Railway Preservation News

SAR Class 25 Condenser Musings
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Author:  Randy Musselman [ Fri Nov 23, 2012 10:56 am ]
Post subject:  SAR Class 25 Condenser Musings


>>>My apologies I posted this in the classified section!? My wires were crossed!<<<

Recently I found a good video of the SAR condenser in operation.


On ~ 2:00 on the clock, it shows one starting from a stop signal. It would be interesting to know if the turbine draft blower was automatically ramped up with throttle position or was it all manual? The draft turbine may be powered from esxhaust steam? Regardless, I'll bet the firemen had their hands full.

There are videos of the "blue" Red Devil Class 26 throughtout this....as noted by its double stacks.

This video shows several shots of the condenser with a clean stack but in the following there is one that is running a bit rich!

http://www.youtube.com/watch?v=fHjAT2_7 ... re=related

It would be an interesting if the last one to survive (No 3511) , could run again in preservation.....a bit more work than a conventional! One of the biggest problems would be keeping the cylinder oil out of the condensed feedwater. I did read in a source they used an oil separator and blow downs to keep the trace oil levels low.

Interesting venture all the same......much more than a test as it was applied on 90 locomotives at new order.



Author:  whodom [ Fri Nov 23, 2012 12:30 pm ]
Post subject:  Re: SAR Class 25 Condenser Musings


I'm fairly certain the draft fan was powered by exhaust steam so that it was self-regulating, just like the draft on a conventional steam locomotive. I'm not sure what they did for a "blower" to provide draft while the locomotive was standing. Perhaps there was a way to admit a small amount of live steam to the turbine for this purpose. I recall reading that there were initially a lot of problems with erosion of the fan blades on the draft fan due to cinder-cutting and this took quite a bit of development work before the fans were made reliable.

The water feed to the boiler was by two steam turbine powered pumps. Wardale used these pumps on the Class 26 Red Devil to allow the use of a feedwater heater. He found the pumps to be extremely troublesome, although this may have been as a result of declining rebuild quality late in steam on the SAR rather than any inherent problems with the pumps.

I believe Wardale provides a short discussion of the 25C water feed arrangement in his book "the Red Devil". I suspect firing these locomotives was no harder than firing a conventional locomotive, but keeping the boiler water level regulated may have been a handfull.

Author:  AmericanStandard [ Fri Nov 23, 2012 3:46 pm ]
Post subject:  Re: SAR Class 25 Condenser Musings

That there sounds like quite the machine!

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