7.25 inch gauge Milner Hunslet

[ettingtonliam]

Just curious, but will a pressure gauge clearly intended for use with oxygen be OK, longterm, with much and more corrosive, steam? I've no idea what, if any, the differences are nternally between an oxygen gauge and a steam gauge.

[mbrown]

Hi Ed,

I am looking forward to a report on your water gauge blowdown as I am hoping to make something on similar lines.

It looks as if the pressure gauge is attached direct and without a syphon. This is surely OK for a hydraulic test but I'd be worried at direct exposure to steam without the usual column of water in between. Or is your gauge off a suitable spec, unlike model gauges?

Best wishes

Malcolm

[terrier060]

No it was just simpler to do this for the hydraulic test. I will put a U-tube on it when I use steam. Regarding the blowdown, it did not leak past the handle, only past the cock, so maybe I made the hole too big. I will try making another cock.

No dea about the question on the oxygen gauge. I rather assumed they would have a brass bourdon tube. I will have a look. In any case this is not a boiler that is going to get much use compared to a steam loco, so I suspect it will be OK. Will take a photo of the inside if I can get the back off.

[terrier060]

First let me wish you all a happy Easter for a very WET Wales today. A real Welsh drizzle. But this beautiful daffodil cheers up the inside of the house!

The test boiler is nearly finished but I have been waiting for the components to arrive for the temperature controller for the heating coil. I thought it would be safer than just relying on me switching the heating element on and off manually. Doing this while experimenting with the injectors would not be easy. There are, of course, two safety valves which I will make sure are not overloaded by the heater. I hate to think what my electricity bill will be!

I have put a small fan in the case as I have no idea yet on how hot the switching module is likely to get. Using a relay may have been a better choice. They do provide a substantial heat sink with the kit.

There is an earth wire attached to the steel foot of the boiler.  I have not fused the REX-C100PID Thermostat temperature Controller, but there is a 13A fuse in the plug.

Happy Easter by ed cloutman, on Flickr

Temperature Controller by ed cloutman, on Flickr

I checked the OXYGEN pressure gauge and the tube is copper.

[Roger]

That's a really neat setup. I don't think it will get hot at all, but there's no harm in having a fan.

[terrier060]

Apr 23, 2023 18:22:43 GMT Roger said:

That's a really neat setup. I don't think it will get hot at all, but there's no harm in having a fan.

Just sorting the 12V power supply for the fan.  I had to make it all unpluggable as the boiler has to be taken off the board for storage.  I may put some lagging on it to save on electricity!

[brucevoelkerding]

regarding the OXYGEN Pressure Gauge, I imagine there may be two different Answers.
1. the Gauge as originally used was part of a Commercial System and as such was purchased with a special Face.
2. here in the States there are specific requirements for cleaning Pressure Gauges used in Oxygen Service (see blog.ashcroft.com/cleaning-for-oxygen-service#SnippetTab). One Pipe Fitting Manufacture (Swagelok) claimed that free Particles left from cutting STEEL Pipe could upon high-speed Flow induced impact at an Elbow create enough of a spark to start Combustion (note Steel, Combustion being the Iron). The Process Piping in our Plants which conveyed Oxygen were Copper with "Oxygen-cleaned" Fittings. The Piping was Silver Soldered. Our Pressure was in the Range of only 100 psi and the Flow Rates were on the low side.

[terrier060]

At last we have got the steam launch into the water. Here we have just finished anti-fouling.
Also the test boiler is now working. The top image shows the setup with two safety valves, one set to blow at 100psi and the other slightly higher. So far only one lifted and the amount of steam issuing was quite small so I suspect that the amount of steam produced by the 2500KWh element is not very great.

The left hand injector is one I built to Brown's design and on the Hunslet works from 100psi down to about 30psi with no adjustment of water or steam. Interestingly it was not so reliable on this setup and gave up below 50psi. I think this is due to the water feed pipe being too small (using the plastic tubing) so will experiment with a larger tube. The feed on the loco is larger bore and very short between the tank and the injector.

The test injector is on the right hand side and this is one to Roger's design with a single combining and delivery cone. I can now fiddle with this until it is perfected. It has larger throats than Roger used for his 1500 Class to produce a greater feed rate for the 7.25 inch gauge Hunslet.

