Sylvania Engineering Bulletin - Incandescent Lamps 1988

8/3/2019 Sylvania Engineering Bulletin - Incandescent Lamps 1988

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EngineeringB u lle tin 0 -3240888

Incandescent LampsIs su ed fro m G TE P ro du cts C orp ora tio n, S ylv an ia L ig htin g C en te r, D an ve rs , M as sa ch us etts


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BULBSoft glass is generally used. Hardglass is used for some lamps towithstand higher bulb tempera-tures and for added protectionagainst bulb breakage due tomoisture. Bulbs are made invarious shapes and finishes.

FILAMENTThe filament material g.enerallyused istungsten. The filament maybe a straight wire, a coil or acoiled-coil.

LEAD-IN WIRESMade of cop per from base to stempress and nickel-plated copper ornickel from stern press to filament;carry the current to and from thefilament.

TIE WIRESMolybdenum wires support lead-in wires.

STEM PRESSThe lead-in wires inthe glass havean air-tight seal here and are madeof a combination of a nickel-ironalloy core and a copper sleeve(Dumet wire) to assure about thesame coefficient of expansion asthe glass.

EXHAUST TUBEAir is exhausted through this tubeduring manufacture and inertgases introduced intothe bulb. Thetube, which originally projectsbeyond the bulb, isthen sealed of fshort enough to be capped by thebase.

GASUsually a mixture of nitrogen andargon is used in most lamps 40watts and over to retard evapora-tion of the filament.

Figure 1. Typical Incandescent Lamp

SUPPORT WIRESMolybdenum wires support thefilament when needed.

BUTTONGlass is heated during manu-facture and support and tie wiresplaced in it.

BUTTON RODGlass rod or tubing supportsbutton.

HEAT DEFLECTORUsed in higher wattage generalservice lamps and other typeswhen needed, to reduce circula-tion of hot gases into neck of bulb.

FUSEProtects the lamp and circuit byblowing if the filament arcs.

BASETypical screw base isshown. Madeof brass or aluminum. One lead-inwire is soldered to the center con-tact and the other soldered orweld-ed to the upper rim of the baseshell.


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INCANDESCENT LAMPSThe incandescent lamp consists of a wire filament on asuitable mount enclosed in a glass bulb containinq a gasor vacuum. When the lamp is connected to an electricalcircuit, the electric current passing through the filament wiremust overcome its resistance, and the power consumedheats the filament to incandescence (causes it to glow)Edison's first successful lamp, which had a carbon filament,operated at an efficacy of only 1,4 lumens per watt, Theefficacy was gradually improved through new filamentmaterials and designs and reached 10 lumens per watt in1911 when drawn tungsten wire filament was first used. Theintroductio n 01 gas-filled lamps in 1913improved this to 14lumens per watt, and developments since then haveresulted in efficacies as higohas 23 lumens per watt in thelarger commercial types of incandescent lamps today. Alew special purpose lamps, particularly designed for pro-jecnon service, have efficacies up to 33 lumens per watt,with photographic lamps reaching 36 lumens per watl.Figwe 1depicts a typical incandescent lamp and itscom-ponent parts.

FILAMENTSEdison experimented with hundreds 01materials to find thebest filament for his firstsuccessful lamp and finally selectedcarbon, which hasthe highesl melting 1 point ofany knownelement (6422F), Although carbon served as the only

"Carbon does not actually melt but goes directly from thesolid to the gaseous state.

2U L T R AV I O L E T

filament material for many years, itwas not entirely satisfactory since it could not be operated at high enoughtemperatures to obtain a desirable efficacy without rapidevaporation which greatly shortened lamp life. Itwas partly replaced by osmium and tantalum for a while and almosuniversally replaced by tungsten when a method of drawing tunsten wire was perfected.Tunsten wire has great strength and is very durable, buthe basic reason for lts selection as the best filament materiais the fact that itcan be burned very near its melling poin(6120 O F ) without evaporating rapidly As the operatingtemperatu re ofthe filament-inc reases, the light output andefficacy become greater, as shown in Table I. Thecretical-Iy,tungsten should yield an efficacy of 52 lumens per watatthe melting point, but the practical limitis about 36 lumenper watt because of losses within the lamp, To reach thiefficacy the life of the lamp is shortened to only eight oten hours, as in the case of photollood lamps.

SPECTRAL ENERGY DISTRIBUTIONAn incandescent lamp radiates only a small percentageof the tolal energy from the filament in the visible regionThe biggest portion of the energy is infrared, with a versmall portion in the ultraviolet region.Figure 2 shows the spectral energy distribution ofa tungstenfilament lamp operated at 3000oK, As the temperature oa tungsten fil:ament is raised, the radiation in the visibleregion increases more rapidly than that in the infraredregion, and thus the luminous efficacy increases,

R A D IA N T E N E R G Y F R O M T U N G S T E N3000,K

I N F R A R E D R E G IO N

o~~~--~------~~a 500 1000 1500 2000 2500W.AVElENGTH NANOMETERS

Figure 2. Spectral Energy Oislributionfor 1000 Watt Lamp With Approximate Color Temperature of 30000K


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TABLE IFILAMENT TEMPERATURES AND EFFICACIES OF

120 VOLT INCANDESCENT LAMPSApprox. Approx. Approx. EfficacyLamp Bulb Hot Res. Filament Color Temp. Initial LumensWatts Size in Ohms Temp. of. Filament Kelvin Lumens per Watt

6 * 8 - 1 4 2 4 0 0 3 8 6 0 C - 9 2 3 7 0 4 0 6 . 51 0 ' 8 - 1 4 1 4 4 0 3 9 0 0 C - 9 2 4 5 0 8 6 8 . 02 5 * A - 1 7 5 7 6 4 1 9 0 C - 9 2 5 5 0 2 3 5 9.44 0 A - i 7 3 6 0 4 4 7 0 C C - 8 2 7 7 0 4 6 0 1 1 , 5 .6 0 A - 1 7 2 4 0 4 5 3 0 C C - 8 2 8 0 0 8 9 0 1 4 . 8 .

