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). 331 71·91558-1 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'of a 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 33J 71-97558-1 shaped into an arc or spiral witl"l 1 end attached to an irdcatlng, ret01ding, Of controlling deliice. A pressure wltl"lln the tlbe makes It less elliptical and more nearly circular, thus actuating Il"Ie attached device. BOX·HEADER BOILER-see WATER·TUBE BOILER. BRAKE-WINDING -the winding in an electric motor which floId9 lhe armature againsl a brake SilOE! to hold the lTDIor In Its open posllion after the mOior limit swllc;h opens;' When both the motor winding and the brake wtr1dir1g are energiZed. I,""" streng1h o1lhe motor wjnd- Ing O\Iercomes the brake Winding. BRANDi CIRCUIT -a secondary cJn;uillaading from the mainoil circulating Ic:q::> 10 a burner or gfOl.q:l ofbUmers. BREAKDOWN (VOLTAGE}-that volla~ et which an In- sulator or dielectric r~lures. BREECHING - a passageway to condJc\ flue gases from tne /umace or bOiler 10 Il"Ie chimney. Also caffed 1!l.Ii ~ Of vanl connector. BRIDGE CIRCUJT ~an eJectrical nalwol1c arranged so lhat the volta~ at a given poinl in the circuit lOan be z&- roed by adjusling the electrical paramelers (resistance. inciJctance, and capacitance) in the branchas until the currents balance. BRING·UP TlME-lhe time required to raise a cold fur· nace and its char~. if any, to operating temperature. BRITISH THERMAL UNIT (Btu)-tl"le quantity of heat ra- q.Jir9d 10 raise the temperature of t pound of water from' degree F. BTU (8tu)-sae BRJTISH THERMAL UNIT BTUI-! (BrUhl-one Btu per hour; 1 million Btuh is eq.;iva- lent to 7 gallons of oil per hour, 800 pounds of steam p&r ho.Jr, or a boiler inpul of 20 boiler horsepower (Be HPJ. BUCKET BRIGADE - a colloquial term, for the elec\(onic setf-checking Circuitry in the flame signal amplifier of scme flame sa1egUard controls. The term refers 10 lhe periodiC "dumping" (discharQlngj of one capacitor in the circuil info anolher. 11 this dumping steps, due to a failure in Ihe flame delection system. the control shuts d:lwn the burnElr. BUNKER ~C~ Otl-a term for heavy oil (No.6 fuel oil). S8IB HEAVY FUEL Oll_ BURNER-a device which introduces fuel and air into a furnace at lhe oasireo velocities. 11 'rt:x;lence, and can. centration to eslablish and mainlain proper ignition and combustion of the fust Also see ATMOSPHERIC. AT· OMIZING OIL, AUTOMATlCALL Y IGNITED. AUTO· MATIC, COMBINATION. INSHOT, LONG FLAME. MAIN, MANUALLY IGNITED, MULTI PORT. NOZZLE- MIXING, PARTJAL-PAEMIX, POWER, PREMIX. RAW GAS, ROTARY OIL, SEMIAUTOMATiC. UPSHOT, and WARMUP BURNERS. BURNER CONTROlLER-an aulomatlc lemperalure or pl"9SSU¥9 sensing device connected In the il'lpJl Circuit 01 a flame safeguard control. 1Ilndirectly acts to tum a bUrner on or off in order to maintain pressure, air tem- pe,ralUTe, waler temperalure, or liq.Jid level wJlhin the desired limits. BURNER HEAD-that end of a burner beyond the nozzle or portS. BURNER-INPUT CONTROL VALVE-see FIRING RATE VALVE. BURNER MOTOR- fhe motor which ctives the blOWer or fan thai delivers air at proper velocity into the corrt>us- tion chamber. BURNER REFRACTORY-see REFRACTORY, BURNING VELOCITY - see FLAME PROPAGATION RATE. BUSHING -a usually removable lining or sleeve of melal or other malerial lhal isc inserted or ecrewed into an q:Jening to Ifmillts size. resl81 wear or erosion, ser\fe as a guide, or protect wires from abrasion and lX'SSib!e shOrt circuit; an internally an:::J exlernally threaded plug fOi connecting a pipe or titling with another of different size. FO(exarnpls. lhepart at the C7015A Intrared(lead sulfide) Flame Detector which Includes the viewing window Of magnifying lens; it1ils over Ihe plug-in lead sulfide cell. ard Is held in place by the mounting collar. BUTANE: - a gaseous hydrocarbon fuel; a mixture of eas- ily liquefiable hydrocarbon gases, principally butane. Bulane is one 01 tne cCll1ll=Of'l8nts of raw natural gas. and is also derived from pe:roleum refini"lQ proces.se:s BUTTERFLY DAMPER-a single blade damper, pivoted abOut ils center; Ihe blade somewhat ~esembles Ihe opened wings of a bullerfly. BUTIERFLY VALVE-a throttling valva tor a pipe, con- sisting of a rotating hinged plate thaI somewhal resem- bles the opened wir1gS of a butterfly; ol1en used as a firint;;l rale valve. lhe Honeywell V51E Bullerfly Valve ~ excellent hi~'<Olume floYl characteristics, makinQ il useful for close mocIulation of the supply of air or fuel gases to lar~ furnaces. This type of ~alve cbes not cloSEl :ightly. so a separate safety shutoff valve musl be US&d wilh it for final closeoff. CAD cal-see CADMIUM SULFIDE CELL. CADMIUM SULfiDE CELL-a ph'>Io.condJclive devlea that responds 10 the visible light emilledby an oil flame. In the presence 01 ~isible lighl, the eleclrkal resistance o11ha cadmium sulfide {CdS) becomes very low and the cell conducts current The cad cell is used In flame detectors 10r Oil burner Systems. 