flame safeguard control phần 10 pdf

ABSOLUTE P~ESSURE-Ihe sum of gauge pressure

plj.,js atmospheric pressure. Absolute pressure can be

zero only in a perlect vacuum.

ACTUAL BODY RATING-see VALVE BODY RATING.

ACTWATOR-a controlled molar, relay or solenoid In

which the electric energy is converted into a rolary, lin￾ear. or switching action. An actuator can effect a

change in the controlled variable by operating the final

control elements a number of times. Valves aM damp'

ers are examples of mechanisms which can

be controlled by actuators. Also see PROPOR￾TIONAL, SPRING RETURN, and TWO-POSITION

ACTUATORS.

AI R-the elastic, invisible mixture of gases that surrounds

lr,e eanh; atmosphere. Also see AMBIENT, ATOMIZ￾ING. COMBUSTION. COMPRESSED. EXCESS, IN￾DUCED. PREHEATED. PRIMARY, SEAL,

SECONDARY, AND VENTILATION AIR.

AIR-ATOMIZING OIL BURNER-see ATOMIZING OIL

BURNER.

AIR CHANGE-a complete replacement of all the air in

the combusllon chamber and breaChing of a furnace or

boiler.

AIRFLOW SWITCH -a conlrollerused to prove proper air

movement through a corrbustlon chamber by measur￾ing wirdlox or breeching pressure or by measuring air

velocity (sail switCh). Also see LOCKOUT and RUN·

NING INTERLOCKS.

AI R·FUEL RATIO - the ratio of the weight, or volume of air

to fuel measured in Ihe same unils under the same con￾ditions. The cptimum air-fuel ratio is the minimum ratio

that will provide complete cOlTtlusllon of the fuel with

enough excess air 10 maintain a stable flame envelope.

Also see STOICHIOMETRIC AIR-FUEL RATIO.

AIR HEATER-an IndirecHired. venled appliance in￾lended to supply heated air for space neating and other

purposes, but not Intended for permanent installation.

AIR REGISTER-a burner mounting which may admit

secondary air to the corrouslion space.

AIR RICH -the air-fuel ratio supplied to a furnace that pro￾vide:s more air than the optimum ratio.

AlA SHUTTER-an adjustable device for varying the size

of Ihe air inlet or Inlets regulating primary and/or secon￾dary air. An air shutler may be automatically or manu￾aUy operated.

ALARM-an audible device or visible signal indicating a

malfunction Of off-normal condition.

ALARM CIRCUIT-an electrical circuit that includes a

bell. horn, or similar device to signal an unsafe

condition.

ALTERNATING CURRENT (ac)-a flow of eleclriclty

which reaches maximum in one direction, decreases to

zero, then reverses itself and reaches maximum in the

opposite direction. The cycle is repeated continuously.

The number of such cyCles per second is the frElQJency

in hertz (HZ). The average value of voltage during any

cycle is zero.

AMBIENT AIR -generally speaking, the air surrounding

t/1e equipment.

AMBIENT TEMPERATURE-the temperature of tne air

surrounding tne eqUipment.

AMPUFIER-a device used to increase the magnitude at

a small input signal to proportions sufficient to perform

some desirable function. Also see FLAME SIGNAL

AMPUFtER.

AMPUFIER SATURATION-the point at whiCh an in￾creased input signal no longer increases the amplifier

output.

ANGSTROM UNIT (.&.) -a unil of measurement of a wave￾length of lilflt and other electromagnetic radiation,

eqJalto one len-thousandth (1/10,000) at a micron.

ANNUNCIATOR-a device which indicates an off￾standard or abnormal condition by visual and/or audi￾ble sig'lals.

ANTIFLOODING DEVICE-a primary control which

causes the fuel flow to be shul off LPQn a rise in fuel

level or receivingexC8SS fuel, and which operates

before the hazardous diSCharge of fuel can occur.

APERTURE DISC-a thin, flat, cIrcular plate of any mate￾rial with an ~nlng or hole (orifice) of predetermined

diameter to restrict the area viewed through it.

AOUADAG TUBE-an electron tlbe sensitive to ultravio￾let radial ion, used in the C7012 Purple Peeper Ultravio￾let Flame Detectors. When saturated with Ultraviolet

radiation. this tube delivers less than' microwallto the

flame $lg'lal amplifier.

ARC GAP PROTECTOR-a devIce which cord.Jcls at

high vollage levels 10 bypass an eleclronic network,

thus protecting tne network agaj~t damage from hlgl

voltage Int9lference ~ch as thai generatac:l by a sp<Irk

ignilion system).

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ARMATURE-the moving eJementln an electrClllleChani￾cal device, such as the movable iron core in a solenoid,

Ihe rotaling part of a generator or motor, the movable

pirt'ofa relay, or lhe spring-mounted, iron portion of a

bell or buner.

ARTIFICIAL FUELS-man-made fuels, Including all

manufactured and byiJroduct fuels.

ARTIST CAP - a fabricated hood, usually of sheetmelal,

placEld on tq:) of a stack to prevent downdrafts or erratic

draffs becauSe of the direcliOl'l8( wind effecls.

