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A hand-crafted, coal-fired, 1:8 scale 2-10-0 'live steam' locomotive in 7 ¹⁄₄ in (184 mm) gauge, built in 14,000 hours over a period of 15 years.

Live steam is steam under pressure, obtained by heating water in a boiler. The steam is used to operate stationary or moving equipment.

A live steam machine or device is one powered by steam, but the term is usually reserved for those that are replicas, scale models, toys, or otherwise used for heritage, museum, entertainment, or recreational purposes, to distinguish them from similar devices powered by electricity or some other more convenient method but designed to look as if they are steam-powered. Revenue-earning steam-powered machines such as mainline and narrow gauge steam locomotives, steamships, and power-generating steam turbines are not normally referred to as "live steam".

Scale models and railroads[link]

A Live Steam Festival displaying equipment ranging from small stationary engines to full-size locomotives. Porvoo, Finland, 2003

The term live steam usually refers to a model steam locomotive, or any other steam-operated model that is powered by steam produced by boiling water, often built by a hobbyist model engineer. Steam rollers and traction engines are popular, in 1:4 or 1:3 scale, as are model stationary steam engines, ranging from pocket-size to 1:2 scale.

Ridable, large-scale live steam railroading on a backyard railroad is a popular aspect of the live steam hobby, but it is time-consuming to build a locomotive from scratch and it can be costly to purchase one already built. Garden railways, in smaller scales (that cannot pull a "live" person nor be ridden on), offer the benefits of real steam engines (and at lower cost and in less space), but do not provide the same experience as operating one's own locomotive in the larger scales and riding on (or behind) it, while doing so.

One of the most famous live steam railroads was Walt Disney's Carolwood Pacific Railroad around his California home; it later inspired Mr. Disney to surround his planned Disneyland amusement park with a working, narrow gauge railroad.

A propane fired 1:8 scale live steam train running on the Finnish Railway Museum's miniature 7 ¹⁄₄ in (184 mm) track.

The live steam hobby is especially popular in the UK, USA, and Australia. All over the world, there are hundreds of clubs and associations as well as many thousands of private backyard railroads. The world's largest live steam layout, with over 25 miles (40 km) of 7 ¹⁄₂ in (190.5 mm) trackage is Train Mountain Railroad ^[1] in Chiloquin, Oregon, USA. Other notable layouts are the one operated by Los Angeles Live Steamers and the one operated by Riverside Live Steamers.

Although not technically live steam, the hobby embraces other scale model locomotives whose prototypes are diesel (gasoline) and electric (battery). A few tracks restrict operation to only live steam engines, such as the Riverside Live Steamers mentioned above, but a visit to most tracks will reveal a mixture of locomotive types.

Scale[link]

A live steam locomotive is often an exact, hand-crafted scale model. Live steam railroad scales are generally referred to by the number of inches of scale per foot. For example, a 1:8 scale locomotive will often be referred to as a 1½ scale locomotive. Common modelling scales are Gauge 1 (1:32 scale), 1/2" (1:24 scale), 3/4" (1:16), 1" (1:12), 1½" (1:8), 2½" (~1:5) and 3" (1:4).

Gauge[link]

Railroad gauge refers to the distance between the rails. The ridable track gauges range from 2 ¹⁄₂ in (63.5 mm) to 15 in (381 mm), the most popular being 3½", 4¾", 5", 7¼" and 7½" (see Rail transport modelling scales). Gauges from 10 in (254 mm) and up are called "Miniature Railways" (in the USA these are known as "Grand Scale Railroads"), and are used mostly in amusement park rides and commercial settings.

Often the gauge has little to do with the scale of a locomotive since larger equipment can be built in a narrow gauge railway configuration. For instance, scales of 1.5, 1.6, 2.5, and 3 inches per foot (corresponding to scales of 1:8 to 1:4) have been used on a 7 ¹⁄₂ in (190.5 mm) track gauge.

The generally accepted smallest gauge for a live steam locomotive is 45 mm (1.772 in) Gauge 1, although O scale live steam models are also common. Producing smaller-scale models remains problematic, as the laws of physics do not themselves scale: creating a small-scale boiler that produces useful quantities of steam requires careful engineering. Hornby Railways has produced commercial live steam-powered locomotives in OO scale by utilising an electrically heated boiler mounted in the tender, with cylinders in the locomotive, and control provided by electrical- signals fed through the track from a remote control unit. They are less mechanically realistic than models in larger scales; the visible valve gear is a dummy, as on the electric-motor-powered models, and steam admission to the cylinders is controlled by a rotary-valve servo inside the boiler casing, which is also a dummy. Nevertheless, the locomotive is driven by steam that is created on board the locomotive and is hence a genuine steam locomotive.

It is technically possible to build even smaller operating steam engines. Hand-made examples, as small as Z scale (1:220), with a gauge of only 6.5 mm (0.256 in), have been produced.^[2] These are fired with a butane flame from a burner in the engine's tender. AA Sherwood of Australia, an engineering lecturer, produced some miniature scale model live steam engines in the late 1960s and early 1970s. His smallest live steam engines were 1:240 scale which is smaller than the 1:220 of Z Scale.^[3] The smallest scale Sherwood worked in was 1:480, though that was not live steam.

