Steam heat query

Discussion in 'Railway History & Nostalgia' started by kermit, 3 Dec 2017.

  1. kermit

    kermit Member

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    I'm old enough to remember seeing passenger diesels wreathed in steam from leaky joints (at intervals along the train as well) on cold days in winter. What never occurred to me at the time was the likelihood that the rear carriages got less heat as the steam supply cooled along the train - and I don't remember ever seeing a trail of steam emerging from the tail end of a train, which surely it must have done to keep fresh, hot steam moving through the system?

    Any photos of the end of a steam heated train to back up this theory?

    Thanks!
     
  2. DelW

    DelW Member

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    I would imagine (though with no evidence to confirm it) that there would be an out and back pipe, like in a central heating system, otherwise as you say, the steam would have to be vented off at the last coach. Maybe someone from a preserved line that still uses steam heat can explain the system?
     
  3. John Webb

    John Webb Established Member

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    According to "The Oxford Companion to British Railway History" there were at one time (late 19th century) three means of heating carriages from a steam loco. These were a hot water system with out and back connections as in a normal building system, radiators filled with Sodium Acetate solution - heated with steam at intervals, and the one pipe system of heating radiators by low pressure steam continuously fed from the engine. Technical details are not given, but I assume the wisps of steam are deliberate small releases to encourage the movement of steam along the pipe.
    There were problems heating long trains, and Sir Nigel Gresley did look at electric heating but this was not practicable at the time on non-electrified lines. Air conditioning, still with heat supplied by steam, was developed, but the advent of DE locos and the ability to generate sufficient electricity for carriage heating made electric heating the preferred choice. (Although many DE locos were first fitted with boilers because they had to haul stock built to be hauled and heated by steam locos, of course.)
     
  4. Bevan Price

    Bevan Price Established Member

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  5. GusB

    GusB Member

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    I remember seeing such internal leaks - I was probably only about 4 or 5 years old at the time, but I recall opening the toilet door in a carriage (probably Mk1 or early Mk2) and being greeted with a rather large cloud of steam. It was rather a long time ago, but I do remember feeling a little disconcerted.
     
  6. xotGD

    xotGD Member

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    That wasn't the toilet - that was the on-train sauna!
     
  7. kermit

    kermit Member

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    Thanks for that - very interesting. Two things stand out - when various people referred to "steam heat bags", do they mean connecting pipes? And the bit about steam under pressure not needing to pass through the system, but behaving like a gas, circulating heat naturally? That seems frankly unlikely for the length of a 12 coach train, but I'm no physicist!
     
  8. edwin_m

    edwin_m Veteran Member

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    Presumably when the steam gets colder it condenses, creates a partial vacuum and pulls more steam in down the pipe. So as long as there is enough steam available and something to get rid of the condensate (which there is, according to the linked thread) then it should keep working.
     
  9. The Lad

    The Lad Member

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    Steam heat works at about 50psi and consequently the temperature is about 140C. As steam condenses it is allowed to escape by various drip valves and true the pressure at the end of a train is reduced but it is not a significant problem up to say 8 coaches
     
  10. Railops

    Railops Member

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    I remember well being in 10-13 coach trains with virtually no heating in the last couple of coaches.
     
  11. ChiefPlanner

    ChiefPlanner Established Member

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    Wily passengers always went to the front of a train for "more heat" , not unknown in days of steam traction for the heating to be reduced if the locomotive was struggling !.....

    I think Scotland was the last area with booked steam heated diesel trains , I recall wonderfully evocative journeys on the Leominster to Cardiff service in the winter of 1979 (which was pretty cold with lying snow for awhile) , when my train home on late turn was a 25+4 MK'1 s - where you could get a warm compartment in a nice steam fug , even the seats were slightly damp - like something out of Anna Karenina......
     
  12. Calthrop

    Calthrop Member

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    There comes to mind a whimsical thought about an essentially un-funny subject. In the bad old days of apartheid in South Africa, standard practice on passenger trains -- established in the days of almost universal steam -- was to have the coaches designated for "Non-Whites" in the forward part of the train, and those for "Whites" in the rear ditto. Cynics ascribed that to black people being reckoned less important than white ones; so with its being found that in passenger-train accidents, the brunt of the damage was more often borne by the coaches toward the head of the train -- blacks were more expendable, so were put in the potentially more dangerous area. Plus, if someone were to be kept from sleeping at night by the noise of the loco, the blacks were seen as the appropriate sufferers re that issue. One wonders now, whether as regards steam heating front versus rear of train (and it's gathered that in South Africa, it can get pretty cold at night), the blacks came out as the winners there?
     
