Welsh Steam Coal

I reiterate that you should read (and digest) the previous posts. The service runs on demand and has long periods of "sitting about" alternating with unpredictable spells of intensive working. Safety valve losses on this loco can be avoided by virtually letting the fire go out but potential passengers are unlikely to appreciate delays whilst a "green" Welsh coal fire makes up its mind to make some heat. Obviously, the firebox plates are unlikely to appreciate the ingress of cold air if the loco is run with bare areas on the grate!

Very free steaming locomotives present problems just as dull steamers do. I once encountered an even freer steaming Burrell showmans which blew off continuously whilst driving its canopy lights. With damper shut, firedoor open (not good in principle I know but there we are) and the very thinnest of fires the balance between far too much steam and none was a fine one.

To return to the topic of the thread as opposed to particular individual's skills or lack of them, decent Welsh coal is lovely in some circumstances but not all. Indeed its use in circumstances which do not warrant it might be seen as wasteful.

P.H.

 

From my experience the Welsh coal that is currently available is not that great. It takes a very long time to get going in the morning and you need to throw an awful lot of wood in to get it hot enough to ignite. Once you're on the move it's very slow-acting so you need to be firing about 20 minutes ahead of when you want something to actually be happening. In terms of volatile gases there are hardly any, which is good for the local residents but not so good if you're used to firing by the smoke on the chimney. But the worst attribute of all is that it's inclined to glue itself together into bin-lid sized sheets and to form molten iron clinker which pours itself down between the bars and won't be budged.
On the Mid Hants we currently use a mixture of Welsh and the harder and much smokier Daw Mill which is a good compromise and lessens the worst attributes of the two types of coal.

 

Personal experiences with alleged 'Welsh Steam Coal' on Sentinel waggons back in the 1960s and '70s were not good. Go to a coal merchant and ask for it and what you got was Anthracite. Might be OK in a domestic boiler (coal fired central heating then!) but useless in a waggon - needs one hell of a draught to get it to burn. In desperation, through a friend who was then (around 1965) a fireman at 81A Old Oak Common we bought a ton of their 'Welsh Steam Coal' from BR, and this turned out to be just as bad.

We then realised why GWR locos have such a sharp exhaust - they need it to get the bloody stuff to burn!

Stuck to the 'black stuff' after that, much more predictable. Rossington was a good one. Hit it with a hammer and it shattered like slate, but the waggons steamed well on it.

 

It takes a bit of getting used to after all the Russian etc we've had for the last 20 years. Needs a lot of primary air & anticipation, but when you've used it a bit, no looking back!

 

PLUS! Just as important- support the home coal industry !!

 

Perhaps I ought to say before I comment that I have never fired or driven a loco, so my approach is most definitely that of an observer; an observer with an engineering background, but an observer nontheless.

I have been most interested in this conversation since it started as it offers insights that would not normally be available to the layman, but I think I ought to say to 'michaelh' that 'feathering' at the safety valves is very much a piece of 'OS Nock' romanticism. What the enthusiast sees as feathering is usually steam leakage from the valve caused by a minor, usually very minor, issue with the valve seating. When the steam pressure in a boiler exceeds the valve setting then the valve will blow and if the valve seating is perfect there won't be the slightest warning; it will just go, violently in the case of pop valves, more gently for the Swindon or Ramsbottom designs.

One point that perhaps should be made about GW engines and soft Welsh steam coal. GW engines coaled in the south did have the Welsh coal, but the GW sheds at Shrewsbury and Chester were supplied with much harder Staffordshire coal and it didn't make any difference to their performance. When the GWR lent Castles for tests the the LNER and LMS ('Launceston Castle', on the LMS, and 'Pendennis Castle', on the LNER) these engines would have been supplied with the coal these railways normally used for passenger turns, quite often coal from Staffordshire and Yorkshire which was a lot cheaper than the Welsh stuff. The Castles beat the home engines hands down for coal and water economy even when though they were using very much harder coal with a lot less bitumen in its makeup.

Regards

 

There is only ony type of safety valve that POP's just like that, its a ball bearing over a hole. The valves on the locos at Statfold are like that, but the traditional type valve with a tapered seat, and flutes will always open initially with less outflow of steam than whan it is fully open.

A valve like this will need to lift say 1/16 before they will blow full bore, and you may need 3 or 4 PSI above the red line for the valve to be in this condition, given the compression/extension of a spring is proportional to the spring constant.

