Steam pumps

Ahh, speaking of: can pick your brain?

The question asks for a description of a double acting steam pump suitable for supplying feed water. I’ve seen a steam piston pump for the diesel burner, and my books cover steam turbine pumps for feed water. But I found this cute drawing on the Internet… do you think this is the thing?

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For what it’s worth (not much probably) this WAFI can say it’s certainly a steam-driven pump and it’s certainly double acting on both the steam and the water sides. And the pump piston is enough smaller than the steam piston that it ought to be able to pump against boiler pressure on the boiler that’s giving it steam.

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Logically I guess old steamers with reciprocating main engines would have had reciprocating feed pumps, similar to your drawing. I’d think they’d have to be pretty high volume though.

Makes me miss steam a little bit, though the only steamship I sailed on was the training ship (turbine not recip)

If memory serves she had turbine driven feed pumps with electric cold startup feed pump (presumably off the emergency genny/ shore power).

The only double acting steam piston pump was the massive general service pump. We were told it would pump anything, sea water, bilge, and bowling balls if you lined up the right tank, but I don’t think feed water was an option.

That’s the item. The one shown in the film was probably a Worthington Duplex pump. They were the most common and are still used in refineries and on fuel docks for stripping and hydro testing. They were very common as feed pumps and fuel pumps on low pressure steamboats.

The Ocean Phoenix had a vertical steam duplex used for ballast water transfer. Tankers used them for stripping pumps since they could live in the pump room.

Regarding the electric feed pump, I remember one on a RRF ship. It was an enormous thing that was probably originally an oil field mud or fracking pump, belt driven and if not lined up properly would scream like a banshee and smoke you out of the engine room.

I think I have some photos somewhere and will post them if I can find them.

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It’s a Worthington or a near copy I am sure. Worthington also made reciprocating air compressors that were practically identical. Heavy indestructible beasts.

This Worthington is T3H CYUTE :heavy_heart_exclamation: :heavy_heart_exclamation: :heavy_heart_exclamation:



Amazing. Where’s the condensate drain?

I don’t know. Is it that tiny flange on the bottom right?

Kinda what I thought but don’t see anything coming out. Maybe air was being used for the demo. At any rate it’s an amazing model

They were also used for hydro testing, cold fill & lightoff of turbo pump fed boilers.

You could fill the boilers running the pump on compressed air, switch the driving medium steam when you got the boilers up to a certain line pressure (while running around trying to get heavy oil heated & circulating and warming up other plant stuff) and at some point you’d be flowing enough steam that the recip couldn’t keep up no matter what but by then it’d be time to crank up the turbo pump.

They lasted longer mounted vertically because the bores would wear even instead of egg shaped but they were much easier to work on mounted horizontally.


How about some photos or videos of the steam clock?

Here’s one in its natural element, used as a bilge pump on an old wood tug.


It’s running on air – common practice in the model engineering hobby.

Here’s a model one steaming and pumping.


So I still have a doubt about this pump: if we set aside the topic of shrink, swell, and P+I control for a moment, how can this guy cope with a change in load? If we use more steam, and we want to put in more feedwater, so we open the throttle valve, but we have less steam pressure because we have increased the load, so we open the throttle more, and we use more steam to deliver feedwater… This little monster eats up more and more of our Sankey diagram as the load increases. Is it true?

Also, is this what a watertender’s job was? Minding the throttle for this pump?

Pump is designed to be big enough for anticipated load swings. Nonessential loads would be shed under wild swings which reduce the feedwater pressure, additionally there is a backup in parallel in case of low feedwater pressure. The feedwater pump is king of the hill, everything else takes a back seat.

Depending on the installation and type of feed regulator, when drum level was high feed was reduced, when low, feed flow was increased. All that happened downstream of the pump. When the flow was reduced, pressure increased and pump speed decreased because it is a positive displacement pump. Look up boiler feed regulators.

Many of the early systems that used those pumps for feed were also fitted with injectors that used steam to accelerate feed water and increase its pressure enough to overcome drum pressure. Look up steam injector as well.

The water tender has the ability to increase or decrease feed rate and help maintain drum levels, he worked in coordination with the fireman who managed the number of burners in response to load.

A working steam plant is a symphony. Every component works in harmony with the others. nothing happens in isolation (except for a sudden failure of some piece of machinery) and nothing happens instantly. Changing one parameter may have an effect that does not show itself for many minutes later.

An old time water tender knew what was going on and was capable of playing his instrument.


I worked with relatively modern steam plants 40 years ago. We did not have firemen or water tenders but we had to be prepared to assume the role if the controls went haywire so we were trained old school. The pneumatic Bailey controls were pretty dependable but at times it was as Steamer said, a symphony if things went south which happened often enough to keep you interested. Everyone better know how to play their part. A lot of that ability to mentally see the big picture in an instant and react accordingly without a computer screen has been lost . There was something akin to art of being able to hear a low water level alarm go off, look at gauges, circular or later strip charts to determine where the load was going, the feed pump pressure and numerous other things that made the big picture clear and act accordingly as a team, many times without a word being spoken. Great stuff.

That’s what I loved about steam. It was a thinking man’s game rather than just being a wrench wielding mechanic.

Or in the case of Coffin feed pumps, the sound of an unexpected speed change or a surge could be the opening bar of a whole new concert!


i sailed pumpman on the ‘mississippi’ many years ago… have not ran any pump that big since but these models are somehow more impressive … i guess those tanker pumps are just overwhelming!