1965 (BSA 250 C11G) I have gained a bit of experience in this field.

Very true.
Stainless steel being one of the worst.

[mhow]

Maybe I have given all you helpers the wrong impression by not explaining just what I am trying to repair so will now give a full explanation as follows:-our bathroom suite is 43 years old and the toilet has a ceramic syphon which had a brass housing in the top of the ceramic syphon in which the brass rod works up and down when flushing.Due to wear and tear over the years the brass housing just gave up the ghost and as no spares or conversion kits are available I have had to make a repair from copper pipe which is now working fine but am looking to purchase some brass pipe,which is proving difficult to find of the right internal diameter.
Hope Aeomech3 enjoyed his time with the BSA 250 cc as the BSA range were great bikes.I had a M20 during the war when in the army and bought a new one with a Watsonian sidecar when back in civvy st.The only bugbear with the M20 was the low sump clearance when rough riding but otherwise great bikes.