The heater element is controlled by the box of electronics which I described above and has a thermocouple which I have located inside a copper tube in the back end cover of the boiler. The controller gives two readings, the upper being the temperature inside the boiler and the lower the set point which I finally set to around 150 deg C to keep the boiler near the 100psi blowing off point. Some experimentation is required here as the is some overshoot, but after a few steamings I should get it about right.

The PTFE blow-down on the water gauge was leaking when I carried out the hydraulic test to 200psi. So for the cold tests I blocked the blow-down with a ball bearing and brass cap. During the steam test I removed the bearing and the heat from the steam must have swelled and softened the PTFE and now it seals perfectly. I will put up the drawings I made shortly so that you can see how they were made.

In the bottom image I am not having a catastrophic boiler failure or a water gauge glass failure, but blowing the boiler down and I liked the way the sunlight was shining through the steam!  I apologise for the crude lagging - we may lag it with timber!  Also for some reason I rarely burn my hands on the loco, but there were a series of OWS! and other expletives as I kept burning the back of my knuckles and can only think it was because the boiler was so silent being electrcally heated and I was used the the 10mm thick steel being cold!

WideAwake by ed cloutman, on Flickr

Boiler Test by ed cloutman, on Flickr

[NickM]

Don't blow yourself up Ed!

[terrier060]

By experiment, if I set the temperature to 150 it keeps the boiler pressure at about 70psi.

[terrier060]

Here are a couple of nameplates for my friend's Gauge 1 Hunslet - they are about 2 inches long. They have not been cut out yet. The 2mm end mill has milled triangular tags to stop the work breaking through during machining, hence the rough edge.

F360 Plate by ed cloutman, on Flickr
Cathy nameplates by ed cloutman, on Flickr

[chrisb]

What springs do you and your friend have on your Hunslets? I'm in NZ and getting springs made to the drawings is expensive. If you are using die springs, whichch ones did you go for?

[terrier060]

Hi Chris
The springs on mine are not to the drawings. It would be better for you to chat with NickM. I will be seeing him tomorrow and will ask him if he will get in touch. He may be able to help. I assume you are working to the Milner drawings?
Have a look at Fexosprings.com. They may be able to help. The nearest spring I could find was Flexospring order code 183716. They are about £3.00 each.

I hope this winter to rebuild mine to the drawings, using long springs and running them in tubes to act as dampers. There is a tendency for these 0-4-0 locos to bounce due to the large overhangs at each end, and mine has a cab and large steam chests and two cylinder lubricators which exacerbates the problem.

Hope this helps
Ed

[chrisb]

Hi Ed, I looked those springs up and they look about right other than the wire gauge wich is a bit light. They are 2.34mm rather than 12swg (2.64mm) so possible not quite as strong.

[terrier060]

Something has annoyed me for some time which has required me to finish the beading around the doors on the cab of the Terriers. The jig has been sat on the table of the Tormach for months and now it has to go!

Cab Door Beading by ed cloutman, on Flickr

The cause of this is the miss-spelling of the name on my Hunslet. It is a Welsh female name from the song and should be spelt MYFANWY, but for some reason it was incorrectly spelt MWFANWY! Living in Wales makes it even more embarrassing, and there have been some comments.

Myfanwy by ed cloutman, on Flickr

So I have a 2ftx4ftx 1/4in sheet of engraving brass which I bought about 40 years ago to make one of the John Wilding skeleton clocks, and it will do nicely to engrave two new nameplates.

Engraving by ed cloutman, on Flickr

[terrier060]

Hi Chris
I think you will just have to try them and see how it goes. They are not that expensive, and the alternative would be to have bespoke ones made, unless you can wind your own. Also the strength varies depending on the material they are made of, which may be worth looking at.

[terrier060]

I used a 2mm endmill for the rough cut, and then cleaned up all the lettering by contouring around them with a 0.4mm engraving bit.

I will now cut the outline of the plate with a 4mm endmill.


Plate01 by ed cloutman, on Flickr


Now the plate needs cutting out and the background painting red.  The plate is 7.75 inches long x 1.5 inches wide x 3/16 inch deep.

[terrier060]

Here are the finished items.
New Nameplates by ed cloutman, on Flickr

[Roger]

Oct 14, 2024 15:15:22 GMT terrier060 said:

Here are the finished items.
New Nameplates by ed cloutman, on Flickr

That's a lovely job Ed, very nice indeed!