Everlasting Blowdown Valves

[John Baguley]

Hi all,

Has anyone any practical experience of these types of boiler blowdown valve as fitted to many full size locos and described by LBSC for his 3½" gauge Britannia and some earlier 5 " gauge locos?

I'm finalising the boiler fittings for a 2½" gauge Lynton and Barnstaple 'LYD'. The blowdown needs to go at the bottom of the throatplate inbetween the frames and the rear wheels and it would difficult to get to to operate the usual screw down type of valve. The Everlasting is operated by a lever and would be much easier to operate from outside the frames.

I see that the Steam Workshop sell castings to build one but it might be a bit big for what I want.

John

[mbrown]

I made one from castings for the Burma Mines loco but couldn't use it as it needed too much space around it to screw it into the bush on the boiler. In other words, as I tried to screw it in, it fouled the frames. A flange fitting would have worked OK but the bush wasn't big enough to take the studs.

LBSC specified a tiny flat spring which he said was available at electrical shops but which seems to be unobtainable now. Douglas Hewson specified a coil or two of a small bronze spring instead, but I found it was difficult to prevent that tipping the tiny valve. I did get mine to seal OK on air but can't vouch for it under steam.

Nevertheless, I think it would be a good solution in an inaccessible spot.

An alternative would be to do what Martin Evans did on (I think) Princess of Wales which is to make a screw down valve where the spindle is vertical and can be reached with a socket spanner from below.

Malcolm

[Jim Woods]

My 70 year old P V Baker has one. you really need to use it quite often, otherwise it does become stuck. if your in an area where lime is a problem, the cavity will fur up somewhat. but when in good condition, great things :-)

Jim

[steamer5]

Hey John,
Here’s a link to make your own, drawings included! As drawn probably to big for your use but gives you a starting point…

livesteamt3.blogspot.com/2016/06/everlasting-blowdown-valve.html

Please let us know how you get on!

Cheers Kerrin

[davewoo]

Hi John
I've never made one but in helping to recommission an ancient LBSC Brit (it was built as the articles appeared in M.E) I have stripped and cleaned one, after cleaning despite years of use it sealed perfectly for the hydraulic test and never gave trouble subsequently. The one in the link above looks a good idea with the teflon seal. If you have not got the Brit drawings I'm sure it is detailed in the live steam book, I'd also be interested in how you get on, good luck.

Dave

Thinking on it I learned to drive a loco on a Bonds Royal Scot ( same builder as the Brit above) which has a sloping throatplate, that was fitted with one too and I don't remember that giving any trouble.

[John Baguley]

Thanks all for your replies.

Kerrin - thanks for the link. I actually found it last night after doing a search for Everlasting Blowdown Valve and that was one of the results. I was already thinking of using a PTFE seat before I saw it but I'm wondering if I can just make the actual valve bit from PTFE rather than the seat?

Dave - I have got the Britannia drawings so have drawn one up in CAD based on that. There's plenty of room to fit it in and remove if necessary. It's just the operating that's awkward. It may still have to be operated from underneath but it would be nice to be able to have a pull rod or similar at one side somehow.

As the loco is one I am designing for the Association I may make some patterns and get some lost wax cast.

John

[nick952]

Roger has designed and made some in his Speedy thread.

Section views:- modeleng.proboards.com/thread/8680/help-speedy-valve-gear-issues?page=465

Machining starts here (I think):- modeleng.proboards.com/thread/8680/help-speedy-valve-gear-issues?page=471

[John Baguley]

Thanks Nick. I should have checked Roger's build! As it happens, the one I have drawn up is very similar to Roger's

John

[dhamblin]

Same experience as Dave - the valve port on Britannia sealed fine once I cleaned it up and that was with the original bronze spring, although I did open the coils up very slightly to give it the 'spring' back. There was a lot of corrosion around the valve body but that was just poor choice of materials e.g. steel nut on stainless steel valve spindle. Also limescale because the original packing on LBSC's design wasn't sufficient and steam / water had clearly leaked out - this was replaced with an O-ring in an enlarged bore, just as you have done with the design above.

Adding a handle was a challenge:

Everlasting Blowdown Valve by Daniel Hamblin, on Flickr

As refurbished with new bronze screws and stainless steel nut and washer on the spindle.


Blowdown Valve Lever by Daniel Hamblin, on Flickr

New steel handle with a silver steel pin at one end for gripping with pliers.


Blowdown Valve Lever by Daniel Hamblin, on Flickr

The whole set up installed on the throatplate.

This was effective when I first started using it last year but the new handle started to quickly get loose on the original handle, it really needs a bolt rather than fully threaded screw as I suspect that has worn the thread and the hole. Also the original handle is loose on the valve spindle where the square section is not sufficiently proud of the valve body, which means tightening the nut is actually clamping the handle to the valve body, not the spindle.

Fix all that and I'm convinced it will work well.

Regards,

Dan

[Jim]

I decided against fitting one to the Britannia as its location on the front of the fire just above the foundation ring meant that it was impossible to get at if a problem should arise without a strip down to lift the boiler. I opted for screwed tap on the side of the fire box at its lowest point. It acts a the blow down valve and also a handy boiler filling point. From memory (a bit shaky thee days) the full size Britannias had a tap in the same location for coupling a cleaning hose to.
Jim

[Cro]

Grandads Brit also has one, always worked well but from memory has gone a bit stiff now and I haven't fancied getting to it to take a proper look, then again then loco hasn't run in around 7 years now so I might have too next time out.

He didn't have a nice lever like Dan's had but simple a bit of firm wire formed to shape and it used to open/close ok with just that.

Must get that loco out next year for a spin!

Adam