I am starting to get to the plumbing phase of building a large scale live steam tank locomotive and I need to plumb up the injectors and feedwater inlet to the boiler. Initially I had planned on placing the inlets one on each side up by the front tubesheet but after looking at many photos of tank engines out there I am not sure that is the way it was typically done, as in almost all of the photos I see I don't see the inlet check valves.

Unfortunately I don't see myself being to check out a prototype anytime soon. I did see one video tour of a small tank engine up at St Louis railroad museum which appeared to show it being put in right above the crownsheet of the locomotive, but I would think this could be pretty dangerous to thermal shock the crown sheet with the coldest water in the boiler? In a low water emergency it seems a little scary.

The locomotive I am building has no real prototype so there is some artistic license here but I would like to stick with the prototype practices as much as possible. Where did they usually get the water into the boiler?

Anyone have any photos?

Thanks,

Adam

You can see a drawing of an 0-6-0T here: http://ogrforum.ogaugerr.com/topic/scal ... 7218559467

The check valves are are just behind the front tube sheet. On the other hand this 0-4-0T viewtopic.php?f=1&t=28753&p=200633 has them farther back and below the tank. The checks have to be accessable without removing the tank.

On our Vulcan 0-4-0T, the saddle goes forward over most of the smokebox, so the check valves are placed under the tank/running board about where the first driver set is. So the valves are not placed on the boiler center line, but obviously quite a bit below it. They are also behind the air tanks (one on each side, under the running boards), so you won't be able to see these check valves in any overall engine photos.

Every saddle tanker I've worked in his been set up as Steve describes. If you put them under the running boards somewhere about three quarters forward in the boiler she'll be fine. The backhead mounted situation generally led to a tube running forward through the water space anyhow, not dumping right over the crown sheet.

Hi Adam: The two saddle tank loco's I've been involved with are as John, Steve, and Dave say. It's worth noting thought that in full size practice it would be normal to have a shut off valve either built into the check valve, or have the boiler entry via a 90 deg. globe valve immediately downstream from the check valve. With the feed entry so far below the water line of the boiler it would be possible to almost completely drain your boiler if a check valve should hang up. I've seen this happen on a nice little 3.5" gauge engine, I could hear the check valve rattling and see boiling water starting to gurgle out from the water tank, the poor fellow running it didn't seem to know what was happening! Fortunately the fire was dumped and no damage ensued.
Pat

Thanks for the replies, the way I have built the saddle tank I actually have a little bit of space to put the inlet check on the side of the boiler before the smokebox but that will put the feedwater inlet almost up against the front tubesheet, I will have to take a measurement to be sure when I am back in the shop but I am estimating 1-3" away from the tubesheet.

Once again I am wondering if thermal shock is something too to take into account so close to the tubesheet, though nowhere near as much of a concern I would think as near the crownsheet. I am wondering if per Pat's comments about a check-valve failure if the possibility exists to keep it above water level that may be the best way to go.

No. Feed water into water away from the firebox, but not up against to the front. The stop valve near the check - between it and the boiler - must be installed, and it also allows the check to be maintained with the engine under steam. This is well established practice for good reason and has withstood the test of time, rethinking it now will not be to your advantage. Some locomotives used top feed checks, but that's a whole other thing unlike your tank engine.

I am working on Coos Bay #11, a 1929 ALCO 2-8-2-T "Minarets" type engine. Looking at the ALCO blueprint for that engine, it is 12'6" between the front and rear tube sheets, the I.D. of the front course is 67". The feed water inlets are located 22" behind the front tube sheet, and 30 7/16" on an arc below the side center line. That puts the inlets at about "5 and 7 o'clock" on the circumference of the boiler, and well below the running boards and bottom of the saddle tank. The saddle tank extends to the smoke box.