Mini Pump P71…..thoughts?

[Blue HeelerParticipant @blueheeler]

have a lot of hours in this P71 pump from eBay, enjoyed every minute of making all the metal parts and woodworking.
Only thing I haven’t done yet is bend and cut the return that will flow the water into the 4″ copper water trough as I’m still pondering a few ideas.
I did toy with the idea of making a ‘shower rose’ but think because it won’t be pressurized it would still just dribble out in one stream.
Anyone got any clever ideas before I cut and bend that brass pipe?

[JasonBModerator @jasonb]

Make a little bibcock tap rather than just have it come out of a pipe.

[AStroudParticipant @astroud]

For a reciprocating pump pressure is developed by any restriction in the outlet so if the showerhead holes are small enough the water should squirt. It should be quite easy to lash something up to test before committing your brass pipe.

[Martin ConnellyParticipant @martinconnelly55370]

It has what looks like a pressure accumulator sticking up above the pump. To me the implication is that it is reasonable to have some restriction to flow and the accumulator will smooth the flow through that restriction. I would consider something like a miniature hose pipe nozzle that allows the flow to be a spray or a jet so you can experiment and see what works best.

Martin C

[BazyleParticipant @bazyle]

Are you going to run it at shows or just glass case it? If running for the public I suggest having it do something extra to entertain children who a) have no idea what it is anyway, and b) like to see things moving. One possibility is a syphon (gent’s loo flush) as the kids then will wait excitedly to see it operate.

[SillyOldDufferModerator @sillyoldduffer]

Restrict orifice and direct upwards for a fountain, or point sideways to drive a water-wheel*.   Find the size of the orifice by experimenting: it’s related to motor power and the receiver capacity, and it’s possible the latter is only ornamental.   Too small and the pump will stall; too big and the water won’t have any pressure behind it.  Try ⌀1.5mm and see how it goes.

* This was done in the real world!  When textile mills first adopted steam engines, it was found steam’s pulsating power output tended to break threads and spoil the weave etc.   So early rotary steam engines were put to lifting water into a higher reservoir that drove a water-wheel at constant velocity.  The reservoir being a smooth source of potential energy took out the pulses.   Later, it seems adding a big flywheel, regulator, and/or more cylinders smoothed the steam engine well enough, and maybe the development of slightly stretchy rope drives helped too.   Filling water reservoirs with steam pumps to turn water-wheels didn’t last long because smoothing by pumping water is costly compared with a direct connection to the engine.  But drinking water supply is still managed with reservoirs and water towers, I guess because pumping direct into the main stresses the pipework and makes it harder to maintain the pumps.

Dave

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