Technology[link]

A wide variety of boiler designs are available, ranging from simple externally fired pot boilers to sophisticated multi-flue internally fired boilers and even superheater boilers usually found only on larger, more complex models.

For basic locomotive models, a simple valve gear can be used, with the reversing (if any) performed by a valve, or by using a "slip" eccentric.

More complex locomotive models can use valve gear similar to real steam machine with the reversing done mechanically, most frequently the Walschaerts type.

Fuels[link]

There are several common fuels used to boil water in live steam models, depending on their scale:

Small scales:

• Hexamine fuel tablets – which produce relatively little heat but are cheap and relatively safe. They are often used on "toy" live steam locomotives and engines, such as the newer models in the range produced by Mamod.
• Methylated spirit, (methanol/ethanol mixture) – which burns hotter than solid fuel, but, as with any flammable liquid, requires more careful handling. Cheap and easy to obtain, this fuel was used with early Mamod models.
• Butane gas – clean burning and safe, but relatively expensive to engineer the burners.
• Electricity – delivered via the track and used to boil the water with an immersion heater. In 2003, Hornby launched a range of 00 gauge models that run from a 10 to 17 Volt power supply, making this method safer than previous, higher voltage versions.

Large scales:

• Coal – which is the prototypical fuel for most full-sized steam locomotives, and the preferred fuel for ridable trains. It can also be used on boilers down to at least 16mm:1 foot scale.
• Oil – also a popular fuel for large, ridable trains.
• Propane gas – an alternative to coal or oil in large-scale models.

Festivals[link]

A live steam festival (often called a "Steam Fair" in the UK and a live steam "meet" in the USA) is a gathering of people interested in steam technology. Locomotives, trains, traction engines, steam rollers and tractors, steam boats and cars, and stationary steam engines may be on display, both full-sized and in miniature. Rides may also be offered.

Publications[link]

There are two popular magazines devoted to the live steam hobby: Model Engineer and Live Steam magazine.

"Model Engineer" is an English publication that is published twice a month and was founded in 1898. Most locomotive articles have an "English" flavour popular in the UK, Australia, New Zealand and South Africa. The magazine is aimed at constructors but also covers non-steam and non-rail model engineering interests.

"Live Steam" is a U.S. magazine, founded in 1966 and devoted to the live steam hobby, as well as to other uses of miniature and full-size steam. Originally, it was a mimeographed newsletter, but soon expanded into magazine format. In 2005, the name was changed to "Live Steam & Outdoor Railroading". It is currently published bi-monthly, with a press run of slightly over 10,000 (Dec. 2004).

A more recent publication, launched in 2006, is "The Home Railway Journal"^[4], which is specifically aimed at enthusiasts with ride-on railways (although not just steam-powered) in North America. It is published quarterly in Sacramento, California, USA.

See also[link]

• Rail transport modelling scales
• List of steam fairs
• Saturated steam
• Superheated steam
• Live Steam & Outdoor Railroading (magazine)
• Category:Steam festivals
• Carpet railway – the 'Birmingham Dribbler' locomotives were a very early form of live steam toy
• Model steam engine

References[link]

External links[link]

Wikimedia Commons has media related to: Live steam

• Boiler types for Live Steam models
• Building Live Steam trains
• Live Steaming, site by Trevor Heath (formerly www.livesteaming.com)
• List of UK Steam Fairs
• online museum of live steam engines
• The Riverside Live Steamers

Steam phase eruption of Castle Geyser in Yellowstone Park A temperature-versus-entropy diagram for steam A Mollier enthalpy-versus-entropy diagram for steam

Steam is the technical term for water vapor, the gaseous phase of water, which is formed when water boils. In common language it is often used to refer to the visible mist of water droplets formed as this water vapor condenses in the presence of cooler air. At lower pressures, such as in the upper atmosphere or at the top of high mountains water boils at a lower temperature than the nominal 100 °C (212 °F) at standard temperature and pressure. If heated further it becomes superheated steam.

The enthalpy of vaporization is the energy required to turn water into the gaseous form when it increases in volume by 1,600 times at standard temperature and pressure; this change in volume can be converted into mechanical work by steam engines and steam turbines. Steam engines played a central role to the Industrial Revolution and modern steam turbines are used to generate electricity. If liquid water comes in contact with a very hot substance (such as lava, or molten metal) it can create a steam explosion. Steam explosions have been responsible for many foundry accidents and may also have been responsible for much of the damage to the plant in the Chernobyl accident.

