Hi
I was curious how the fireman gets water into the pressurize boiler. Is the water pumped in at a pressure greater than the boiler pressure?
I asked a Cass Engineer and did not get a clear answer.
Happy days.
Lee
Maybe THIS will help explain it. Here’s another one relating directly to steam locomotives.
I can be pumped into the boiler via a “feedwater pump” which is a box-like appliance usually slung in a gap in the running boards or just below them. In many steamers, the water is injected manually by either (occasionally both) of two injectors, one each for the fireman and the engineer. In cases where there is a feedwater pump, there are still injectors to supplement what the feedwater pump supplies, and as a back-up in case the feedwater pump packs it in.
In all cases, the water is forced through a check-valve near the rear of the smoke box, one on both sides of the boiler.
-Crandell
Very early steam locomotives had pumps operated by the main drive pistons, mounted at the ends of the crosshead guides. That’s what those funny-looking cylindrical things are.
Crosshead pumps were superseded by injectors. However, pumps didn’t vanish. Locomotives with feedwater heaters have pumps to force the cold water from the tender through the feedwater heater and on into the boiler. Injectors don’t work properly if the feed water is too hot. Usually, the pump is a piston pump (the Elesco pump used on the NYC loco shown in Steam Locomotives looks rather like a miniature cross-compound compressor) but it can also be a centrifugal pump. The Worthington BL feedwater heater includes the pump as part of that ‘sidearm*’ package. Worthington’s SA feedwater heater usually used a single piston pump, usually under the cab but sometimes on the pilot deck.
My own prototype used Elesco-style feedwater heaters, with a slightly humongous single-piston pump mounted on the side of the boiler opposite the air compressors.
- On page 17 of Steam Locomotives, Fig. 38 implies that the BL heater was used on, “Smaller modern locomotives.” It was standard on N&W Y-various, finally superseded when the Y6b was built. Those 2-8-8-2s were big enough for most purposes!
Chuck (Modeling Central Japan in September, 1964)
All locomotives had to have two ways of injecting water into the boiler. Some railroads used one steam injector for the fireman and one for the engineer. The IC used two non lifting injectors which means the water from the tender ran directly down to the injector lower than the tender water level.
On the many early locomotives, you can see a lifting injector just ahead of the cab on both sides of the locomotive with a rod running up to the injector from the cab. This was the control rod to turn on the injector. This type sucked the water up to the injector and used expansion to insert it into the boiler.
Water feedheaters were very common on later locomotives and it was controlled by the fireman, but the right hand side had a steam injector in addition to the feedwater heater. The SA Worthington Feed Water heater had a cold water pump directly under the fireman side and a hot water pump up front to pump into the boiler under high presure. The feed water heater was desired since it could pump water into the boiler at a reduced rate and the water was heated so it would not cool down the boiler temperature like the steam injector. Railroads used the feedwater heater most of the time on the road since it was adjustable. the fireman could turn a valve and keep watch on the water glass unlike using the steam injector which would would flow water at a high rate. Using the Feed water heater would allow the water level to be more consistent.
The steam injector used the boiler steam and expansion of the cold water to add addtional presure so it could overcome the boiler presure. All forms of water inserted into the boiler used a check valve so the steam could not flow backwards out of the boiler.
CZ
Some more explanations from a search.
You use the pressure of the steam in the boiler.
If the pressure in the boiler is 100 psi and I have a pump with a piston that has a surface of 10 sq inches, that’s 1000 lbs of pressure on the piston (100 x 10). If the piston is connected to a 1 sq inch with water on it and the water is connected to the boiler it has 100 lbs of force on it (100 x1).
Obviously the 1000 lbs of force will overcome the 100 lbs of resistance and force the water into the boiler.
you couldnt get water into the boler unless you could get the force greater than the boiler pressure.
Injectors are an ingenious device, it makes use of the pressurized steam mixed with water to create a vacuum effect, its mixed into a sort of reverse nozzle chamber where the mixing occurs and a one way valve into pipe leading into the boiler. You have 2 valves to operate the injector, the water and the steam. Start the steam up then slowly open the water, it takes learning testing which is the best setting on the valves, you will first have steam coming out of the exhaust pipe for the injector, this you watch. Open up the water, watch and listen, when the injector kicks in, it will have this “singing” sound and no steam or water exits the exhaust pipe. When the balance goes off water or steam will come out of the exhaust pipe so you tinker with your valves to correct. usually after a while of successful injecting water will come out, so you shut it down then or until you have finished watering the boiler.
The injector is literally a device putting science to work.
Great stuff guys. Excellent answers.
I can now see how it’s done but was not sure which process the Cass engineer was trying to explain.
I could hear pumps kick on and assumed that to be air pumps keeping the air pressure up
Steam injectors would be the hiss from time to time.
Thanks [:D]
Lee
I saw an example of this in the early 1980s. I was working for an oil company in Saudi Arabia, and we had a model RR group that had live steam locomotives. One summer day when the air temperature was around 120F, they just could not get the locomotives to run well due to low water. Our cans of make-up water had sat in the hot sun and the water was so hot that the injectors would not pull anything.
One of the guys there related a story he heard from a UP engineer or fireman who had a similar problem. They were running a Big Boy somewhere up in the mountains and stopped for water. The water in the tank was too hot and they could not get the injectors to pull, so they limped some miles up the track to where there was a snow bank left from last winter. They shoveled snow into the tender until the water was cooled enough to get the big locomotive going again. I heard this story 3rd or 4th hand, so can not verify how plausible it is.
A description of how the injector works that I read said that it is the coldness of the water entering the venturi relative to the greater heat of the steam driving into the venturi’s mouth that causes the tremendous force that cause the water to flow past the restrictive check valves. So the above makes sense.
-Crandell
Hmmm
I missed the Challenger when it came though St. Louis, I was down in W. Virgina eye balling the Cass motive power , but if I get a chance to fire the Big Boy I’ll know exactly what to look for. [:-^]
Have a Good day.
Lee