Editing Kylchap (section)

==Examples of use==

===France===
Chapelon developed the Kylchap exhaust in 1926, and it was tested on [[compound locomotive|compound]] [[4-6-2|"Pacific" locomotives]] of the 4500 and 3500 classes, and a simple expansion Pacific of the 3591 class, producing significant improvements in steaming and in one case a 41% reduction in back-pressure.  However, it first came into prominence in 1929 when applied to compound Pacific No 3566 which combined enlarged steam circuits, increased superheat, feedwater heater, thermic syphon, [[Hugo Lentz|Lentz]] poppet valves with double Kylchap exhaust extractors and chimneys. On a test in November 1929, the indicated horsepower (ihp) output was found to have increased by over 60%, from 1850 ihp to 3000 ihp, while its fuel and water consumption had improved by 25% compared to un-rebuilt engines of the same class. Those results made Chapelon's name and 3566 became well known both within France and in most countries of the Western world.<ref>{{Citation|last=Rogers |first= H.B.C.(Col.)|title=Chapelon - Genius of French Steam |publisher=Ian Allan, London |year=1972 |isbn=0-7110-0281-9}}</ref>

===Great Britain===
Sir [[Nigel Gresley]] of the [[London and North Eastern Railway|LNER]] became a proponent when he incorporated [[double chimney|double]] Kylchap exhausts into four of his A4 Pacifics, including the world speed record holder [[LNER Class A4 4468 Mallard|''Mallard'']]. [[Arthur Peppercorn]]'s post-war LNER Pacifics also incorporated them, including preserved [[LNER Peppercorn Class A2|A2]] [[LNER Peppercorn Class A2 60532 Blue Peter|532 ''Blue Peter'']], and the recreated [[LNER Peppercorn Class A1 60163 Tornado|''A1 Tornado'']].

Originally, Kylchap exhausts were expensive and rarely used because the design was patented and subject to a licence fee but, after the patent expired, many more locomotives were retrofitted, including all the remaining A3 and A4 class, because the manufacturing cost was relatively low.  The last steam express passenger locomotive built in Britain, [[BR Standard Class 8|''Duke of Gloucester'']], was not fitted with a Kylchap exhaust in service, despite plans to do so, but one was fitted when it was renovated in preservation, after it was realised that poor draughting had been one of the biggest reasons behind its poor performance in its service days. A Kylchap exhaust is fitted to the [[Stainmore Railway Company]] industrial [[0-4-0]][[Tank_locomotive#Saddle_tank|ST]] locomotive "F.C. Tingey", located at Kirkby Stephen East station. Kylchap exhausts were also fitted to some British-built export locomotives, primarily [[Garratt locomotive]]s for Africa.{{cn|date=January 2025}} 

===Czechoslovakia===
The only other nation to take the Kylchap system in quantity was [[Czechoslovakia]], where all later [[standard-gauge railway|standard gauge]] steam locomotives used the design.