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[Bunkerbarge]

This thread has been put into the R&D board as a guide for all modellers new to the delights of steam plant to help them with any challenges they may encounter along the way.  Beginners can feel free to ask any question, no matter how simple it may seem, and one of our esteemed experts will help out in any way they can.

I would also ask any experienced steam modellers to add any post in this thread that they feel may be of benefit to newcomers such as defenitions, explanations or even tutorials.  Please keep them at a level that can be understood by all and therefore will be of benefit and interest to everyone.

Let's not forget that there is no such thing as a daft question and encourage all to ask whatever may be on thier minds.

[sheerline]

Hi Bunkerbarge, I'm not involved with steam boats as such, don't own or run them (as yet) but recently I have had a little insight to the regulations regarding steamboat safety checks and boiler testing regs etc.
What are the regulations, if any, governing the use of flash steam plants, presumably they are not subject to the same rigorous test proceedure?
Many thanks.......Chris

[gondolier88]

Hi Sheerline,

Flash steam plants, if that is definitely what you are building, are not covered by current EU regs, or most model engineering clubs.

The reason is that usually they are made of one continuous length of thickwall small diameter (hence very high safety rating) tube with extremely small water content (so if it did do the unlikely and explode then it would not do any damage- steam expands at a ratio of 1600:1 so 1L of water would theoretically become 1600Lt of steam).

If however you have an accumulator or header that stores the steam or water then it becomes a shell boiler and has far more stored potential energy and this would need to be pressure tested to 1.5 x working pressure in the presence of a boiler inspector.

Greg

[Bunkerbarge]

I am not actually aware of any regulations that cover Flash steam plants because technically they are not an enclosed pressure vessel.  The "Blue Book" and the MPBA rules therefore do not apply and, as Greg has already said, neither do current EU regs.  The minute however you enclose a space and subject it to a pressure it becomes a pressure vessel and hence rules apply.

[sheerline]

Thanks for that chaps. No, I wasn't intending to build one....( yet) but I met a fellow the other day who has done so many times. He uses uniflo engines for hi speed runs and it fired my imagination a tad.
Two of the main problems for me though A: time and B: noise ....but the whole scenario of pumping water and turning it into a red hot gas to be instantly used up has a kind of poetic engineering beauty about it. Anyway, for now the world is a safer place as I'm bogged down with work.
My main question was the regs and you have answered it kind sirs.
Regards...........chris

[gondolier88]

Uniflow engines are by their nature very noisy and you can buy pre-built engines and kits Sheerline...

Uniflow engines are noisy because they have limited cutoff and use a quick steam exit from the cylinders making for fast and furious running.

Greg

[sheerline]

Don't tempt me Greg!! I have enough trouble trying to pursue all the current projects on my 'want to do' list as it is.
I get easily distracted and go off on tangents. Whilst raking through some stock materials in my junk box one day, I found some spare brass and ally etc and decided i could build a V twin I had had in mind for some time. I started doodling and mulling it over and so one weekend i grew this 'contraption' from my scrapbox. Once the lathe was going I couldn't stop, even though I had work to do but it was worth it.
12mm bore,20mm stroke, 60deg double acting oscillator with 4mm stainless shaft running in ballraces.Chassis is made from Duralumin. I disposed of the usual cylinder tensioning springs and made brass cups containing silicone 'O' rings so I could pre-tension the cylinders to the ported backplates for max seal/min friction (you can fine tune it when underload). Backplates are stood off the chassis to mininise heat loss. Pistons are grooved and use silicone'O' ring seals. At 25 psi offload it is scary fast but underload it is virtually unstoppable, masses of torque. I did compile figures for it when I tested it but they have vanished and i can't remember now how many watts of power it produced.  I loaded it with a small generator and got 9.6 volts at something like 1/2Am (4.5W approx).
 One day i will find something to put it in as it will turn a good size prop. I ran it for a couple of days just to see if it would wear out, once the pistons had bedded in I whipped them out and replaced the 'O' rings and it runs like a real sweetie. It will creep round at an agonisingly slow pace and despite the 60deg angle it is very regular with only the tiniest perceptible hesitation at one spot but that is probably my fault with drilling the porting.
Anyway, that is the sum of my '' build it for fun' diversion for the last couple of years... looking at what you have been up to lately just puts my efforts to shame I'm afraid but at least it worked.
 Ah well, back to work!

