I need to make a reciprocating water pump as :-

http://good-times.webshots.com/photo...ost=good-times

for a small marine engine.
Casting and machining one is out of the question, so it is piece one
together.
Steel tube outer casing with brass inner sleeve and using silver
steel rod for the piston.
Question : Would the brass sleeve and the silver steel rod be
compatible materials, corrosionally speaking, if left in contact with
fresh (not salt) water together for any length of time?

Thanking you in advance.
Regards,
DJC.

"D.J.Carter" wrote in message
...
I need to make a reciprocating water pump as :-

http://good-times.webshots.com/photo...ost=good-times

for a small marine engine.
Casting and machining one is out of the question, so it is piece one
together.
Steel tube outer casing with brass inner sleeve and using silver
steel rod for the piston.
Question : Would the brass sleeve and the silver steel rod be
compatible materials, corrosionally speaking, if left in contact with
fresh (not salt) water together for any length of time?

Thanking you in advance.
Regards,
DJC.

(For the American readers, "silver steel" is oil-hardening tool steel.)

I can't comment on the galvanic corrosion relationship, but silver steel is
only slightly corrosion resistant, all by itself.

--
Ed Huntress

On Tue, 4 May 2010 14:21:23 -0700 (PDT), "D.J.Carter"
wrote:

I need to make a reciprocating water pump as :-

http://good-times.webshots.com/photo...ost=good-times

for a small marine engine.
Casting and machining one is out of the question, so it is piece one
together.
Steel tube outer casing with brass inner sleeve and using silver
steel rod for the piston.
Question : Would the brass sleeve and the silver steel rod be
compatible materials, corrosionally speaking, if left in contact with
fresh (not salt) water together for any length of time?

Thanking you in advance.
Regards,
DJC.


Use stainless for the piston. Marine grade.

D.J.Carter wrote:
I need to make a reciprocating water pump as :-

http://good-times.webshots.com/photo...ost=good-times

for a small marine engine.
Casting and machining one is out of the question, so it is piece one
together.
Steel tube outer casing with brass inner sleeve and using silver
steel rod for the piston.
Question : Would the brass sleeve and the silver steel rod be
compatible materials, corrosionally speaking, if left in contact with
fresh (not salt) water together for any length of time?

Thanking you in advance.
Regards,
DJC.


Bronze would be a better choice if you can get it.

Brass will wear fast and the silver steel will rust regardless of what
water it's in.

Will this be pumping hot water or is it the intake pump pulling in cold
water?

--
Steve W.
(\___/)
(='.'=)
(")_(")

Thank you, Ed.
I wasn't too sure on the corrosion resistance of silver
steel. A bit less resistant than I thought.


Thank you, Brian.
Marine grade stainless it is for the piston.


Thank you, Steve.
Bronze it is for the sleeve

The pump is for drawing cold water up and pushing it through
cylinder jacket and water cooled exhaust . It will be mounted on the
cylinder similar to this one.

http://good-times.webshots.com/photo...ost=good-times

Thank you very much, gentlemen. Much appreciated.

Regards,
Dave Carter.

On May 5, 2:38*pm, "D.J.Carter" wrote:
* *Thank you, Ed.
* * * * *I wasn't too sure on the corrosion resistance of silver
steel. A bit less resistant than I thought.

* Thank you, Brian.
* * * * Marine grade stainless it is for the piston.

* Thank you, Steve.
* * * * Bronze it is for the sleeve

* *The pump is for drawing cold water up and pushing it through
cylinder jacket and water cooled exhaust . It will be mounted on the
cylinder similar to this one.

http://good-times.webshots.com/photo...3FbliXM?vhost=....

* Thank you very much, gentlemen. Much appreciated.

Regards,
* * Dave Carter.

If it's not a model, use a centrifugal pump, ala car water pump.
You'll have a lot fewer problems. Can't see your pics here, so have
to guess from your application description. It's a high-flow, low-
pressure application, centrifugal is the way to go.

Stan

On 6 May, 17:22, wrote:
er.

If it's not a model, use a centrifugal pump, ala car water pump.
You'll have a lot fewer problems. *Can't see your pics here, so have
to guess from your application description. *It's a high-flow, low-
pressure application, centrifugal is the way to go.

Hello Stan,
Sorry for the delay in replying.
The engine needs a reciprocating pump because of the water cooled
exhaust system. The water pump has to be timed to pulse water through
the system between crankshaft tdc and bdc, irrespective of crankshaft
rotation. (The engine is two cycle and reversible).
An adjustable amount of water is squirted into a chamber (attached to
the exhaust port) on the power stroke, and is vapourised by the heat
energy of the exiting gasses, thus cooling and quietening them. After
the initial blast of gasses out of the port, and before the piston
covers the port on the compression stroke, there is a negative
pressure wave going back into the cylinder. If a rotary pump were
used, then any water still entering the chamber at this point could be
sucked back into the cylinder with disasterous consequencies.
The bore and stroke of the pump is 7/8" and 1/2" respectively, so
quite a low flow rate at 600rpm. The engine is of 1911-14 vintage
and will be for show purposes only.

Regards,
Dave Carter.