Heating Oil Tenders in Cold Weather

I have read how steam from the locomotive would be used to warm / heat the oil in the tender
of oil burning steam locomotives during cold temperatures. Just how was this done? Was steam
"shot" directly into the oil via piping / nozzles? Were there heating "tubes" - much like flues - that
ran through the oil bunker? Was the steam fed to the bunker constantly, or, as needed? How was
the need determined? Thanks in advance.

T -

There were several schemes for heating tenders, but in general the most common was a closed loop of pipe in the tank fed by steam and regulated by a steam trap and/or valve at the discharge end of the pipe. You don't want to put steam directly into the oil as the steam condenses to water and contaminates the oil. Most engines returned the condensate to the tender cistern to be put back in the boiler. Where the steam came from on the engine, the design of the heater and other specifications usually came from the individual RR's Master Mechanic, often in consultation with the locomotive builder.

Most fuel oil was heated year-round to get it up to a better temperature for combustion and aid in pipe flow. Oil burners used different grades of oil depending on a host of factors, and the type of oil and burner are the predominant factors in determining the amount of heating needed. Oil was anywhere from a few steps above tar to nearly diesel fuel, and some locomotives do use diesel in the modern era. The thicker the oil, the more heating needed to make it useable.

Also, similar heating was used in the water cistern on both oil and coal burners to keep the water from freezing in the winter.

Train Detainer -

Thanks for the answers. I had wondered about the water as well, but, had never seen any reference to it being heated.
I figured that there was enough motion, along with the actual draw of water to the boiler, to keep it from freezing. I did not
realize that there was different grade oils used. I have heard of an oil they referred to as "bunker C" oil, thought that was the
"common" oil used.

Bunker C was a very common grade for locomotive use and is very dense, requiring a good amount of heat to make it useable. It is residual oil and usually much cheaper than higher refined oils, hence the attraction to the RR's motive power departments.

As for water in winter - while some steam locomotives had relatively short turn-around times and shorter operating districts, many had longer layover times that would keep hostlers busy watching the water in the winter. Most commuter engines spent the better part of the weekend laying over in their outlying terminals, many water pipes for injectors and water supply weren't insulated (injectors usually have heater cocks to keep the nozzles from freezing) and tender valves were often located beneath the tender deck where there wasn't much warmth to keep them from freezing. You also have to consider the efficiency problems from trying to dump relatively cold feedwater into the boiler (using boiler HP just to heat water instead of going to the cylinders/rail), so there was a very real need to keep water warm.

Also some of the tenders were pressurized with air in addition to heaters, most notably Southern Pacific's Cab Forwards

Bunker C is a high-viscosity residual oil requiring preheating to 220 – 260 °F before it will flow through pipes. It's what's left over after all the good stuff (kerosene, gasoline, diesel oil, etc.) is removed during the distillation process at the refinery. Since it's the leftover stuff, it's dirt cheap in comparison to the good stuff. It's also the oil used in ocean-going, steam-driven ships. It's basically one step up from tar.

Statkowski wrote:Bunker C is a high-viscosity residual oil requiring preheating to 220 – 260 °F before it will flow through pipes. It's what's left over after all the good stuff (kerosene, gasoline, diesel oil, etc.) is removed during the distillation process at the refinery. Since it's the leftover stuff, it's dirt cheap in comparison to the good stuff. It's also the oil used in ocean-going, steam-driven ships. It's basically one step up from tar.

Union Pacific used Bunker C in their fleet of Gas turbine electric locomotives. They also had some GP9's modified to run on it. The fuel was very economical in the late 40's/early 50's but rapidly increased in price in the later 1950's and the 1960's as the U.S plastics industry grew, Bunker C being a major feed-stock for plastics production..