Stroudley Regulator problem

[runner42]

I am having problems with my Stroudley regulator. It leaks when tested on air pressure which is applied at the output of the regulator, this method tends to force the two discs apart instead of in use the steam pressure is applied to tend to force the discs together. However, I can't simulate this condition by applying a vacuum to the output, only me sucking which is not enough of a representative test. First question is applying air pressure to the output the usual and a representative test?

The leak paths as you would expect is from the two holes to the outer periphery of the disc. The distance of the leak path is 0.140625", which maybe on the low side. Would an increase in the leak path by bringing the two holes closer together and slightly reducing the diameter of the holes improve matters? My assumption here is that increasing distance of the leak path would enable a greater metal to metal contact thus improving the sealing.

Brian

Regulator drawing by Brian Leach, on Flickr

[andyhigham]

Even if you get the most expensive vacuum pump available you will only have a pressure differential of 1 bar / 15psi

[Boadicea]

Brian, I think you've answered your own question - it's not a valid test. I don't think a vacuum pump is a valid test either. Both because they do not replicate the conditions in use.
There is no better way than sticking it back in the boiler (or some sort of test chamber if you haven't got it yet).

I think you have far more experience than me at this game, but my experience is as follows....

It takes loads of time and patience to get this type of regulator to seal when cold. I have done it using what LBSC recommended - pummice powder, really boring and time-consuming, but can be done.
The chances are that if you have taken care with it - it is as good as it gets and will perform well in steam.

There is always a problem at hydraulic test time - block off the regulator - it's not part of the test - a fault will show up at the steam test.
I have not read your regulations but the UK regs say that, where possible, superheaters should be included in the test - in which case, what the regulator does is irrelevant at that stage.
This option is avoided like the plague here, but is actually a good way of doing it, particularly if you fit tails to the superheater outputs to block off when needed.

The best option is to use a stainless gas valve - solved all problems for me.

So, unless you are interested in solving your problem for its own sake as an interesting project, I would do the above.

That's just me. Other solutions are available!

[uuu]

Yes, I would try and rig up a better test arrangement. Or, as noted, wait until you can see it perform under steam.

I would have thought over 1/8" of sealing distance is ample. And you could argue that increasing the area of metal to metal contact is going the wrong way. I've seen designs where non-active parts of the mating surface are cut away to reduce the area, and increase the contact pressure.

Wilf

[firebird]

Hi

I had the same problem with Conway my first loco build. I tried endlessly to get the regulator to seal and eventually gave up with it and converted the regulator to a stainless steel ball valve. Cured it perfectly.

All my trials are documented here

www.modelenginemaker.com/index.php/topic,6756.930.html

Look in the VEHICLES AND MODELS section then CONWAY which is currently on page 2 then go to about page 65

Cheers

Rich

[runner42]

Thanks for the replies however I have to stay with the existing design the boiler is constructed specifically for the
Stroudley regulator. Advice on how to get a good finish on both discs would be helpful. Specifically is the fixed disc finished before silver soldering to the main body and are the discs individually finished or as a pair?

Brian

[Boadicea]

When I got mine to seal completely, the back disc was actually on the loco but I was really careful not to get any abrasive into the boiler.
I used diminishing grades of valve grinding paste whilst grinding the two discs together, finishing off with the dreaded pummice powder.
In your case, I think you should solder the fixed disc on before grinding - just in case the soldering results in some kind of distortion. The support might make a useful handle.
Hope it goes well.
On the lighter side, I expect we won't hear from you for a while - your finger-ends may be too tender to type

[britannia]

I see that you you really don't want to replace your Stroudley arrangement, but I had the same problem with the Stroudley regulator on my 5 inch Black 5. The plates seem to get dirty with use, and I tried all sorts of methods to clean them, including fitting a thin PTE back plate, with no success. I certainly lost a couple of springs into the boiler whilst trying to refit the outer plate after polishing! I simply could not get it through a boiler test as it just leaked come what may. Covid lockdown was the opportunity to spend a long time in the workshop, and this I did designing an arrangement to use a process (gas)valve. Having fitted this new valve I have had no problems, and in fact prefer the more linear response from the regulator. The design was written up in the Model Engineer magazine and published Spring 22 over three editions. I can let you have the article if you need it.

[stevep]

This may not be the way you want to proceed, but the regulator on my 2-6-4 Stanier always leaked at boiler tests, so my process was to remove the superheaters, and fit a blanking plug into the fitting where the superheater wet header joined the steam pipe from the regulator. The pipe filled up with water (presumably) but the plug ensured it didn't go anywhere else, and held pressure.

