Steam Pipeline question

[Dark KnightParticipant @darkknight31337]

Hi,

I started doing work on pipeline and I encountered 1 problem. I will bend copper pipe at a little bit of angle for condensate to flow down. I drilled hole a little bit deeper then hole for steam to flow into the cylinder so condensate could sit there and not clog cylinder with condensate. My only concern is that steamer flow will be very slow because I know steam doesn’t like 90° angles and this one’s even worse becouse its drilled and not smooth as pipe. Will there be to much condensate? I added cross-section sketch for reference. Should I have drilled hole different. Does anyone have any experience with this?? I also added model image for cylinder reference.

[Nigel Graham 2Participant @nigelgraham2]

That’s a neat design!

I don’t think you need worry too much about 90º bends on a small model like this, but you can buy or make small pipe-benders for such projects. Their minimum bend radii are 3X pipe diameter.

Nor the drilled passage: most internal steam-passages on model steam-engines are simply drilled, and they work well.

Smooth bends and smooth passage walls really only matter on larger, more powerful engines where you want maximum efficiency.

The sketch did not appear – well, I can’t see it here anyway. So don’t really understand where the drilled hole is, but you need remove the condensate somehow, until the pipe and cylinder have reached their operating temperature.

Am I right that this an oscillating-cylinder engine, with the cylinder held to the port face by a spring? If so the cylinder will tend to lift slightly off the port face if it becomes full of water. Usually, the condensate in such an engine blows out of the exhaust.

 

 

[Dark KnightParticipant @darkknight31337]

Hi thanks for reply. I will again add image, I hope this time you will be able to see it. Im really worried of condensate building up and filling cylinder to that extent that engine would stop spinning because this boiler will probably be able to produce wet steam, and yes its oscillating-cylinder engine. I will also insulate pipeline with layer of ARMAFLEX.

[Nigel Graham 2Participant @nigelgraham2]

Thankyou – yes I see it now. That drilling won’t stop the cylinder filling with condensate when it is still cold. Most of the condensation happens in the cylinder, not the pipe, until it warms up and runs properly. That is true of more or less any steam-engine, even in full-size.

Really, there is not much you can do on an oscillating-cylinder engine to help, but you could try putting a little drain-valve down-stream of the exhaust-port of the valve-face so the condensate can be removed cleanly until the engine is hot enough to run smoothly. You then close the drain-valve.

It is still likely that you will have to help the engine to start, by giving the flywheel a push round each time the water in the cylinder stops it, but it should soon reach its running temperature and then run smoothly. During this process, don’t be surprised if the water escapes by pushing the cylinder away from the valve-face slightly.

When I was a boy I had a “Mamod” model oscillating-cylinder engine, and that behaved in just the same way!

.

Your photo and sketch seems to show the steam-pipe enters the engine by being soldered in place. It is better to use a union there (larger engines have a bolted flange) to make any future repairs easier.

I’d also recommend you fit some way of lubricating the cylinder and valve-face. A simple way is to put a little screwed plug in the valve-block so you can put in a few drops of oil before steaming it.

[duncan webster 1Participant @duncanwebster1]

Believe it or not, insulating the pipe can make it worse. That is because it increases the area from which you are losing heat. See recent article by Mike Tilbey. Not sure where if was, ME or SMEE journal.

I had one of those Mamod models as a teenager (long time ago). If you put another meths burner or in my case a gas bunsen under the pipe it improves performance noticeably.

[Dark KnightParticipant @darkknight31337]

But how can it make it worse, I know air is good insulator but still copper is really conductive metal and losses heat quickly and ARMAFLEX has very low coefficient of heat transfer. I will check the article, thanks

[Dark KnightParticipant @darkknight31337]

Could I preheat the cylinder to 120°C with small butane torch, I’m not sure but there shouldn’t be any damage to cylinder right?

Most likely I will just solder pipe in place, because it is easier than cutting threads for joints and I dont even have the right thread cutters, I only mostly have metric threads. I will make pipe from 2 sections – 1st will be soldered on boiler, 2nd will be soldered onto valve-block.

[Nigel Graham 2Participant @nigelgraham2]

You can make pipe fittings with metric threads, though ISO-Metric Fine would be better than the common ISO-M Coarse threads, for pipe fittings.

Not a very good idea to preheat the cylinder. That could lead to damage from unequal expansion. It’s better to let the steam heat the cylinder in the natural way even though the engine will not run very well until it has reached its operating temperature.

 

A very simple way to reduce heat loss from pipes, is to polish them!

They look very good too, but a smooth polished surface radiates less heat than a dark or rough one.

Large full-size engines installed in water-pumping stations and factories often had insulation round the cylinders but the cylinder covers were polished to reduce heat loss.

[Harry WilkesParticipant @harrywilkes58467]

DK you may or may not be like me and don’t like polishing 😉 there a guy on youtube Keith Appleton  https://www.youtube.com/user/keithappleton  who lags his steam pipes if i remember correctly with string and then applies a coat of white paint over the string. Keith has many steam engine videos on youtube and is a good source of information but be warned some of the things he does should be frowned on

H

[Nigel Graham 2Participant @nigelgraham2]

You can insulate pipes etc with string but if you then paint it you immediately lose most of its insulation value. Such insulation works rather like string vests and woollen clothes, by trapping air in innumerable tiny cavities. Paint fills the cavities and stops them working.

[Harry WilkesParticipant @harrywilkes58467]

Hummm now where did I put that old string vest 😉 thanks for that piece of info Nigel

H

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[Grindstone CowboyParticipant @grindstonecowboy]

Always thought that wrapping steam or hot water pipes with string or asbestos rope was to stop you burning yourself on them, rather than insulating them.

Rob

[Harry WilkesParticipant @harrywilkes58467]

Rod surely it works both ways

H

[Grindstone CowboyParticipant @grindstonecowboy]

I guess it does, Harry 🙂

But I’m still about 75% in favour of the safety aspect.

Rob

[Harry Wilkes]

On Harry Wilkes Said:

Rod surely it works both ways

H

But

On Grindstone Cowboy Said:

Always thought that wrapping steam or hot water pipes with string or asbestos rope was to stop you burning yourself on them, rather than insulating them.

Rob

But if the thin layer of string has little no insulating effect, as per recent ME/MEW article, it is not going to stop you burning your fingers on it. It will be as hot as the pipe inside it.

A better idea to get nice warm dry steam to the engine cylinder might be to do like many of the commerical toy steam engines of the 20th century did and run the steam line out the top of the boiler, then back down under the boiler drum so it is exposed to the heat in the back of the firebox aft of the meths burner, then out the other side and over to the engine. Basically like a low-calorie superheater, it will not super heat the steam but adds enough extra heat to cause much of the water entrained in the steam pipe to evaporate and thus dry the steam.

You could even run the steam line in a loop up to the front of the firebox, directly over the meths burner, and then back again before exiting, like a pukka superheater. A simple meths flame is never going to melt  copper, even if you let the line run dry.

[Howard LewisParticipant @howardlewis46836]

Since it is an oscillating engine, the cylinder is held against the port face by a spring.

If the cylinder fills with condensate (hydraulics) the pressure will be communicated, via the cylinder port, (Albeit small = small actual force, but for practical purposes, water is incompressible, so high pressre = high force)  so that the cylinder is pushed off the port face against the spring.

Never caused problems with my Mamods, as a boy.

Howard

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