Steam & Excursion > When do the flues need sanding?

I've never been clear on how often the flues need sanding.

When 3751 runs to San Diego, when are the flues sanded?

How can you tell when it's needed and what factors are involved, speed, hills, fuel quality?

TIA for your help with this.

On oil fired locomotives combustion is never perfect and the flues get built up with a lot of soot. Scouring them out with sand takes care of the problem. The sand goes through the flues on the draft and takes the soot with it. The engine should be working steam so there is a good draft through the firebox and flues. Sanding is done at regular intervals and is at the discretion of the fireman. As you've seen, it makes for a lot of really black smoke so the location is important, especially in these environmentally-sensitive times. As for the 3751, anywhere there is some open space would work. As I recall the 3751 has a pedal and a damper on the firedoor air duct that shuts off some of the air coming in via that route (by design) and creates a good rush of air through the peephole in the firedoor where the scoop of sand goes. BTW, the firedoor is never opened while the locomotive is working.
Hope this helps.

Have fun, be safe,

Doc Jones

Mind you it can be a little tough to hand bomb a coal burner with the door closed.

RE: firedoor closed - I was referring to an oil-fired locomotive. Different animal than a coal-burner.

More for brassjournal: When to sand. I would imagine a good fireman can tell when soot has either messed up his draft or reduced heat transfer to the water from the flues. Also, experience. Of course poor fuel and an engine that smokes a lot is going to be a good indication that soot will up fast. The guys I've talked to try to sand regularly to prevent trouble.

Have fun, be safe,

Doc Jones

Probably more frequently when burning bunker c and probably rarely when burning diesel.

Usually, the fireman would shut all the dampers, to get a better draft at the peep hole. Put 2 to 5 scoops of sand in the peep hole ( Also depending on the size of boiler). Also letting the draft suck the sand in, don't pour it in.

Flus can get dirty firing with diesel too.

Anything that produces soot will dirty up flues and incomplete combustion only makes
it worse.

I've seen sand applied at speed, and yea the draft just educts the sand right out of the can, you just have to tip it towards the peephole and woosh, in it goes.

The sanding procedure also illustrates why you need to keep the door closed, you don't want any more cold air drawn into the firebox than you need for combustion.

That's why it's also important to keep a clean stack - if there's partially burned or unburned fuel coming out, it's also coating the flues. If you run an engine rich/dirty, the flues will get coated a lot faster.

In scale live steam world we don't sand the flues as we are rodding them out / punching them daily. I vaguely recall on mainline steam they would punch the flues maybe once a month during routine maintenance? Someone with more knowledge can comment.

Mike Massee
Tehachapi, CA
Photography, Railroading and more..

Just about every place i've ever run or fired,we tried to sand the flues every 7-10 miles,when the engine was working hard, and above 20 miles an hour. there was a place i worked where they didn't keep the speed up when they sanded,and they wondered why there was all that sand in the smokebox during the 30 day boiler wash....