Injector steam valve and pipe

[rogsteam1959]

I have a problem with a new mounted No4 injector that is not working below 80psi. The overflow don’t get dry, better said the water comes out like crazy. Now I read that some fine scale valves can cause that kind of problems. I have a 5/32” pipe for steam. But the injector fitting is made for 3/16” pipe.
Now I’m thinking about to modify the valve for a 3/16” pipe, but don’t know if it makes sense. The bores in the valve should be big enough not to restrict the steam flow.

[rogsteam1959]

Here the injector at 75psi

youtu.be/JrqXAIhRCTg

[rogsteam1959]

At 80psi

youtu.be/xRsGfL5iKkc

[uuu]

I would be testing the injector first, on another loco, or a test rig, if you can find one. If you know it works, then you won't be chasing phantoms on your own set-up.

Wilf

[Deleted]

sorry if this is 'sucking eggs' but have you tried varying the water rate?

Pete

[rogsteam1959]

May 28, 2020 17:45:32 GMT @greenglade said:

sorry if this is 'sucking eggs' but have you tried varying the water rate?

Pete

I will do on the weekend. I had to fix the water valve also, didn’t realized during the test that the couldn’t be regulated 😩😩😩

[coniston]

On my B1 (not my build) which had original Martin Evans designed steam valves I had a similar problem. I had 3/16" pipe to both No4 injectors. I traced the problem to the valves, the spindles didn't unscrew far enough to allow free steam passage past them so restricted the steam flow. You may have the same problem? But as Wilf said if possible try your injector on a boiler system that you know works, maybe another loco?

Chris D

[simon822]

If you find that the injector works, but not on the engine it might be worth looking at the water delivery side. Any air getting in here is like.y to cause chaos in the injector. An example of this occurred with my Wren, the water valve is a taper plug, and when tight so it won’t move it picks up fine, if backed off enough to turn the injector won’t pick up cleanly. Well actually there is a sweet spot where it does pick up nearly cleanly and delivers plenty of water to the boiler.

The only irritation is everyone telling me my injector is overflowing!

Simon.

[rogsteam1959]

Hello everybody,
I’d like to bring this thread in live again.
Still have the problem with the injector. It’s not working down below the 75psi mark.
The injector is working on a test rig from 25psi up to 100psi.
The clack valve that I had on my jubilee I replaced with an inline clackvalve. The feeding point is on top of the boiler.
I saw a video on YouTube from Keith Appleton where he thinks that the steam will be cooled down feeding water into steam and he put a pipe to the clackvalve that the injector feeds into the water.
What is your experience? Could this be the reason the injector isn’t working on my loco like on the test rig?
Thanks in advance for your input.

[andyhigham]

You could try lagging the steam pipe to maintain the temperature

[simon6200]

I think a recent article in ME showed that lagging in our models doesn’t work. I have 5/32 steam pipe to my 26 oz injectors but it is very thin walled K&S tube, about 1/64 wall, so a reasonable bore. The valves are adequate and there are no sharp bends. The water feed is 3/16 x 22G pipe. The water valves can’t suck air and the clacks I made are good. If your steam valves are limiting, that might explain why only higher pressures work.

[rogsteam1959]

As I said earlier I made a new steam pipe and reworked the steam valve.
Today I made a test with injectors I inherited from my late father in law. I used the boiler of my dismantled MoK. The injectors were all working fine.
Even with leaks on the steam side and water side the worked well.
youtube.com/shorts/bkZkTZ1qvwM?feature=share
I put them in citric acid and do a test after some work on the connection also.

[rogsteam1959]

In this video you see the injector, repaired years ago by Julian Atkins, tested on the low pressure range. On my jubilee he only works from about 60- 120 psi.
On the MoK boiler the steam pipe is smaller. And the valve are not big also.

youtube.com/shorts/waISwNVh7zo?feature=share

Still I think that Keith Appleton might have the right idea that the feeding on top of the boiler might cool down the steam and that might be the reason the injector isn’t working with lower pressure on the Jubilee

[oldnorton]

If Appleton is talking about top feeds into the boiler, I cannot see that the reasoning is correct. When steam flow pulls in the water in the injector, theory says that ALL the steam condenses. That is how the latent heat of evaporation energy is converted to pressure and mass velocity. That is what makes an injector work. That is why if the supply water is too hot the injector fails as the steam cannot all condense.

Just my understanding of it, but a rocket scientist is welcome to disagree!

[rogsteam1959]

He has a 4 inch scale traction where the injector isn’t working well. And when the boiler was almost overfilled the injector was working. I’m waiting for his next video. He made an extension pipe to the checkvalve that the injector can feed into the water.



I had a look at my top feed assembly and found out I cannot extend the tube into the water space because the tube from the regulator is going underneath my top feed. I measured the distance between the end of the black tube and the regulator tube. It’s a little less of a 1/4”. It’s almost like feeding against a wall? I’ll remove the black tube and see if it’s working better. At high pressure it’s working but not down below 60psi.