WALTER'S STEAM ENGINE DRAINS

[Stanley]

You do set me some puzzles don’t you…… Never mind, here goes….

Two different topics here, the drains on your engine and the way you are running the Sulzer. Let’s start with your drains.

Nowt wrong with being a perfectionist as long as you recognise that there is no such thing and the trick is to decide when the return on the investment in the pursuit of excellence gets to the point where it just doesn’t make sense. You’re workmanship is superb but you’ve still hit the problem of the drains. My workmanship is just good enough and my drains would be OK. So everything I say may sound like criticism but isn’t.

The first thing to do is to recognise that if the cylinder casting had a boss cast in the correct place and there was provision in the design of the bed for installing the pipework you would have no problem but that isn’t a solution, it’s a pointer for the next engine you make.

Now then, get back to basics and clear all the undergrowth and obstacles out of the way. Think about what it is that you want to do. You want to make a hole in the lowest point in your cylinder that will allow condensate to drain out of the engine while it is being warmed. Dead simple, just slacken the cover nuts off and the water will run out. When you put steam on to run, wait until steam comes out of the joint and tighten it up. Bob’s your uncle, problem solved. I can hear you snorting but go back and think again, this is exactly the process you want and will work efficiently so there might be some clues here.

When you slacken the cover water will flow out of the bottom of the joint and steam out of the rest. It’s the water you want to get rid of so the only part of the gap you need is at the bottom. Move on, how can you get that circumstance without slackening the cover? You need to duplicate that gap.

Consider the problems that a traction engine builder has when installing his drains, he can’t go out vertically downwards because the steam passages inside the casting mounted directly onto the boiler block him so he drills in from the side so that the drainage passage hits the lower diameter of the inside of the cylinder at a tangent, more usually, he drills or mills a small slot into the bottom of the casting clear of the cover and drills in to hit that cavity. Think Corliss valve cavities and ports. In practice, the aperture doesn’t need to be at the lowest point, it will do if the lowest point of the drilling coincides with very near the lowest point. I know you won’t do it this way but all you have to do is measure up accurately, poke a hole tapping size in through the cladding and cylinder, open the hole in the cladding slightly to clear the tap, tap the hole, make a stub of the correct length and screw it in. Then install your cock and drain pipe wherever you want. You’ve got a perfectly serviceable and authentic drain. Do it for all the cylinder ends. You can think of all sorts of refinements and variations on this but essentially this is your way out. A perfectionist would drill into the bottom of the cylinder, plug the end of the drilling and drill in from the side to hit the cavity formed in the casting. Safer that way because slight wander in the drill wouldn’t matter. Personally I’d start the drilling into the side of the casting by milling a flat with a slot drill or similar so I was starting from a flat surface. You have drains……

Now then, the Sulzer……

Absolutely nothing wrong with what you are doing as long as it works but it’s not English practice and is unnecessarily complicated. It also contains the seeds of a disaster.

Let’s start from the beginning. I can see what you are trying to do with the ventilating etc., you are trying to eliminate corrosion in the pipework. Start by asking yourself what causes corrosion. Very complicated subject because there are so many primary causes ranging from pressure differentials and temperature gradients through to dissimilar electrical characteristics of fluids at boundary events and vibration or fretting. Some of these can take place even under total lubrication and absence of oxygen but the type we are looking at here is the simple corrosion cell which needs carbon, iron, oxygen and a conducting fluid, in this case water. I have taken down piping that hasn’t been disturbed for over 100 years and the only corrosion beyond a protective surface layer of oxide is in the interstices caused by the pipe joints and all the ventilation in the world won’t stop that. So, in my opinion, the ventilation is a complete waste of time.

The bits that matter are the internal surfaces starting from the interior of the junction valve at the engine and right through the system to the condenser. Again, I have demolished large engines that have lain dormant for twenty years and the interior of the bores has been as good as the day the engine was stopped simply because there is no oxygen replenishment of the atmosphere and the castings are oil soaked and covered from the last running. As long as the drains are opened before the engine is stopped and any condensation present is blown out the rate of corrosion is so slow that it can be disregarded particularly if during the last five minutes of running the lubricant supply to the engine is increased.

On all of the engine I ran I introduced the lubricant into the engine by atomiser into the steam main above the junction valve so that the steam itself becomes the lubricant, this plus the correct grade of oil makes sure that all the internal surfaces are protected. At Ellenroad , the original LP cylinders from 1892 had no lubrication at all apart from the top oiler on the centre line which could be used just before stopping time to introduce a dose of cylinder oil to make sure the rods and bore had a good coat at stopping. On the whole, steam engines are all over-lubricated. Think of a marine engine with no cylinder lubrication at all because of the necessity to keep oil out of the condensers. This is why Rowan Rings were invented.