334 CAGE VALVE-a single-seated valve containing a frame or box (cage) Inside which Ihe plug slides, cpening the ports. CALL FOR HEAT-when the controlled lemperature or pressure drops below the cperallng set p:linl, Ihe burner controller contacts make to iniliale burner cperation. CALQRIE-Ihe quanllty or heat required to raise the tern- . peralure o~ 1 gram of waler 1 degree C. CA~pLlNG. (CANDLEUGHTING}-the deterioration or the pilot to an unsatisfactory condition, characterized by a lazy, yellow 1lame; usually caused by a high ambi· ent temperature or an excessively large pilot burner orifice. CAflACInVE LOAD-a leading load; a load that is pre- oominantly capacitive, so that the alternating current leads the alternating voltage, I.e., the voltage doeS not change direction until afler the corresponding current does. CAPACITY INDEX (Cvl-the quantity or waler, in gallons per minute at 60 F, thatllows through a given valvewilh a pressure drop or , psi. The flow or a.ny fluid through the same valve can be calculated from the C v . Also ca.lled the Flow Coefficient. CASlNG-l) a. covering of sheets of metal or other mate- rial such as a 1ire resistanl comJXlSition l::::oard l.lSed 10 enclose all or a portion or a steam generating plant; 2) an enclosure torming the outside of a.n appliance, no parts 01 which are likely to be subjected 10 intense heat. CAST IRON SECTIONAL BOILER-a OOPer comJX)S9d or a. number of separale sections 1a.stened together, re- sulting in a large heal transfer area. It can be fired by an LPShot or :nshol gas burner, or by a pressure atomizing oil burner. Sizes range up to 4 million Btuh (about 80 BoHP). . , CELL - a single unit that produces voltage Of currEW11 by converting radiant energy into electrica.l energy. Also see CADMIUM SULFIDE and LEAD SULFIDE CELLS. CENTRAL FURNACE-a seI1-contained, indirect-fired furnace designed to supply heated air through ducts to spaces remole 1rom or adjacenllo the furnace location. CENTRAL HEATER-a stationary. indirect-fired, vented awliance in one of these classes: boilers, cenlral fur- naces, 1100r furnaces, recessed healers, and floor- mounted unit heaters connecled to a ducl system. CENTRIFUGAL ATOMIZING OIL BURNER - see ROTARY OiL BURNER. CHARACTERIZED GUIDE-a valve guide with notches or V's cui inlo il to determine the valve flow characteris· tic; also known as a skirted guide. CHARGE-a. load; the maximum or necessary QJNItity thaI a conla.iner or awaratus is buill to accommodate; e.g., fuel in a furnace. In electricity, the elsclricat energy stored in a capacilor or ba!tery or held on an insulated object. CHASSIS-a sheetmelal bOx, frame, or single plate on which the components of a device are mounted; the asserrbled frame and parts. CHATTER-see RELAY CHATTER. CHECKING RELAY -a relay iri the selt-checklng circuit or some flame safeguard controls which makes ard breaks periodically (~Checking~ or ~peCking· action) when the flame signal is strong enough. While check- ing, it trans1ers energy to hold in the 11ame relay. It slops MChecking M it the flame signal becomes too weak or disappears. CHIMNEY-a brick, metal, or concrete stack enclosing 1 or more 11ues for conveying 11ue gases to !he ouIside atmosphere. CHIMNEY CONNECTOR-the pipe which connects a fuel burning appliance to the chimney; a.lso called a smoke pipe. CIRCUIT-see ELECTRICAL CIRCUIT. CIRCULATING LOOP- themain loop in which oil is circu- lated from the storage tanks to 1M branch circuilsand then back to the storage tanks. CLOSED CIRCUIT OIL SYSTEM-a system in which oil may be pu~ completely through the circulating loop and back into the oil storage tank. CLOSED IMPELLER-see IMPELlER. CLOSE-OFF RATING -the maximum allowable pressure drop to which a valve may be subjected while fully closed. It is a function of the JXlWer available from the valve actuator for holding the valve closed, and is ll'k:ie- pendenl of the actual valve l:xxtf raling. COCK-a manually