1 0 0 A 1 7 1 4 4 4 6 7 0 ccs 2 8 7 0 ' 1 7 5 0 1 7 . 41 5 0 A - 2 1 9 6 4 7 1 0 C C S 2 9 0 0 2 8 5 0 1 9 . 22 0 0 A 2 3 7 2 4 7 6 0 C C - S 2 9 3 0 3 9 4 0 1 9 . 73 0 0 P S - 3 0 4 8 4 8 3 0 C - 9 2 9 4 0 6 0 0 0 2 0 . 05 0 0 P S - 3 5 2 9 4 8 4 0 C C - 8 2 9 6 0 1 0 6 0 0 2 1 , 0

1 0 0 0 P S - 5 2 1 4 4 9 8 0 GG-8 3 0 3 0 2 3 1 0 0 2 3 . 11 5 0 0 P S - 5 2 1 0 5 0 1 0 C - 7 A 3 0 7 0 3 3 6 2 0 22.4

"vacuum

Not only isthe color temperature higher for lamps of greaterefficacy, but for any particular lamp the color temperature

3100

Z 3000s-'u . . o~Vl. . . . .w0::o 2900. . . . .0z. . . . .0::::JI-0{ 2800O!. . . . .a. .~wI-0::0-'0 2700u

2600

/_/V//

/_//V

/V/V

/V/

increases with line voltage. This is shown in Figure 3 fora 2 0 0 watt A - 2 3 lamp.

90 95 100 105 11 0 115 120 125 130LINE VOLTS

Figure 4. Coiled Coli Filament

Figure 3. Change of Color Temperature with L.ine Voltage for 200 Watt, A23, 120 Volt Lamp

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GAS-FILLED AND VACUUM LAMPSItwill be noted from Table 1that lamps smaller than 40wattsare general.ly vacuum type. All others listed are gas-filledlamps. Previous to the introduction of gas-filled lamps in1913all lamp filaments were operated in bulbs containinga vacuum to prevent the filament from combining withoxygen and "burning up." Gas is placed inside the bulbto introduce a pressure which reduces filament evapora-tion and permits higher filament temperature. The first gasused was nitrogen, but modern lamps use a mixture ofargon and nitrogen in varying amounts depending on thewattage. These are inert gasses which do not combinechemically with tungsten. They are usually introduced intothe buIb at about 80 percent of atmospheric pressure whichrises to approximately atmospheric pressure when the lampis operated at normal voltage. However, projection andquartz lamps use a fill gas pressure greater than at-mospheric. Gas-Iilied lamps are desig nated asClass C andvacuum lamps as Class B. The Large Lamp Catalog in-dicates the class of each lamp.Krypton is a relatively rare and expensive gas which con-ducts heat from the filament more slowly than either argonor nitrogen. Krypton would be broadly used except for costsince it is a heavier gas than argon with similar generalcharacteristics. Currently krypton is used in a full line ofenergy-saving general service, extended service and traf-fic signal lamps. Additional special types of lamps that usekrypton gas to advantage are descri bed on page 15ofthisbulletin.

FILAMENT DESIGNFilaments are made in various forms for different uses asshown in Figure 5 (next page) and their descriptions inTableIII. The designations are a letter to indicate the wire con-struction and an arbitrary numeral to identify the filamentform. The wire may be either a straight wire (8), a coil (C),or a coiled-coil (CC). Thus a C-9 filament is a coiled wireof Form 9.Itis possible to design an incandescent lamp filament thatwill burn almost forever, but only by greatly reducingefficacy. The length, diameter and form of a filament aredetermined by considerations of application, lamp watts,volts and lifedesired, with the objective to design a sourcethat produces light most economically for the serviceintended. The straight wire filament, formerly used in alllamps, requires many supports due to its long length andis employed in very few lamps today. Coiling the filamentreduces heat losses and increases the efficacy. The coiled-coil construction isformed by again coiling the original coil-ed filament as shown in Figure 4.This double coiling resultsina still higher concentration of heat which results in abouta 10 percent increase in efficacy for the 60 watt lamp. TableII below liststhe uncoiled and coiled filament wire lengthsfor a few standard lamps.

TABLE IIINCANDESCENT LAMP FILAMENT DIMENSIONS

Uncoiled Coiled FilamentFilament Filament WireLamp Bulb Length Length DiameterWatts Size Volts Filament Inches Inches Inches25 A-19 120 C-9 26.3 2.1 .001240 A-17 120 CC-8 19.0 0.9' .001460 A-17 120 CC-8 20.5 1.1* .0018

100 A-23 30 C-9 7 .7 1.1 .0060100 A-17 120 CC-8 21.7 1.1* .0025100 A-21 230 C-9 35.7 2.0 .0016150 A-21 120 CC-8 25.8 1.3 .0033200 A-23 120 CC-8 27.3 1.3' .0040300 PS-30 120 C-9 29.4 2.8 .0051500 PS-35 120 CC-8 36.7 1.6' .00731000 PS-52 120 CC-8 41.6 2.1 ' .01121500 PS-52 120 C-7A 41.8 6.8 .0146

'Coiled-coil

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C-2V c-s CC-6 C-7 C-7A c- a c-s C-1l C -l1V C-13 C-17-7 CC-s

Figure 5. Incandescent Lamp Filament Designations

TABLE IIIVARIOUS INCANDESCENT LAMP FILAMENTS

Filament TYpical LampDesignation Description Using This FilamentC-2V Fairly short coiled filament which requires one support. 6000 lumen, PS-40, Street