ASH - the noncombustible mailer that remains after a fuel

is burned.

ASPU?Al1NG BURNER-a burner in which the fuel in a

gasElCIU& or finely divided form is burned in suspension.

the air for combustion being su~lied by bringing into

contact With the fuel, air drawn thrClUQh one or more

openings by lhe lower stalic pressure created by the

velocity of the fuel stream. Also see VENTURI and

ZERO·GOVERNOR BURNER.

ASPIRATOR MIXER-a gas-air ptoportioning device thaI

causes the flow 01 cOmbuslion air to induce the proper

amount of gas inlo the airstream. It is used with low

pressure air and zero gas. Also called a Suction Type

Mixer. Also see ZERO·GOVERNOR BURNER.

ATMOSPHERE-the invisible mixture 01 gasas (air) sur￾rounding the earth: a unit of pressure defined 'as lhe

pressure of 760 millimelers 01 mercury at sea level and

at 0 C [32 Fl, which is equal to 14.6969 p::lUncts per

square inch (PSi), or 29.92' inchas of mercury.

ATMOSPHERJC BURNER-a gas burner relying on at￾mospheric pressure to bring in combustion air. It si~

permits Ihe air required for combustion to enter the

CO!T1:lustion 'Chamber, or It draws air into the combus￾lion chamber from the area surrounding the burner.

Two methods are used 10 draw air into the combustion

space.

Natural·Draft Burner the natural draft produced by

the product!> of combvstion moving L.p Ihrough

Ihe chimney, or staCK, draws air in atlhe bottom

of the burner.

InliQiratlng Burner the fuel gas Is allowed 10 es￾cape at high velocity into the throal of a venturi

tLbe, creating a lower static pressure which

draws In the air. Also called an Injection or Ven￾turi Mixing Burner.

A typical atmospheriC burner draws In pari Of the c:om￾bustion air by venturi action and the rast by a natural

draft.

ATMOSPHERIC PRESSURE-the prBSSUre exerled on

lhe earlh's surface by the weight of lhe air and moislure

above it; a unit of pressure equal 10 about 14.7 psi (see

ATMOSPHERE). Also called ~rometfrc Pressure.

ATMOSPHERIC REGULATOR see ZERO

GOVERNOR.

ATOMIZE-Io reduce a liquid into a multitude of liny drop￾1e1.9 or a fine spray.

ATOMIZER-a device which breaks liquid fuel into a fine

spray. It may require the assistancs of an atomizing

medium such as steam or air. Also sea MECHANICAL

ATOMIZER.

ATOMJZING AIR-the air su~IiBd 10 an air·atomizing oil

burll8r (usually about 10 percent) which IS used to

break the oil stream into tiny droplets. Ths atomizing air

is also later used 10r combustion.

ATOMiZING MEDIUM-a supplementary fluid, such as

sleam or air, which assists in breaKing oil into a finely

divided stale.

ATOMIZING OIL BURNER-an oil burner which delivers

fuel oil to the combustion ZOIl8 in the form 01 tiny drop￾leis. It uses some form at nozzle or ori1ice to spray the

oil into the combustion charrCer. An atomizing oil

burner is classified by the medium used to breaK up the

oil into fine particles.

Air-Atomizing Oil Burner compressed air.

Steam-Atomizing QII Burner-steam at pressuras

greater Ihan 25 pounds per square inch (psig).

MeC,l',anical-A\Omizinq Oil Burner no mBdium; the

oil is p....mped at hig'l pressures (50 to 300 psig)

through a suitabie burner nozzle orifice which

breaks il into a fine mist. Synonymous

with fressure-Atomizina Oil Burner. (Also

see PRESSURE-ATOMIZJNG GUN TYPE

BURNER.)

Air· and Steam-Atomizing Oil Burners can be further

classified by the location at which the atomization takas

place.

External·Mix Oil Burner-the high velocity air or

steam strikas lhe oil after it has left the nozzle.

Internal-Mix Oil Burner the high velocity air or

steam striKes jets of incoming oil in atomizing

cha/Ttler, and the oil is discharged from the noz￾zle in completely atomized 10rm.

AUTO-shan for automatic; lhe firing rate position (on a

programmer) lhat provides a period during Which lhe

firing fate motor is operating frem an external Control￾ler. Also see MODULATE.

AUTOMATIC-self·ragJlaling or self-acting; Capable of

responding to cMain predetermined Conditions.

AUTOMAl1CAl1.Y IGNITED BURNER - burner In which

fuel 10 the main burner is aulonalically turned on and

i~iled.

AUTOMATIC BURNER -a burner that stMs and stops

automalically.

AUTOMAl1C CONTROL-ij sy6Iem thai reacts to a

change or unbalance in one of its variables by adjusting

the other variables 10 restore the system to the desired

balance. For example, a 6y8Iem for control 01 air-fuel

ratio can be set up so lhat a change in the selling of the

combustion air valve results in a corresponding change

in the fueJ input.