Thus keep the pressure at the red line pressure or perhaps 1 or 2 PSI over and the valve will only open the valve a small amount and will not be open full bore, hence a 'feather'.

Also sometimes either by design or accident one valve will lift marginally before the second. Thus you also get a 'feather'.

 

I think you'll find that the GWR supplied all their MPDs with Welsh coal. I have an old wagon label for coal to be transported from Six Bells colliery Abertillary to the GWR MPD at Chester.

 

Not entirely the case Mr. J. :tongue:

A large number of model/miniature safety valves use a ball-bearing as the valve - and they don't necessarily give a 'pop' action.

It's possible to make a ball bearing safety valve with either a gradual opening, or to give a pop action. In the same way a valve using a tapered seat with guide flutes can also be made as gradual or pop.

In a gradually opening valve the seat just sits within the body of the safety valve. As the valve opens the 'waste' steam is able to vent to atmosphere with ideally no back pressure. These valves will sit there feathering quite happily on the verge of starting to lift properly.

To gain a 'pop action' the valve seat needs to sit down inside a counterbore. This means when the valve initially starts to lift, the steam passes the first seat and rapidly finds the surface area over which it is acting increases. This gives the steam a greater mechanical advantage against the spring so the steam is able to quickly open the valve to 'full flow'. As the pressure drops the reverse action applies as the area open to the steam quickly reduces - hence the sudden shut off.

Pop action safety valves can be a right pain to make in miniature sizes, and even harder to make really well! In theory the point at which they open should be slightly higher than the point at which they close, to give the snap action. Unfortunately if you're not careful then the small ones will suddenly open without warning before then sitting there blowing an annoying rasberry sound as they ocillate, before eventually fully closing at a much lower pressure! The other variety of miniature pop valve will suddenly open without warning before sealing again 1 or 2 seconds later - making everybody nearby jump out of their skin with surprise!!!

 

The big railway companies used to have inspectors for coal. They could also rely on labs, etc, to determine how much ash, etc, was in the coal. I suppose you could determine the grade of coal by putting it through a quality process, but most coal merchants would not be happy to see their 'product' go under the microscope.

Add to that, there are different calorific values, depending on the seam, etc. Usually deeper the seam, the higher calorific content, and lesser ash. If the coal is being opencasted, then you can expect a higher ash content, depending on which 'face' is being taken. Most opencast is mixed coal, regardless of seam, as some opencast sites are quarrying coal, rather than mining. When you are faced with a wall of coal, you might not readily appreciate that there might be a difference of over 15,000 years in the makeup of the seam, from top to bottom, and that will affect how it burns. If you are quarrying mutiple seams, then multiply the problems expotentionally!

Welsh Loco coal was taken from particular seams, in order to capitalise on calorific value, per ton of coal. By modern preservation definition, coal from Wales must be the same stuff Grandad used to fire the 'Bristolian'... Not a bit of it, I'm afraid..... Rhondda coal is no longer mined, and I believe Six Bells & Tymawr were the last Welsh collieries with the correct grade seams.

If you want the best steaming coal, employ a chemist first, then send the respective firemen on a course to learn how to burn the stuff....

Regards,
Ian

 

No problem with this in theory. Trouble is, the last time I applied this philosophy in practice I ended up with an Austin Metro...........

P.H.

 

It's really good stuff! Perhaps change the way you light up and don't lay all the coal down first? Get the wood burning and then add the coal. Thinking ahead isn't a problem, something that should be done all the time but the beauty is that it doesn't make that smoke. Daw Mill produces the clinker that you mention that melds with the bars and I'm not convinced that mixing it with Welsh helps that.

 

Welsh coal has never been great, IMHO. I was brought up on the stuff and, like a lot of people, brainwashed into thinking it was the best. It was only when I started to fire with hard coals that I realised that they were much more user friendly from the fireman's point of view. Bearing in mind that the combustible component of the black stuff, wheher Welsh or any other variety, is essentially carbon and the variation CV is effectively dependent on the ash content and little else. Thus, the lower the ash, the higher the CV. The other significant combustible is hydrogen and that is generally largely present as water and thus, of no use. You only get combustible hydrogen as a component of the volatile matter, which Welsh coal is usually light on.
An inescapable problem with Welsh coal is its friability, hence its reference to soft coal. It soon turns to dust with handling and this makes it harder to usefully burn.
Give me a good hard coal, any day.

