Steve Lusardi wrote:
Gary, It is very difficult, if not impossible to electrically isolate every
component. It is possible to not use copper and brass in salt water.

Agreed.

You
should NOT use dissimilar metals without a sacrificial anode

This surely does not follow from the first sentence. There is a
significant leap of analysis between accepting the near impossibility of
isolating every component and reaching the conclusion that dissimilar
metals should therefore not be used without a sacrificial anode.

Using a sacrificial anode requires that the protected metal be connected
electrically (usually with a wire) to the anode. I think one might even
say that it is very difficult, if not impossible, to electrically bond
every protected component to the anode. But that doesn't suggest that we
should not protect where necessary.

Fortunately, in the case of a metal valve connected to a non-metallic
hose attached to a metal tee, electrical isolation is all but
guaranteed. Unless the valve came into direct contact with the metal
tee, good isolation would be had. The seawater inside the hose does NOT
provide the electrical connection between the tee and the valve required
for galvanic corrosion.

and I will
point out that plastic valves are not allowed in engine spaces under Loyds
100A1 and IMO standards, if below the waterline. If however, you have a
plastic boat, you are screwed anyway.

Had to read that a couple of times before I caught on. Good point, Steve.

Chuck

Steve

"Gary" wrote in message
news:FwJVf.188292$B94.140618@pd7tw3no...

My boat has a tee off the sal****er cooling intakes that can act as an
engine driven bilge pump. The tee is copper pipe with the hoses coming up
from the thru hulls. On the leg of the tee is a brass valve that has a
hose that reaches down into the bilge for pumping.

My problem is the corrosion from galvanic action between the copper tee
and the brass valve that controls the bilge suction hose.

Can anyone tell me how to stop the corrosion of the valve? The one I have
in my hand is almost completely pink because the zinc has completely
dissolved.

Ideas?

Gary