AUTOMATIC CONTROL VALVE-an electrically oper￾ated valve which combines a valve l::lc.dy and a valve ac·

tuator or motor. A signal from some remote point can

.e(lergize the actuator or motor to qJen or close the

valve, or 10 proportion lhe rate of flow through the valve.

Also see CONSTANT·LEVEL, FIRING RATE, MODU￾LATING, MOTORIZED, and SAFETY SHUTOFF

VALVES.

AUTOMATIC IGNITION-a system in which a burner is ig￾nited direttly, without manual intervention, by an aulo­

.matically supervised ig1ltion spark or pilot.

AUTOMATIC SAFETY SHUTOFF VALVE-see SAFETY

SHUTOFF VALVE.

AUTOMATIC SYSTEM-a system which regJlates itself

, and requires no manual operations: a system in which

the burner is cycled completely automatically under

control of an automatic temperature or pressure

controller.

AUXIUARY POTENTIOMETER-a potentiometer

mounted in or on a modulating motor, which is used to

control an external device in response to movements of

the motor.

AVAILABLE HEAT-the quantlly of heat released in a

combustion chamber that is available for useful pur￾poses. II is the total quantity of heat released minus

both the dry flue gas loss and the moisture loss.

BAFFLE-a metal or refractory plate or wall used to de￾flect the flow of gases or liquids or to minimize the ef￾fects of flame, heal, or flue gases.

BAG ASSEMBLY - closely related parts grouped together

in a single packaQEl, purchased as 1 unit.

BALANCING RELAY -a relay with an armature pivoted

between 2 etectromagnelic coils. The armature con￾trols the position of the Wiper on a feEKDack potenti.

ometer In the electrical circuit. If the currents through

the 2 coils differ, the armature moves toward the coil

with the most current (strongest electrornagnetit

force). As the armature moves, the potentiometer wiper

changes the resistance in series with both coils unlil

the currents are equal. The armature stops when the

circuit is balanced. Besides the electromechanical type

just dBscribed, there is also a solid slate type which per·

forms tile same functions electronically. A balancing

relay is used in a Modutrol motor to position it. Also

called a "mouse trap. "

BAR CHART-a representalion of the ~raling se￾quence 01 a flame safeguard programming control us￾ing bars shaded to show the times when various

circuits are energiZed.

BAROMETER-an instrument used to measure atmos￾pheric pressure.

BAROMETRIC PRESSURE - see ATMOSPHERIC

PRESSURE.

BASE-the main s~rting frame or structure of an as￾sembly, excluding the legs.

BATCH TYPE FURNACE-a furnace thai Is shul down

periodically to remove lhe old charQEI and add a new

charQEl; as dlsllngulshed from a ContinUJUS Furnace.

BELLOWS-a metallic accordian-like box which can be

compressed mechanically or with fluid pressure Oike a

spring}, and which will return to its normal shape when

Ihe pressure is released.

BENT-TUBE BOILER-see WATER-TUBE BOiLER.

BlAST FURNACE GAS-a gas of low Btu content result￾ing from burnirg coke with a defiCiency 01 air in a blast

furnace.

BLEEDER-an intentional leak, usually used to rectJce

pressure in an impulse line.

BLEEDING-intentional leak3Qe (usually of gas). Leak·

age that mi'lt't occur during shutdown In a safety shut￾off valve "block-and-bleed- arrangement. Gas bleeds

off 10 the atmosphere through a normally qJen vent

valve. When the safely shutoff valve(s) is opened, the

venl or bleed valve closes and "bleecjing" slq:lS. Also

see DOUBLE-BLOCK-AND-BLEED.

BLOCK-AND·BlEED see DOUBLE-BLOCK·AND￾BLEED.

BLOWER -a fan used to deliver air under pressure to the

desired space. Also see BURNER MOTOR.

BODY RATING-see VALVE BODY RATING.

BOILER-a closed vessel in which a liquid is heated or va￾porized; used to s'-W1y hot waler or steam for heating,

processing, or power purposes. Also see CAST IRON

SECTIONAL, DRYBACK, FIREBOX, FIRE-lUBE,

HIGH PRESSURE, HIGH TEMPERATURE, LOW

PRESSURE, PACKAGED, SCOTCH, WATER·lUB~

and WETBACK BOiLERS.

BOiLER HORSEPOWER (BoHP)-the EQJivalent of the

heat rElQJired to evaporate 34.5 Ib [15.648 kC] of waler

per hour lrom a temperature of 212 F [100 Cl into dry,

saluraled steam al the same temperature. ~i\/a'enl

to 33,472 Bluh, 9.803 kilowalls, or 40 poundS of steam

per hour.

BONNET-see VALVE BONNET.

BOOSTER HEAlER-a heater used 10 raise the tempera·

ture of oil from thai tEQJired for pumping 10 thai re￾quired for atomization.

BOTTLED GAS-see UQUEFIED-PETROLEUM GAS.

BOURDON TIJBE-a lube thai responds 10 pressure

changes. The ILbe, with elliptical cross section, i6

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