Launch-type boiler
Encyclopedia
A launch-type, gunboat or horizontal multitubular boiler is a form of small steam boiler. It consists of a cylindrical horizontal shell with a cylindrical furnace and fire-tubes within this.
Their name derives from the boiler's popular use at one time for small steam yacht
s and launches. They have also been used in some early Naval torpedo boat destroyers.
(the short cylindrical furnace). As a fire-tube boiler it has generous heating area and so is an effective steamer. Firebox construction is also simpler, thus cheaper, than for the locomotive firebox.
The firebox is of limited size though, and unlike the locomotive boiler cannot expand beyond the size of the boiler shell. This limits the sustained output that is possible. The grate and ashpan are also limited in size, the grate being a set of bars part-way across the furnace tube and the ashpan the restricted space beneath this. These features limit the boiler's ability to burn hard bituminous coal
and they require a supply of Welsh steam coal, or similar, instead. The small ashpan also restricts their ability to steam for long periods.
One drawback of the boiler was the large diameter of the furnace relative to the boiler shell, and thus the small steam space above the crown of the furnace. This made the boilers prone to priming
, particularly on a rough sea, where water could be carried over into the steam pipe.
A more serious danger was the limited reserve of the water level, where the water level had only to drop by a small amount owing to inattention before the furnace crown would be exposed, with likely overheating and risk of boiler explosion. The boiler was safe when correctly fired, but could not be left unattended.
The boiler did see some popularity in mainland Europe, as a boiler for small portable engine
s. A similar boiler, but arranged with return fire-tubes, was built in America as the Huber boiler.
s, although they were notably used by Sir Arthur Heywood for his 15" minimum gauge railway
s at Duffield Bank
and Eaton Hall
.
Other minimum gauge railways, notable the 18 inch gauge works railways at Crewe
, Horwich
and the Guinness brewery in Dublin, also used lauch-type boilers, owing to the limited space between the frames for a conventional firebox.
s of 1890. The boiler design was German in origin. A similar boiler, the 'Vanderbilt' was used in the USA.
with an 0-8-0
Class 30 near Knottingley
in 1901 Their Chief Mechanical Engineer Henry Hoy
, sought to avoid the problems of the stayed firebox altogether and so developed an alternative boiler and firebox. This used a corrugated tubular furnace and cylindrical outer firebox, as for the Lentz. The furnace was also of steel, rather than the copper
used for fireboxes at this time. Hoy's involvement was ironic, as a major cause of the original accident had been Hoy's invention of a new brass alloy for firebox stays, an inelastic alloy that turned out to have serious drawbacks.Hewison, Locomotive Boiler Explosions, p. 111 One Class 30, 396, was rebuilt in 1903 and 20 more were built new with this boiler. The new boiler design did not last long in service and the locomotives were rebuilt with conventional boilers after ten years.The eight to ten year interval before rebuilding would be a typical service life for such a boiler. It indicates that the boilers were adequate, and were not withdrawn from service merely to replace them, but also that the experiment was not considered a success and so they were not continued with. Hoy's successor, George Hughes
, described these boilers unfavourably in papers read to the I. Mech E..
Their name derives from the boiler's popular use at one time for small steam yacht
Steam yacht
A steam yacht is a class of luxury or commercial yacht with primary or secondary steam propulsion in addition to the sails usually carried by yachts.-Origin of the name:...
s and launches. They have also been used in some early Naval torpedo boat destroyers.
Description
The boiler has similarities with both the locomotive boiler (the multiple small fire-tubes), and the Scotch marine boilerScotch marine boiler
A "Scotch" marine boiler is a design of steam boiler best known for its used on ships.The general layout is that of a squat horizontal cylinder. One or more large cylindrical furnaces are in the lower part of the boiler shell. Above this is a large number of small-diameter fire-tubes...
(the short cylindrical furnace). As a fire-tube boiler it has generous heating area and so is an effective steamer. Firebox construction is also simpler, thus cheaper, than for the locomotive firebox.
The firebox is of limited size though, and unlike the locomotive boiler cannot expand beyond the size of the boiler shell. This limits the sustained output that is possible. The grate and ashpan are also limited in size, the grate being a set of bars part-way across the furnace tube and the ashpan the restricted space beneath this. These features limit the boiler's ability to burn hard bituminous coal
Bituminous coal
Bituminous coal or black coal is a relatively soft coal containing a tarlike substance called bitumen. It is of higher quality than lignite coal but of poorer quality than Anthracite...
and they require a supply of Welsh steam coal, or similar, instead. The small ashpan also restricts their ability to steam for long periods.
One drawback of the boiler was the large diameter of the furnace relative to the boiler shell, and thus the small steam space above the crown of the furnace. This made the boilers prone to priming
Priming (steam engine)
Priming is a condition in the boiler of a steam engine in which water is carried over into the steam delivery. It may be caused by impurities in the water, which foams up as it boils, or simply too high a water level...
, particularly on a rough sea, where water could be carried over into the steam pipe.
A more serious danger was the limited reserve of the water level, where the water level had only to drop by a small amount owing to inattention before the furnace crown would be exposed, with likely overheating and risk of boiler explosion. The boiler was safe when correctly fired, but could not be left unattended.