  13. ChiefPlanner

    ChiefPlanner Established Member

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    Whilst 222 Marylebone Road was being cleared (on sale to a hotel chain) , it was possible to rummage around empty senior officers desks , and I discovered a pre WW2 Tanganika Railways Rule book - loads of distinctly non PC comments on "natives must not travel on wagons , or sit on station benches" , and the hierarchy of trains was "Mail and Trans conveying his Excellency the Governor" as top priority , and predictably 3d class native trains at the bottom. (behind light engines and empty wagon trains)
     
  14. Taunton

    Taunton Established Member

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    Steam heat in Canada did suffer in bitter winters and special heater cars (with attendant) were attached at the rear. The steam pipes were disconnected and shut at the train midpoint, and each half was supplied separately, loco back to the front half, heater car forward to the rear half. Russia had a different approach and coal-fired heaters were (and still are) installed in each coach in older non-ETH vehicles.

    Steam visibly escaping is not how the system is designed, that's a leak, or imperfect valves. The steam was intended to condense in the heaters and drain to the track. Maintaining pressure with intermittent on/off demand worked fine from a steam loco supply through the special reducing valve, but diesel boilers which were designed to cycle on/off were never got to reliability. Slightly loosening the valve on the last coach could help by ensuring a continuous flow but you then ran the risk of running out of water on longer diesel runs. Quite how the Canadians managed far greater reliability from their steam generators is a good question.

    Non-Parliamentary language from a fireman who was uncoupling a steam loco at Taunton platform was generally a sign that, although the shut off cocks on both pipes may have been closed correctly first, there had been some hot condensate still in the pipe which was now over the fireman's clothes! If my mother had heard it, I'd never have been allowed to go down to the station again.

    "Bags"? The connecting steam (and vacuum) pipes. I've not heard the expression outside Scotland.
     
    Last edited: 5 Dec 2017
  15. AndrewE

    AndrewE Established Member

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    If it was just water draining there is a serious risk it would freeze up in very low temperatures. BR definitely required the steam cock on the rear buffer beam to be kept cracked open so that there was a slight flow of steam to keep it unfrozen, and I would think the radiator drains would work the same way.
    The "Bags" that I know in England are the leather water column hoses.
     
  16. kermit

    kermit Member

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    Thanks all for sharing further knowledge!

    So....if all was running properly, steam under pressure really could heat a single pipe all the way along a short to medium length train, by condensing and dripping out of drain cocks. A long train ( not unusual in those days? ) might struggle to feel the heating effect towards the rear. A partially opened valve on the last coach could improve matters by drawing more steam through the system, but along with leaks, this would deplete the water supply faster, and reduce the efficiency of the system by reducing the pressure. Diesel locomotive steam heat boilers were all basically poorly designed and troublesome, and 25kv electrics never had boilers fitted, though class 76/77 Manchester - Sheffield electrics did?

    Would the diesel-electrics have done better with electric boilers supplied from their alternators?
     
  17. edwin_m

    edwin_m Veteran Member

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    I get the impression the electric heat systems on diesels were more reliable than the earlier steam boilers.
     
  18. Calthrop

    Calthrop Member

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    Cripes ! And this was under relatively benign British rule... they were different worlds, then and now.
     
  19. kermit

    kermit Member

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    Sorry, I don't think I wrote what I meant very clearly. It seems to me that the necessity for diesels up to the 70s to supply steam heat for the very many steam-heat-only Mk1 carriages was poorly served by the idea of oil fired boilers, the various designs of which were troublesome. It might have been better if electrically heated boilers were installed, using power from the traction supply (not on diesel hydraulics, obvs), as was the case later on when direct electric train heating was put in place.
     
  20. John Webb

    John Webb Established Member

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    I understand that the oil-fired boilers in diesel locos for steam-heating were ones designed originally for static use; they did not like being bounced up and down in a railway engine, leading to problems.......
    In that sense an electrically-fired boiler might well have been better, but no doubt the expense of developing one might have been considered too expensive?
     
