The Steamboating Forum

Hello, I have been weathered in a bit so I proceeded to make a boiler feed pump to back up the small hand pump already on my boat. I hope there are pictures attached. I would welcome any advice on the piece & would also like some input on the type of packing that works best.
This was made with a cylinder & plunger that was a botched reproduction for a Locomobile car - the cylinder was bored right through the valve area. The lever geometry is the same as the original pump. The cylinder is red brass & the plunger is an unknown alloy of stainless steel.

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Hey Jack

Very nice design! I really like the handle arrangement, very handy setup. I hope ya don't mind but I may just have to borrow that idea from ya.

I just finished building a nice 32' x 40' shop but at the moment I only have space where a future mill will be. But I have a nice lathe already so I am part way there! Look forward to seeing more interesting mechanisms from ya!

Cheers,
Scott

Are you thinking of something other than standard square braided packing?

http://www.palmettopackings.com/Style1389.pdf


Ken

Nice work! Especially like the pump frame, with the contoured bolt holes, plus the guide of the piston rod to eliminate side thrust forces.

My hand feed pump uses ordinary 1-1/4 inch brass pipe for the cylinder, a brass plug plunger, with two O-ring grooves cut about 1/8 inch wide x 1/8 inch deep on the piston plunger. The O-rings are spaced about 1/2 inch apart, with waterproof plumbers grease between the O-rings. This pump has been in service for 3 years now, has never been taken down, and has never given trouble. No visible water getting past the O-rings.

The O-ring outside diameter setting in the groove is 0.002 - 0.003 inch more than the cylinder bore, per inch of bore. The O-ring manual directs that the O-ring groove volume should be filled by the O-ring 80-85% when compressed into the cylinder bore. If you compress the O-ring more than that it will be a tight fit, and probably will wear out faster. Break the sharp edges of the O-ring grooves, so the rubber O-ring (Buna-N) will not be cut when being installed.

I have a 3/4 inch "Y" strainer, with 50 mesh stainless screen, and it finally got clogged with rust this summer (un-galvanized steel feed water tank), very much slowing pump suction capability. Cleaned the screen and all has worked well since then.

I've used O-rings and packing - both work just fine. For packing, I've had excellent luck with Teflon faucet packing.... if you have space, the traditional square stuff works well too.

It's easy to spot water leaks - air leaks are harder. I carry spare O-rings for my hand pump; I have replaced them three or four times in the 23 years Otter has been steaming.

- Bart

Interesting! I thought Teflon seals, packings and Teflon tape was outlawed at most nuclear plants.

Teflon however is a very good seal material for temperatures up to a few hundred F, provided the radiation field is low intensity, which is the case for our steamers.

fredrosse wrote:Interesting! I thought Teflon seals, packings and Teflon tape was outlawed at most nuclear plants.

Teflon however is a very good seal material for temperatures up to a few hundred F, provided the radiation field is low intensity, which is the case for our steamers.

Thank you Fred. It seems the nuclear installation near here is divided into two definite sides - the nuclear side & the steam side. Teflon is definitely not used in the nuclear side but in frequent use on the steam side. b]

Nice work Jack, wish I had the skills to build one, so still looking.


Regards:

Captain Vern

I thought I was the only person in the world with an Index mill.

The guide to reduce side forces is a good idea. I'm building a pump out of an old shaft log and was fussing over that problem. Thanks.

Mike