The World's Smallest Lempor
On plenty of occasions the webmaster has heard it said that modern steam technology is not scaleable be it exhaust ejectors, liquid fuel firing systems, water treatment or whatever. Well here is something many would have believed impossible - a Lempor exhaust ejector system on a 45mm gauge, coal fired, live steam locomotive belonging to Roger Hahn in the USA. Following a meeting with Nigel Day at Mount Washington early in 2005 he sought Nigel's advice on the practicalities of a Lempor exhaust on such a small loco and this is the end result!
Before and after photos of the loco showing (left) the old arrangement and new parts whilst (right) the first Lempor as installed with signs of a test steaming!
© Roger Hahn
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(left) A view showing how the mixing chamber and diffuser was temporarily fitted during testing and tuning. © Roger Hahn
The locomotive has not had the results of the modifications scientifically quantified but there does seem to have been a definite reduction in coal and water consumption. Perhaps more importantly, in this case, the loco now steams much better across the range of outputs. Steam production is now matched to the requirements. With the original plain blast nozzle, no petticoat and a parallel chimney liner at high output the boiler steamed too well leading to constant blowing off whilst at the other end of the scale when running gently the blower was required to keep pressure up. It is also reported that the loco even has the distinctive Lempor exhaust sound! |
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The loco on its first test run with a load. October 2005 © Roger Hahn |
Experimentation pointed to the likelihood that a second set of Lempor nozzles to a different design might give even better results. So, unlike the previous 4 nozzle set, it was decided to experiment with a 3 nozzle Lempor. The results are reported to be even better. It was felt the individual nozzle sizes with the 4 nozzle version were just too small leading to the undesirable phenomena of 'wire drawing' of the steam. The 3 nozzle Lempor, where each nozzle was proportionally larger, removed this problem.
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The world's first three nozzle Lempor? The webmaster is unaware of any others. November 2006 © Roger Hahn |
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A winter outing for Roger's locomotive. January 2006. © Roger Hahn |
In addition to the Lempor the locomotive has also gained a stainless steel combustion arch in an effort to improve combustion conditions further by making maximum use of the available firebox volume.
(right) A view into the loco's firebox showing the stainless steel combustion arch added to the locomotive. © Roger Hahn |
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In June 2007 Roger Hahn and locomotive visited Mount Washington. Since the photographs above the locomotive has gained a name - Casper. Roger reports that with the 3 nozzle Lempor Casper continues to run extremely well.
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Roger, Casper & Vicki at Mount Washington Cog Railway base station. June 2007. © Nigel Day |
A close view of Casper sat on Vicki's running plate. June 2007. © Nigel Day |
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