Glossary of boiler terminology - AbsoluteAstronomy.com

Boiler

A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:...

s for generating steam

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...

or hot water have been designed in countless different shapes, sizes and configurations. An extensive terminology has evolved to describe their common features. This glossary provides definitions for these terms.

Terms which relate solely to boilers used for space heating or generating hot water are identified by (HVAC
HVAC
HVAC refers to technology of indoor or automotive environmental comfort. HVAC system design is a major subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer...

).

A-B

Definitions	Points of Interest
Ashpan: A container beneath the furnace, catching ash and clinker that falls through the firebars. This may be made of brickwork for a stationary boiler, or steel sheet for a locomotive. Ashpans are often the location of the damper. They may also be shaped into hoppers, for easy cleaning during disposal. Blastpipe Blastpipe The blastpipe is part of the exhaust system of a steam locomotive that discharges exhaust steam from the cylinders into the smokebox beneath the chimney in order to increase the draught through the fire.- History :... : Blow-down cock: a valve mounted low-down on the boiler, often around the foundation ring, which is used to periodically vent water from the boiler. This water contains the most concentrated precursors for sludge build-up, so by venting it whilst still dissolved, the build-up is reduced. When early marine boilers were fed with salt water, they would be blown-down several times an hour. Blower Blower Blower may refer to:* USS Blower , a submarine of the United States Navy* a ducted centrifugal fan, especially when used in a heating, ventilating, and air-conditioning system* a supercharger on an internal-combustion engine... : the blower provides a forced draught on the fire, encouraging combustion. It consists of a hollow ring mounted either in the base of the chimney or on top of the blastpipe. Holes are drilled in the top of the blower ring, and when steam is fed into the ring, the steam jets out of the holes and up the chimney, stimulating draught. Boiler Boiler A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:... : Boilermaker Boilermaker A boilermaker is a trained craftsman who produces steel fabrications from plates and sections. The name originated from craftsmen who would fabricate boilers, but they may work on projects as diverse as bridges to blast furnaces to the construction of mining equipment.-Boilermaking:Many... : a craftsman skilled in the techniques required for construction and repair of boilers. Historically known as a boilersmith. Boiler suit: heavy-duty one-piece protective clothing, worn when inspecting the inside of a firebox for steam leaks, for which task it is necessary to crawl through the firehole door. Boiler ticket: the safety certificate issued for a steam (locomotive) boiler Boiler A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:... on passing a formal inspection after a major rebuild, and generally covering a period of ten years. Additional annual safety inspections must also be undertaken, which may result in the locomotive being withdrawn from service if the boiler requires work. When the ticket "expires" the locomotive cannot be used until the boiler has been overhauled or replaced, and a new ticket obtained. Brick arch: A horizontal baffle of firebrick within the furnace, usually of a locomotive boiler. This forces combustion gases from the front of the furnace to flow further, back over the rest of the furnace, encouraging efficient combustion. The invention of the brick arch, along with the blastpipe and forced draught, was a major factor in allowing early locomotives to begin to burn coal, rather than coke Coke (fuel) Coke is the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Cokes from coal are grey, hard, and porous. While coke can be formed naturally, the commonly used form is man-made.- History :... . Bridge clamp:

C-E

Definitions	Points of Interest
Carryover Carryover with steam Carryover with steam, in steam technology, refers to transport of moisture and impurities with steam.The moisture carryover with steam is quantified by the mass flow rate of liquid water per mass flow rate of steam... : the damaging condition where water droplets are carried out of the boiler along with the dry steam. These can cause scouring in turbines or hydraulic lock in cylinders. The risk is accentuated by dirty feedwater. See also priming. Check valve Check valve A check valve, clack valve, non-return valve or one-way valve is a mechanical device, a valve, which normally allows fluid to flow through it in only one direction.... : or clack valve, from the noise it makes. A non-return valve where the feedwater enters the boiler drum. They are usually mounted halfway along the boiler drum, or else as a top feed, but away from the firebox, so as to avoid stressing it with the shock of cold water. Cladding: The layer of insulation and outer wrapping around a boiler shell, particularly that of a steam locomotive. In early practice this was usually wooden strips held by brass bands. Later and modern practice is to use asbestos Asbestos Asbestos is a set of six naturally occurring silicate minerals used commercially for their desirable physical properties. They all have in common their eponymous, asbestiform habit: long, thin fibrous crystals... insulation matting (or other, less hazardous, fibres) covered with rolled steel sheets. The outer shape of the cladding is often a simplification of the underlying boiler shell. Also termed "clothing" in LMS London, Midland and Scottish Railway The London Midland and Scottish Railway was a British railway company. It was formed on 1 January 1923 under the Railways Act of 1921, which required the grouping of over 120 separate railway companies into just four... practice. Crinolines: The framework of hoops used to support cladding over a boiler. Named from the similar hoops under a crinoline Crinoline Crinoline was originally a stiff fabric with a weft of horse-hair and a warp of cotton or linen thread. The fabric first appeared around 1830, but by 1850 the word had come to mean a stiffened petticoat or rigid skirt-shaped structure of steel designed to support the skirts of a woman’s dress into... skirt. : The upper sheet of the inner firebox on a locomotive boiler. It is the hottest part of the firebox, and sometimes at risk of boiler explosion, should the water level drop and the crown sheet be exposed and thus allowed to overheat. Supported from above by complex stays. Damper: An adjustable flap controlling the air admitted beneath the fire-bed. Usually part of the ashpan. Disposal: The cleanup process at the end of the working day, usually involving dropping the fire and blowing down the boiler. Dome: a raised location on the top of the main boiler drum, providing a high point from which to collect dry steam, reducing the risk of priming. Downcomer: large external pipes in many water-tube boilers, carrying unheated cold water from the steam drum down to the water drum as part of the circulation path. Drowned tube: Either a fire-tube or water-tube that is entirely below the water-level of the operating boiler. As corrosion and scaling is most active in the region of the water-level, this reduces wear and maintenance requirements. Exhaust injector: a feedwater injector that economizes on steam consumption by using waste steam, such as engine exhaust.

F

Definitions	Points of Interest
Feedwater Boiler feedwater Boiler feedwater is water used to supply a boiler to generate steam or hot water. At thermal power stations the feedwater is usually stored, pre-heated and conditioned in a feedwater tank and forwarded into the boiler by a boiler feedwater pump.... Feedwater pump Boiler feedwater pump A boiler feedwater pump is a specific type of pump used to pump feedwater into a steam boiler. The water may be freshly supplied or returning condensate produced as a result of the condensation of the steam produced by the boiler... Field-tube: A form of single-ended thimble water tube with an internal tube to encourage circulation. Firebar: Replaceable cast-iron bars that form the base of the furnace and support the fire. These wear out frequently, so as designed for easy replacement. See Rocking grate Firebox Firedoor Fire dropping: Emptying out the remains of the fire after a day's work. A time-consuming and filthy task; labour-saving ways to improve this became important in the final days of steam locomotives. Fire-tube: Fire-tube boiler Fire-tube boiler A fire-tube boiler is a type of boiler in which hot gases from a fire pass through one or more tubes running through a sealed container of water... : A boiler where the primary heating surface is tubes with hot gas flowing inside and water outside. See water-tube boiler Flash steam Flash boiler A flash boiler is a type of water-tube boiler, whose tubes are strong and close together with water pumped through the tubes. The tubes are kept very hot so the water feed is quickly flashed into steam and superheated... Flue Flue A flue is a duct, pipe, or chimney for conveying exhaust gases from a fireplace, furnace, water heater, boiler, or generator to the outdoors. In the United States, they are also known as vents and for boilers as breeching for water heaters and modern furnaces... : A large fire tube, either used as the main heating surface in a flued boiler, or used as enlarged firetubes in a locomotive-style boiler where these contain the superheater elements. Flued boiler Foundation ring: The base of the firebox, where the inner and outer shells are joined. Furnace Furnace A furnace is a device used for heating. The name derives from Latin fornax, oven.In American English and Canadian English, the term furnace on its own is generally used to describe household heating systems based on a central furnace , and sometimes as a synonym for kiln, a device used in the... Fusible plug Fusible plug A fusible plug is a threaded metal cylinder usually of bronze, brass or gunmetal, with a tapered hole drilled completely through its length. This hole is sealed with a metal of low melting point that flows away if a pre-determined, high temperature is reached... : A safety device that indicates if the water level becomes dangerously low. It melts when overheated, releasing a jet of steam into the firebox and alerting the crew.