SeriesC-S Concentrated filament for small light sources. SOOW,G-40 Floodl.ightC-6 Short coiled filament requiring few or no supports. SOW,A-21, 6 voltCC-6 Short coiled-coil filament requiring few supports. ?SR-30, Spot or FloodC-? Fairly long filament supported at top for base up burning or at 10,000 lumen, PS-40,bottom for base down burning. 20 amp., Street SeriesC-7A Long filament supported top and bottom for universal burning. SOOW,PS-40, 230 voltC-S Coiled filament mounted along axis of bulb. May be elongated 25W, T-10,Showcaseas in lumiline lamps.CC-8 Short coiled-coil filament along axis of bulbs. 100W, A-17C-9 Filament of average length; well supported. Semi-circular. 25W, A-19Also used for vibration service.C-11 Concentrated filament of some length. 250W, G-30, Infrared,C-11V Well supported. "M'!_shaped. 50 A-19Traffic SignalC-13 Monoplane filament, high concentrated for projectionequipment SOOW,1-20, Spotlightc-ir Long filament requiring more than average number of supports. 100W, A-21, Rough ServiceC-23 Coiled filament mounted along axis of bulb and alternated 40W, T-8, Showcasealong the length.

See the Large Lamp Catalog for complete list of lamps and their filament shapes.

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AXIAL MOUNTINGA design improvement, originally used in street lamps isaxial mou nling of the filament along.the lamp's vertical axisas shown in Figure 6, This provides more filament contactwith the stream of hot gases circulating inside the lampwhen burning in a base-up or base-down position. Theresult is a decrease in bulb blackening and an increasein lig!htoutput throu ghoul lamp life.Axial mounti ng also per-mits use of a smaller, more compact bulb.The combination of axial mounting with the coiled-coilfilament gives another important boost to light output-providing 6% more light in 100 watt lamps-and 12% to15% more light in lamps of 300 to 1000 watts.

RELATIVE EFFICACIESThe 100 watt, 30 volt and 230 volt lamps are included inTable II, to show that the low voltage f Iament is shorter andof larger diameter than the standard voltage filament whilethe high voltage one is longer and smaller in diameter.A low voltage filament requires a higher current and a lowerresistance for the same wattage, When this is accompl ish-ed by shortening the filament, the total! surface areabecomes smaller and the surface temperature rises,because the same wattage must be dissipated from asmaller surface. The rise intemperature produces and in-crease in efficacy. Another effect in the same direction isthat the shorterfilamenl requires fewer supports and thusreduces heat losses.

CC-8TUNGSTENFILAMENT

LEAD-INWIRESSUPPORTWIRE

Figure 6. Axial FilamentOn the other hand, if the filament were made too short, iwould reach the melting poi ntoftungsten. Also, a very shorfilament has too high a proportion of "end losses" from thelead-in wires. Therefore, part ofthe reduction in resistanceisaccomplished by shortening the f.ilament and part by increasing its diameter.Conversel:y,the smaller diameter of a high voltage filamencauses lower efficacy, and the greater length needs moresupport, thus increasing heat losses and further reducingefficacy. Table IV shows how efficacies of several types o100 watt lamps vary with voltage and service.

TABLE IVEFFICACIES OF 100 WATT LAMPS

I Initial Efficacy LifeVoltage , Service Lumens per Watt Hours227 ;1 General Lighting 12.0 1000120 Rough Service 12.6 1000230 General Lighting 12,6 1000120 Vibration Service 14.0 1000120 General Lighting 19.5* 75030 Train Lighting 18.0 1000120 Extended Service 14.9* * 2500

* Greater efficacy attained by designing for life of 750 hours."Lower efficacy attained by designing torlite of 2500 hours.Rough service and vibration service lamps require special filament construction which reduces efficacy and are norecommended for general lighting service. They are discussed in more detail later in this bulletin.

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FILAMENT RESISTANCE ANDINRUSH CURRENTThe tungsten filament increases in resistance to the flowof electric current as its operating temperature rises. Thecarbon filament has the opporsite characteristic and showsgreater resistance when cold than when hot. Since the coldresistance of the tungsten filament isconsiderably lessthanthe hot resistance, the inrush current wil l be much greaterthan the operating current. A convenient fact to rememberisthat the cold resistance of the tungsten filament in stan-dard lamps is approxiamtely 1/15th of the hot resistanceat rated voltage burning. Although this value will vary slightlyfor each lamp size,it represents a good approximation. Hotresistances are given in Table I.

BULB SHAPESPictured in Figure 7 are the lamp bulb shapes most corn-manly used for Sylvania's Incandescent Lamps. Bulbshapes are indicated by letters which have the meaningsgiven below:Most of the incandescent lighting in stores,offices, factoriesand homes is done with lamps having A or PS shapedbulbs. The principal difference between A and PS bulbsis that the neck of the latter is straight from the base to thepear shaped part of the bulb, while the neck o f the A bulbis slightly curved. The most common lamps, from 15Wattsto 200Watts, used largely for home lighting have A bulbsand are generally referred to asthe' 'A" I i n e . Standard lampsof the PSshape will be found inwattages ranging from 150to 2000Watts. Their main use is for commmercial, school,industrial and street lighting.The reasons for the F and T shapes are inherent in theiruses, but some of the others are not so obvious. When allwere vacuum lamps, the Sshape was universal, but whengas-filled lamps were developed it became necessary toget the filament further from the glass walls and from thebase. The PSbulb uses a long, straight neck to accomplishthis.The C-shape bulbs inthe 10watt size have special filamentdesign to withstand moderate vibration and shock whenused in sewing, washing and industrial machines, C-shapebulbs in the 4 and 7 watt size are used as night lights andinconsoles, appliances, signs, control and luminous panels.As lower wattage lamps came to bemade ingas-filled types,the need was felt for a new and more pleasing shape, whichwas achieved in the A line, It was necessary to retain thePSshape in large sizes sothat the narrow neck ofthe lampwould fit fixtures already in use.