The grade of oil is important and the biggest mistake made by amateurs running and engine for exhibition is to use the same oil that was used when the engine was running at full load. These oils are too heavy for the lower temperatures in the engine and preference should be given to an oil that will atomise easily and possess the necessary resistance to emulsification with water. At Ellenroad I got the Total laboratories to come up with a new formulation that had the lubricating characteristics I wanted and on cooling down set almost like a coating of grease on the surfaces.

So, on the subject of lubrication and corrosion prevention, forget the ventilation. Go to any competent boiler surveyor and ask what the best way to mothball a boiler is. They’ll tell you that it is to blow down the water and leave the boiler shut up with a closed atmosphere. The only alternative is to take the lids off and leave it totally ventilated. You can’t do that with and engine and pipework.

Different subject now, the drains on the Sulzer….. I don’t know if the set-up in the photograph of the drains is Sulzer practice or some system dreamed up by an enthusiastic amateur but I am dead against it. It looks to me as though the drain is piped through a steam trap with no by-pass and provision for draining the system into a bucket if needed. If this is indeed the cylinder drain the most informative thing about the picture is the rust in the bottom of the bucket. There shouldn’t be any, the bucket should be oily because of the oil carried over in the condensate. As I said before, drains should connect direct to atmosphere with nothing between the cock and the eventual destination. If oil carry over into watercourses and sewers is a problem, simply discharge all condensate into a tank or well where the outlet is below the surface. The oil floats on the top and can be skimmed or gulped at the necessary intervals. It is essential that these outlets should be visible so that the engineer can assure himself that before starting the drains are discharging nothing but steam. If any condensation is suspected during running, say by carry-over from the boiler, the engineer can open the drains and have a look at what comes out. Apart from anything else, wherever a steam trap is fitted it should have a by-pass that can be left open during warming and only closed when the operator is assured that the system is up to temperature and that steam is flowing.

Of course I may have it all wrong and this is nothing to do with the cylinder drains…….

Different subject, warming the engine. One hour of warming is not enough. Apart from anything else, it means that you are starting with warm cylinders and a cold bed. It’s just as important to get some heat in the bed as in the cylinder. Even on preserved engines like Ellenroad, 5 hours warming was the minimum. At Bancroft we always fired the boiler the day before and left the warmer on a crack all night. In my working days, the last thing I did at night when leaving the engine house was to open the warmer a crack and leave it whispering all night. All I had to do in the morning before starting was bar the engine over a couple of times to check there was no water in the cylinders and give the bearings in the shafting a few turns to break the stiction due to lubricant setting overnight. At Victoria Mill in Earby they barred the engine for half an hour before starting to get the extensive shafting free enough to allow the engine to start without excessive load on the crank pins.

Also at Ellenroad and Bancroft I had a Lunkenheimer piped directly to the atomiser in the steam main so I could pump some oil in before starting, that way you were sure there was a good level of lubricant going in until the automatic HP lubricators got up to full delivery.

That’s enough for now……. You’ll no doubt tell me where I went wrong. Come back if you need clarification.

30 June 2008





Stanley,
 
Being a bloody perfectionist can be a nuisance. Arnold Throp just left out the drainage valve in his design of the engine which I am building. But I would like to do better.
 
From the drawing and from the attached photo you can see that there is a possibility to drill a hole on the ends of the cylinders and fit a pipe with a valve. However, that would mean that I have to go through the engine base. Will have to think carefully about it.
 
Your solution with an outlet at the cylinder covers appeals to me, but hardly any space to put a pipe fitting there. Maybe I have to scrap my model and build a much bigger engine?
 
For the Sulzer engine I am working on an instruction to operate the engine (see attachment) (22) Drain Valves Lever, (24) and (26) Check Valves Condensation.
Before we start the engine we warm her up for one hour, a half an hour each in two positions. After we close down the engine we dry the whole system with ventilated air for one hour, which includes the complete pipe work and the engine. That way we minimize the possibility of condensation.
The instructions that I am working on, includes the water treatment plant and the boiler system.
 
That link will show you the progress that I have made on my Corliss http://s89.photobucket.com/albums/k206/Gugger_2006/
 
Wife – dog or vice versa, something to have a good laugh about.
 
It is very warm again, I have to spend Sunday afternoon in the cellar.
 
All the Best
 
Walter