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Cold Fires

Discussion in 'Locomotive M.I.C.' started by Cassanova, Jan 19, 2009.

  1. Steve

    Steve Part of the furniture Friend

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    Yes, you never get 100% mixing in the time available. Most oil and gas burners work on around 10% excess air to get complete combustion. BR quote 20% excess air in the Black Book but a loco firebox does not have the benefit of fuel/air pre-mixing or much else to aid complete combustion. From the moment the air hits the firebed, it only has a very short time for the oxygen moleclues to mix with the carbon and hydrogen before the gases reach the tubes where combustion effectively ceases. That is one of the reasons for having a brick arch. It lengthens the path the gases take and gives longer for combustion to take place. The combustion chamber provided on some locos similarly adds to the length of available flame path.
     
  2. Sponge Cake

    Sponge Cake New Member

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    oxygen only makes up approx 20% of the amosphere. most of the air passing though a firebox is nitrogen which does sweet FA.
    an extra 10% excess air isn't really much more oxygen to aid combustion.
     
  3. 1306 mayflower

    1306 mayflower New Member

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    on the subject of cold fires ive found that a wedge shaped fire suits long sloping grate fireboxes better as the fire starts to move forward keeping the grate covered because of the draw from the exhaust and vibration of the loco it also suits a drop grate on a B1 and is also very controlable. Not realy sure how it would suit a wide firebox though.
     
  4. 1306 mayflower

    1306 mayflower New Member

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    having spoken to a friend of the owner of 9466 he told me that he had travled on the footplate of a king which needed two firemen who were firing up hill into the box the fire was so deep (he thought they had gone mad) but it still ate coal at an alarming rate
     
  5. spindizzy

    spindizzy New Member

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    This is a very interesting thread.

    Here is a picture I took on the foot plate of Tangmere. we were at the water stop at Paddock Wood after a sustained 70mph+ run up from Dover.

    [​IMG]

    So is this what is being referred to as a Wedge fire? What ever it is it did the job very well.
     
  6. aldfort

    aldfort Part of the furniture

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    Certainly seems to have a good back end in on that fire.
     
  7. Steve

    Steve Part of the furniture Friend

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    Obviously the fireman was steeped in ther GW tradition.......
     
  8. Ann Clark

    Ann Clark New Member

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    Steve looks more like a proper Southern fire! On second thoughts the back could always be a bit bigger!
     
  9. aldfort

    aldfort Part of the furniture

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    [-X Bigger!!!! :-$
     
  10. Ann Clark

    Ann Clark New Member

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    Have you never watched a Cornish ex Southern man fire a West Country? The back is huge but the fire is under perfect control. It is an education!
     
  11. Steve

    Steve Part of the furniture Friend

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    Have you never watched a Cornish ex Southern man fire a West Country? The back is huge but the fire is under perfect control. It is an education![/quote:jnvkk0bd]
    The usual reason for filling the door up like that is to stop the heat from the fire radiating back on you when you're firing! Nothing to do with the size of the fire. Decent locos have a flap for that purpose!
     
  12. Ann Clark

    Ann Clark New Member

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    The usual reason for filling the door up like that is to stop the heat from the fire radiating back on you when you're firing! Nothing to do with the size of the fire. Decent locos have a flap for that purpose![/quote:38ezsy2p]


    I always thought West Country's were decent locos!
     
  13. Steve

    Steve Part of the furniture Friend

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    The usual reason for filling the door up like that is to stop the heat from the fire radiating back on you when you're firing! Nothing to do with the size of the fire. Decent locos have a flap for that purpose![/quote:hd09qc1p]


    I always thought West Country's were decent locos![/quote:hd09qc1p]
    You've obviously led a sheltered life. :) ;-)
     
  14. spindizzy

    spindizzy New Member

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    I've got a picture of the "man on the Shovel" if it helps. He was very interesting to talk to but I cant remember his name.
     
  15. aldfort

    aldfort Part of the furniture

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    They are decent loco's but they lack that GWR charm and simplicity! (along with the rubbish cab and the coal on the floor firing position. :-# I've heard it said the GWR firemen, who are supposed to all be ex-miners preffered it this way :-$ )
     
  16. twr12

    twr12 Member

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    So, is this the right way to fire a WC or not?
     
  17. Nigel Clark

    Nigel Clark New Member Loco Owner

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    [-X i'm surprised at you aldfort !!!!! ;-)
     
  18. sirhectimere

    sirhectimere New Member

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    Hi all
    Below a snippet from my notebook scribbled a long time ago! Might help a bit in this interesting discussion.

    With engines well known for being ‘bad steamers,’ (not a common fault on a Spam it must be said,) it is necessary to try different firing techniques. A Spam, with its large grate area and thermic syphons, does not normally give any problems, if fired in the customary manner. But with a ‘shy’ engine, keeping the fire light, bright and tight is generally the best way to offset any really debilitating steaming difficulties. Also, with a Spam, the maximum boiler pressure of 250lbs means that more pressure can be lost, without undue affect on the steam being applied to the steam-chest, and significant loss of performance.

    Cheers
    Sir Hectimere (ex73A)
     
  19. jtx

    jtx Member

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    If he's managed from Dover to Paddock Wood at 70, he must have been doing something right. However, you can't really see the fire. As Steve said, he's put that lot there to cut down the radiance from the firehole. I've done it on various engines from 1501, where you can't get very far away from the fire, to 92212, where you've got this damn great oval firehole. It cuts down on smoking overalls syndrome.
     
  20. Edward

    Edward New Member

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    That photo totally misses the point. The key area with a wide box engine is the back corners. You can fill them up, and have a sit down for a bit, or you can fire them with 8 - 10 inches even all over the grate (how I was first told to do it by a gent who used to earn his living firing and driving them). Either method will work.
     

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