Identify this steam pipe valve please?

[mmagliaro]

Can anyone tell me what this thing is?

The pipe comes from the cab and that fitting where it attaches to the side of the boiler appears to be some type of valve.
Is it a pop off?  (and if you can't see the picture below, reload your browser page... the caching thing is still
causing that problem and the photo won't load the first time the page is viewed, at least for me)

[Chris333]

It's a check valve. Or do you mean the little nipple on top?

https://image.slidesharecdn.com/boilers11-140806063451-phpapp01/95/boilers-1-1-23-638.jpg?cb=1407306944

BTW, on my HOn30 locos I started using O scale "T" pipe fittings for them.

[randgust]

That's the water injector line coming from the cab, with a check valve at the boiler.   Usually you'll see one on both sides - one for the engineer, one for the fireman.   You always want a backup as injectors can be downright balky in operation so if one hangs, fails, or won't 'catch', you won't blow the boiler for lack of water while you're swearing at the balky injector.

Steam pop-offs (safeties) are usually on top of the steam dome or on a separate turret, set for multiple pressures.

That 90-degree bend and low'drop' right below the valve is a little odd.  The gentle bends in boiler water supply lines are deliberate design as to not restrict flow, so that sharp bend, short vertical piece and then into the check valve strikes me as different. 

Near identical situation on HVRR #5, fireman side:   http://www.randgust.com/hv5b.jpg
Engineer side:  http://www.randgust.com/Hv5C.jpg

[Lemosteam]

That 90-degree bend and low'drop' right below the valve is a little odd.  The gentle bends in boiler water supply lines are deliberate design as to not restrict flow, so that sharp bend, short vertical piece and then into the check valve strikes me as different. 

Near identical situation on HVRR #5, fireman side:   http://www.randgust.com/hv5b.jpg
Engineer side:  http://www.randgust.com/Hv5C.jpg

Probably carries hot water so they did not want anybody accidentally using it as a pseudo handrail, or stepping up on it.

[randgust]

Remember how an injector works - you're injecting steam into a cold-water supply to force the tender water into the boiler by the check valves.  It's a venturi effect - rather simple concept and a very sophisticated device to do it.   The steam isn't to heat the water, it's really to pump it - under pressure - into the boiler against the existing boiler pressure (200 psi and above usually).  Don't confuse with a feedwater heater, entirely different animal and a later technology.   It's not like there is an electric water pump somewhere.    When the water hits the boiler, you get to watch the steam pressure gauge drop - it's still a lot colder than the boiler water, so you can literally drown your boiler and loose steam at precisely the wrong time, like headed upgrade.   Put a cup of lukewarm water into a pot of boiling water and watch it stop boiling until the heat recovers, exact same problem.

Because of that timing, it's all manually controlled.   My 'lifetime bucket list' included training as a locomotive fireman, I did on #1225, and learning how to get that %$$#! injector to work the first time when the water glass is running low was one of the more gut-wrenching exercises on the real thing.    You can do a lot of things wrong on a steam locomotive and live to tell about it, but low water and a bad injector is not one of them.   Full water glass and pressure just below the pops, and get a smile from your trainer, one of my better days.

[mmagliaro]

Thank you everyone for the information.  It makes a lot more sense to me that it is the check valve for the injector water.
And yes, there is one just like it on the other side, in the same place, on this engine.

It is shown on the erecting drawing side elevation, but it isn't labeled in any way.

Chris, I am making mine from a tiny hex-head bolt slipped through a tiny piece of tubing, with a tiny hex nut on
the other side to create the look of this thing. ( And when I say "tiny", I mean M0.5! )  The tubing itself will have
a wire soldered to it going into the boiler.  It will all be clearer when I post the next project update, perhaps in a week or so.

[Chris333]

This is what I used (Again they are O scale for HO uses)
http://www.grandtline.com/products/images/quarter_inch/100%27s/112.JPG
Upper right two "T" pieces. I use the shaft seen to attach into the boiler. The other side of the part is cored so you can insert wire into it to use as pipe.


Some larger locos the check valve is on top of the boiler.
http://www.rr-fallenflags.org/el/loco/erie-s239blb.jpg
right behind the bell.

[mmagliaro]

This is what I used (Again they are O scale for HO uses)
http://www.grandtline.com/products/images/quarter_inch/100%27s/112.JPG
Upper right two "T" pieces. I use the shaft seen to attach into the boiler. The other side of the part is cored so you can insert wire into it to use as pipe.


Some larger locos the check valve is on top of the boiler.
http://www.rr-fallenflags.org/el/loco/erie-s239blb.jpg
right behind the bell.

That Erie 0-8-0 with the Vanderbilt tender is pretty!

Meanwhile... Grandt Line doesn't make that same part set in HO, and the O scale one would be much too large to use in N.  I'm not allowed to use those anyway.  Unless I find that I am physically unable to make a part myself, I have to make it myself.  I can't buy it commercially.   That's the rule.

[metalworkertom]

I found this Old Catalog that shows various Locomotive Parts if it is of any use to you. https://books.google.com/books?id=y0w-AQAAMAAJ&pg=PA920&lpg=PA920&dq=plumb+tool+catalog&source=bl&ots=LJWS8UD-pZ&sig=ho09N8W8v4pMWt4nBS5SZ6i4gdc&hl=en&sa=X&ved=0ahUKEwjsgNTI4LLVAhXI3YMKHXZvCZU4FBDoAQgJMAA#v=onepage&q=valve&f=false

[Chris333]

That's the rule.

Well there are brass HO scale pipe parts (not Grandt) that may work for N. That is if you wanna break the rules