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BULB BLACKENINGBulb blackening isthe result of normal evaporation of thefilament and is caused by the depositing of tungsten par-tic~es on the inner bulb surface. In a vacuum lamp theblackening occurs rather evenly over the entire inside ofthe bulb, In a gas-filled lamp the convection currents setup bythe hot gas carry the particles upward to be depositedon the bowl when the lamp is burning base down, or onthe neck when burning base up. In some lamps an activematerial known as a "getter" is applied to the filament orleads during manufacture to reduce residual gas pressureand to clear up the atmosphere when the lamp is firstl ighted. Inthe case of vacuum lamps, the "getter" materialcauses a slight yellow appearance and reduces blacken-ing throughout life.

The G shape was added chiefly for decorative reasons,but this shape also serves a useful purpose in certainspotlight and floodlight lamps which are burned either basedown or horizontally.The Fand G bulb lamps along with the B,C, and GT bulbsare generally used for decorative effects, These shapes arenot only pleasing for residential lighting but are ideal formany commercial applications, such as restaurant, moteland hotel lighting. G shaped bulbs in larger sizes aredesigned for spotlights and floodlights, and P shaped bulbsare standard for medical spotlight, street, railway, andlocomotive headlights. S bulbs have their biggest use inthe fields of sign and decorative lighting.T bulbs offer variety in lighting applications since they canbe placed in narrow reflectors for showcase lighting or ininconspicuous reflectors for use on such home appliancesas vacuum cleaners and sewing machines. Tubular bulbsare also used for projection lamps because of the limitedspace available for light sources inthis type of equipment.Also employing the T bulb is the lumiline lamp, which isapplied for decorative effects and the lighting of bathroommirrors.PAR, ER, KR. and R bulbs are used as spotlights,floodlights. t racklights and high bay Iighting and the R bulbis now commonly furnished lor various sizes of infraredreflector drying lamps.Both "PAR", "KR", "ER", and "R" types of lamps are design-ed with a built-in reflector-a pure aluminum or silvercoating hermetically sealed inside the lamp. This reflectorcoating in conjunction with the filamenllocation and finishon the bulb face is capable of furnishing a variety of lightdistribution patterns from a narrow concentrated beam forspotlighting to a very wide beam for floodlighting.


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Because the sealed- in reflecting surfaceis completely pro-tected from dust and dirt, light output remains highthroughout lamp life.In lamp design, the size and shape of the bulb dependon the wattage of the lamp, its principal use,and the desired

operating temperatures of the glass and the base. Maximum desirable bulb temperatures, selected bythe industras awhole, are well below the maxim um safetemperaturesat which the glass bulbs could be operated withousoftening.

TABLE VVARIOUS BULB S:HAPES OF INCANDESCENT LAMPS

Bulb Shape Meaning 1}Ipical Lamps Using This BulbA Standard 60 Watt, A-19,A-H, Standard CoatC Cone 7 Watt, C-7, Night LightB Candle 15, 25, 40, 60W, B-10, DecorativeF Flame 15 Watt, F10, DecorativeG Globe 40W, G-25, DecorativeGT Globe, Tubular SOW,Gr:24, G"['19,Small Chimney Lampp Pear 150 Watt, P-25, SpotlightPAR Parabolic Reflector 150 Watt, PAR-38, SpotPS Pear, Straight Neck 500 Watt, PS-40, ClearR Reflector 150 Watt, R"40, ReflectorS Straight Side 11Watl, S-14,Sign and DecorativeT Tubular 25 Watt, 1-10,ShowcaseT Tubular (Lumiline) 40 Wate T-8, Lumiline

Note: For complete list of lamps with their bulb shapes, see the Large Lamp Catalog.The figures following the tetters designate the butb's maximum diameter in eighths of an inch.Thus, a G-30 bulb is a globe shaped lamp with a diameter of 30/8 inches, or 33/4 inches.

Q Q QCone"GT"Chimney

"S" "P"Pear "F "Flame

"PAR"ParabolicReflector

"G"Globe "' ,B"Decor

"R" "PS"Reflector 'Pea.rStraight Neck"ER"Elliptical

I I"T" (Lumiline Type)

Figure 7. Incandescent Lamp Bulb Shapes

"A"Standard "T"Tubular

-=. "MB"Midbreak


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COLORE.DLAMPSColored lamps are availablei n a variety ofcolors and manyfinishes: outside colored (ceramic and transparent), insidesmoke colored, dich roic and stained. Transparent coloredlamps have been designed for the sign industry and areexceptionally well suited for outdoor application.Silicone Colored PARand dichroic col.ored lens PAR lampsare excellent sources for color floodlighting and displaylighting. Dichroic lamps are described in more detail laterin this bulletin.

GLASS FOR BULBSMost lamp bulbs are made with a so-called "soft" or limeglass which has a maximum safe operating temperatureof about 700F before the bulb will be weakened enoughto fail. Lamp bulbs using hard glass, such as projectionlamps have a maximum safe operating temperature of885F. Pyrex glass bulbs, asused for PARReflector Lamps,will safely withstand temperatures up to 975F. Hard glassis needed when it is desired to have smaller bulbs withhigher wattages or to prevent glass breakage due tomoisture or bugs when lamps are used outdoors. Eventhough maximum bulb temperature is an important con-sideration, it doesn't necessarily determine the maximumsafe operating temperature for the lamp. This temperature'is controlled by several factors including breakdowntemperature of the basing cement, or melting point of thesolder. Presently, lamps designed for use in an oven willsafe'ly operate in temperatures up to 475F. .

TABLE. VIMAXIMUM BARE BULB TEMPERATURESOF STANDARD INCANDESCEN!T LAMPS

Watt s : Bulb Fahr .25 A-19 11040 A-19 26060 A-19 255100 A-19 300150 A-23 280200 A23 345300 PS-30 385500 PS-35 4151000 PS-52 4801500 PS-52 510

'Bare lamp burning vertically, base up.Table VI' shows that lamp bulb temperatures are con-siderably below the safe operati ng maximu rnof 7000 F . forsoft glass.

