||Pressure above zero pressure;
the sum of the gauge and atmospheric pressures.
||(STEAM) A pressure vessel containing water
and/or steam, which is used to store the heat of
steam for use at a later period and at some lower
||The process of cleaning the interior
surfaces of steam generating units by filling
the unit with dilute acid accompanied by an
inhibitor to prevent corrosion, and subsequently
draining, washing and neutralizing the acid by a
further wash of alkaline water.
||Represents the amount of free carbon
dioxide, mineral acids and salts (especially
sulphates of iron and aluminum) which hydrolyze
to give hydrogen ions in water and is reported
as milliequivalents per liter of acid, or ppm
acidity as calcium carbonate, or pH the measure
of hydrogen ions concentration.
ADIABATIC FLAME TEMPERATURE
||The theoretical temperature that would be
attained by the products of combustion provided
the entire chemical energy of the fuel, the
sensible heat content of the fuel and combustion
above the datum temperature were transferred to
the products of combustion. This assumes: No
heat loss to surroundings and no dissociation.
||The mixture of oxygen, nitrogen, and other
gases, which with varying amounts of water
vapor, forms the atmosphere of the earth.
|AIR ATOMIZING OIL BURNER
||A burner for firing oil in which the oil is
atomized by compressed air, which is forced into
and through one or more streams of oil which
results in the breaking of the oil into a fine
air, in an air-fuel mixture, to supply the
oxygen required for complete oxidation of the
||The descriptive characteristic of a
substance from which air has been removed.
||The ratio of the weight, or volume, of air
||The leakage of air into a setting or duct.
||Air which contains the maximum amount of
water vapor that it can hold at its temperature
valved opening in the top of the highest drum of
a boiler or pressure vessel for venting air.
||A suitable horn, bell, light or other device
which when operated will give notice of
malfunction or off normal condition.
||Represents the amount of carbonates,
bicarbonates, hydroxides and silicates or
phosphates in the water and is reported as
grains per gallon, or ppm as calcium carbonate.
|ALLOWABLE WORKING PRESSURE
||See design pressure.
||The air that surrounds the equipment. The
standard ambient air for performance
calculations is air at 80 °F, 60% relative
humidity, and a barometric pressure of 29.921
in. Hg, giving a specific humidity of 0.013 lb
of water vapor per lb of dry air.
||The temperature of the air surrounding the
||Quantitative determination of the
||Chemical analysis of solid, liquid or
gaseous fuels. In the case of coal or coke,
determination of carbon, hydrogen, sulfur,
nitrogen, oxygen, and ash.
||Water limit temperature control, a safety
device often used on boilers.
||A device to impede the flow of large dust
particles or sparks from a stack, usually
screening at the top.
||Fuel in the condition as fed to the fuel
||The incombustible inorganic matter in the
||The method of reporting fuel analysis,
whereby ash is deducted and other constituents
are recalculated to total 100%.
||A pit or hopper located below a furnace
where refuse is accumulated and from which
refuse is removed at intervals.
||The American Society of Mechanical
||A burner in which the fuel in a gaseous or
finely divided form is burned in suspension, the
air for combustion being supplied by bringing
into contact with the fuel, air drawn through
one or more openings by the lower static
pressure created by the velocity of the fuel
||Fuel in the condition as received at the
||Air under the prevailing atmospheric
||The barometric reading of pressure exerted
by the atmosphere. at sea level 14.7 lb per sq
in. or 29.92 in. of mercury.
||A device by means of which a liquid is
reduced to a very fine spray.
||The draft which may be utilized to cause the
flow of air for combustion or the flow of
products of combustion.
||The fraction of time during which the unit
is in operable condition.
||Consists of a propeller or disc type of
wheel within a cylinder that discharges air
parallel to the axis of the wheel.
||Back to Index
||A plate or wall for deflecting gases or
||A tile for deflecting gases.
||A device in gas paths utilizing baffles so
arranged as to deflect dust particles out of the
||A device containing one or more cloth bags
for recovering particles from the dust laden gas
or air which is blown through it.
||A filter in which the cloth filtering medium
is made in the form of cylindrical bags.
||atmospheric Pressure as determined by a
barometer usually expressed in inches of
||Base load is the term applied to that
portion of a station or boiler load that is
practically constant for long periods.
|BEADED TUBE END
||The rounded exposed end of a rolled tube
when the tube metal is formed over against the
sheet in which the tube is rolled.
||A nipple, or a short piece of pipe or tube,
closed at one end.
||Boiler Water that is removed from the Boiler
in order to maintain the desired concentration
levels of suspended and dissolved solids in the
Boiler and removal of sludge.
|BLOWDOWN SAFETY VALVE
||The difference between the pressure at which
a safety valve opens and at which it closes.
