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Post by districtgrandmaste on May 15, 2007 10:06:26 GMT
Work on the LBSC Steam Crane progresses and the boiler approaches completion.
LBSC specifies all pipework from the stop valve to the engine inlet to be 3/32" copper. He would like a couple of turns within the firebox to provide some super-heating. (It's a vertical boiler 3" diameter).
I have a fair bit of 5/32" copper in stock and I am thinking of using that from the stop valve to the outlet of the super-heater and runing from the outlet of the super-heater to the engine inlet in 3/32".
The length from stop-valve to super-heater outlet is about 9" and from super-heater to engine another 4".
The boiler SWP will be 40 psi maximum.
Anybody got any suggestions?
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Post by baggo on May 15, 2007 11:10:20 GMT
I've just had a look at the ME article and the drawings show all the pipework to be 5/32" ? 3/32" might be a bit on the small side although dry superheated steam is more fluid than wet steam and will pass through smaller pipes with less resistance.
John
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Post by Shawki Shlemon on May 16, 2007 9:05:02 GMT
I would use 5/32 in preference to a smaller pipe as the control of steam to an engine is by the regulator and not the pipe unless the pipe was smaller and restrictive .
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Post by Nigel Bennett on May 16, 2007 12:08:11 GMT
I built the Tubal Cain steam crane, and used rather more superheater pipe than suggested by TC - 5/32" diameter IIRC. I ran it up the chimney and back a fair way. It sucked up virtually the entire heat output from the burner, and it would run (eventually) a very short time before runing out of steam. The regulator valve turned a funny brown colour (it was painted red initially), so goodness knows what the steam temperature was! I shortened the superheater to the right dimensions, and it worked just fine after that.
So I suppose that 5/32" is fine - don't make it too long!
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Post by districtgrandmaste on May 17, 2007 8:36:41 GMT
Many thanks for these comments - particularly Baggo - as I had read the drawings as 3/32" tube but I see now that LSBC specifies 5/32". Thanks to Nigel too for the advice about Super-heater length. I'm pleased somebody else has built one of these. I'm firing mine by gas - I expect it will be horrendously expensive to run- but grandchildren deserve it ; if you worry about how much it costs you can't afford it anyway!
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Post by chameleonrob on May 17, 2007 19:31:23 GMT
I built the Tubal Cain steam crane, and used rather more superheater pipe than suggested by TC - 5/32" diameter IIRC. I ran it up the chimney and back a fair way. It sucked up virtually the entire heat output from the burner, and it would run (eventually) a very short time before runing out of steam. The regulator valve turned a funny brown colour (it was painted red initially), so goodness knows what the steam temperature was! I shortened the superheater to the right dimensions, and it worked just fine after that. So I suppose that 5/32" is fine - don't make it too long! I've been trying to think why having a longer superheater would make an engine run short of steam. unless I'm missing something the only way it could was if the superheater in the chimney was impeding the flow of smoke. rob |
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Post by Nigel Bennett on May 21, 2007 12:08:34 GMT
A lot of the heat from the burner was being used heating the superheater to frightening levels, rather than boiling water. No boiling water = no steam = doesn't go!  |
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