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B U LB iF IN IS H ESThe most common bulb finishes are clear, light inside. in-side frosted, daylight (clear and inside trostec), white bowl,silver bowl, soft-white and soft-pink.Light inside coat (standard coat), which is by far the mostcommon of all bulb finishes, spreads the bril liant fi lamentimage and partially diffuses the li.ght,thus reducing glarewhen lamps are used bare and minimizing shadows andstriations when used in lighting fixtures. However, itshouldbe remembered: that a standard coat lamp is still far tooglari ng for comfort when burned exposed. With a sacrif iceof about 3% of the raw light output, more complete diffu-sion can be obtained by use of the soft white coating.This hides the filament and gives a ball of light the size ofthe lamp.Daylight lamps produce a Iight that ismore nearly "daylight"in color bylhe use of blue ceramic which absorbs someof the red and yellow wavelengths. This results in a lossin lamp efficacy of approximately 35 percent. A good ruleto remember here is that ,it takes the next larger size ofdaylight lamp to supply the same quantity of light as thewattage of inside frosted lamp being replaced. In otherwords, a 300 Watt daylight lamp has approximately thesame lumen output as a 200 Watl inside frosted lamp.White bowl lamps have a white diffusing coating on thebowl, opposite the base, to direct about 80 percent of thelight upward and 20 percent through the bowl. These lampsare often used in open-type direct lighting industrial reflec-tors to lessen glare and soften shadows.Silver bowl lamps have a reflector coating of pure silver onthe inside of the lower half 01 the bulb. Since the bulb isinside frosted the silver bowl appears to bemore white thansilver in color.

TYP E S O F B AS E SThe base of an incandescent lamp performs two very im-portant funclions~(1) it holds the lamp firmly in the socketinthe electrical circuitand (2) itconducts the electricity fromthe circuit to the lead-in wires of the lamp. For a majorityofapplications lamps are lurnished with one ofthe varioussizes of screw bases shown in Figure 8. Standard screwbases havea right hand:thread I but the medium screw basemay be supplied with a left hand thread if required.


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TABLE VIIVARIOUS INCANDESCENT LAMP BASES

Base Type lYplcal Lamp Using This BaseMini-Can Screw 250 Watt, 1-4,Tungsten HalogenCandelabra 15 Watt, F-10,DecorativeInlermediate 10 Watt, S-11,SignMedium 100 Watt, A-19,StandardMedium Skirted-(cement) 250 Watt, G-30, InfraredMedium Skirted Mechanical (1 piece) 150 Watt, PAR-38, ReflectorThree Ken-fact Medium 50-100-150 Watt, A-21, Three-IiteMogul 1000 Watt, PS-52, StandardThree Contact Mogul 100-200-300 Watt, PS-25, Indirect Three-liteMedium Prefocus 500 Watt, 1-12, ProjectionMogul Prefocus 1000 Watt, G-40, SpotlightDouble Contact Bayonet Candelabra 25 Watt, 1-8, Home ApplianceDisc 40 Watt, T-8,LumilineMedium Side Prong 150 Watt, PAR-38, Reflector

Note: For complete list of lamps with their standard bases, see the Large Lamp Catalog.

u u U 0 tMini-Can Candelabra Intermediate Double Contact DiscStrew Cando Inter. Bayonet (Lumiline)CandelabraD.C.Bay

MediumMed.u.-,MogulMog.

Medium SkirtedMed. Skt.(Mechanical)

3 Kon.TactMedium3 C. Med.Medium SideProngMediumPrefocusMed. PI.o-.

Three ContactMogul3 C. Mog.MogulPrefocusMog. Pf.

Medium SkirtedMed. Sirt.(Cement)

Figure 8. Basesfor Incandescent Lamps

The candelabra, intermediate, medium and mogul screbases for most generallighti ng service lamps are cementeto the glass bulb, but in higher wattage lamps (generathose over 500 watts) which submit the cement to hightemperatures, even the best standard baSing cement mlose some some of its strength and permit the baseloosen. To insure greater strength and durability for somstreet lamps and for higher-wattage general lighting svice lamps and floodlights, a combination of cemendesigned for high temperatures are used.The 300 Watt, PS-35 lamp employs a mogul base as stadard equipment, but isalso furnished with a medium skirtbase that is cemented to the bulb.When it is necessary that a light source be very exacplaced with respect to a lens or reflector. the mediummogul prefocus base isused to insure the proper locatiof the filament. The prefocus base consists essentiallyan inner shell which is attached to the bulb with cemeand an outer brass shell which isset in the proper positito insure an exact light center length. After positioning, tparts are soldered together.Sylvania's PAR-38 Reflector lamp has a medium skirtbase of only one piece which is crimped near the tophold the glass bulb.


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The bayonet base has two pins, placed on opposite sides,to slide into slots in the socket. These hold the lamp firmlyand prevent it from becoming loose enough to break theelectrical connections or to fallout. Home Appliance lampsare supplied with double contact bayonet bases to keepthem tightly inthe sockets on sewing machines or vacuumcleaners. The double cotact bayonet medium base ismoreor less standard in England, but is seldom used in thiscountry.

The three Ken-fact Base is best known for its applicationon the 50-100-150watt, A-21 lamp. A tapered ring contact,set at an angle, provides positive contact under pressurewith contact elements of the socket. This lamp has twofilaments, which may be operated separately or togetherto furnish three levels of il lumination. The base consists ofan outer screw shell, a ring contact and a center contact.One end of the low wattage filament is connected to thering contact, one end of the high wattage filament to thecenter contact and the other ends of the two filaments tothe common lead attached to the base shell.An alternative to the 3-way product is the Sylvania Hilalamp. This lamp provides two light levels utilizing a diodecircuit. The Hila lamp is never partially inoperative as inconventional 3-way lamps.The lumiline lamp is unique inthat it utilizes two disc basesat opposite ends of the bulb with each one connected tothe filament.Recessed Single and Rectangular Recessed Single Con-tact bases with special ceramic, instead of metal, are usedfor double based Tungsten Halogen lamps.On the single-based Tungsten Halogen lamp the'base typecommonly used is the Mini-Can Screw.

