Quick NKP 765 Question

That is the Wilson Blowdown separator, which separates the sludgy boiler water from the steam. Generally, both the Engineer and Fireman have remote control valves which open a large cock on their respective sides of the firebox mudring. The sludgy boiler water is then piped up to that turbine looking device and the internal blades sling the dirty water outwards to a discharge pipe, which then shoots the sludgy water out onto the right of way, right under the Engineer's side of the cab (that way the Engineer can look down and see the condition of the sludgy water being expelled). The saturated steam is exhausted out the top of the separator device. The more contaminated the boiler water is, the more often the Wilson system must be used in order to rid the boiler of the sludge.

Thanks for the info!  I appreciate it!

Hot Water,  you are a fountain of information.  I really like reading your posts!  

The blowdown separator would have been my 2nd guess.

And unlike an operation that shall remain nameless, they aren't one bit shy about using it and getting the locomotive dirty either. I saw them using it twice while I was chasing the train on Sunday, once right before it got to me at a grade crossing.

Blowing down the boiler on a regular basis is critical to maintaining the "health" of the boiler's innards. It prevents the build-up of scale deposits inside the boiler.

It also helps keep the water PH at the proper level for good steaming and a clean boiler.

In raw water used to feed the boiler, there are two constituents which are harmful to the boiler. Raw fresh water contains dissolved gases such as oxygen and carbon dioxide along with a host of others. The other constituents are dissolved solids including iron, calcium  and other minerals and mud depending on the water source. During the steaming process, the minerals  adhere to the boiler internals in the form of scale. As the scale builds up, it impedes heat transfer and reduces efficiency. Frequent blowdown gets the solids out of the feedwater and you may see a white colored material where the water was discharged. That is those materials.

@Bill Park posted:

In raw water used to feed the boiler, there are two constituents which are harmful to the boiler. Raw fresh water contains dissolved gases such as oxygen and carbon dioxide along with a host of others. The other constituents are dissolved solids including iron, calcium  and other minerals and mud depending on the water source.

That is why treatment chemicals are added to the water in the tenders.

During the steaming process, the minerals  adhere to the boiler internals in the form of scale.

The use of proper treatment chemicals prevents the dissolved solids from "sticking" to the internal sheets of the boiler. That is way continuing use of blowdowns throughout the trip, expel those settling solids, i.e. sludge.

As the scale builds up, it impedes heat transfer and reduces efficiency. Frequent blowdown gets the solids out of the feedwater and you may see a white colored material where the water was discharged. That is those materials.