Types of steam and conversion[link]

Water vapor that includes water droplets is described as wet steam. As wet steam is heated further, the droplets evaporate, and at a high enough temperature (which depends on the pressure) all of the water evaporates and the system is in vapor-liquid equilibrium.^[1]

Superheated steam is steam at a temperature higher than its boiling point for the pressure which only occurs where all the water has evaporated or has been removed from the system.^[2]

Steam tables contain thermodynamic data for water/steam and are often used by engineers and scientists in design and operation of equipment where thermodynamic cycles involving steam are used. Additionally, thermodynamic phase diagrams for water/steam, such as a temperature-entropy diagram or a Mollier diagram shown in this article, may be useful. Steam charts are also used for analysing thermodynamic cycles.

enthalpy-entropy (h-s) diagram for steam	pressure-enthalpy (p-h) diagram for steam	temperature-entropy (T-s) diagram for steam

Uses[link]

Agricultural[link]

In agriculture, steam is used for soil sterilization to avoid the use of harmful chemical agents and increase soil health.

Domestic[link]

Steam's capacity to transfer heat is also used in the home: for cooking vegetables, steam cleaning of fabric and carpets, and heating buildings. In each case, water is heated in a boiler, and the steam carries the energy to a target object. "Steam showers" are actually low-temperature mist-generators, and do not actually use steam.

Electricity generation (and cogeneration)[link]

About 90% of all electricity is generated using steam as the working fluid, nearly all by steam turbines.^[3]

In electric generation, steam is typically condensed at the end of its expansion cycle, and returned to the boiler for re-use. However in cogeneration, steam is piped into buildings through a district heating system to provide heat energy after its use in the electric generation cycle. The world's biggest steam generation system is the New York City steam system which pumps steam into 100,000 buildings in Manhattan from seven cogeneration plants.^[4]

Energy storage[link]

Fireless steam locomotive
Despite the resemblance to a boiler, note the lack of a chimney and also how the cylinders are at the cab end, not the chimney end.

In other industrial applications steam is used for energy storage, which is introduced and extracted by heat transfer, usually through pipes. Steam is a capacious reservoir for thermal energy because of water's high heat of vaporization.

Fireless steam locomotives were steam locomotives that operated from a supply of steam stored on-board in a large tank resembling a conventional locomotive's boiler. This tank was filled by process steam, as is available in many sorts of large factory, such as paper mills. The locomotive's propulsion used pistons and connecting rods, as for a typical steam locomotive. These locomotives were mostly used in places where there was a risk of fire from a boiler's firebox, but were also used in factories that simply had a plentiful supply of steam to spare.

Lifting gas[link]

Owing to its low molecular mass, steam is an effective lifting gas, providing approximately 60% as much lift as helium and twice as much as hot air. It is not flammable, unlike hydrogen, and is cheap and abundant, unlike helium. The required heat, however, leads to condensation problems and requires an insulated envelope. These factors have limited its use thus far to mostly demonstration projects.^[5]

Mechanical effort[link]

A steam engine and steam turbines use the expansion of steam to drive a piston or turbine to perform mechanical work. The ability to return condensed steam as water-liquid to the boiler at high pressure with relatively little expenditure of pumping power is important. Condensation of steam to water often occurs at the low-pressure end of a steam turbine, since this maximizes the energy efficiency, but such wet-steam conditions have to be limited to avoid excessive turbine blade erosion. Engineers use an idealised thermodynamic cycle, the Rankine cycle, to model the behavior of steam engines. Steam turbines are often used in the production of electricity.

Sterilization[link]

An autoclave, which uses steam under pressure, is used in microbiology laboratories and similar environments for sterilization.

Steam in piping[link]

Steam is used in piping for utility lines. It is also used in jacketing and tracing of piping to maintain the uniform temperature in pipelines and vessels.

Wood treatment[link]

Steam is used in the process of wood bending, killing insects and increasing plasticity.

Concrete treatment[link]

Steam is used to accentuate drying especially in prefabricates.

Cleaning[link]

Used in cleaning of fibers, sometimes prior to painting.

See also[link]

Look up steam in Wiktionary, the free dictionary.

Wikimedia Commons has media related to: Steam

Wikimedia Commons has media related to: Water vapor

• Electrification
• Food steamer or steam cooker
• Geyser—geothermally-generated steam
• IAPWS—an association that maintains international-standard correlations for the thermodynamic properties of steam, including IAPWS-IF97 (for use in industrial simulation and modelling) and IAPWS-95 (a general purpose and scientific correlation).
• Industrial Revolution
• Live steam
• Mass production
• Nuclear power—and power plants use steam to generate electricity
• Oxyhydrogen
• Psychrometrics—moist air/vapor mixtures, humidity and air conditioning
• Steam locomotive

References[link]

External links[link]

• Steam Tables & Charts by National Institute of Standards and Technology, NIST
• What Is Steam? (general article about the properties of water/steam)
• Steam Tracing
• Online steam properties calculator (Spirax Sarco)
• Free Steam Tables Online calculator based on IAPWS-IF97 (MegaWatSoft)
• Online Steam Tables Calculator based on IFC-67
• freesteam a free (GPL) library for calculation of steam properties using the IAPWS-IF97 standard.
• JSteam A Windows library and free calculator for the calculation of steam properties using the IAPWS-IF97-07 standards.
• JSteam Excel Add In An Excel add in for modelling and solving steam utility systems using the JSteam library.