IMPORTANCE OFCORRECT LAMP VOLTAGEAlthough most of us realize just how important it is to usea lamp of the proper wattage to furnish the necessaryamount oflight for good seeing, we do not alwaysconsiderthe importance of employing a lamp of the right voltagefor the circuit in which it is installed. If the lamp is not burn-ed at a voltage which is fairly close to the rating etchedon the bulb, the user generally wi.11ot be receiving the mostvalue for the money spent on lighting. There are excep-tions to this, such as the rather common use of 110VoltIamps on 120 Voltcircuitsfor spa rts floodl ighti ng to greatlyincrease the light output at a sacrifice in life. This is dis-cussed later.In the majority of lighting installations, however, lampsshould be operated at rated voltage to give the best com-bination of light efficiency and life. It is not the purpose ofthis bulletin to discuss the economics of burning lamps atother than rated voltages, but rather to point out the effectsof voltage variations on operating characteristics.

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VOLTAGE RANGESThe following voltage classes, now being used, will meetnearly all needs of convenience, efficacy and electrical safe-ty for each type of lighting service.1. Standard Voltage, 115, 120 and 125 Volt Circuits

This is the voltage range for the majority of generallighting service lamps but certain lamps are alsodesigned for 105, 110 and 130 volt service. A surveyof central station voltages in the United States indicatesa minimum voltage of 118and a maximum of 125 withan average of about 123 volts. A trend toward thesehigher voltages seems apparent.

2. High Voltage, 220 to 300 Volt CircuitsThis range includes 220,230,240,250,277,285 and300 volt lamps, but 230 and 250 Volt lamps take careofmost high voltage circuit requirements. Inthe UnitedStates the demand for these lamps has never beenlarge, although they are common in Europe.

3. Low Voltage, 6 to 75 Volt Circuitslamps available inthis range are designed for severalclasses of lighting service for which the power isgenerally supplied by storage battery-generator sets.Lamps for train lighting are rated at 30, 32, 34, 60, 64,and 75 Volts. Actually, 30 and 60 Volt lamps can beused, inmost instances, for railroad car lighting. Similarlamps, which are known as country home lampsbecause they are used primarily in low voltage rurallighting service, are manufactured only in the 30 Volttype. Inthe low wattage sizes, 6 and 12VaIt Iamps arelisted for battery outfits on boats, airplanes, RVs,housetrailers and small wind-driven charger battery sets.

4. Special VoltagesThis refers to the few lamps which are not properly in-c I uded ina nyofthe othe rthree classes. Am ong theseare 47,48,135 and 155 Volt lamps. Another groupingwould include lamps designed for series burning.Street series lighting uses lamps rated for 6.6 and 20amperes in conjunction with a constant currenttransformer. Railway series applications use 120 and30 volt lamps on a 600 v supply

EFFECTS OFLINE VOLTAGE VARIATIONAlmost everyone has noticed how incandescent lamps maydim when a hair dryer,toaster, coffee maker or microwaveisplugged into an outlet athome. The heavy current drawnby the electric appliances may cause a drop inthe voltageon the circuit, which reduces the light output of all lampsconnected to it. At other times, an electrical storm may pro-duce a momentary rise in voltage, which will cause thelamps to burn brighter than normal. These temporarychanges in voltage will not noticeably affect the life of alamp, but consistent operation of the lamp at other thanrated voltage will vary the life and generally increase theoverall cost of lighting.


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2001 . & . 1I.&.: : : : iczc:(~l-e(:!t(I)z 100I . & J:E:=I...JI-ZW0crl& JQ..

Figure 9 shows how variations above or below normalvoltage affect the characteristics of a lamp. Itwill be notedthat lumens and life are altered greatly by only a small,change in voltage while watts are not affected to as greatan extent An increase in voltage forces more currentthrough the filament wire, increasing its temperature andthus causing it to glow brighter and produce more lumens,At the same time, the wattage consumed is increasedbecause the component volts and amperes are greater andthe resistance of the filament is increased because itsoperating temperatu re is hig her Life 01 the lamp isshorten-ed due to the more rapid evaporation of the tungsten wireas itstemperatu re rises"Conversely, a decrease in voltageaffects all the characteristics in an opposite manner.300

\\,1 \

~ \\\, ,"i\ I~MENS ... . . . . . . . .\ ..",. ~- _ . . .~ ~ . . .'C.-" " ' -~.-_'" ~~

;;


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DEPRECIATION DURING LIFEFig'ure 10a depicts how an incandescent lamp on a multi-pie circuit slowly depreciates duri ng life,consuming slightlyless watts and producing fewer lumens at reduced efficacyasthe hours of use increase. As the filament burns itslowlyevaporates, becoming smaller in diameter (higher inresistance) and allowing lesscu rrent to pass throughi!, thusreducing the power consumed. At the same time the lumenoutput fal'lsoff, due to a lower operating temperature of thefilament and increased bulb blackening,The performance characteristics of series lamps on cons-tant current circuits differ from muIliplelam ps, The increasein filament resistance during life causes an increase invo'taqe across the lamp and a resultant increase in wattsand volts. The lumen output also increases early in life butdecreases somewhat later as the gain is offset by the ab-sorption of tight due to bulb blackening. However, light out-put is maintained at a relatively constant level.Figure 10b shows these changes for high-current serieslamps,

