Steam locomotive working of injectors

[georged38]

Hi all, this is a post for any loco firemen out there.

I am training as a fireman and trying to get to grips with best practice of using the injectors and putting a round on.


Obviously when there is need to raise pressure, more coal needs to be added to the fire and possibly more air provided through dampers if not already fully open. My question is, does putting on the injectors and adding coal together whilst the regulator is closed cool down the fire too much?

Thanks in advance,
George

 

[Wilts Wanderer]

Hi
I trained as a fireman about 20 years ago, hopefully my knowledge isn’t too out of date! (We we’re using the 1953 rulebook so hopefully not.)

Putting the injectors on won’t cool the fire, but it does reduce boiler pressure (particularly the live steam injector.) The impact of fresh coal will depend on the type you’re burning, if it’s fast burning then if you get it under the brick arch / down the front then you’ll get a fairly quick steaming response, whereas other types of coal need maybe 10 mins to ‘cook’ and burn off the noxious elements before you get the heat value. Unless you’re substantially changing the shape / density of the fire you shouldn’t really need to adjust the dampers, if you try to regulate steaming by closing dampers this can result in clinkering and cause you problems further down the line.

Edit/addition: The wider question about whether you should fire with the regulator open or closed seems to vary railway to railway in my experience. When I was trained it was almost anathema to have the firehole doors open with the reg open; firing with the flap on a GW loco was acceptable but required practice. Whereas on other railways it seemed that you should ONLY fire with the regulator open. Again it probably came down to the coal as much as anything. On the main line of course, you don’t have any option but to fire with the regulator open due to the prolonged high power requirements.

Do you have a copy of the engineman’s ‘black book’? It’s an essential read for those becoming a student of footplate disciplines.

 

[John Webb]

....Do you have a copy of the engineman’s ‘black book’? It’s an essential read for those becoming a student of footplate disciplines.

I assume this is a reference to the "Handbook for Railway Steam Locomotive Enginemen", first published in 1957 by the British Transport Commission for BR, and indeed had a black cover? There have been more recent reprints in 1977 and 1998 by Ian Allan.

 

[georged38]

Thanks

Hi
I trained as a fireman about 20 years ago, hopefully my knowledge isn’t too out of date! (We we’re using the 1953 rulebook so hopefully not.)

Putting the injectors on won’t cool the fire, but it does reduce boiler pressure (particularly the live steam injector.) The impact of fresh coal will depend on the type you’re burning, if it’s fast burning then if you get it under the brick arch / down the front then you’ll get a fairly quick steaming response, whereas other types of coal need maybe 10 mins to ‘cook’ and burn off the noxious elements before you get the heat value. Unless you’re substantially changing the shape / density of the fire you shouldn’t really need to adjust the dampers, if you try to regulate steaming by closing dampers this can result in clinkering and cause you problems further down the line.

Edit/addition: The wider question about whether you should fire with the regulator open or closed seems to vary railway to railway in my experience. When I was trained it was almost anathema to have the firehole doors open with the reg open; firing with the flap on a GW loco was acceptable but required practice. Whereas on other railways it seemed that you should ONLY fire with the regulator open. Again it probably came down to the coal as much as anything. On the main line of course, you don’t have any option but to fire with the regulator open due to the prolonged high power requirements.

Do you have a copy of the engineman’s ‘black book’? It’s an essential read for those becoming a student of footplate disciplines.

Thanks for this detailed response. I do indeed have a copy of the black book which provides a great deal of useful info. At the moment we have some quite smoky coal, even when coal hasn't been recently added to the fire. I was slightly confused when on the footplate a fireman said that when we were coasting it was a good time to put on the injectors because steam wasn't being used... are you able to clarify this for me?

 

[AndrewE]

Thanks

Thanks for this detailed response. I do indeed have a copy of the black book which provides a great deal of useful info. At the moment we have some quite smoky coal, even when coal hasn't been recently added to the fire. I was slightly confused when on the footplate a fireman said that when we were coasting it was a good time to put on the injectors because steam wasn't being used... are you able to clarify this for me?

