Cold Fires

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.

 

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.

 

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.

 

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

 

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.



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

 

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

 

Obviously the fireman was steeped in ther GW tradition.......

 

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

 

[-X Bigger!!!! :-$

 

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!

 

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!

 

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!

 

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. ;-)

 

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.

 

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 :-$ )

 

So, is this the right way to fire a WC or not?

 

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

 

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)

 

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.

 

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.