IwATTS "NO tPE"ES

~ r=-:~--------fL---- ------ - - - - - r : : : - r -:---( a J

100f-ZL UU 90rrWn,80

10o 20 40 60 80PERCENT RATED LIFE 100 120

f- 801---+--+--+---+---+--+---+--1----1--+-+---1ZW~60~-+-~-~~-,r-~-+-,_~--+-+--,tiJc, 40~-+-~-~~-~-~-+-4-~-~-+-~

20 40 60 80 100PERCENT OF RATED AVERAGE LIFE

120

Figure 10. Changes in lamp Characte.ristlcsthroughout Life(a) Multiple Lamps (b) Series lamps

LAMP MORTALITYBecause of slight variations inlamp making operations andlamp materials.it isimpossible to have each individuallam poperate for exactly the life for which it was designed. Forthis reason lamp life is rated as the average life of a largegroup. At the end of rated life, approximately 50 percentof the lamps in a large group have burned out and 50 per-cent remain burning aspictured by the curvefor good quali-tyincandescent lamps in Figure 11.12

100

..J BO (!)t ~z >> 60u, rr0 :;,I- tilZ til 40W Q.U ~rt: w .J 20!l.

-N1\\\\""l20 40 60 80 100 120 140 160 180PERCENT RATED LIFE

Figure 11. Rangeof TypicalMortality or Life ExpectancyCurvesfor Incandescent Lamps

GROUPRELAMPINGLamps in a lighting systemcan either be individually replac-ed as they burn out or replaced in a group at one time.As the lifeexpectancy cu rve in Figure 11shows,i ncandes-cent lamps begin to fail faster after reaching 70 percentof rated life. Besides this, light output decreases as bulbblackening increases. Therefore, substantial savings aremade possible by scheduling group relamping between70 percent and 85 percent of rated life. The mosteconomical relamping schedule should be determined byconsideration of lamp and labor costs for each specificinstallation.


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SOME MAJOR TV ES OF INCANDESCENT LAMPSRO UGH SE RVICE & VIB RATIO N LAM PSLamps for rough service and vibration service furnishlonger life in installations where standard lamps cannotstand up because of rough treatment or vibration. Theselamps are built for two different kinds of specialized ser-vices and should be used only for the purposes for whichthey are designed Inother words, vibration service lampsare not suitable for rough service, nor are rough servicelamps satisfactory for vibration service. And neither typeisrecommended for general lighting use because of lowerefficacies and limited burning positions, inthe case of vibra-tion lamps.

VIB RA TIO N SE RVICE LAM PSVibrations produced by high speed machinery, or similarhigh frequency vibrations, are very destructive to ordinary

C-9 FILAMENT

FIL.SUPPORTSLEAD-INSUPPORTSLEAD-IN WIRESGLASS BUTTON RODARBOR WIRESTEM PRESS

Figure 12. Tvpical Vibration Service Lamp

R O UGH SER VICE LAM PSRough service lamps are designed primarily for highamplitude/low frequency shocks. The lamps are built towithstand shocks, bumps and rough handling, such astheymight receive on extension cords in machine shops orgarages The 25 and 50-watt rough service products arevacuum type lamps and are made C-g filament shape witha specially processed tungsten wire which resists breakage.They are no! designed to resist vibration.

lamp filaments. Vibration service lamps are intended fohigh/low amplitude vibration. Lamps for general lightingservice have coiled coil filaments made of tungsten wirwith a crystal structure that resists sagging. This wire wnot resistthe punishment given it by vibration and will breakthus resulting in short lamp life.Vibration lamps use a filament made with specially blended tungsten. Itismore flexible and will sag when subjectedto vibration. Itwill not break aseasily as non-sag wire. Sincthe wire is allowed to sag, more supports are necessaryThese increase the heat loss, lower the efficacy and addto the cost of construction. These points aremore than ofset by the longer life obtained under vibration conditionsThe lamps are not recommended for horizontal burningsince the coils are apt to sag together, causing poor lampperformance. Sylvania vibration service lamps are madwith Cog f ilaments. (See Figure 12.)

ARBOR WIRE

-STEM PRESS

Figure 13. Typical Rough Service Lamp

The 60 watt and larger are gas filled and have filamentmade with non-sag wire, as in standard lamps, but theare coiled on very small mandrels which form relatively loncoils. Rough service filaments are carefully mounted anheld by many supports as shown in figure 13.Although thextra supports add to the cost, they increase the life of thlamp under shock conditions.Even though Rough Service Lamps will burn in any postion, they are not recommended for general lighting sevice because ofhigher costs and lower efficacies than stadard lamps.


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SAFE LINE LAMPSSylvania's Safe Line lamps have a clear silicone rubbercoating which absorbs impacts and greatly reduces bulbbreakage. If the bulb is struck hard enough or droppedon a hard surface, the glass will break but will not shatter.Thecoating squeezes the segments together sothatthereis practically no problem of scattered pieces of glass.Neither hot weld splatter nor cold rain will cause the bulbof a Safe Line lamp to break. The hot glass is protectedfrom the shock of sudden chilling or thermal shock of hotmetals by the Safe Une coating. Safe Line lamps can beused safely indoors or outdoors in all kinds ofweather. Sincethe coating is clear, the light loss is less than 1/ 2 of 1 per-cent. Some of the applications for which Safe Line lampsare recommended are found in amusement parks, con-struction projects, garages, food packing and walk-infreezers, shipyards, and used car lots. The clear Safe Linebulb is popular with used car dealers who prefer the glitterof strings of clear lamps. Sizes of Safe Line lamps rangefrom 60 to 200 watts in standard inside frost types, 60 and100 watts in clear bulbs, 75R30,and 50 to 200 watts in roughservice construction.

STREET SERIES LAMPSOne of the rarely used street lighting systemsemploys streetseries lamps which are designed to operate in series onconstant current circuits. The most common system uses6.6 amperes, automatically regulated to maintain this value.These lamps are rated in lumens and amperes and areavailable in three basic life designs. The 2000-hour lampsare generally not employed for planned group replace-ment The 3000-hour and 6000-hour dssiqns are chosenfor group relamping twice-a-year and once-a-year,respectively.