If the driver doesn't need it (to haul the train) then you might as well use the steam to fill the boiler. Otherwise the safety valves will lift and that is coal and energy/CO2 "down the drain" - and water wasted. Likewise when you stop at a station or unexpectedly at a signal and you don't want the safety valves to lift (wasted fuel and water again) then put the injector on if there is space in the boiler, otherwise open the firehole door to cool the air being drawn through the firetubes and prevent it blowing off.

 

[Wilts Wanderer]

If the driver doesn't need it (to haul the train) then you might as well use the steam to fill the boiler. Otherwise the safety valves will lift and that is coal and energy/CO2 "down the drain" - and water wasted. Likewise when you stop at a station or unexpectedly at a signal and you don't want the safety valves to lift (wasted fuel and water again) then put the injector on if there is space in the boiler, otherwise open the firehole door to cool the air being drawn through the firetubes and prevent it blowing off.

^What he said

In my experience when the driver closes the regulator thats the ideal moment to put the injector on and open the fire hole doors / drop the flap (depending on the loco.) As you build experience you’ll be able to anticipate the driver’s action. When the regulator is opened you want to turn off the injector and close the doors. When I was learning, the challenge was to maintain a suitable water level in the boiler so that you had space to do this without reaching the upper limits of the water level and risking priming. It will depend on the line/loco but maintaining the water level in the 1/2 to 2/3 range is ideal for general conditions, which also gives plenty of steam space. It’s easy to forget but if you keep the glass too full, the boiler pressure will fluctuate more as there’s physically less volume of steam present.

I think an important thing to remember is that the fire keeps producing steam regardless of whether it is being used or not. Having the regulator open will boost the steaming rate and closing it will reduce it, but it’s not a binary on/off machine. Particularly on a preserved line (which I’m assuming you work on) where using full regulator for long periods is probably unlikely? The line I worked was certainly very start/stop with short sharp gradients and periods of standing/coasting, quite a challenge to maintain the water and steam without overdoing the firing, for a novice. Great fun though

 

[david_g]

And don't forget that as a fireman you have another tool at your disposal to alter the steaming rate - the blower. A decent blower will have a big effect on the draught through the fire, particularly when the engine isn't working hard.

 

[Wilts Wanderer]

And don't forget that as a fireman you have another tool at your disposal to alter the steaming rate - the blower. A decent blower will have a big effect on the draught through the fire, particularly when the engine isn't working hard.

Although be aware that the driver will be periodically increasing / decreasing it as the regulator is opened or shut, and in the vicinity of bridges / tunnels etc.

 

[georged38]

We don't tend to alter the blower much as it generally provides enough draught cracked open and we don't have any tunnels. The issue I've found is that sometimes I have put the injector on and the pressure drops quite significantly but it's all a learning curve I suppose!

 

[InkyScrolls]

I would second the previous posters' comments, and add that firing is as much art as it is science. It takes years to master, as I'm sure you're aware - but there's nothing so satisfying as a trip well fired.

 

[SECR263]

I would second the previous posters' comments, and add that firing is as much art as it is science. It takes years to master, as I'm sure you're aware - but there's nothing so satisfying as a trip well fired.

Another thing is always turn up early to start prep, as time always seems to disappear quickly. A quick face wash before leaving shed helps, remember you can always put the coal on but you cannot take it off, if you get my drift, and if available a bacon butty or similar always fires up the fireman or woman before the green flag.

 

[Wilts Wanderer]

Another thing is always turn up early to start prep, as time always seems to disappear quickly. A quick face wash before leaving shed helps, remember you can always put the coal on but you cannot take it off, if you get my drift, and if available a bacon butty or similar always fires up the fireman or woman before the green flag.

A cornish pasty or jacket potato in silver foil on top of the steam manifold valve