operaled faucet or valve tor shutting oft or throttling down the~ow or a li~id or gas. usua.11y by means of a tapered plug. Also see PETCOCK ard SUPERVISORY FUEL COCK. COMBINATlON BURNER-a burner by means of which more than 1 fuel can be burned. eilher separa.lety or si· multaneously. Also called a Mullifuel Burner. A C1.lil!:. Fuel Burner uses , prime fuel, but can switch to a stanchy 1ue1 under peak load conditions. A .Gas:Ol! ~ is capable of burning either gas or oil-some. types can burn OOlh at the same time. Ex~les of a Combination Burner: Pressure-Atomizing Oil/Gas Ring BuOl9f'. Horizontal Rotary Oil/Gas Ring Burner. Combination of 2 burners (under separate Sl.4l9r- vision) in 1 asserrbly. COMBUSTlBLE MATERIAL-material that will iglile and bum. k3 pertaining to materIals ad}acent to Of in con- tact with heal-prodJcing Wiances, chimney connec· tors, vent connectors, steam and hoi water pipes, m warm air wcts, II is material made or or surfacedwilh 335 71-97558-1 wood. COlTpfElSsacI paper, plant fibers, or other mate- rtalthat wlllignite and burn. Such material shall be con- sidaTEld as combustible even lhough flameproofed, fire-retardant treated, or plastered COMBUSTION-the act or process ofbutning; the rapid oxidation of fuel accompanied by the production at heat, or heat and light. Complete col'1'bustlon req.Jires an adequate suppl)l of oxygen. Also se& COM PI.ETE, INCOMPLETE, and PERFECT COMBUSTION. COMBUSTION AIR-the air r&q Jired tor clJl'l'lllele and sanSfactory combustion of the fuel; ooes nol inclUde the air used for atomization. Also called main air. The actual amounl of air supplied Is usually expressed as a percentage of the lheoretical amount required for can- p1ete combustion. , ,. COMBUSTION AIR SWITCH-se& AIRFLOW SWITCH. COMBUSTION CHAMBER-the panion of the heating or prcx:ess equipment where fuel is burned. Also called the~. COMBUSTION CONTROL-see FIRING RATE CONTROLLER. COMBUSTION CONTROL VALVE-5ElEl FIRING RATE VALVE. COMBUSTION DETECTOR-see FLAME DETECTOR. COMBUSTION PRODUCTS- mailer resulting from COITI- bUstion. such as flue Qi!S8S, water,vapor, and ash; but excluding excess air. COMBUSTION RATE-se& FIRING RATE. COMBUSTION SAFEGUARD-see FLAME SAFE- GUARD CONTROL COMMON-a terminal, connection. leadwire, circuit, or other part of an eleClricj;l1 networ'K which is shared by olher parts of tho networ'K. On a flame safeguard co~ trol, the terminal and leadwire which are in lhe circuit for all JXlSitions 01 the firing rate swllching circuit COMPlETE COMBUSTION-burning with stoichiometric P'C90rtions of air and fuel pllAi a rncderale excess of air 10 ensure Ihal all of the fuel is burned. COMPRESSED AIR-air al a pressure of 5 or more jX)Unds per SQ,Jare inch above atmospheriC pressure. COMPRESSED-AIR-ATOMIZING OIL BURNER-see ATOMIZING OIL BURNER. COMPRESSIBLE FLOW-flow of hiQh pressure gas or air which undergoes a pressure drop sufficient to resull in a siglificant reduction 01 its density. CONDENSATE-condensed water resulting from the removal of lalent heal from steam. CONDUCTION-the transfer of heat or transmission of electricity through a materia! (cal/eel a condUclor) by passing II from molecule to molecule. CONDUCTIVITY CiRCUIT -a flame proving circuit which operates on an ac flame aignal and utilizes the electri- cal corOJction of a flame, as d1sllnculsheci fran rectlfi- calion. Also 5ElEl CONDUCTIVITY FLAME ROD SYSTEM and FLAME CONDUCTIVITY. CONDUCTIVITY FLAME ROD SYSTEM-a flame roo deteclioo system based on the ability of the flame 10 conClucl a currant; conducts the same amount of cur- rent in eUher dlrectioo, as distinguished tram flame reeliflCatioo. CONDUIT -a tlbe or trOlJl;;flfor carrying and protecting electrical wires. CONSTANT-lEVEL VALVE-an automatic control valve for maintainIng, within a reservoir, a constant level of fuel for delivery 10 the bumer. CONSTANT PILOT -se& CONTINUOUS PILOT, CONTlNUOUS CHECK RELAY-see DYNAMIC SELF CHECK. CONTlNUOUS COMPONENT CHECK-5ElEl DYNAMIC SElF CHECK. CONTINUOUS FURNACE-a furnace ~rated on an un· intern pted cyCle, In which the charge iEi being con- stantly added to, moved thrOUgh, and removed from the furnaCe; as diSIlngulsheel from a Batch Type Fumace. CONTlNUOUS IGNlTlON-ignition by an energ,o source which is continuously maintaineelthroughout the time the burner is in service, whether the main burner is tiring or not. CONTINUOUS PILOT -a pilot that burns without turndown throughout the entire time the burner assem· bly