G-K

Definitions	Points of Interest
Galloway tubes: tapered thermic syphon Thermic syphon Thermic siphons are heat-exchanging elements in the firebox or combustion chamber of some steam boiler and steam locomotive designs. As they are directly exposed to the radiant heat of combustion, they have a high evaporative capacity relative to their size... water-tubes inserted in the furnace of a Lancashire boiler. Gauge glass: part of the water level gauge, which normally consists of a vertical glass tube connected top and bottom to the boiler backplate. The water level must be visible within the glass at all times. Grooving: erosion of a boiler's plates from the internal water space, particularly where there is a step inside the shell. This was a problem for early boilers made from lapped plates rather than butted plates, and gave rise to many boiler explosion Boiler 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... s. In later years it was a problem for the non-circular water drums of Yarrow boiler Yarrow boiler Yarrow boilers are an important class of high-pressure water-tube boilers. They were developed byYarrows and were widely used on ships, particularly warships.... s. Handhole: A small manhole, too small for access but useful for inspection and washing out the boiler. See: mudhole Injector Injector ʎ̩An injector, ejector, steam ejector, steam injector, eductor-jet pump or thermocompressor is a pump-like device that uses the Venturi effect of a converging-diverging nozzle to convert the pressure energy of a motive fluid to velocity energy which creates a low pressure zone that dɯaws in and... : a feedwater pump without moving parts that uses steam pressure and the Bernoulli effect to force feedwater into the boiler, even against its pressure. Klinger gauge glass: A form of gauge glass where the water level is visible through a flat glass window in a strong metal frame, rather than a cylindrical tube. These were popular with some operators, and increasingly so for high pressure boilers.

M-R

Definitions	Points of Interest
Manhole: an oval access door into the boiler shell, used for maintenance and cleaning. Manholes are sealed with a removable door from the inside. As they are oval, this door may be turned and lifted out through the hole. Doors are clamped in place from the outside with one or two bridge clamps spanning the hole and tightened down with a nut on a stud. As the cutting of a manhole weakens the boiler shell, the surrounding area is strengthened with a patch. : a sludge of boiler scale particles, precipitates and general impurities that builds up in the lower parts of a boiler. Mud reduces water circulation and so a local buildup may lead to localized overheating and possibly explosion Boiler 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... . Mud drum: a water drum, particularly one mounted low on the boiler whose function is primarily to trap mud from circulation. Mudhole: A small manhole, too small for access but useful for washing out the boiler, either as an inlet for a hose or as a drain for removed mud. See: washout plug Priming Carryover with steam Carryover with steam, in steam technology, refers to transport of moisture and impurities with steam.The moisture carryover with steam is quantified by the mass flow rate of liquid water per mass flow rate of steam... Regulator Rocking grate: An advanced form of firebar, where sections of the grate may be rocked or tipped to either break up clinker within the fire, or to drop the fire after a day's work.