[firebird]

Hi

With the success of fitting a ball valve to Conway I went straight for the ball valve idea on my current loco build Chub.

Made a body from bronze



Then fitted the ball valve



Sealed first time with no issues

Cheers

Rich

[runner42]

Apr 23, 2023 14:28:41 GMT britannia said:

I see that you you really don't want to replace your Stroudley arrangement, but I had the same problem with the Stroudley regulator on my 5 inch Black 5. The plates seem to get dirty with use, and I tried all sorts of methods to clean them, including fitting a thin PTE back plate, with no success. I certainly lost a couple of springs into the boiler whilst trying to refit the outer plate after polishing! I simply could not get it through a boiler test as it just leaked come what may. Covid lockdown was the opportunity to spend a long time in the workshop, and this I did designing an arrangement to use a process (gas)valve. Having fitted this new valve I have had no problems, and in fact prefer the more linear response from the regulator. The design was written up in the Model Engineer magazine and published Spring 22 over three editions. I can let you have the article if you need it.

Thanks for the offer, I would very much like to get a copy of the article, I PM you with my e-mail address.

Brian

[runner42]

Thanks Rich, I can see how it is configured so it appears to be very doable for my locomotive. A picture speaks a thousand words.

Brian

[britannia]

Apr 24, 2023 0:31:30 GMT runner42 said:

Apr 23, 2023 14:28:41 GMT britannia said:

I see that you you really don't want to replace your Stroudley arrangement, but I had the same problem with the Stroudley regulator on my 5 inch Black 5. The plates seem to get dirty with use, and I tried all sorts of methods to clean them, including fitting a thin PTE back plate, with no success. I certainly lost a couple of springs into the boiler whilst trying to refit the outer plate after polishing! I simply could not get it through a boiler test as it just leaked come what may. Covid lockdown was the opportunity to spend a long time in the workshop, and this I did designing an arrangement to use a process (gas)valve. Having fitted this new valve I have had no problems, and in fact prefer the more linear response from the regulator. The design was written up in the Model Engineer magazine and published Spring 22 over three editions. I can let you have the article if you need it.

Thanks for the offer, I would very much like to get a copy of the article, I PM you with my e-mail address.

Brian

Copy sent Brian.  Good luck with what I think is a logical solution.  Not sure I would want to be taking my superheaters out just for the boiler test.  Rich shows a very neat arrangement in this thread, close to my own design,  The big issue is getting a suitably sized (and operating temperature) process valve, and making the design suitable for a low steam dome as per the B5.

[uuu]

I've chopped the top off the ball valve to get it to fit in the dome on Jessie - which is fortunately a tall one:

JessieDome2 by Wilf, on Flickr

If it's possible to fit a flat flanged joint between superheater and cylinders, it's easier to block off than a coned union.

Wilf

[firebird]

Hi

On Conway it took a bit of fiddling to get the ball valve to fit because I was working with an existing boiler.

On Chub I made a boiler from a bit of plastic drain pipe



With an MDF back head



And an aluminium dome bush



From there I was able to design the regulator. I had to increase the size of the dome bush by 1/8''

Cheers

Rich

[simon6200]

The builders I know gave up on disc regulators long ago. We use ball valves or simple needle valve screw down regulators, neither of which leak.

[kipford]

Rich
Where did you get your ball valve from. I have one to use on my Aspinall but yours looks a lot smaller?
Regards
Dave

[firebird]

Hi

Initially I tried one of the cheaper valves but wasn't too impressed so changed to one of these





They worked perfectly

Cheers

Rich

[oldnorton]

Yes, a good idea to show the better type of ball valve to use. It would also be really helpful if we said which size was selected and how it performed in use.

There is a danger in selecting valves with too large a bore size; the 3/8" bore cheap gas valves seem to be hard to control.

I have used an 1/8" BSP valve that has a 1/4" bore and it works fine on my 5 inch Britannia. I will use the same size on my Black 5 build.

The type I buy have an adjustment screw pad, just like you can see in UUU's picture. As delivered these screws are set to seat the valve at its rated pressure, way above what we need, and at room temperature. The PTFE pads either side of the stainless ball expand when hot so I set the adjustment to just seal the valve when cold. It makes the force needed to operate it quite a bit less.

Norm

[steamer5]

As a thought, if you used the male / female or female / female one & find that the bore thru the ball was a bit on the large size you could screw a restriction orifice in to the female end maybe.
no idea if it would work in this situation but using orifice plates in industry to constrict flow rates is common

Cheers Kerrin