Author Topic: Superheaters for model loco  (Read 629 times)

Offline ChuckKey

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Re: Superheaters for model loco
« Reply #15 on: January 08, 2017, 04:38:25 PM »
You dont by chance have a reference to Jim's article do you? Be interested to have a read, 954C is pretty HOT!.
Last place I worked we ran 100 bar steam at 525 C so Like Dave said, you paint wont last long!

It was originally a paper read to The SMEE, and later published in Model Engineer, March-April 1966 (which is the year before my library starts), but also reported in 'Model Locomotive Boilers: their design and construction' by Martin Evans, MAP, 1969.

I have quoted it wrongly. That temperature was of the superheater itself, not the steam, which was up to 620F, and which admittedly sounds more like it. This is still a somewhat higher degree of superheat than is usual in full size (the saturated steam temperature being higher at the higher full size working pressures). He reports that after 9 years and 1000 miles hard running, using a high-superheat grade of Shell Valvata cylinder oil, the pistons were withdrawn to replace the graphite packing. The cast phosphor bronze cylinders and drawn bronze pistons were found to be in excellent condition. (Nothing is said about the packing though.)
« Last Edit: January 08, 2017, 04:45:28 PM by ChuckKey »

Offline steamer

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Re: Superheaters for model loco
« Reply #16 on: January 08, 2017, 04:59:02 PM »
OK ....sounds more like it....100 bar  ( about 150 psi) is at 377F   round abouts......  so 620 would be 243  degrees of superheat....

Still....hard on everything and you MUST use internal lubrication with a suitable oil.....and mechanical injection   ( Lube pump)

...and forget paint....gonna get smoked right off...

Dave




"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Steamer5

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Re: Superheaters for model loco
« Reply #17 on: January 09, 2017, 10:33:03 AM »
Hi Chuckkey,
 Thanks for the reference, my copies don't go back that far either, I'll have to check out the club library, think they have ME issues back that far. Yes the temp sounds better.

Dave,
 7 feet! Who delivered the popcorn,  :lolb:

Julian
 Sorry for kind of hijacking your thread, I hope you have found the banter....er... discussion on superheaters of interest. Keep us posted on how you get on making yours. Getting my stainless ones to fit turned into a mission, easy a making the wet header bush, had to do it twice, melted the first trying to silver solder the tubes in! Then the gentle tweaking to get the tubes to be central & the bush to fit & seal to the boiler bush took awhile to sort. Hope you have better luck!


Cheers Kerrin
Get excited and make something!

Offline Barneydog

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Re: Superheaters for model loco
« Reply #18 on: January 16, 2017, 12:54:18 PM »
Thanks Guys.

To repeat one of the questions.....Will displacement lubricators still work with a superheater installed?

Thanks

Julian

Offline ChuckKey

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Re: Superheaters for model loco
« Reply #19 on: January 16, 2017, 01:39:41 PM »
To repeat one of the questions.....Will displacement lubricators still work with a superheater installed?
Yes, but you might have to use a separate feed pipe to the lubricator with a condenser coil in it, as per full size GWR locos, for example. Such a feed would need a very fine needle valve.

Offline Barneydog

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Re: Superheaters for model loco
« Reply #20 on: January 16, 2017, 04:49:51 PM »
Thanks Chuckkey,

Not sure exactly what you mean. My plan was to make two displacements...one for each cylinder of the style designed by Bogstandard in one of his posts as built and detailed by Rich some time ago. This is to ensure each cylinder gets enough lube.

Julian