Blow down valves

[JonL]

I think the blowdown valves on my William are a bit clunky. They are difficult to unseat without accidentally unscrewing the main body. It took a while for me to get them to seal properly, in the end I put a small ball bearing into the seat which is embedded into the screw in portion, but I don't like it. Also I'd like the ability to easily fill the boiler when cold using these valves.

I've got a rough idea of what I'm going to make in my head but before I go in all guns blazing, does anyone have any suggestions of good designs they have seen or used please? They cannot be too tall as then need to clear the motion.

[coniston]

I bought the ones from Polly for my Simplex, they have O ring sealing so you don't need to tighten them much to close them off. I had to reduce the length of the spindle to miss the motion but there was enough to put a hex on it for my preferred 'key' which is the common for both my loco's. Not sure how big a thread you have in the boiler but worth checking the out.

Chris D

[steamer5]

Hi Nobby,
You could go hard out & make one or two of these...

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

It’s for a 71/4 so would need to scale to suit, pretty sure I’ve seen a 5” but didn’t bookmark it!

Cheers Kerrin

[cplmickey]

Jan 26, 2021 23:30:23 GMT coniston said:

I bought the ones from Polly for my Simplex, they have O ring sealing so you don't need to tighten them much to close them off. I had to reduce the length of the spindle to miss the motion but there was enough to put a hex on it for my preferred 'key' which is the common for both my loco's. Not sure how big a thread you have in the boiler but worth checking the out.

Chris D

I bought some from Polly too for my Simplex (they are less than a mile down the road). However I've had problems with both valves. The ptfe valve material spread a little which meant that as they were opened it caught on the threads and pulled off the spindle, so the valves couldn't be opened. I pulled the valves apart and removed the burr from the edge which cured the problem but one of them is doing it again. I don't screw the valves closed really tightly so I don't think it's me that's causing the problem. I suspect the material is too soft and easily deformed in such small pieces. Ian

[millman]

Dear old LBSC described a very similar everlasting blowdown valve in his Shop Shed and Road book, three pages of drawings and instructions. I think I have seen Doug Hewson listing castings for an everlasting blowdown valve but that was a few years ago.

[barlowworks]

I seem to remember Jim covering blowdown valves on his Britannia thread, not sure of the page. Drop him a PM, he’s always very helpful.

Mike

[92220]

Mike Jack (NZ) is working on B.R. style Everlasting Blowdown valve castings. It might be worth dropping him a PM to see if he is doing 7.1/4" as well as the 5" valves.

Bob.

[mbrown]

I made an everlasting blowdown from Doug Hewson castings and drawings (essentially identical to LBSC's). I couldn't use it, as it needs a fair bit of room to screw it into the bush on the boiler and I couldn't turn it far enough before it fouled something or other.

So check how much space you have to play with before going to the trouble of making one - although they are nifty little gadgets.

Malcolm

[JonL]

I will be using an Everlasting blow down on the Britannia (the drawings are all in the LBSC drawings and ME words and music) however in this case it's not really practical as I've got very limited space. On the William the blowdowns face outwards through the frames.

I'll have a think and see what I can come up with. Thank you all for all the "food for thought"!

[andyhigham]

You can always screw an elbow fitting into the boiler and mount the valve remotely

[johnd]

Have recently been looking at the LBSC design everlasting blowdown valve.
Was really interested until I read it needed a 3 turn 5/32” diameter flat section “bronze spring washer” “as used in many Milly-Amp fittings”............. No idea what that is.
Pretty sure the design by Doug Hewson mentioned above was fully described in EIM during the standard BR tank series.

[mbrown]

Doug Hewson's description in EIM used a few coils of ordinary bronze spring - seems to work fine. I couldn't find the flat spring washers described by LBSC anywhere although I vaguely remember seeing them on some electrical kit encountered before I realised they might have an ME use!

Malcolm

[coniston]

Jan 27, 2021 9:16:44 GMT cplmickey said:

Jan 26, 2021 23:30:23 GMT coniston said:

I bought the ones from Polly for my Simplex, they have O ring sealing so you don't need to tighten them much to close them off. I had to reduce the length of the spindle to miss the motion but there was enough to put a hex on it for my preferred 'key' which is the common for both my loco's. Not sure how big a thread you have in the boiler but worth checking the out.

Chris D

I bought some from Polly too for my Simplex (they are less than a mile down the road). However I've had problems with both valves. The ptfe valve material spread a little which meant that as they were opened it caught on the threads and pulled off the spindle, so the valves couldn't be opened. I pulled the valves apart and removed the burr from the edge which cured the problem but one of them is doing it again. I don't screw the valves closed really tightly so I don't think it's me that's causing the problem. I suspect the material is too soft and easily deformed in such small pieces. Ian

I think Polly must have changed the design, my dad had a similar problem with one like you describe utilising a PTFE plug on the end of the spindle. The ones I bought are sealed with an O ring on the end of the spindle so I don't foresee any problems with them. I did however make new bronze seats as that is the part that is in the boiler and I didn't want brass in that application. I think I covered in 'What I've Done Today' about a year ago.

Chris D

[dhamblin]

The LBSC blowdown valve could do with updating for modern 3 1/2" gauge use - swapping out the steel parts for stainless or bronze e.g. lever, 9BA screws and the 8BA nut. Making the body halves out of bronze would be a big improvement too.

Certainly a snug fit between throatplate and rear driving axle on the Brit.

Regards,

Dan

[mugbuilder]

I use this design shown. It is simple and easily made. The head opens into the boiler and can be made quite short as it doesn't need a gland. I have had some in use over 20 years without any problems. One shown is mounted on the lower backhead and the other on the outside of the firebox side and dummied up to look a bit more prototypical.

[mugbuilder]

[Jim]

Barry's design works perfectly and I used an adaptation of his design for the Britannia. The placement has the added advantage of being easily 'got at' should a problem arise...and they do for some of us especially if located in spots that are impossible to get at.

I know the drawings show the blowdown valve for the Britannia being an Everlasting valve located between the frames at the front of the fire box in a position almost impossible to reach should a problem arise.

After some consideration I blanked the bush off and relocated the blow down valve to the side of the fire box where the Britannias had a hose tap fitting. In that location the blowdown valve also doubles as the boiler filling point.

Jim

[JonL]

Some excellent tips there, thanks. One thing I quite like about the idea of remotely mounting the blowdown is that it would remove the risk of accidentally damaging the boiler Bush. Barry's fitting looks grand, I'll investigate further. Many thanks all

[ettingtonliam]

Just to be difficult, I'm looking for a design of blowdown valve which fits into a bush on the underside of the boiler barrel, discharges downwards but has the spindle mounted horizontally so it can be operated with a box spanner from the side. Any suggestions?

[RGR 60130]

Jan 28, 2021 12:58:01 GMT ettingtonliam said:

Just to be difficult, I'm looking for a design of blowdown valve which fits into a bush on the underside of the boiler barrel, discharges downwards but has the spindle mounted horizontally so it can be operated with a box spanner from the side. Any suggestions?

How about something along the lines of a large cylinder drain cock?

Reg