is in service, whether lhe main butner is firing or not. The pilot ignites fuel which may leak into the corrbus· tion chamber whan the burner is off, thus prevenling a hazarcbus cordilioo at stanup. (~Gontinuous Pilol" is Underwriters laboratories Inc. term for the old term "Standing PlIot ) CONTROL-a device which dir&crJy operates a system to reg.Jlate the fuel, air, waler, or electrical Eiul=Ply to the controlled equipment. It may bEl automatic, semiauto- malic, or manual. Also see AUTOMATIC. FLAME SAFEGUARD, MODULATING, NONRECYClING, ON-QFF, OPERATING, PRIMARY, PROGRAMMING. RECYClING, AND SAFETY CONTROLS. CONTROL AGENT -the meellum which is manipulated by the control syslem 10 cause a change in the con- trolled medium. For ellample, suppose a heating coil thrClllgh which steam is flowing Is used to heat a room. The rcom thermostat is placeel so that it measures tem- perature (conl(olleel variable) in the room air (conlrolleel medium), and operates a valve which regulates Ihe flow jmanipulateel variable} of the steam (control agent) thrOlJl;;fl the heating coil. Heal from the coHls thus fur- nished to the room air. CONTROL POINT -the value 0: the controlled variable which the controller operates to maintain. Also see SET POINT. CONTROL SYSTEM-the entire system, including the controlled system And the automatic conlrol eq.Jip- ment. see CONTROLLED SYSTEM. CONTROL VALVE-see AUTOMATlC CONTROL VALVE. CONTROL lONE- the section of a furnace In which tem- perature'is controlled by the throllling action of a single valve. Also see VALVE ZONE. CONTROLLED MEDIUM-the substance (usually aIr, water, or steam) whose characteristics (such as lem- I perature, pressure, flaw rate, volume, level, or concen· tration) are being controlled. CONTROLLED SPACE- the volume of the controlled me- dium. For example, a room in which the air temperature is being cootrolled. CONTROLLED SYSTEM-the system made up of all equipment In which the controlled variable exists, but which does not include the automatic control eqUipment. CONTROLLED VARIABLE~that quantity or condition of a controlled medium which is measured and controlled. For example, temperature, pressure. flow rate, vol- ume, level, or concentration. CONTROLLER-a device which senses and measures changes in the controlled variable and indireCtly acts to maintain the controlled variable within preset limits. It direCtly affects the operation of a flame safeguard con- trol. Also S99 LIMIT; and BURNER, FIRING RATE, MODULATING, PRESSURE, PROPORTIONING, SAFET'(, !lind VACUUM CONTROLLERS. CONVECTION-transfer of heat by moving masses of mailer. Convection currents are set l4> in a fluid by me- chanical agitation or because of differences in elensity al different temperatures. CRACKING-the process of breaking c:bwn hydrocar- bons by heat and pressure into simpler compounds or elements: e.g., the breaking down of petroleum Into gasoiine. CRITICAL PRESSURE DROP-see PRESSURE DROP. CROSS'CONNECTED-two pipes or systems of flow connected to each other, usually to proviele an equali. zation or interplay of pressures. CROSS·DRUM BOILER-see WATER-TUBE BOILER. CRUDE OlL-unrefined oil in its natural stale as it comes tram the ground. Also called petrgleum or !<II.!Q!i. CURTAIN TYPE DAMPER-a damper composed of flex- ible material, which moves in a venical plane as it is rolled. 337 CUTOFF - immediate shutdown of a system atter loss of the main burner flame, wilh no attempt to recyCle or to relight the burner. Cv-see CAPACITY INDEX. DAMPER -a elevice for introducing a variable resistance for regulating {he volumetrIc flow of gas or air. Also sea BUTTERFLY, CURTAIN, FLAP, LOUVER, andSLJDE TYPE DAMPERS: and OPPOSED and PARALLEL BLADE DAMPERS. DAMPER MOTOR-see FIRING RATE MOTOA. DEAD END LJNElSYSTEM-the end of a pipe line which does not lead back 10 an oil Slorage tank, so the oil in that end of the line cannot be recirculated. A system which does not contain a return line 10 an all storage lank, so the oil cannot be recirculated in a closed circuit. DEFICIENCY OF AIR -a supply of air which is inadequate lor complete combustion of a fuel. (This is [he same as an excess of fuel.) Also see FUEL RICH. DELAYED MIXING-a process in which the fuet and air leave Ihe burner nozzle unmixed and, thereafter, mix relatively slowly, largely through diffusion. This results in a long, luminous 1lame. called a diffusion flame, long Ilame, luminous flame, or yellow 11ame. Also see LONG FLAME BURNER. DETECTOR -a elevice that produces an electrical OOlput that Is a measure of the radiation incielent on the device. Also see FLAME DETECTOR, SMOKE DETECTOR, and SENSOR. DEVIATlON-the difference between the sel point and the value of the controlled variable at any inslant. DIAPHRAGM VALVE-a SOlenoid-operated. gas valve in which a membrane or partilion separates lhe inlat and outlet. When the solenoid is d&-energlzed, the main gas supply applies pressure to the top oflhe dlaphragn 10 help hold the valve closed. When the solenoid is an· ergized, a plunger opens a bleed pon in the I~ side of Ihe valve. As the gas bleeds off the I~ of lhe dia- phragm, main gas pressure on lhe underside of the dia· phragm cpens the valve. Honeywell V4B and V88 Diaphragm Valves are generalty used on atrra;pheric type gas burners tor srTlOClth lightoff. Thej fealure vari- able, slow q::lefling times and fast closing 1IrTeS. Also see SOLENOID. DIFFERENTlAL-the sroallesl range through which the controller variable must pass in oreler to move the final control element 'rom one 10 the other of il~ 2 possible positions, such as from ON 10 OFF. DIFFUSION FLAME BU RNER -see LONG FLAME BURNER. 71·97558-1 DIRECT CURRENT (de) -an essentially ccnstanl-value curr&/\! lhat flows In ally one direction. DIRECT·FIRED HEATER -a heater In whie" thepnxiJclS 01 e6iTb.istlon (l'lue gases) are Inlerm1xec:l with the medium being "eatec:l (e.g., ail1. Also see DIRECT- FIRED EXTERNAL and DIRECT-FIRED INTERNAL HEATERS. DIRECT·~IRED EXTERNAL HEATER-any oven healing SyStEll!" in whiCh 'he products of cootlusUon frem the burnel'\,l!\rs discharged into the oven chamber by a cir· culating fan or blower, and in which the bul'119r'S are in a cOlTbJstion chamber ellectively separalec:l frem Ihe oven chamber. ll"Jere are 2 types: 1. Nonreclrculating-prodJCIS of combusllon are ''discharged into the oven cl'\arrt)er and are nat returned to the combustion charrtler. 2. ReCirculating - oven chamber atmosphere is recirculated to the combustion chamber and Is In conlact wit" the burner flame. DIRECT-FIRED INTERNAL HEATER-any oven healilll;l system in which Ihe burners are within the oven cham ber, and the products of combustion are in contact with the oven atmosphere. DIRECT SPARK IGNIllON~use of an Ignition spal1l. generated by a high voltage transformer, 10 lir,tll lhe main burner; aw1ies 10 burners not using a pilot, usually small oil burners. Also see PROVED SPARK iGNITION. DISCONNECT SWITCH - see MASTER SWITCH. DISSOCIATION-the process by which a chemical com· pound breaks c:bwn inlo sil"llJler cCllTPJl1enl.6. For ex· al"llJle. breaking up CombUSliQi"l products into cOl'Tbustibles and oxygen, aCCot'T'flanied by an absorp- tion of heal. Thi.6 ·usually occurs at high tefTC)9ralures, and Ills one of the factors limiting the maximum tem- peralure ot a flame. DJS11UATE OIL-light fraction of oil separated frem cru& oil by fractional distillation. DIVER11NG VALVE-a three-way valve with linlel and 2 oullels. A fluid entering the Inlel por1 Is diverted to either of the 2 outlet ports in any prq:lOrtion desirec:l by moving Ihe valve stem. A diverting valve is doLble- seeted with a aisc tor each seat, so It can generally be used in mixing ~lications also. DOUBLE-BLOCK·AND·BLEED-a valve arrangement In which a normally open vent valve just c:bwnstream from an automatic safety Shutoff valve (SSOV) allows any gas that leaks past the SSOV during shutc:bwn to es- cape to the outside atmosphere. A second SSOV lust c:bwnsUearn from the vent valve blocks any gas which is not ventec:l. When the $SOV's are open, the vent valve is closed. Also see BLEEDING. DOUBLE-SEATED VALVE-a valve with 2 seats and discs arranged so thai in Ihe closed posilion there is very Uttle fluid pressure forCing the stem toward the open or closed position; rEQJlres less power to operate than a single-sealed valve the same size; ofIen has a larger port area tor a given pipe size; cbes not have tir,tlt shuloff. (Do not contuse lhis valve with the type 01 valve with a second seal used in a valve-closed inlerlock.) DOWNFLOW FURNACE-a forcB(j.air, central furnace with essenlially vertical airflow, whjch discharges air at or near lhebotlom at the furnace; es distingUished 'rom an uptJow Furnace. DRAFT-the difference between atmospheric pressure and some lower pl9SSUre existing in the furnace or gas passages of steam generating unll; also, the move- ment of air Into anc:I thro~ a corrtluslion charrber, breeching, stack:, anc:I