||A valve generally used to continuously
regulate concentration of solids in the boiler,
not a drain valve. See
||A specially designed, manually operated,
valve that connects to the Boiler for the
purpose of reducing the concentration of solids
in the Boiler or for draining purposes. (often
called bottom blowdown.)
||A fan used to force air under pressure.
||A closed vessel in which Water is heated,
steam is generated, steam is superheated, or any
combination thereof, under Pressure or vacuum by
the application of heat from combustible fuels,
electricity or nuclear energy.
||The term boiler efficiency is often
substituted for combustion or thermal
efficiency. True boiler efficiency is the
measure of fuel-to-steam efficiency.
||The evaporation of 34-1/2 lbs of water per
hour from a temperature of 212 °F into dry
saturated steam at the same temperature.
Equivalent to 33,475 Btu/hr.
||The heating capacity of a boiler expressed
in boiler horsepower, Btu/hour, or pounds of
||The outer cylindrical portion of a Pressure
||A term construed to mean a representative
sample of the circulating boiler water, after
the generated steam has been separated and
before the incoming feed water or added chemical
becomes mixed with it so that its composition is
||The conversion of a liquid into vapor with
the formation of bubbles.
||The boiling of highly alkaline water in
boiler pressure parts for the removal of oils,
||A device for increasing the Pressure or flow
of a gas.
||A duct that transports the products of
combustion between parts of a steam generating
unit or to the stack.
||A wall in a furnace over which the products
of combustion pass.
|BRITISH THERMAL UNIT
||(Btu) A Btu is essentially 252 calories. The
mean British Thermal Unit is 1/180 of the heat
required to raise the temperature of 1 lb of
water from 32 °F to 212 °F at a constant
||A structural member placed against a furnace
or boiler wall to restrain the motion of the
|BUNKER C OIL
||Residual fuel oil of high viscosity commonly
used in marine and stationary steam power
plants. (No. 6 fuel oil)
||A device for the introduction of fuel and
air into a furnace at the desired velocities,
turbulence and concentration.
||A plenum chamber around a burner that
maintains an air pressure sufficient for proper
distribution and discharge of secondary air.
|BURNER WINDBOX PRESSURE
||The air pressure maintained in the windbox
or plenum chamber measured above atmospheric
||A passage for a fluid, permitting a portion
of the fluid to flow around its normal pass flow channel.
||Back to Index
element, the principal combustible constituent
of all fuels.
mean calorie is 1/100 of the heat required to
raise the temperature of 1 gram of water from
Zero C to 100 °C at a constant atmospheric
pressure. It is about equal to the quantity of
heat required to raise one gram of water 1 °C.
Another definition is: A calorie is 3600/860
for determining the calorific value of a fuel.
ratio of the average load carried to the maximum
The principal combustible constituent of all
chemical solids and liquid entrained with the
steam from a boiler.
covering of sheets of metal or other material
such as fire resistant composition board used to
enclose all or a portion of a steam generating
power plant or steam heating plant that
generates power or steam.
of a fan rotor or wheel within a housing that
discharges air at a right angle to the axis of
of the principal chemical constituents.
|CHEMICAL FEED PIPE
pipe inside a boiler drum through which
chemicals for treating the boiler water are
brick, metal or concrete stack.
movement of water and steam within a steam
ratio of water entering a circuit to the steam
generated by that passes that circuit in a unit
pipe or tube to pass steam or water between
upper boiler drums usually located where the
heat absorption is low. Also used to apply to
tubes connecting headers of horizontal water
tube boilers with drums.
door placed so that accumulated refuse may be
removed room a boiler setting.
device used for removing gas borne solids from
finely divided organic substance which tends to
inhibit the formation of dense scale and results
in the deposition of sludge, or causes it to
remain in suspension, so that it may be blown
from the boiler.
loss representing the unliberated thermal energy
occasioned by failure to oxidize completely some
of the combustible matter in the fuel.
heat producing constituents of a fuel.
rapid chemical combination of oxygen with the
combustible elements of a fuel resulting in the
release of heat.
used in the combustion process. Air contains
oxygen which is required to combust fuel.
effectiveness of the burner to completely burn
the fuel. A well designed burner will operate
with as little as 10 to 20% excess air, while
converting all combustibles in the fuel to
complete oxidation of all the combustible
constituents of a fuel.
