How Do You Get Water Into A Steam Locomotive Boiler?

[@Steven_Rowe]

Sounds simple, but I'm amazed at the genius of the person who understood the physics involved and then designed it.

[@trainsimulatordriver]

You're not wrong there! Humans come up with some really clever things.

[@Steven_Rowe]

@@trainsimulatordriver what really fascinates me is walschearts valve gear and how a loco is reversed by raising or lowering the radius rod in the expansion link and how you can effectively in a way gear a loco by linking it up with cut off. Pure genius.

[@trainsimulatordriver]

@@Steven_Rowe so many variations on that principle to, probably trying to avoid patent licensing - as fireman I can certainly tell when my driver is being nice with the reverser and their steam usage - never upset your driver they'll get you 🤣

[@Daytona2]

I've never seen the insides before, all I knew was that it functioned by the Venturi principle. Another of these simple, powerful concepts 😁 Thanks Paul 👌

[@trainsimulatordriver]

Yep so simple its hard to figure out how they work

[@PugFaceMusic]

I’m digging the cross section

[@trainsimulatordriver]

Imagine the conversation. Take this old bit of kit that we could restore and cut it in half. Errr ok.

[@hoopoo3721]

Thank you! I've never heard this explain better.

[@trainsimulatordriver]

Glad it was helpful! Thanks

[@ukdave57]

Most interesting, thanks for sharing.

[@trainsimulatordriver]

you're welcome

[@datamagii]

Great video, even better than the first version.

[@trainsimulatordriver]

Thanks

[@savvnz]

Well explained Paul, not a type I am used to seeing! You'll have to do a series now on all the different bits on the loco :D

[@trainsimulatordriver]

that might take a while - we do have a few in bits :)

[@savvnz]

@@trainsimulatordriver I look forward to the hour plus long session on how the Westinghouse compressor works, with all them fun valves inside :D :D

[@trainsimulatordriver]

@@savvnz probably more like four lol. So many moving bits even inside other moving bits.

[@NevilTh]

Great video, and very informative.

[@trainsimulatordriver]

Thanks NevilTh - I must get off my butt and finish this series

[@MarkLotus2005]

What is the leverage that allows steam at boiler pressure to inject water into the boiler; it sounds like magic so there must be a physics trade here where more energy exits the boiler than re-enters with the cold water?

[@trainsimulatordriver]

While its certainly not a perpetual motion machine, the leverage is velocity. The combined steam and water as they pass through the delivery cone are accelerated to the point that the flow overcomes the check valve and boiler pressure to enter the boiler. Left running without pushing in a matching amount of heat and the injector will quickly cool the boiler reducing pressure to the point the injector will stop.

[@andrewparker318]

I still don't understand how the water pressure inside the injector is able to get higher than the boiler pressure. Given the law of conservation of energy, wouldn't the injector only be able to provide as much pressure as the boiler is already producing?

[@trainsimulatordriver]

The pressure does not get higher from the injector, what overcomes the boiler pressure is the velocity of the water coming out of the injector heading for the boiler. It isn't creating magic energy so yes conservation still applies :). It only seems like magic.

[@andrewparker318]

@@trainsimulatordriver ohh got it! So it’s like a rocket engine, the exhaust is not necessarily at a higher pressure than the surrounding atmosphere, it’s just traveling so fast that it’s able to overcome the pressure of the surrounding atmosphere. That’s fascinating :D

[@trainsimulatordriver]

Yep that is about it. Similar idea anyway. The Venturi principle is quite interesting.

[@jon170484]

What stops the incoming steam pressure push past the low pressure water inlet ?

[@trainsimulatordriver]

@@jon170484 nothing, that's exactly what it does do, but on the way it picks up the water and is condensed but the cool water itself changing state from steam to water.

[@jon170484]

@@trainsimulatordriver surely steam would flow through the easiest path, I can’t help but see the path of least resistance being for the steam to flow through the cold water feed and into the water tank instead of a wall of pressurised steam in the boiler. I believe it works but there is something missing that’s preventing the logic in me to understand why.

[@trainsimulatordriver]

@@jon170484 there's a non-return valve on the way to the water tank so the steam can't actually get in there

[@antonylawrence7266]

I have always wondered how the tender feeds the engine when it’s under pressure. Finally KZbind it. Did Stephenson have a clacks valve on his rocket ?

[@trainsimulatordriver]

I think Rocket was pre injectors and used a pump to push the water in. Traction engines work this way too. Yes it would be likely there were one way (clack) valves.

[@antonylawrence7266]

@@trainsimulatordriver just found out the clack was patented in 1850. And it’s not changed much ! Many thanks.

[@trainsimulatordriver]

@@antonylawrence7266 it is a fairly simple thing, its cool that it survives - how many times do people try to make something great "better" :)

[@FloydBromley]

Minor mistake: at 4:04 you said that at the centre of the steam cone the steam is compressed. This isn’t true. As the area decreases, the velocity increases (up to Mach 1 at the choke point) as mass flow rate must remain constant, and thus the pressure decreases. Then as the nozzle diverges again, the pressure energy is converted to kinetic energy, thus increasing the velocity further to supersonic speeds and dropping the pressure further. This is how it is able to “suck” water.

[@trainsimulatordriver]

@@FloydBromley thanks Floyd, that makes sense. I put this together to pass my exam and it was good enough for that. Extra information is always helpful thanks.

[@FloydBromley]

@@trainsimulatordriver no worries mate. It was still a very excellent video!

[@trainsimulatordriver]

@@FloydBromley 😁

[@VioletsInspirationSoup]

Very interesting hope you are well today

[@PaulPavlinovich]

Yep getting better 🎉

[@trainsimulatordriver]

@@PaulPavlinovich lol wrong me

[@woodstock911snoopy]

Thanks for the informations, i seen steam engines with injector dumping water then stop

[@trainsimulatordriver]

They always do, you watch or listen for water at the overflow before you open the steam. After you close both steam and water they will run or drip for a while as they empty. They can also drip from steam condensate if the steam valve doesn't seat properly.

[@BradMcArthur]

Very interesting. The best way to learn a subject is to teach it. 😉

[@trainsimulatordriver]

yeah, that is kind of what I'm thinking