chimney. Drall may be natural, resulting frem the difference in denslly of the heated air rising through the stack and the cooler displacing air. Artificial drall may be prOVided by mechanical means, Drall is affected by chimney height and cross section, wind, makeup air c:penlng in the boiler room. and wealher conditions (barornelfic reading). Also see FORCED, INDUCED, MECHANICAL. NATURAL, and OVER-FIRE DRAFT. DRAFT LOSS-the reduction of drall intensity caused by resistance to flow of flue gases through the boiler, breaching and chimney, plus any resistance to flow of air through the burner. DRAFT REGULATOA-a device which acts to mainlain a desired draft by automatically controlling the chimney drall in:erLSily at the desired value. DRYBACK BOILER-a Scotch, fire-tube ooiler with a ce- ramic baffle al the back of the furnace to direct the products of cornb Islion from the combustion chamber to the second pass. ll"Je ballle is separate from the pressure vsssel and 'IS constrUCled of heal·resistant malerial (generally refractory brick and insulation). Also see FIRE-TUBE and SCOTCH BOILERS. DRY CONTACTS-contacts isolated from any source 01 power. DUAL·FUEL BURNER-a burner using 1 prime fuel, but. capable of using a slancbl fuel under peak load cond!- lions. Changeover from one fuel 10 the other can be made aUlomatically usIng an electriC temperature controlle! or by use of a manual switch. Also see COMBINATION BURNER. DUCT -a passage for air or gas flow; a protective pipe through which wires or cables are run. DUCT FURNACE-a central furnace designed lor instal· lation in a duct 01 an air dislribution system to supply warm air for healing. For air circulation, II depends on a blower not furnished as part of the furnace. DYNAMIC AMPU-CHECK-HonB'jYfelitrademerk:; a fea- ture in some Infrared flame sil;1l81 amplifiers; circuitry tests only the flame signal amplifier during burner 338 operation and shuts down the burner if lhe amplifier fails (including a flame-simulating failure). DYNAMIC SELF CHECK- Honeywell trademark; a fea- .·ture in the rectification type llame signal amplifiers or some flame safeguard controls: circuitry tests all elec- tronic components in the flame detection system (am- plifier and detector) 60 to 240 times a minute during burner operatior) and shuts down the burner if the '.detection system faits (including a flame-simulating failure). EA~,LY SPARK TERMINATlON-a feature of some pro- gramming controls which allows ignition cutoff be10re the main fuel valve(s) opens, resulting in a periOd dur- ing which onlv the pilot is on. ELECTRICAL CIRCUIT -an electrical path between 2 or more points; the interconnection of a number of de- vices in 1 or more closed paths to pertorm a desired electrical or electronic tunction. Also see OYNAMIC AMPLI·CHECK and OYNAMIC SELF CHECK; and ALARM, BRIDGE, CONDUCTIVITY, FIRING RATE SWITCHING, FUP-FLOP, HIGH-VOLTAGE, ISO- LATED LIMITED SECONDARY, LINE-VOLTAGE, LOW-VOLTAGE, OPEN, SHORT, SOUD STATE, and TUNED CIRCUITS. ELECTRIC IGNITION-ignition or a pilot or main burner bV an electric spark generated by a transformer, which is eilher automaticallV or manuallv energized. Also see DIRECT SPARK IGNITION. ELECTRODE-;-a conductor by means of which a current passes into or 001 of a,gas; often one terminal of a lead. Examples: ignition electrcxles, ftame rods, electron tube elements. ELECTROMAGNETIC SPECTRUM-a chart or graph showing the relationship between all known eleclro- magnetic waveforms classified by wavelengths. ELECTROMAGNETIC WAVE-the radiant energy pro- duced by oscillation of an electric Charge. lncluc\edare radio waves; infrared. visible, and ultraviolet light waves: and X-, gamma, and cosmic rays. ELECTRONIC-of or pertaining to devices, circuits, or systems utilizing the motion or emission of cur- rents 01 free electrons, especiallv in vacuum, gas, or phototubes, and special conductors or semiconduclors. EQUAL PERCENTAGE CHARACTERISTlC-a valve flow characteristic which causes like movements of the valve stem at any point of the now range to change ex- Isting flow an equal percenlage. regardless of the exist- ing flow quantity. EXCESS AIR-air which passes through the combLstion chamber and flues in aQjiUon to the quantity which is theoreticallv required for complete corrtlustion, to enSlJre that all of the tuel is burned. EXHAUST FAN-a fan which provides a SlJcUon to re- move the air, gases, and producls of combustion from the