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Boiler- & Burner-Related Glossary Terms

Trying to learn your way around your boiler? These terms are a great place to start.

# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
There are currently 45 names in this directory beginning with the letter S.
safety valve
An automatic, full-open, pop-action valve that is opened by an overpressure in a boiler and used to relieve the overpressure before damage occurs.
safety valve blowback
See safety valve blowdown.
safety valve blowdown
A drop in pressure between popping pressure and reseating pressure as a safety valve relieves boiler overpressure. Also known as safety valve blowback.
safety valve capacity
The amount of steam that can be relieved by a safety valve, measured in the number of pounds of steam per hour it is capable of discharging under a given pressure.
saturated steam
Steam that is in equilibrium with water at the same temperature and pressure.
saturation pressure
The pressure at which water and steam are at the same temperature.
saturation temperature
The temperature at which water and steam are at the same pressure.
An accumulation of compounds like calcium carbonate and magnesium carbonate on the water side of the heating surfaces of a boiler.
scotch marine boiler
A firetube boiler with an internal furnace.
secondary air
The air supplied to the furnace by draft fans to control combustion efficiency by controlling how completely the fuel is burned.
Particles of foreign matter present in water.
selective catalytic reduction (SCR)
An emissions control method in which ammonia gas is introduced over a catalyst located in a module that is installed in the boiler exhaust stack.
See primary element.
sequencing system
See burner management system.
shear stress
Stress that occurs when two forces of equal intensity act parallel to each other but in opposite directions.
The process where the water level in a boiler momentarily drops with a decrease in steam demand.
single-point positioning
A modulating control strategy that uses steam pressure as the input signal and outputs a signal to a modulating motor that turns a jackshaft to modulate the air and fuel flow.
The accumulated residue produced from im­purities in water.
soft coal
See bituminous coal.
The carbon deposits resulting from incomplete combustion.
soot blower
A device used to remove soot deposits from around tubes and permit better heat transfer in the boiler.
specific gravity
The ratio of the weight of a given vol­ume of a substance to the weight of the same volume of water at a standard temperature of 60°F.
spontaneous combustion
The process where a material can self-generate heat until its ignition point is reached.
spreader stoker
A stoker that feeds the coal into the boiler in suspension and on the grate. Also known as an overfeed stoker or sprinkler stoker.
sprinkler stoker
See spreader stoker.
squirrel cage blower
A blower with a wheel that has blades attached at the rim and rotates in a housing.
state implementation plan (SIP)
A plan that gives the states the responsibility for developing their own programs to reduce air pollution.
The vapor that forms when water is heated to its boiling point.
steam atomizing burner
A fuel oil burner that sends steam and pressurized fuel oil through a nozzle into the furnace where the vaporized fuel mixes with air and is ignited.
steam impingement
The condition where steam strikes a metal surface, causing erosion of that surface.
steam pressure gauge
A boiler fitting that displays the amount of pressure inside a boiler, steam line, or other pressure vessel.
steam quality
The ratio of dry steam to the total amount of water evaporated.
steam separator
A device located in the steam drum of a boiler used to increase the quality of steam. Also known as a drum internal.
steam trap
An accessory that removes air and non condensable gasses and condensate from steam lines and heat exchangers without a loss of steam.
steam turbine
A rotary mechanical device used to drive rotating equipment, such as a generator, by extracting thermal energy from pressurized steam.
A mechanical device used for feeding coal into the boiler.
stop valve
A valve that is opened or closed by the operator and typically used to isolate the feedwater to the boiler or the steam discharge from the boiler.
straight-tube boiler
A watertube boiler with box heads connected together by straight, inclined water tubes.
Pressure or tension applied to an object.
superheated steam
Steam that has been heated above the saturation temperature.
A bank of tubes through which steam passes after leaving the boiler where additional heat is added to the steam.
surface blowdown
The process of removing water from the boiler near the NOWL to control the quantity of impurities in the remaining water or to remove a film of impurities on the surface of the water.
The process where the water level in a boiler momentarily rises with an increase in steam demand.
A panel or an assembly of panels containing electrical switches, meters, busses, and other overcurrent protection devices (OCPDs).
Any electrical device that switches or interrupts another device or circuit.
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