The weight of solids contained in a unit weight
of boiler or feed water. (2) The number of times
that the dissolved solids have increased from
the original amount in the feedwater to that in
the boiler water due to evaporation in
water resulting from the removal of latent heat
transmission of heat through and by means of
matter unaccompanied by any obvious motion of
material property relating heat flux (heat
transferred per unit area per unit time) to a
temperature difference. In American units, it is
typically defined as the amount of heat (Btu)
transmitted in one hour through one square foot
of material 1 inch thick, with a temperature
difference of 1°F between the two surfaces of
the material. (2) The property of a water sample
to transmit electric current under a set of
standard conditions. Usually expressed as microhms conductance.
uninterrupted removal of concentrated boiler
water from a boiler to control total solids
concentration in the remaining water.
manual or automatic device for the regulation of
a machine to keep it at normal operation. If
automatic, the device is motivated by variations
in temperature, pressure, water level, time,
light, or other influences.
valve used to control the flow of air, gas,
water, steam or other substance.
transmission of heat by the circulation of a
liquid or gas. It may be natural, with the
circulation caused by buoyancy affects due to
temperature differences, or forced with
circulation caused by a mechanical device such
as a fan or pump.
wasting away of metal due to chemical action. In
a boiler, usually caused by the presence of O2,
CO2, or an acid.
firebox boiler, the plate forming the top of the
for the ASME standard for Controls and Safety
||Back to Index
device for introducing a variable Pressure drop
in a system used for regulating The volumetric
flow of a gas, such as air.
||The structure on large firetube boilers from
which the front and rear doors are suspended
of air and gases from boiler feed water prior to
its introduction to a boiler.
||Removal of gases from samples of steam taken
for purity test. Removal of CO2 from water as in
the ion exchange method of softening.
||A continuation of combustion beyond the
furnace. (See also Secondary Combustion.)
||The load for which a steam generating unit
is designed, considered the maximum load to be
||The pressure used in the design of a boiler
for the purpose of calculating the minimum
permissible thickness or physical
characteristics of the different parts of the
|DESIGN STEAM TEMPERATURE
||The temperature of steam for which a boiler
||The temperature at which condensation
||The surface of the boiler water from which
steam is released.
||The process by which a chemical compound
breaks down into simpler constituents, as do CO2
and H2O at high temperature.
||Those solids in water which are in solution.
fuels distilled usually from crude petroleum.
||Vaporization of a substance with subsequent
recovery of the vapor by condensation. Often
used in less precise sense to refer to
vaporization of volatile constituents of a fuel
without subsequent condensation.
||Water produced by vaporization and
condensation with a resulting higher purity.
tube or pipe in a boiler or waterwall
circulating system through which fluid flows
||Amount of time a piece of equipment is not
||The difference between atmospheric pressure
and some lower pressure existing in the furnace
stack or gas passages of a steam generating
||The difference in static Pressure between
two points in a system.
||A device for measuring draft, usually in
inches of water.
||A valved connection at the lowest point for
the removal of all water from the pressure
||A cylindrical shell closed at both ends
designed to withstand internal pressure.
||Air with which no water vapor is mixed. This
term is used comparatively, since in nature
there is always some water vapor included in
air, and such water vapor, being a gas, is dry.
||Firetube boiler with a refractory lined back
door. Door opens to allow maintenance and/or
||Gas containing no water vapor.
||The loss representing the difference between
the heat content of the dry exhaust gases and
their heat content at the temperature of ambient
||Steam containing no moisture. Commercially
dry steam containing not more than one half of
one percent moisture.
||A passage for air or gas flow.
||Back to Index
||Utilizes waste heat by transferring heat
from flue gases to warm incoming feedwater.
||Equivalent direct radiation is the rate of
heat transfer from a radiator or convector. It
is equivalent to the square feet of surface area
necessary to transfer heat at the same rate at
which it is produced by a generator. A single
boiler horsepower equals 140 ft2 EDR.
||The ratio of output to input. See also
Combustion, Fuel-to-Steam and Thermal
||A device which utilizes the kinetic energy
in a jet of water or other fluid to remove a
fluid or fluent material from tanks or hoppers.
||A boiler in which electric energy is used as
the source of heat.
||A device for collecting dust, mist or fume
from a gas stream, by placing an electrical
charge on the particle and removing that
particle onto a collecting electrode.
||The conveying of particles of Water or
solids from the Boiler Water by the steam.
||Connections between parts of a boiler to
||Evaporation expressed in pounds of water
evaporated from a temperature of 212 °F to dry
saturated steam at 212 °F.
||The change of state from a liquid to a
||The number of pounds of water that is
evaporated in a unit of time.
||Air supplied for combustion in excess of
that theoretically required for complete
||The joint to permit movement due to
expansion without undue stress.
||A door in a furnace or boiler setting that
is designed to be opened by a pre-determined gas
||Treatment of boiler feed water prior to its
introduction into the boiler.
||Back to Index
||A machine consisting of a rotor and housing
for moving air or gases at relatively low
||A measure of fan operation in terms of
volume, total pressures, static pressures,
speed, power input, mechanical and static
efficiency, at a stated air density.
