The Inquiring Mind Wants To Know!

[chuff_n_puff]

Am I right in assuming, that on the videos of the old steam trains, that when the exhaust smoke changes from white to black, is when the fireman is stoking the firebox with fresh coal?

[ebtnut]

That's certainly one probability.  However, it might indicate simply that the engineer has opened up the throttle, sucking more unburned coal and cinders out of the firebox.  If the loco was an oil burner, it might be that the fireman has dumped a shovel-full of sand into the firebox.  The draft sucks the sand through the tubes, knocking out much of the accumulated carbon and thereby improving the draft. 

[Doneldon]

chuff-

The best way to get black smoke is throwing sand into the firebox; firemen have known this for years and are historically known to do this when they see railfans and/or photogs. Actually, anything which disturbs the status quo in the firebox -- increased draft, tossing something in, even just opening the firebox door -- can lead to black exhaust.

                                                                                                -- D

[Guilford Guy]

The sanding of the firebox produces black smoke because- when the sand particles are drawn through the flues they act to scrape off the carbon buildup and this is then taken out the smoke stack with the exhaust.

[Jim Banner]

Sounds like you can kill three birds with one stone:
- please the foamers
- cheese off the smoke inspector
- increase boiler efficiency by cleaning the tubes

Jim

[rogertra]

Sounds like you can kill three birds with one stone:
- please the foamers
- cheese off the smoke inspector
- increase boiler efficiency by cleaning the tubes

Jim

And in the UK, get the fireman a severe written warning and a verbal dressing down for putting sand in the firebox.  Absolute no-no in the UK.

[Guilford Guy]

I know some steam excursion railroads with oil burners throw a can of sand in fairly often- perhaps every trip? Is the residue build up in an oil burning locomotive different than in a coal burning locomotive? If not, I find it surprising that the railroads would risk whatever problem there may be in sanding the firebox.

[ebtnut]

The low quality of the oil generally used in steam locos produces a tarry kind of soot that can stick to the inside of the boiler tubes.  Coal burners create cinders, which are rough and hard and will mostly keep the tubes pretty clean. 

[Johnson Bar Jeff]

Even without throwing sand in the firebox, does oil fuel create more black smoke than coal?

[pipefitter]

I rode an excursion on the P&W in Connecticut behind Valley Railroad's SY #1647 (before it became NYS&W #142). It was notable for the extreme lack of smoke emitted by this oil burner (plenty of white steam though). Heard some railfans grumbling As this was a relatively recently built engine it had the benefit of all the modern efficiencies that could be built into it.

Robert

[Doneldon]

pipeguy-

I'm guessing that the oil which is used today is much more highly refined than the tar/sludge which was typical when there were thousands of steamers around and lots of servicing facilities for them.  The water used today is certainly much purer than years ago, as a way to forestall operating and maintenance problems.
                                                                                                   -- D

[pipefitter]

Yea, you're right. Probably some kind of fuel oil, like would be used for residential boilers. And the water... One of my favorite things about long distance excursions was when the local fire departments would be enlisted to fill tenders from a hydrant at the far end of a round trip. They always showed up with sharp uniforms and a well polished engine, obviously taking pride in their work. I believe that hydrant water is usually the same potable water you get in your house.

Robert

[Jim Banner]

I believe the CPR used to burn bunker C (a.k.a. #6 fuel oil) in their oil burners.  This crud is also used on ships because of its low price.  The last excursions where I rode behind oil burners ran on diesel fuel (which differs from #2 fuel oil only by the additives.)  The price is considerably higher but it is readily available.

One of the last uses of bunker C in our province was as a standby fuel at the university.  They had a large tank of it on hand in case the supply of natural gas was interrupted.  They finally got rid of it and filled the tank with diesel fuel when they realized how much natural gas they were using every year just to keep the standby fuel supply warm enough for the bunker C to flow if they ever needed it.  Diesel fuel flows without heating down to -50^o or so.

Based on this, I am wondering if the lack of smoke was because they were burning diesel fuel instead of bunker C.  You can still make black smoke with diesel fuel but you have to work at it.

I am still wondering why you can sand a North American boiler but not a boiler in the UK.  I doubt if the steels used to make boiler tubes are vastly different but the sands might be.  Crushed limestone is relatively soft and while it is hard enough to scrape out carbon, it will not do much to steel.  Other sands are harder, with silica sand being particularly so.  I can well imagine that sanding with silica sand would take out not only the carbon but also some of the steel.

Jim

[RAM]

bunker C will make blacker smoke than coal. When I was in the navy, we tried not to make any smoke.  We did but only for 10 to 15 seconds.  I think we blew the tubes every 4 hours.  We used high pressure steam, not sand.  That was 57 years ago but I could still do it.

[Kevin Strong]

Depends on the grade of coal being burned, too. The coal mined by the East Broad Top was advertised as "smokeless," and by many accounts lived up to its name. (Its ability to burn very cleanly was responsible for launching "Alan's Products" brand of dog food, today known as Alpo.)

Having said that, I was up on the Georgetown Loop a few weeks ago, and their oil-fired loco produced little to no visible smoke (until they sanded the flues).

Later,

K