Bedtime blow-down. Sitting right in front of the Boothbay Railway Village engine house, Henschel #6 undergoes a quick firebox blow-down, before backing into quarters for the night. In this case, her Engineer has opened a valve at the bottom of the firebox water legs, allowing superheated water to be ejected at full boiler pressure. The water carries with it sediment and other impurities that have settled around the mud ring area, and it instantly flashes to steam when it hits atmospheric pressure. Even on a small boiler such as this one, it makes a pretty loud roar, and a reasonably impressive plume. That plume might be scalding hot out to perhaps 6 feet, beyond that, it cools very rapidly due to evaporation and is just wet. Along with boiler treatment chemicals to reduce oxygen in the water and prevent scale build-up, this blow-down procedure is something steam locomotive crews typically do several times a day, to keep the boilers healthy. Of course, the larger the steam engine, the more impressive (and loud) it is.
Of further interest to folks who are unfamiliar with these German Henschel tank engines, the locomotive's water tank is located between the frame rails below the boiler. The fill pipe for the tank is located just above the pilot. The coal bunker is the squarish, green enclosure, which sits on the running boards just forward of the cab on the Fireman's side. It doesn't hold much, but then, these locomotives were not designed to travel very far.
The little engine house behind #6 holds 2 locomotives and is located just across the tracks from Thorndike Station. The passenger boarding platform is visible in the foreground.