|FAN PERFORMANCE CURVES
||The graphical presentation of total
pressure, static pressure, power input,
mechanical and static efficiency as ordinates
and the range of volumes as abscissa, all at
constant speed and air density.
||A pump that supplies water to a boiler.
||Water introduced into a boiler during
operation. It includes make-up and return
||The treatment of boiler feed water by the
addition of chemicals to prevent the formation
of scale or to eliminate other objectionable
||Flue Gas Recirculation or the recirculation
of flue gas with combustion air to reduce NOx
||Porous material through which fluids or
fluid - and solid mixtures are passed to
separate matter held in suspension.
is an extended surface, a solid, experiencing
energy transfer by conduction within its
boundaries, as well as energy transfer with its
surroundings by convection and/or radiation,
used to enhance heat transfer by increasing
||A tube with one or more fins.
|FIRED PRESSURE VESSEL
||A vessel containing a fluid under pressure
exposed to heat from the combustion of fuel.
||A type of boiler design in which combustion
gases flow inside the tubes and water flows
outside the tubes.
|FIRING RATE CONTROL
||A pressure temperature or flow controller
which controls the firing rate of a burner
according to the deviation from pressure or
temperature set point. The system may be
arranged to operate the burner on-off, high-low
or in proportion to load demand.
||The carbonaceous residue less the ash
remaining in the test container after the
volatile matter has been driven off in making
the proximate analysis of a solid fuel.
luminous body of burning gas or vapor.
||A device which indicates if a fuel (liquid,
gaseous, or pulverized) is burning, or if
ignition has been lost. The indication may be
transmitted to a signal or to a control system.
|FLAME PROPAGATION RATE
||Speed of travel of ignition through a
||A control that sequences the burner through
several stages of operation to provide proper
air purge, ignition, normal operation, and
shutdown for safe operation.
||Susceptibility to combustion.
||The process of producing steam by
discharging water into a region of pressure
lower than the saturation pressure that
corresponds to the water temperature.
||The lowest temperature at which, under
specified conditions, fuel oil gives off enough
vapor to flash into a momentary flame when
||A passage for products of combustion.
||The gaseous product of combustion in the
flue to the stack.
||The continuous formation of bubbles which
have sufficiently high surface tension to remain
as bubbles beyond the disengaging surface.
||The circulation of water in a boiler by
mechanical means external to the boiler.
||A fan supplying air under pressure to the
fuel burning equipment.
||The accumulation of refuse in gas passages
or on heat absorbing surfaces which results in
undesirable restriction to the flow of gas or
||Ash which is not included in the fixed ash.
||A substance containing combustible used for
||Mixture of fuel and air.
||The ratio of the weight, or volume, of fuel
||A liquid fuel derived from petroleum or
||The ratio of heat added to boiler feedwater
to produce the output steam to the amount of
energy inputted with fuel.
||An enclosed space provided for the
combustion of fuel.
||Pressure occurring inside the combustion
chamber; positive if greater than atmospheric,
negative if less than atmospheric, and neutral
if equal to atmospheric.
||The cubic contents of the furnace or
||A hollowed threaded plug having the hollowed
portion filled with a low melting point
||Back to Index
||The determination of the constituents of a
||A burner that uses gas or fuel.
|GAS PRESSURE REGULATOR
||A spring loaded, dead weighted or pressure
balanced device which will maintain the gas
pressure to the burner supply line.
||A valve attached to a Water column or drum
for checking Water level.
||The transparent part of a water gauge
assembly connected directly or through a water
column to the boiler, below and above the water
line, to indicate the water level in a boiler.
||The pressure above atmospheric pressure.
classification according to quality, generally
based on ASTM specifications.
|GRAINS PER CU-FT
||The term for expressing dust loading in
weight per unit of gas volume (7000 grains
equals one pound).
||A unit of measure commonly used in water
analysis for the measurement of impurities in
water (17.1 grains = 1 part per million - ppm).
||Weight index of fuels: liquid, petroleum
products expressed either as specific, Baume or
A.P.I. (American Petroleum Institute) gravity;
weight index of gaseous fuels as specific
gravity related to air under specified
conditions; or weight index of solid
||Back to Index
||An access opening in a pressure part usually
not exceeding 6inches in its longest dimension.
||A handhole closure.
||A measure of the amount of calcium and
magnesium salts in water. Usually expressed as
grains per gallon or ppm as CaCO3.
||Water which contains calcium or magnesium in
an amount which require an excessive amount of
soap to form a lather.
||The thermal energy above a fixed datum that
is capable of being absorbed for useful work.
||An accounting of the distribution of the
heat input, output and losses.
||A vessel in which heat is transferred from
one medium to another.
||Rate that describes the heat available per
square foot of heat-absorbing surface in the
furnace or per cubic foot of volume.