The boiler did see some popularity in mainland Europe, as a boiler for small portable engine
Portable engine
A portable engine is a small steam engine, mounted on wheels or skids, which is used for driving machinery using a belt from its flywheel. It is not self-propelled and is towed to the work site by horses or bullocks, or even a traction engine. Portable engines were used mainly for driving...
s. A similar boiler, but arranged with return fire-tubes, was built in America as the Huber boiler.
Railway locomotives
The boiler was only rarely used for railway locomotiveSteam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...
s, although they were notably used by Sir Arthur Heywood for his 15" minimum gauge railway
Minimum gauge railway
Minimum gauge railways have a gauge of less than or , most commonly , , or . The notion of minimum gauge railways was originally developed by estate railways and by the French company of Decauville for industrial railways....
s at Duffield Bank
Duffield Bank Railway
The Duffield Bank Railway was built by Sir Arthur Percival Heywood in the grounds of his house on the hillside overlooking Duffield, Derbyshire in 1874. Although the Ordnance Survey map circa 1880 does not show the railway itself, it does show two tunnels and two signal posts.-Overview:It was more...
and Eaton Hall
Eaton Hall Railway
The Eaton Hall Railway was an early gauge narrow gauge estate railway built in 1896 at Eaton Hall in Cheshire.It was built for the Duke of Westminster by Sir Arthur Percival Heywood, who had pioneered the fifteen inch gauge with his Duffield Bank Railway, and connected the hall to the GWR...
.
Other minimum gauge railways, notable the 18 inch gauge works railways at Crewe
Crewe Works Railway
The Crewe Works Railway was a narrow gauge internal tramway system serving Crewe Works, the main locomotive construction works of the London and North Western Railway and later the London Midland and Scottish Railway...
, Horwich
Horwich Works
Horwich Works was a railway works built in 1886 by the Lancashire and Yorkshire Railway in Horwich, near Bolton, in the North West of England when the company moved from its original works at Miles Platting, Manchester.-Buildings:...
and the Guinness brewery in Dublin, also used lauch-type boilers, owing to the limited space between the frames for a conventional firebox.
Lentz boiler
A large launch-type boiler with a corrugated furnace, described as the Lentz boiler, was fitted to the Heilmann steam-electric locomotiveHeilmann locomotive
The Heilmann locomotives were a series of three experimental steam-electric locomotives produced in the 1890s for the French Chemins de Fer de l'Ouest . A prototype was built in 1894 and two larger locomotives were built in 1897...
s of 1890. The boiler design was German in origin. A similar boiler, the 'Vanderbilt' was used in the USA.
Lancashire & Yorkshire Railway
The Lancashire & Yorkshire Railway suffered problems with firebox stays, leading to a boiler explosionBoiler explosion
A boiler explosion is a catastrophic failure of a boiler. As seen today, boiler explosions are of two kinds. One kind is over-pressure in the pressure parts of the steam and water sides. The second kind is explosion in the furnace. Boiler explosions of pressure parts are particularly associated...
with an 0-8-0
0-8-0
Under the Whyte notation for the classification of steam locomotives, 0-8-0 represents the wheel arrangement of no leading wheels, eight powered and coupled driving wheels on four axles, and no trailing wheels...
Class 30 near Knottingley
Knottingley
Knottingley is a town within the metropolitan borough of the City of Wakefield in West Yorkshire, England on the River Aire and the A1 road. It has a population of 13,503....
in 1901 Their Chief Mechanical Engineer Henry Hoy
Henry Hoy
Henry Albert Hoy was a locomotive engineer with the Lancashire and Yorkshire Railway . Hoy was born on 13 January 1855 in London, and educated at King Edward VI's Grammar School in St Albans, and at St John's College, Liverpool University....
, sought to avoid the problems of the stayed firebox altogether and so developed an alternative boiler and firebox. This used a corrugated tubular furnace and cylindrical outer firebox, as for the Lentz. The furnace was also of steel, rather than the copper
Arsenical copper
Arsenical copper contains up to 0.5% arsenic which, at elevated temperatures, imparts higher tensile strength and a reduced tendency to scaling. It is typically specified in boiler work, especially locomotive fireboxes. It also helps prevent embrittlement of oxygen free copper by bismuth, antimony...
used for fireboxes at this time. Hoy's involvement was ironic, as a major cause of the original accident had been Hoy's invention of a new brass alloy for firebox stays, an inelastic alloy that turned out to have serious drawbacks.Hewison, Locomotive Boiler Explosions, p. 111 One Class 30, 396, was rebuilt in 1903 and 20 more were built new with this boiler. The new boiler design did not last long in service and the locomotives were rebuilt with conventional boilers after ten years.The eight to ten year interval before rebuilding would be a typical service life for such a boiler. It indicates that the boilers were adequate, and were not withdrawn from service merely to replace them, but also that the experiment was not considered a success and so they were not continued with. Hoy's successor, George Hughes
George Hughes (engineer)
George Hughes was a locomotive engineer, and Chief Mechanical Engineer of the Lancashire and Yorkshire Railway and the London, Midland and Scottish Railway.-L&YR:...
, described these boilers unfavourably in papers read to the I. Mech E..