 

I think we'll have to agree to disagree on the clinker issue;the worst clinker I've ever seen in the Standard 5 came from pure Welsh coal. Took the Monday disposal team best part of a day to clean the grate properly because it had glued itself so firmly to the bars. Sure the Daw Mill clinkers up too but it's more brittle and easier to shift.

 

In the traction engine world, the views on the 'Welsh' currently availible is also mixed. Many, and it has to be said most think its the best thing since sliced bread, others report clinker, and it has a joke name of 'NO STEAM COAL' as engines with soft blast don't steam well on it.

It has to be said also that many users have 'trolley dollys' that never get used in anger so are probably not best placed to comment.

I've found the welsh as crap for sitting about at rallies, it produces no smoke, but you also dont get any steam so its no good. On the road it is grand, but because it is small can turn into a pudding that wont let air through, and it can and does clinker when this happens.

Personally I'd rather a good hard coal also. Bigger lumps the better.

 

Clinker is simply molten ash. Ash fusion temperature varies with the constituency of the ash and its proportions and that can vary even within the same seam. A coal with a low ash fusion temperature (say 800C) will invariably clinker whereas one with a high ash fusion temperature (say 1400C) is unlikely to clinker. However, a fireman who stirs up a hot fire with fireirons can create clinker even with a high ash fusion temperature coal if he brings the ash to the top of the fire. Closing the dampers on a white hot fire when the regulator is closed will also help with clinker formation as there is little air flow cooling the ash on the grate (as well as the firebars), allowing it to heat up. The reducing atmosphere (lack of air) caused by closed dampers will also reduce ash fusion temperature.
One of the problems with Welsh coal is its friability and thus the amount of dust created. and every fireman knows that putting slack onto a fire is a recipe for clinker formation, whatever the coal.

 

Yeah, but slack is brilliant for banking down! ( I'm just an old fashioned optimist!)
I refer you gents to my previous posts on the last page.

 

Heard all this before in the 60's heard it called Welsh blind and worse.
I too had problems the first time I used it, the bl**dy fire went out!
I adapted and got on well with it, I found that it paid off to not fire it too thick.
I heard someone say that it needs ex GWR engines to burn it because of the fierce blast they have.
My father and I spent a very pleasant afternoon on Salisbury station back in the early 60's and we were invited onto the footplate of several Bulleid pacifics of both types guess what they were burning Welsh steam coal.
They all were well up to the mark with nice bright fires!

Cheers Dave

 

I will refer you to earlier posts on here, about Welsh coal. It does come in various grades, some good, some bl**dy awful. The last pits that used to mine the best stuff went in the late 'eighties, so I don't know where you are getting it from now. Some merchants will tell you that the coal will come from anywhere you like, just to get a sale. After all, its your business they are after.

If you want a specific grade of coal with a recognised ash content, and recognised 'inclusions', such as iron, sulpher, etc, then its down to the buyer to specify this on the order form. Its no use complaining when the merchant drops 20 tons of 'slack' on the deck, and swears blind "Its best Welsh Cobbles, from Uppercwmskwtt".

Not all puddings come from Yorkshire......

Ian

 

Get it hot, keep it hot and clinker isn't usually a problem. If you have a layover between trips and it cools and starts to set, clean the fire!
I do remember a main line trip Padd to Stratford and back as support crew pre privatisation where the loco was delayed for turning on the triangle.
Due to time, the BR crew wouldn't let us clean, by then, the cool fire before we set of homeward. We were in trouble by Banbury, and finally declared a failure by Gerrards Cross with a mountain of un-burnt coal on a non cleaned and clinkered firebed. The abuse we got over the station carpark fence from the punters was un-beliveable, no one was interested in the fact we wern't allowed to clean the fire. It was all our and the locos fault that they didn't get back to Padd much before 23:00.
Keep it hot, keep it clean has been my motto ever since and I've had few problems with Welsh. For me at Didcot, considering one end of the site sits in a housing estate, we have to be very careful when using hard coal which can produce too much smoke if badly managed.
Maybe the truth of the matter is it's all down to experience and fire management. What ever coal you've got, by the time it's gone wrong, you should have seen it coming and managed the fire accordingly!