||Those surfaces which are exposed to products
of combustion on one side and water on the
other. This surface is measured on the side
receiving the heat.
quantity of heat released by a fuel through
complete combustion. It is commonly expressed in
Btu per lb, per gallon, or cu-ft.
|HIGH GAS PRESSURE CONTROL
||A control to stop the burner if the gas
Pressure is too high.
|HIGH OIL TEMPERATURE CONTROL
||A control to stop the burner if the Oil
temperature is too high.
||A chemical compound of hydrogen and carbon.
||A strength and tightness test of a closed
pressure vessel by water pressure.
||Back to Index
||The initiation of combustion.
temperature of a fuel at which combustion
||Light Oil or coal compounds that readily
burn with a luminous flame, such as ethylene,
propylene and benzene.
||The partial oxidation of the combustible
constituents of a fuel.
|INDUCED DRAFT FAN
||A fan exhausting hot gases from the heat
|INERT GASEOUS CONSTITUENTS
||Incombustible gases such as nitrogen which
may be present in a fuel.
||A substance which selectively retards a
chemical action. an example in Boiler work is
the use of an inhibitor, when using acid to
remove scale, to prevent the acid from attacking
the Boiler metal.
||A device utilizing a steam jet to entrain
and deliver feed water into a boiler.
||A material of low thermal conductivity used
to reduce heat losses.
||A blower built as an integral part of a
device to supply air thereto.
||A burner of which the blower is an integral
||A device to prove the physical state of a
required condition, and to furnish that proof to
the primary safety control circuit.
||The blowing down of Boiler Water at
||The treatment of Boiler Water by introducing
chemicals directly into the boiler.
||A charged atom or radical which may be
positive or negative.
||Industrial Risk Insurers.
||Back to Index
||A light gauge steel covering used over a
boiler, usually combined with insulation, to
provide a low temperature outer surface.
||The uncontrolled quantity of fluid which
enters or leaves through the enclosure of air or
||See Heat Release.
||A switching device that completes or breaks
an electrical circuit at predetermined pressures
or temperatures. Also known as an interlock. See
||The material used on the furnace side of a
furnace wall. It is usually of high grade
refractory tile or brick or plastic refractory
||The rate of output required; also the weight
||The ratio of the average load in a given
period to the maximum load carried during that
|LOW GAS PRESSURE CONTROL
||A control to stop the burner if gas pressure
is too low.
|LOW OIL TEMPERATURE CONTROL
Oil Switch) a control to prevent burner
operation if the temperature of the Oil is too
|LOW WATER CUTOFF
||Safety device that shuts off the
Boiler/burner in the event of low Water,
preventing Pressure vessel failure.
projection, like an ear, used for supporting or
||Back to Index
||The Water added to Boiler feed to compensate
for that lost through exhaust, blowdown,
||The opening in a pressure vessel of
sufficient size to permit a man to enter.
||A pipe or header for collection of a fluid
from, or the distribution of a fluid to a number
of pipes or tubes.
|MANUAL GAS SHUTOFF VALVE
||A manually operated valve in a gas line for
the purpose of completely turning on or shutting
off the gas supply.
||Fuel gas manufactured from coal, Oil, etc.,
as differentiated from natural gas.
|MAXIMUM ALLOWABLE WORKING
||The maximum gauge pressure permissible in a
completed boiler. The MAWP of the completed
boiler shall be less than or equal to the lowest
design pressure determined for any of its parts.
This pressure is based upon either proof tests
or calculations for every pressure part of the
boiler using nominal thickness exclusive of
allowances for corrosion and thickness required
for loadings other than pressure. It is the
basis for the pressure setting of the pressure
relieving devices protecting the boiler.
|MAXIMUM CONTINUOUS LOAD
||The maximum load which can be maintained for
a specified period.
|MAXIMUM INSTANTANEOUS DEMAND
||The sudden load demand on a Boiler beyond
which an unbalanced condition may be established
in the boilers internal flow pattern and/or
surface release conditions.
|MECHANICAL ATOMIZING OIL BURNER
burner which uses the Pressure of the Oil for
||The negative pressure created by mechanical
||One millionth of a meter, or 0.000039 in. or
1/25400 in. The diameter of dust particles is
often expressed in microns.
||Fire pressure vessels which do not exceed
the following limits: 16 in. inside diameter of
shell; 42 in., overall length to outside of
heads at center; 20 sq ft water heating surface;
or 100 psi maximum allowable working pressure.
||Millions of Btus (British Thermal Units).
||Water in the liquid or vapor phase.
|MOISTURE IN STEAM
||Particles of Water carried in steam,
expressed as the percentage by weight.
||The Boiler flue gas loss representing the
difference in the heat content of the moisture
in the exit gases and that at the temperature of
the ambient air.
