Blowing down a boiler

Blowing down the boiler makes no change in the steam pressure.

"Blowing down" is the process of opening a valve at the bottom of the water legs in the firebox. All the scale, sediment and other undissolved solids end up at the bottom of the water legs. Opening this valve exhausts WATER, not steam. The high flow of water carries with it all the "crap" at the bottom of the boiler.

Best done on a bridge or other safe spot...

I have never seen or heard a blow on all the steam trains over the years... they must do it when all the tourists have gone home.

I know Strasburg does (did?) do it every trip when they get to Paradise. It was done just before the engine coupled to the train to return to Strasburg. Whoever was narrating the trip would often describe the process and invite passengers to (safely) lean/look out their windows to see. With the new track alignment, that practice may have changed. 

There's not a lot to hear, it sounds kinda like a waterfall and lasts only a few seconds.  And there may not be much to see, depending on where the blowdown is directed.

At IRM we always blew down the boiler while in "push" mode, backing from the east end returning to the depot.  1630's fireman's blowdown exited directly to the left, while the engineer's was directed to between the rails beneath the ashpan.

Rusty

Our blow downs on a trip were always done in an area where there wasn't any people. They can be done standing still or while underway. 

Ron