[Circlip]

You've opened the padded room BB, Flash Steam, TRUE Sooperheating.   


   Regards  Ian.

[Bunkerbarge]

It didn't take long for a Beginners Guide to become yet another place to advertise our talents did it?

[sheerline]

Sorry BB, wasn't my intention and I didn't set out to hi-jack your thead. The bit I posted was however informative with some specs on the engine and may inspire some raw beginners by showing what can be done with a box of scrap rather than an expensive set of castings and an envelope of engineering drawings. 

[benjaml1]

I have a question for our experts. Gas nozzle sizing....

Larger more heat ? I'm sure it's not as easy as that..... What defines the correct size for a given power plant ?

[kiwimodeller]

Certainly dont profess to be any sort of expert but we can all play around and note down the results. I quickly established when trying to get more steam out of a boiler that could not keep up with the engine's demands that a bigger gas jet size does not mean more heat unless you can get more air in too. Even that does not make much difference unless you can balance the proportions of primary and secondary air. Get those right and the amount of steam does not increase much unless you can increase the size of the burner and the surface area of the flue and cross tubes to transfer that heat in to the water. I guess what I am saying is that there are several factors to the package. The modern ceramic burners are neater, tidier, quieter and more reliable but I can still get more heat out of the old Primus - Sievert "Roarer" type burner as used on plumbers torches. Old timer once told me that the best set up is the one that has the hottest temperature at the flue entrance and the coldest temperature at the top of the funnel as then all the heat is going in to the water. I must get a thermometer to test with. I guess this is why manufacturers have to build in an R & D cost - me, I just drill holes and see what happens. Have fun experimenting, you will try 100 different things to find 99 that dont work but the other 1 is worth knowing! Cheers, Ian.

[benjaml1]

Thanks for that Kiwi... 

[Bunkerbarge]

Another angle that seems to get forgotten here is that playing around with the burner configuration invalidates any "steaming" certification that may be in place on the boiler, as opposed to hydrostatic pressure tests. 

Such steaming tests as required by the "Blue Book" require you to demonstrate that the safety valve will not allow the pressure in the boiler to rise by more than 10% of the working pressure with the burner on full.  The certificate issued for this is only valid as long as you do not make any alterations to the burner, the reasoning being well demonstrated to me only recently.  I was testing a boiler with the safety valve fully open and venting however the pressure was continuing to rise to well over 10%.  We changed the jet for a smaller one and repeated the test and the safety valve was then able to cope with the heat input however if the owner was to replace the original jet then the boiler would be in an unsafe condition.

[Circlip]

But doesn't that suggest that the safety valve was inadequate for the boiler heating requirements BB? Yes I know you went the other way and reduced the burner jet size, but would not increasing the safety valve outlet diameter have achieved the same effect??

  Regards  Ian

[Bunkerbarge]

But doesn't that suggest that the safety valve was inadequate for the boiler heating requirements BB? Yes I know you went the other way and reduced the burner jet size, but would not increasing the safety valve outlet diameter have achieved the same effect??

  Regards  Ian

Of course, but I was only making the point that you cannot play around with the burner configuration, or the safety valve, once it has been certified.

[benjaml1]

Discussion of a moot subject amongst Gentlemen is always a win win situation for all....

[Circlip]

The main problem that has to be overcome is the one of "Mindset" As we often see(?) in audio reproduction, as far as the younger generation is concerned LOUD IS GOOD.

  Ian (Kiwimodller) highlighted a misnomer in that applying a higher heat source would substitute for a lack of steam volume production in a specific boiler. Heating area was the answer, not heat intensity, having said that, steam overproduction is just as big a vice. Why have a boiler producing vast volumes of steam to power an oscillator when most is escaping via the safety valve.