||A burner by means of which more than one
fuel can be burned.
||A burner having a number of nozzles from
which fuel and air are discharged.
||Back to Index
||The circulation of water in a boiler caused
by differences in density.
||Gaseous fuel occurring in nature.
|NET POSITIVE SUCTION HEAD (NPSH)
||The liquid Pressure that exists at the
suction end of a pump. if the NPSH is
insufficient, The pump can cavitate.
||Abbreviation for all of the family of oxides
||A short flanged or welded neck connection on
a drum or shell for the outlet or inlet of
fluids; also a projecting spout through which a
||Back to Index
||A burner for firing oil.
|OIL HEATING AND PUMPING SET
||A group of apparatus consisting of a heater
for raising the temperature of the Oil to
produce the desired viscosity, and a pump for
delivering the Oil at the desired pressure.
||A control to start and stop the burner -
must be in addition to the high limit control.
||The Pressure at which a Boiler is operated.
||Compounds containing carbon often derived
from living organisms.
||(1) The opening from the whirling chamber of
a mechanical atomizer or the mixing chamber of a
steam atomizer through which the liquid fuel is
discharged. (2) A calibrated opening in a plate,
inserted in a gas stream for measure velocity of
||A gas-analysis apparatus in which certain
Gaseous constituents are measured by absorption
in separate chemical solution.
||Minimum operating pressure of a hot water
boiler sufficient to prevent the water from
||Chemical combination with oxygen.
||An atmosphere which tends to promote the
oxidation of immersed materials.
||Corrosion or pitting in a Boiler caused by
||Back to Index
||A Boiler supplied with all of its components
- burner, controls and auxiliary equipment,
designed as a single engineered package, and
ready for on-site installation.
|PACKAGED STEAM GENERATOR
||See Packaged boiler.
||A measure of dust size, expressed in microns
or per cent passing through a standard mesh
screen. pass - a confined passageway, containing
heating surface, through which a fluid flows in
essentially one direction.
||The complete oxidation of all the
combustible constituents of a fuel, utilizing
all the oxygen supplied.
||Naturally occurring mineral Oil consisting
predominately of hydrocarbons.
||The hydrogen ion concentration of a water to
denote Acidity or Alkalinity. A pH of 7 is
neutral. A pH above 7 denotes alkalinity while
one below 7 denotes acidity. This pH number is
the negative exponent of 10 representing
hydrogen ion concentration in
|| A flame which is
utilized to ignite the fuel at the main burner
||An instrument which will register total
Pressure and static Pressure in a gas stream,
used to determine its velocity.
||A concentrated attack by oxygen or other
corrosive chemicals in a Boiler, producing a
localized depression in the metal surface.
||An opening through which fluid passes.
||A method of scavenging the furnace and
boiler passes to remove all combustible gases
after flame failure controls have sensed pilot
and main burner shutdown and safety shut-off
valves are closed.
||Abbreviation for parts per million. used in
chemical determinations as one part per million
parts by weight.
||To separate materials from a solution by the
formation of insoluble matter by chemical
reaction. The material which is removed.
||The removal of solid or liquid particles
from a fluid.
||Air at a temperature exceeding that of the
ambient air. PRESSURE - Force per unit of area.
||The difference in pressure between two
points in a system, caused by resistance to
closed vessel or container designed to confine a
fluid at a pressure above atmospheric.
||Air introduced with the fuel at the burner.
||The discharge of steam containing excessive
quantities of water in suspension from a boiler,
due to violent ebullition.
||Steam used for industrial purposes other
than for producing power.
|PRODUCTS OF COMBUSTION
||The gases, vapors, and solids resulting form
the combustion of fuel.
||Rapid fluctuations in pressure.
||To introduce air into the furnace and the
Boiler flue passages in such volume and manner
as to completely replace the air or gas-air
mixture contained therein.
||Back to Index
||A comprehensive term used in a boiler-unit
heat balance to account for the conduction,
radiation, and convection heat losses from the
boiler to the ambient air.
||The manufacturers stated capacity rating for
mechanical equipment; for instance, the maximum
continuous capacity in pounds of steam per hour
for which a boiler is designed.
|RATE OF BLOWDOWN
||A rate normally expressed as a percentage of
the Water fed.
supplied to the plant before any treatment.
||A chemical transformation or change brought
about by the interaction of two substances.
||The recombination of the products of
||The reintroduction of part of the flowing
fluid to repeat the cycle of circulation.
||An atmosphere which tends to 1) promote the
removal of oxygen from a chemical compound; 2)
promote the reduction of immersed materials.
||Removal of oxygen from a chemical compound.
||Brickwork or castable used in boilers to
protect metal surfaces and for Boiler baffles.
||The ratio of the mass of water vapor present
in a unit volume of gas to the maximum possible
mass of water vapor in unit volume of the same
gas at the same temperature and pressure.
|RELIEF VALVE (Safety Relief
||An automatic pressure relieving device
actuated by the pressure upstream of the valve
and characterized by opening pop action with
further increase in lift with an increase in
pressure over popping pressure.
||Products remaining from crude petroleum by
removal of some of the water and an appreciable
percentage of the more volatile hydrocarbons.
||A bead-like material used in chemical
exchange for softeners and dealkalizers.
||Impediment to gas flow, such as pressure
drop or draft loss through a dust collector.
