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Post by Deleted on Mar 25, 2014 23:29:45 GMT
The important thing to remember in all this is that the smokebox unit as a whole (door seal included)needs to be vacuum-tight when operating or your steaming etc will be, how can I put it ??-------up a certain creek without a paddle Comprende'??
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jma1009
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Post by jma1009 on Mar 26, 2014 13:08:47 GMT
depending on the type of loco (and i try and ensure there is only one connection at the front of the smokebox base inside for the steam pipe with a branch pipe underneath for outside cylinder locos) the said same connection is made as low as possible so that to remove the smokebox after unscrewing the blastpipe the smokebox/boiler only has to be tilted up at the front the minimum amount. the union for same can be accessed from the smokebox door opening. i have on occasions made the odd special spanner for same but usually an ordinary spanner will reach quite happily. smokebox innards are extremely difficult to draw - or most of the well known designers show things so that they are easier to draw than build and maintain! a little bit of thought and ingenuity and practical re-design of smokebox innards can easily result in considerable improvements all round! cheers, julian
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redmog
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Post by redmog on Mar 26, 2014 13:54:41 GMT
depending on the type of loco (and i try and ensure there is only one connection at the front of the smokebox base inside for the steam pipe with a branch pipe underneath for outside cylinder locos) the said same connection is made as low as possible so that to remove the smokebox after unscrewing the blastpipe the smokebox/boiler only has to be tilted up at the front the minimum amount. julian Thanks. I'm starting to see the picture now. And - It's not too late to try it on the V4 when I return to the project. It's just a matter of working out the steam supply coupling. Chris
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Post by Deleted on Mar 26, 2014 14:32:19 GMT
"-----smokebox innards are extremely difficult to draw - or most of the well known designers show things so that they are easier to draw than build and maintain! a little bit of thought and ingenuity and practical re-design of smokebox innards can easily result in considerable improvements all round!" Isn't that the truth !! EDIT}----- You could always opt for the horizontally split smokebox ??.. Have a look at this}--- www.stationroadsteam.co.uk/archive/2393/index.htm -----------------
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redmog
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Post by redmog on Mar 26, 2014 14:52:30 GMT
" You could always opt for the horizontally split smokebox ??.] Thanks for the thought but... Sorry ... no... I intend trying Julian's suggestion first,,, but not just yet!
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robmort
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3.5" Duchess, finishing 2.5" gauge A3 and building 3.5" King
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Post by robmort on Mar 30, 2014 10:04:52 GMT
I use a simple push fit for the steam pipe from the smokebox to the cylinders, using an o-ring joint as devised, amongst others, by Collin & Wiese for the Flying Scotsman. I use o-ring joints wherever possible elsewhere too, e.g. exhaust joints, for easy dismantling.
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Post by Deleted on Mar 30, 2014 10:56:34 GMT
I wouldn't recommend ordinary O rings for steam pipe joints if you have a decent level of superheat. There are high temperature versions (e.g. Kalrez) but they seem to be hard to source and are very expensive.
I originally used silicon O rings on the steam manifold joints for my Helen Longish and they just disintegrated with the heat (went like chewing gum!) Not sure what temperature the steam is but the bronze manifold turned a nice blue colour the first time she ran. I eventually had to use proper compression joints with copper olives.
You should be ok on something like the Scotsman though. The superheat will be fairly moderate as the elements only extend the length of the flues.
John
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redmog
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Post by redmog on Mar 30, 2014 12:54:42 GMT
I wouldn't recommend ordinary O rings for steam pipe joints if you have a decent level of superheat. John Thanks John but .. No I don't intend using O rings but it is an interesting suggestion and would be suitable in some cases. When I work out an easy smokebox removal method, to enable ease of access, it’ll be nuts and nipples. But not just yet. I'm messing about with other things! Chris
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robmort
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3.5" Duchess, finishing 2.5" gauge A3 and building 3.5" King
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Post by robmort on Mar 30, 2014 13:27:27 GMT
EPDM is the recommended o-ring material for superheated steam, or Viton perhaps would do. Slightly more expensive than the usual but still obtainable.
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redmog
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Post by redmog on Mar 30, 2014 14:38:28 GMT
EPDM is the recommended o-ring material for superheated steam, or Viton perhaps would do. Slightly more expensive than the usual but still obtainable. Thanks. I'll do some research!
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Post by Deleted on Mar 30, 2014 15:51:38 GMT
Sorry for my ignorance but just what is EPDM ??---------- (Electro Plated Dung Metal )
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robmort
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3.5" Duchess, finishing 2.5" gauge A3 and building 3.5" King
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Post by robmort on Mar 30, 2014 16:22:19 GMT
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jma1009
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Post by jma1009 on Mar 30, 2014 16:22:28 GMT
hi alan, im not an expert on such things but i think EPDM is pond liner. i wouldnt have thought it has a high temperature threshold or be ok in an oily environment. back to the gardening and the lawnmower! cheers, julian
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Post by Deleted on Mar 30, 2014 16:38:36 GMT
hi alan, im not an expert on such things but i think EPDM is pond liner. i wouldnt have thought it has a high temperature threshold or be ok in an oily environment. back to the gardening and the lawnmower! cheers, julian -----------------------I thought it was short for Epidermis ?? ie something that might form a "skin" ??
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robmort
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3.5" Duchess, finishing 2.5" gauge A3 and building 3.5" King
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Post by robmort on Jul 25, 2014 11:34:22 GMT
hi alan, im not an expert on such things but i think EPDM is pond liner. i wouldnt have thought it has a high temperature threshold or be ok in an oily environment. back to the gardening and the lawnmower! cheers, julian Julian, you are quite right; it is used for pond liners, roofing etc. and has properties very similar to butyl rubber pond liners. For those who find it too difficult to click on the link above: Ethylene Propylene Diene Monomer: Ethylene propylene rubber is an elastomer prepared from ethylene and propylene monomers (ethylene propylene copolymer) and at times with an amount of a third monomer (ethylene propylene terpolymers). Ethylene propylene rubber has a temperature range of -50°C to +120°/150°C (-60°F to +250°/300°F), depending on the curing system. It has a great acceptance in the sealing world because of its excellent resistance to heat, water and steam, alkali, mild acidic and oxygenated solvents, ozone, and sunlight. These compounds also withstand the affect of brake fluids and Skydrol" and other phosphate ester-based hydraulic fluids Special EPDM compounds have good resistance to steam. EPDM Sulphur cured: inexpensive material for normal use, maximum temperature of +120°C (+250°F). EPDM Peroxide cured: for hot water, vapor, alcohols, ketones, engine coolants, organic and inorganic acids and bases. Not resistant to mineral oils. For maximum temperatures of +150°C (+300°F).
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