 Many years ago, pre-motorways, I fitted an 18T engine sprocket to a motorbike that nomally had a 21T as standard everyday use. This was because I was going "Down the A1" on a long (For me) trip. Top gear on the long straight roads was great, no stress on the engine, BUT in towns, what a b***h, I was counting all four strokes of the engine in first gear and having to slip the clutch to keep moving.

 How many try to employ the same parameters to toy engines?? The two "reference" books that should be in every steam addicts library are K.N.Harris's Model Stationary and Marine Steam Engines and Model Boilers and Boilermaking (Oh H**l is he wittering about those AGAIN). To find the answer, one needs to understand the problem and by looking at and applying first principles which the forementioned volumes explain fully, it becomes obvious that for a given engine size and steam requirement a suitable boiler type and size can be deduced. "But I'm not very good at Maffs"   OK, DON'T meddle, if you can't work it out, leave the construction and experimentation to someone who can or play in isolation far from any you might injure if you've got it wrong. Seen so many Gung Ho threads on "Other" sites where a caveat emptor attitude is taken re safety or common sense[/b for that matter exists.

 The only difference in the books mentioned is that the safety valve requirements to comply with the Blue Book would have to be changed as more recent thinking on steam escape hole sizes has been further investigated in recent years (well forty at least). I'm not trying to put the beginners off, but there are well founded reasons for not putting a Vee8 in a Mini, and the basic steam principles still apply from their original conception, thanks Messers Boyle, Stevenson, Rev. Stirling et al.

  Regards  Ian

[vintagent]

Since this is supposed to be a Beginners' Guide, may I ask where one could find an absolute beginners' explanation of the principles of steam engines?  A friend in America, a long term modelmaker in plastics and resins has decided to go all "model engineer" on us due to a late life allergy to the forementioned.  He LOVES British traction engines, but just wants to be talked/shown through steam practice from A-Z.  He's a VERY intelligent, urbane chap and will be most appreciative if anyone could point him in the right direction.
He already has LBSC's Shop, Shed and Road, but wants something a little more universal as explanatory notes.
He has a nice Sherline lathe and Mill with all the goodies, too.  B*****d!!

Many thanks in anticipation.
Regards,
Vintagent

[Bunkerbarge]

Both of these books have been long out of print however they can both be obtained as .pdf copies from here:

http://www.fastonline.org/CD3WD_40/JF/424/19-423.pdf

and here:

http://www.fastonline.org/CD3WD_40/JF/424/19-422.pdf

Circlip will be asking questions later!

[Bunkerbarge]

.....and they are also both available from here:

http://www.teepublishing.co.uk/search.php

[barryfoote]

I am sorry to sound a grump, but as a beginners guide, so far this thread is a complete waste of time. I have had a read through it and found nothing for the beginner!!! I am more confused than ever now......

[KenP]

I agree with Footski, canwe get bsck to thr beginners bit.

What bits do you need to power a ship?

How do you decide which boiler to use?

How do you decide which engine to use?

How do you keep the boiler toped up with water?

How do you start the bloody thing?

[Colin Bishop]

Ken,

Bunkerbarge covered most of your points in his recent series in Model Boats magazine last year. If you don't take the magazine then back copies are available.

I think there is another pertinent point to be made here and that is that there may be two types of beginner, the person who wants to build his own plant (as per Vintagent's post above) and the person who wants advice on how to choose, fit and operate commercially obtained equipment. It is the latter that Bunkerbarge's articles were really intended for and theye were very well set out and easy to understand. Definitely worth getting hold of as they are up to date too. The first article and one or two of the others are free to view on the Model Boats website: http://www.modelboats.co.uk/news/article.asp?a=4447

Colin

[Circlip]

Not only Colins addition, but the two References I gave, that Bunkerbarge has given free download copies and saved "Beginners" about thirty quid as already quoted contain the basics. ???????    How big does the spoon need to be?


  Oh yes, and I hope if Ripslider is reading this, he lets me have my copies back

   Regards  Ian