Usually measured in inches water column (iwc).
|RETURN FLOW OIL BURNER
||A mechanical atomizing oil burner in which
part of the oil supplied to the atomizer is
withdrawn and returned to storage or to the oil
line supplying the atomizer.
||A series of four rectangular grids of black
lines of varying widths printed on a white
background, and used as a criterion of blackness
for determining smoke density in stack gas
|ROTARY OIL BURNER
||A burner in which atomization is
accomplished by feeding oil to the inside of a
rapidly rotating cup.
||Back to Index
||A casting, fabricated chair, or member used
for the purpose of support.
|SAFE WORKING PRESSURE
||A spring loaded valve that automatically
opens when Pressure attains the valve setting.
used to prevent excessive Pressure from building
up in a boiler.
|SAFETY SHUT-OFF VALVE
||A manually opened, electrically latched,
electrically operated safety shut-off valve
designed to automatically shut off fuel when
||The removal of a portion of a material for
examination or analysis.
||Air which contains the maximum amount of
Water vapor that It can hold at its temperature
||Steam at the temperature and pressure at
which evaporation occurs.
||The temperature at which evaporation occurs
at a particular pressure.
||Water at its boiling point.
||A hard coating or layer of materials on
surfaces of Boiler Pressure parts.
||Air for combustion supplied to the furnace
to supplement the primary air.
||Treatment of Boiler feed Water or internal
treatment of Boiler-Water after primary
Matter in water which can be removed from
suspension by gravity or mechanical means. (2) A
non-combustible solid matter which settles out
at bottom of a liquid; a small percentage is
present in residual fuel oils. SEGREGatION - The
tendency of refus
|SELF-SUPPORTING STEEL STACK
||A steel stack of sufficient strength to
require no lateral support.
||General purpose Water which may or may not
have been treated for a special purpose.
||The cylindrical portion of a Pressure
||A soft Water-formed sedimentary deposit
which normally can be removed by blowing down.
large "dose" of chemical treatment applied
internally to a steam boiler intermittently.
Also used sometimes instead of "priming" to
denote a discharge of water out through a boiler
steam outlet in relatively large intermittent
||Small gas borne particles of carbon or soot,
less than 1 micron in size, resulting from
incomplete combustion of carbonaceous materials
and of sufficient number to be observable.
||The act of reducing scale forming calcium
and magnesium impurities from water.
||Water which contains little or no calcium or
magnesium salts, or water from which scale
forming impurities have been removed or reduced.
||A liquid, such as Boiler Water, containing
||Unburned particles of carbon derived from
||A mechanical device for discharging steam or
air to clean heat absorbing surfaces.
||The breaking off of the surface of
refractory material as a result of internal
||The quantity of heat, expressed in Btu,
required to raise the temperature of 1 lb of a
||The Weight of Water vapor in a gas
Water-vapor mixture per unit Weight of dry gas.
||The angle included between the sides of the
cone formed by liquid fuel discharged from
mechanical, rotary atomizers and by some forms
of steam or air atomizers.
||A nozzle from which a liquid fuel is
discharged in the form of a spray.
||A vertical conduit, which due to the
difference in density between internal and
external gases, creates a draft at its base.
||The magnitude of the draft measured at the
inlet to the stack.
||That portion of a Pressure differential
resulting from difference in elevation of the
points of measurement.
||Gas and solid products discharged from
||The condition of being free from movement or
||Dry air weighing 0.075 lb per cu ft at sea
level (29.92 in. Barometric Pressure) and 70 °F.
|STANDARD FLUE GAS
||Gas weighing 0.078 lb per cu ft at sea level
(29.92 in. Barometric Pressure) and 70 °F.
||The measure of potential energy of a fluid.
||The vapor phase of Water, unmixed with other
|STEAM ATOMIZING OIL BURNER
||A burner for firing Oil which is atomized by
steam. It may be of the inside or outside mixing
||A restriction in circulation due to a steam
pocket or a rapid steam formation.
||A gauge for indicating the pressure of
|STEAM GENERATING UNIT
||A unit to which Water, fuel, and air are
supplied and in which steam is generated. It
consists of a Boiler furnace, and fuel burning
equipment, and may include as component parts
Water walls, superheater, reheater, economizer,
air heater, or any combination thereof.