S

Definitions	Points of Interest
Safety valve Safety valve A safety valve is a valve mechanism for the automatic release of a substance from a boiler, pressure vessel, or other system when the pressure or temperature exceeds preset limits.... : an automatic valve used to release excess pressure within the boiler. dissolved minerals from hard water Hard water Hard water is water that has high mineral content . Hard water has high concentrations of Ca2+ and Mg2+ ions. Hard water is generally not harmful to one's health but can pose serious problems in industrial settings, where water hardness is monitored to avoid costly breakdowns in boilers, cooling... that precipitate out in the steam space around the water-level. Where this scale falls to the bottom of the boiler and mixes with other contaminants, it is termed mud. Scum valve: A blow-down valve mounted at the water-level of a boiler, used to blow-down lighter oily or foamy deposits within a boiler that float on the water-level. Sludge, another term for mud. Smokebox Smokebox A smokebox is one of the major basic parts of a Steam locomotive exhaust system. Smoke and hot gases pass from the firebox through tubes where they pass heat to the surrounding water in the boiler. The smoke then enters the smokebox, and is exhausted to the atmosphere through the chimney .To assist... : an enclosed space at the extremity of a fire-tube boiler, where the exhaust gases from the tubes are combined together and pass to the flue or chimney. Snifting valve Snifting valve A snifting valve is an automatic anti-vacuum valve used in a steam locomotive when coasting. The word Snift imitates the sound made by the valve.... Steam accumulator Steam accumulator A Steam accumulator is an insulated steel pressure tank containing hot water and steam under pressure. It is a type of energy storage device. It can be used to smooth out peaks and troughs in demand for steam. Steam accumulators may take on a significance for energy storage in solar thermal... Steam drum Steam drum A steam drum is a standard feature of a water-tube boiler. It is a reservoir of water/steam at the top end of the water tubes. The drum stores the steam generated in the water tubes and acts as a phase-separator for the steam/water mixture... : a cylindrical vessel mounted at a high point of a water-tube boiler, where dry steam may separate above the water level, so that it may be drawn off without risk of priming. This is similar to the function of a dome in a fire-tube boiler. Steam & water drum: a steam drum that contains a turbulent mixture of steam and water, with a substantial part of this being water. The terms are used somewhat interchangeably. Steam drier, a form of mild superheater that adds additional heat to wet- or saturated steam, thus ensuring that all water in the steam has been evaporated, thus avoiding problems with water droplets in the cylinders or turbine Steam turbine A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884.... . Unlike the superheater, the steam drier does not attempt to raise the temperature of the steam significantly beyond the boiling point. Steam generator Steam generator A steam generator is a device used to boil water to create steam. It may refer to:Boiler , a closed vessel in which water is heated under pressure... Steam separator Steam separator A Steam separator, sometimes referred to as a moisture separator, is a device for separating water droplets from steam. The simplest type of steam separator is the steam dome on a steam locomotive... Suction valve: an automatic non-return valve, which opens when the boiler is at less* than atmospheric pressure. This avoids any risk of vacuum collapse, when a hot boiler is allowed to cool down out of service. Superheater Superheater A superheater is a device used to convert saturated steam or wet steam into dry steam used for power generation or processes. There are three types of superheaters namely: radiant, convection, and separately fired...

T-W

Definitions	Points of Interest
Thermic siphon Three-drum boiler: A generic term for water-tube boilers of the Yarrow pattern. In Royal Navy Royal Navy The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service... practice, a reference to the specific Admiralty example of this. Throatplate: a plate forming the lower front of the outer firebox of a locomotive boiler, below the barrel. Top-feed: in locomotive boilers, a feed water check valve placed on the top of the boiler drum. This encourages rapid mixing of the cold feedwater with the hot steam, reducing the risk of thermal shock to the heated parts of the boiler. Tubeplate: a plate across the barrel of a fire-tube boiler, containing many small holes to receive the fire-tubes. A locomotive boiler has two tubeplates: one at the front of the inner firebox and one at the front of the boiler, adjacent to the smokebox. Vertical boiler Vertical boiler A vertical boiler is a type of fire-tube or water-tube boiler where the boiler barrel is oriented vertically instead of the more common horizontal orientation... Water level Water level Water level or gage height or stage is the elevation of the free surface of a stream, lake or reservoir relative to a specified datum .... : Water-wall: a furnace or other wall within a boiler enclosure that is composed of numerous closely set water-tubes. These tubes may be either bare, or covered by a mineral cement. Washout plug: A small mudhole used for washing out the boiler. Plugs, as compared to mudholes, are usually screwed into a taper thread, rather than held by clamps. Water drum: See: mud drum Water-tube boiler Water-tube boiler A water tube boiler is a type of boiler in which water circulates in tubes heated externally by the fire. Fuel is burned inside the furnace, creating hot gas which heats water in the steam-generating tubes... : a boiler whose primary heating surface is composed of many small tubes, filled with water. Tubes of 3 inch diameter and above are termed "large-tube" boilers. Later water-tube designs used smaller "small-tubes" of 2 inches or less. Wet bottom furnace Wet bottom furnace A wet-bottom furnace or wet-bottom boiler is boiler that contains a wet bottom furnace. It is a kind of boiler used for pulverised fuel firing.In wet bottom boiler the bottom ash is kept in a molten state and tapped off as a liquid...

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