Author Topic: Simple old style hand-operated feed pump  (Read 1358 times)

Offline Paul

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Simple old style hand-operated feed pump
« on: February 04, 2017, 08:08:25 PM »
Almost finished this simple boiler feed pump (excuse the temporary screws and the oily handle!) which is a variation on one in an old book. Works ok even with oiled string (!) rather than graphited yarn in the stuffing box, will shift half a pint in thirty seconds or so and squirt about 10 foot  :Lol: It has a design fault in that it's too easy to pull the plunger out completely; it needs some sort of stop  :Doh:


What I learned: how to make a neat container for the inlet valve, how the delivery pipe orifice needs to keep away from the outlet valve, the effect of water hammer and why there's an air chamber on old pumps!

EDIT: It's about 5" tall (that's a UK penny)

Offline Gas_mantle

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Re: Simple old style hand-operated feed pump
« Reply #1 on: February 04, 2017, 09:10:11 PM »
Hi Paul,

Glad you posted this as I've just bought a small boiler and have thought about making a small feed pump for mine but having never made one before I wasn't sure what kind of pressure I could realistically hope to achieve.

Have you any idea of the pressure you get from your design ? My boiler operates at upto 60 psi which to me seems quite a lot to push against with a simple homemade pump.

Peter

Offline Paul

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Re: Simple old style hand-operated feed pump
« Reply #2 on: February 04, 2017, 09:37:08 PM »
Hi Peter,

I asked that very question over on the ME forum: http://www.model-engineer.co.uk/forums/postings.asp?th=124440 might provide what you're looking for.

Having watched a youtube video of the output of a Stuart Turner hand pump I think this would be comparable. You could always fabricate one similar to the ST pump and gain some mechanical advantage from the lever which also solves my issue with the ram coming out completely. There are oodles of such designs (google->images) - I'll probably be building one my self shortly.

Paul

Offline Gas_mantle

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Re: Simple old style hand-operated feed pump
« Reply #3 on: February 04, 2017, 10:00:04 PM »
Thanks Paul, it's something to ponder over. I had thought of making something similar in operation to the Stuart pump if I can be sure of being able to get sufficient pressure.

Offline crueby

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Re: Simple old style hand-operated feed pump
« Reply #4 on: February 04, 2017, 10:15:26 PM »
The style pump that I made for my Shay build will put out quite a high pressure, it was used to do the static pressure tests on the boiler. It is a simple build, the type has been in use for many years. Kozo has plans for it in all his books, there must be plans elsewhere too. Sellers like PMResearch have kits and finished versions.

Offline Gas_mantle

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Re: Simple old style hand-operated feed pump
« Reply #5 on: February 04, 2017, 10:23:30 PM »
Thanks Crueby, what is the piston and ring made from ?

Offline crueby

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Re: Simple old style hand-operated feed pump
« Reply #6 on: February 04, 2017, 10:37:07 PM »
Thanks Crueby, what is the piston and ring made from ?
The body is brass, the shafts are stainless steel (303). Kozo's plans all use viton o-rings. The check valves are a small stainless steel ball. The piston is basically just the end of the shaft, sealed with an o-ring where it goes through the side of the body. It does not need a ring at the 'piston' end since it it just displacing the volume inside the pump body. I'd post the plans, but they are part of his book and I don't want to get in trouble. I'm sure there are plans for that kind of pump around on the web, basically the same as a PMR or a Stuart hand pump, very simple to make.

Offline Gas_mantle

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Re: Simple old style hand-operated feed pump
« Reply #7 on: February 04, 2017, 10:45:10 PM »
Thanks Crueby, I'll take a look and see if I can see some plans but failing that it should be easy enough to make one up as I go along :-)