||The degree of contamination. Contamination
is expressed in ppm.
||The percent by Weight of vapor in a steam
and Water mixture.
||A device for removing the entrained Water
||A device, such as a filter, to retain solid
particles allowing a liquid to pass.
existing transversely in a gas stream.
||A projecting pin serving as a support or
means of attachment.
||Steam with its temperature raised above that
of saturation. The temperature in excess of its
saturation temperature is referred to as
||Removal of water, foam, etc. from the
surface at the water level in a boiler. The
equipment for such removal.
||The sudden displacement or movement of Water
in a closed vessel or drum.
|SUSPENDED SOLIDS -
solids in Boiler water.
||A load that changes at relatively short
||Back to Index
||Air for combustion supplied to the furnace
to supplement the primary and secondary air.
||The quantity of air required for perfect
||The draft which would be available at the
base of a stack if there were no friction or
acceleration losses in the stack.
|THEORETICAL FLAME TEMPERATURE
Adiabatic Flame Temperature
unit of heat applied especially to gas. One therm = 100,000 Btu.
||The efficiency of a Boiler, based on the
ratio of heat absorbed to total heat input. This
does not include heat loss from the boiler
||A cycle of temperature swings that result in
failure of metal due to expansion and
||A temperature measuring instrument.
||A preformed refractory, usually applied to
shapes other than standard brick.
||The total quantity of air supplied to the
fuel and products of combustion. percent total
air is the ratio of total air to theoretical
air, expressed as percent.
||The sum of the static and velocity
|TOTAL SOLIDS CONCENTRATION
||The Weight of dissolved and suspended
impurities in a unit Weight of Boiler Water,
usually expressed in ppm.
||A receptacle for the collection of
||Water which has been chemically treated to
make It suitable for Boiler feed.
||Ancillary Boiler components, like Water
level controls, Pressure controls, and
||A hollow cylinder for conveying fluids.
||A hole in a drum, heater, or tube sheet to
accommodate a tube.
||A burner in which fuel and air are mixed and
discharged into the furnace in such a manner as
to produce turbulent flow from the burner.
||Ratio of maximum to minimum fuel or steam
input or Boiler output.
||Back to Index
||See Analysis Ultimate
||Product certification that indicates the
product meets safety standards determined by
Underwriters Laboratories. (ULC and cUL indicate
||That portion of a boiler heat balance which
represents the difference between 100 per cent
and the sum of the heat absorbed by the unit and
all the classified losses expressed as per cent.
||The combustible portion of the fuel which is
not completely oxidized.
|UNFIRED PRESSURE VESSEL
||A vessel designed to withstand internal
pressure, neither subjected to heat from
products of combustion nor an integral part of a
fired pressure vessel system.
||The ratio of hours in operation to the total
hours in that period.
||Back to Index
||The Gaseous product of evaporation.
||The change from liquid or solid phase to the
||The measure of the kinetic energy of a
||An opening in a vessel or other enclosed
space for the removal of gas or vapor.
||An arrangement of a burner such that air and
fuel are discharged into the furnace in
practically a vertical direction.
||Measure of the internal friction of a fluid
or its resistance to flow.
||Those products given off by a material as
gas or vapor, determined by definite prescribed
|VOLUME OF AIR
||The number of cu ft of air per min expressed
at fan outlet conditions.
||Back to Index
||Sensible heat in non-combustible gases
discharged to the environment.
||A liquid composed of two parts of hydrogen
and sixteen parts oxygen by weight.
||A vertical tubular member connected at its
top and bottom to the steam and Water space
respectively of a Boiler, to which the Water
gauge, Water level controls, and fuel cutoff may
||The gauge glass and its fittings for
||A sudden increase in Pressure of Water due
to an instantaneous conversion of momentum to
elevation of the surface of the Water in a
||Removes hardness (CaCO3) from water through
an ion exchange of sodium with calcium and
||A tube in a boiler having the water and
steam on the inside and heat applied to the
||A synonym for steam, usually used to denote
steam of low absolute pressure.
||A term usually applied to a minute leak in a
boiler joint which forms droplets (or tears) of
water very slowly.
||Firetube Boiler design wherein the back
portion of the Boiler has a Water jacket.
||The Lowest temperature which a Water wetted
body will attain when exposed to an air current.
This is the temperature of adiabatic saturation,
and can be used to measure humidity.
||A term used to designate the percentage of
Water in steam. Also used to describe The
presence of a Water film on heating surface
||Steam containing moisture.
||A chamber below the grate or surrounding a
burner, through which air under pressure is
supplied for combustion of the fuel.
||The static Pressure in the windbox of a
burner or stoker.
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