turnace or oven. In some systems, it also brings in combustion air. Also called a ventilator. EXPANDING PILOT -a pilot that burns throug,out the entire lime the burner assemblV is in service whether the main burner is firing or not Up:lI'I a call for heat, !he pilol flame is automaticaliV Increased in size so as to reliably Ignite the main burner. This pilot may be turned down automaticaliV at the end of the main burner 1lame-ilstablishing periOd. EX PLOSION - combustion occurring within a confined environment at such a rapid rale as to cause detona- tlon, called a Fireside Explosion. Also the rupturing of a vessel due tothebuildup otprassure of water or steam, called a Waterside Explosion. EXPLOSIVE MIXTURE-a flammable mixture in a con- fined space. EXTERNAL HEATER~a heater in which the burners and combustion chamber are effectivelv separated lrom the oven chamber or the medium being heated. Also see DIRECT-FIRED EXTERNAL and INDIRECT- FIRED EXTERNAL HEATERS. EXTERNAL-MIX OIL BURNER-see ATOMIZING OIL BURNER. FAN -any device or machine used to set up a current of air. Also see BLOWER and BURNER MOTOR; and EXHAUST, FORCED-DRAFT, and INDUCED- DRAFT FANS. FANMIX BURNER-a mechanical-oraft burner which uses the energy of high-pressure gas (10 to 50 psi) to Completely premix the air and gas. Gas is permitted to escape IhrClll'j"l a row of small orifices on the ecV3 of prq:>eller-Hke blades mounted on a ffee-spinning shaft. Reaction of the escaping gas rotales the blades, which are mechanically CQl4)led 10 a fan that draws in the primary air. The speed of the fan varies with the gas pressure, theretJy automatically adjusting the air volume [0 maintain optimum corrt:lUstion. Also see MECHANICAL-DRAFT and PRE-MIX BURNERS. FAN MIXER-an air blower in which gas is ad"nitled to lhe inlet to be mixed with air. FEEDBACK POTENTIOMETER-the potentiometer In a mcdJlaling motor which forms part of a briOole circuit along with lhe controller potentiometer and balancing relaV in the molor. When lhe Wiper on the controller po- tenllcmeler l'T'lOVeS dJe 10 a change In the controlled 339 71-97558-1 variable, the motor runs and drives the wiper on the feecback polen(fomeler in the proper direction to rebalance the bridge circuit. When the circuit Is bal- anc9d ~ElI motor stops. FIELD WIRING-wiring thaI musl be done althe Installa· lion site (in aetjilion to 1actory wiring) in order to com plete an Installation. FILTER a device to remove solid malerial from a fluid ~i~)d Of" gas). In~electronics, a saleclive network or resistors Il"d.Jctors, or capacitors which otters COOl- paratively 1i1lle q::positlon 10 certain fr9QUBl1cies or (0 direct current, while blocking or anenuating other trEQJencies. FIREBOX-see COMBUSTION CHAMBER. ,. FIREBOX BOILER-a horizontal, fire-lube boiler with a small, internal corrt>usllon chamber of cubical dasi'OJ'l. TIle short, first-pass bank of lubeS Is COr"ll"l9cted be- tween the rear of the combustioo chamber and lhe rear of lhe OOiler. The remaining banks of tubes extend the full length of the ooiler, above the combustion chamber and the first-pass bank. The combustion chamber may be steel, refractory. or waler-cooled refractory. AlSO see FIRE·TUBE, MULTIPASS. and WATER-LEG BOILERS. FIRE POINT -the minimum temperature at which a flame is suslained for at least 5 secondS. FIRESIDE EXPLOSION-see EXPLOSION. FIRE-ruBE BOILER-a boiler in which the prCXi.Jcls 01 combustion pass through slraighttubes surrounded by water and steam. The tubeS may run horizontally or vertically. The HOlizonlal-Return-TuOO (HRn type has a horl· zonlal shel: conlarning the tubes. The prooucls of com- bustion pass from Ihe external combusllon chamber underneath the bottom of the she:1 to the end of the boller, and relurn thrOl.:gh the tubes. If the prOducts 01 cQfTClustion are paSSEd Ihrough the shell more than once,. it Is called a Mullipass Boller. l1le Y w1!