  21. Taunton

    Taunton Established Member

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    Electric boilers on diesels might have overcome some issues, but there were others. Failure of the water pump which pumped it up from the underframe tank was a longstanding problem. More fundamentally, the power of early diesels was principally not one of choice, but of getting the maximum power for traction out of what was on the market. The slow manner in which Sulzer progressed from 2,300hp (early Peaks) to 2,500hp (production Peaks) and then 2,750hp (Class 47), and then the latter proved too much and they were derated to 2,650, shows how things were really on the edge for power. Having a separate steam boiler rather than tapping the main generator was a means of avoiding sucking the power available at the motors. There were also longstanding issues with getting an auxiliary electric load off the generator when the loco was not under power, which never got wholly resolved with the initial diesels in days when power electronics were not developed.
     
  22. kermit

    kermit Member

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    Thanks - both these responses make sense!
     
  23. Taunton

    Taunton Established Member

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    One may wonder, if the power of early diesels was insufficient to drive an electric boiler, how was the same heating later achieved with ETH fitted to the same locos. One reason was that ETH was more efficient, but another was that train sizes, and weights, progressively reduced. When the diesels first came out it was quite common for long distance expresses to load to 13/14 coaches - and with just a 2,000hp Class 40 over Shap and Beattock. They could be down to 20mph over the top if not banked. Train sizes progressively reduced - the ECML even introduced "Deltic plus 8" to give trains with a good high speed performance.
     
  24. John Webb

    John Webb Established Member

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    Didn't they add an extra alternator to some classes to supply ETH?
     
  25. edwin_m

    edwin_m Veteran Member

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    I don't believe so, and they certainly didn't add an extra diesel engine. The later diesels had a bit more power so probably more able to handle the extra load, and it was also possible to shut down the supply temporarily when on a long gradient.
     
  26. Taunton

    Taunton Established Member

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    You can add an extra alternator, but on the same diesel engine that just takes power from driving the main one. I think some were added, on the opposite end of the crankshaft to the main one. THe problem is engine speed varying with traction demand.

    The only different approach was the 12 ETH Class 27 used on the Glasgow-Edinburgh push-pull, which had an extra auxiliary Deutz diesel installed specifically to drive an ETH generator. That really does give an extra power source. Probably seemed like a good idea at the time. It made more noise than the main power unit, and when you walked across Waverley Bridge in Edinburgh, across the platform ends, you could hear the auxiliary underneath if there was a 27/2 stopped there without hearing the Sulzer. I've written elsewhere about the initial unreliability of these units which must have driven their commissioning engineers mad, with overheating, in extreme cases catching fire, additional fire warnings and automatic extinguishers being installed which in turn developed their own faults, rang false fire bell alarms, filled the engine room with foam - some things are just not simple.
     
    Last edited: 6 Dec 2017
  27. Dai Corner

    Dai Corner Member

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    The Class 31/4 s apparently had only two thirds the traction power after conversion from steam heat to ETH.

    https://en.m.wikipedia.org/wiki/British_Rail_Class_31

     
  28. RT4038

    RT4038 Member

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    I think the imagination may be getting a little out of hand........ Passenger trains in South Africa did not crash any more than they did here. Far more likely that the upper class coaches were placed at the rear to reduce the smoke and noise nuisance of the locomotive, particularly the large quantities of unburnt coal specks emitted from the average stoker-fitted SAR passenger locomotive, which rained down on the leading vehicles and through the open windows (no a/c then). Passenger trains also needed the segregated coaches in the correct part of main stations, sometimes this meant re-marshalling en-route, so the 'white' coaches travelled coupled up to the engine for part of their journeys.
     
  29. Calthrop

    Calthrop Member

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    This part of things -- "put the types who don't matter, in the front part of the train, because accidents" -- was indeed cited to me as a bit of hyperbolic black humour on the part of passionate opponents of apartheid -- the more-mundane factors which you give, would for sure be more realistic.

    I sometimes think, about "that kind of stuff" in any society sufficiently race-obsessed, to make rigid rules about "who could go where" -- it must have made life maddeningly complicated, with even sincere supporters of the status quo who belonged to the favoured race, sometimes finding it so and feeling irritated thereby.
     
  30. RT4038

    RT4038 Member

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    I am sure "that kind of stuff" (and there was lots of it involving transport) did make life complicated in the background, but the average person would have taken it for granted. I suspect irritation would have been most likely felt by those who had the money (and/or passport) to escape the results of a more normal system!
     

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