£.Il! type has a vertical, cylindrical shell Cln" talnlng the lubes. Thfl prodJcts of combustion pass from the irternal cO/T'tlusUon charroer below the shell, l.p IhrOLV'i the lI.bes. In a Submerged VertIcal type. lhe water level exlends h;gher than the tcp endS of the lubes. Also sea FIREBOX, MULTIPASS, and SCOTCH BOILERS. FIRING RATE-corrbuSlion rate; the rate e! which fuel. or an air-fuel mixture is supplied 10 a burner or furnace, expressed in volume. weight, or heat units ~1ied per unit lime. Also see HIGH FIRE, LOW FIRE. and MODULAllNG FIRE. FIRING RATE CONTROLLER-a centrallar which p;::lSi- lions lhe firIng rate motor 10 automalically regUlate the burner firing rate al a predetermined air-fuel ralio in ac- cordance with load demand, II ma'1 p;::lSllion the air and fuel SUWI;8S for low fire or for high fire, or it may be a proportioning (mooulaling)lype which grao."al'lY varies the eir and tuel supplied wlchln limits to meet (he lOad demand, Also see FIRING RATE MOTOR. FIRING RATE MOTOR-a modulating or a two-posilion (q::.en·closed) malar WhiCh p:::lSitions the tiring rale valve anOior Ihe damper in response to the firing rale controller, FIRING RATE SWITCHING CIRCUIT -a circUit In a pro- grammin\jl conlrol which switches external devices at predetermined limes 10 conlrol the firing rale 01 lhe bJrner. FIRING RATE VALVE-an automaUc control valve for reg.rlating the input of fuel to a burner in response 10 load demand. Also called a Burner-Input Control yalve, Combustion Control Valve, Meterino Valve or Jh!Ql- \Iino Valve. Also see BUTTERFLY, MODULATING, and MOTORIZEO VALVES. FIRST-OUT INDICATION-a device (usually a lamp) for each bur'ler in a mulliburner system. The device Indi- cates the first burner having flame failure. FIRST·STAGE OIL VALVE-in oil burners wiln more lhar1 1 firing rate level (stage), the automatic safely shutoff valve which opens firslto admit the 1uel required for the lowest rale of corrtJostion. In direct spark ignition sys- 'tams, the first stage may take the place of a gas pilot. FLAME-the visible or other physical evidence of Ihe cnemical procsss 01' rapidly convening fuel end air into products 01 combustion. FLAME BlOW-OFF-the phenomenon which occurs when a llame moves awa:f from a burner, often result· ing in the flame being exlinguiStlEla. A flame blows off when lhe air-fuel mix:ure leaveslhe burner af a velOCity greater than Ihe velocity wilh which the flame front pro- \jIress8S lhrough the mixture. FLAME CONDUCTIVITY -the abilit'1 01 the ionized gases of a flame 10 conduct an electriC current. FlAME CURRENT -sea FLAME SIGNAL FLAME DETECTION SYSTEM-Ihe flame detector, flame signal ampliflS", and flame relay (In a flame safe- QJard control) which logether delermine whether a sut- ficientflame is present 10 continue Ihe q::.erallon Of a burner. FlAME DETECTOR-the components of a fla:ne detec- tion system which delect the presence or absence 01 a fJame. Also see DETECTOR and FLAME ROO; and INFRARED. OPTICAL, RECTIFICATION TYPE. RECTlFYING PHOTOCELL. and ULTRAViOLET FLAME DETECTORS. FLAME DETECTOR RELAY-a control consisting of a flame detection electronic network and a switching re- lay which pulls in when flame is detected. This control 340 [...]... RATE FLAME VELOCiTY -see FLAME PROPAGATION RATE BURNER FLAMMABLE LIMITS-the maximum and minimum per­ centages of fuel in an air-fuel mixture that 'l'¥iU burn FLAME RELAY-the relay in a flame safeguard control which pulls in when a flame or a condition simulalinga flame, is detected It drops out on loss ot flame signal causing Ihe flame safeguard control to shut down the burner Do not confuse it with FLAME. .. system 'l'¥hich increases the lIame signal 10 a mag­ nitLJje SUfficient to pull in the flame reray In the flame saleguard control TIle amplifier may be a permanent part at the flame safeguard contrOl, or It may be a replaceable, plug-in unit FLAME FRONT-the plane along which combustion starts or the base of the flame FLAME PROPAGATION RATE-the rate at which a flame fronltravels through a corrbustible... burning velocity, flame SPeed and flame velocity FLAME SIMULATOR -a device used 10 substitute tot the presence 01 flame in a flame detection circuit II is used during trOUbleshooting, to check the performance of the flame delection system Flame simulators are avail· able for use wilh rectification or ultraviolet amplifiers In infrared systems, the flame Signal can be simulaled wllh a 'l'¥ire FLAME RECTIFICATION-the...I.> . ASSEMBLY_ FLAME RELAY-the relay in a flame safeguard control which pulls in when a flame. or a condition simulalinga flame, is detected. It drops out on loss ot flame signal. causing Ihe flame. mixture. FLAME CONDUCTIVITY -the abilit'1 01 the ionized gases of a flame 10 conduct an electriC current. FlAME CURRENT -sea FLAME SIGNAL FLAME DETECTION SYSTEM-Ihe flame detector,. function as an electrode in a flame detection circuil. Also see CONDUCTIVITY FLAME ROD SYSTEM and RECTIPfING FLAME ROD. FLAME SAFEGUARD CONTROL- a safely control which provideS a means