MULTIPLE STREET LAMPSMultiple street lamps are rated in nominal lumens and dif-fer from ordinary standard voltage lamps in that they aredesigned to have their average lumens throughout life cor-respond approximately to the average lumens of serieslamps of the same initial rating. Odd wattages are requiredto produce the desired lumen outputs. The 1500-hour typesare used principally for one-at-a-time replacement. The3000-hour and 6000-hour lamps are intended for twice-a-year and once-a-year group relamping, respectively.

TRAFFIC SIGNAL LAMPSTraffic signal lamps are subjected to more severe servicecondit ions than most types of incandescent lamps. Theyare made to be compatible with the design requirementsof the optical systems of standard traffic signals. Typesavailable include 2000-hour, 3000-hour, 4000-hour,6000-hour and 8000 hour lamps. Energy-saving kryptontraffic lamps with compact filaments are available in reduc-ed wattages.14

SIGN LAMPSIncandescent lamps designed specifically for use in out-door signs are available. They are genrally low wattagelamps and can be operated exposed to furnish the colorand brialliance desired in signs such as the spectaculars,flashing letters, travelling borders, time and temperaturetypes. Commonly used sign lamps include the 10watt and11watt sizes in S-shaped bulbs and the 12,20 and 33-wattsizes in A-shaped bulbs. These are available in severalweather resistant colors. Reflector sign lamps in fivetransparent colors or light inside frost glass are also on themarket.

"LONG LIFE" LAMPSSome dealers sell "long life" or "guaranteed" lamps withclaimed long life, usually at a premium price. There is nospecial trick to designing a lamp for longer life: and it wasstated earlier inthis bulletin that it is possible to design anincandescent lamp filament that will burn almost forever,but only by greatly reducing the light output. The choiceof the design life is simply a matter of how much light theuser is wil ling to sacrifice.General service incandescent lamps, from 15to 150watts,including "long life" lamps, must have their ratings shownon the sleeves or containers in which they are packaged.The ratings that must be listed are: (1)average initial watts,(2)average initial lumens, (3)average laboratory life inhours.This information helps the purchaser decide which bulboffers the best value for a particular application.

EXCEL LINE LAMPS-SUPER SAVER TYPESFor locations where maintenance costs are the primary con-sideration, Excel Line lamps having a life of 2,500 hoursare available. In hard-to-get-at installations, relamping canbe difficult or expensive. Examples of such locations mightbe high up in a boiler room, stairwell, or in the ceiling 01an auditorium.The longer life of Excel Line lamps is obtained by a reduc-tion in light output and efficacy. Lumen output is approx-imately 15% less than that of standard 750-hour and1000-hour lamps. Sizes available range from 40 watts to1500 watts.

REFLECTORIZED LAMPSIncandescent lamps ofthis category are made in both stan-dard and special bulb shapes with a reflecting coating ap-plied directly to part of the bulb surface. This is usually ahighly efficient aluminum or silver reflector on the inner sur-face of the bulb which is sometimes referred to as a "built-in" reflector. These metallic coatings are applied internallyby condensation of vaporized aluminum or silver on thebulb surface.


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Reflector lamps ofthe "R" type are ofone-piece blown glassconstruction primarily for indoor use but, are also madein hard glass for outdoor applications. They are availablein many sizes from 30 watts R-20 to 1000 watts R60 withmost sizes having both flood and spot light distributions.For decorative tracklite lighting, R lamps in various colorsare widely used.PAR lamps have a parabolic bulb shape of molded two-piece glass construction fused into a single unit. Althoughthey are made of hard glass primarily for outdoor use,theyare often used indoors because oftheir accurate light beamcontrol. This versatile line includes sizes from 55 watt,PAR-38 to 500 watt, PAR64. Light distribution patternsrange from very narrow spot to very wide flood but not inall wattage sizes.Other reflectorized lamps for special applications areSylvania 75-watt ER30 and 120-watt ER40which have ellip-tical bulb shape. The elliptical reflector causes the lightbeam to have a soft concentration (crossover) at an areaapproximately 2 inches infront ofthe lensand then broadeninto a flood pattern. This enables fixture designers to usethe ERlamps ina shallow recess down-lie ht (high-hat)typeof fixture in producing more usable light with less glare.

DICHROIC REFLECTOR LAMPSDichroic coatings on the inside surface of the lens of thereflector make it possible to control the radiant energy fromPAR Reflector lamps. In the dichroic colored PAR lampsseveral thin layers, carefully controlled, on the inside sur-face ofthe lens provide any desired color by.reflecting everycolor except the one the coating is designed to transmit.A dichroic material is defined as one that will separate ra-diant energy into spectral bands, some transmitted andothers reflected from the surface. Dichroic color PAR lampsproduce brilliant colors very efficiently. Five colors areavailable in 150 watt, PAR-38 Spots only.Since most of the energy in the beam of an ordinary PARlamp is in the form of heat, it is often desirable to have alamp with less heat in the beam. Cool-Lux PAR lamps aremade with a special multi-layer dichroic coating on thereflector surface which efiici.entiy reflects light but transmitsheat. This sends the useful light raysto the front ofthe lampand transmits the unwanted heat rays out of the back;removing about 65 percent of the heat from the beam. Forthis reason, Cool-Lux lamps should be used only infixtureswhich are designed to allow the heat to escape. Cool-LuxPAR lamps aremade in 75watt , 150watt and 300 watt sizes.

KRYPTON LAMPSIn certain lamps for special applications, the advantagesof krypton as a fill gas (mentioned on page 3) more thanoffset the additional cost. Among the Sylvania lamps thatare filled with krypton are the 250 watt KR-38 types in spotand flood distribution. These have a one-piece hard glass

parabolic reflector bulb which may be used Indoors oroutdoors exposed to the weather.The krypton gas fill keepsthe buIb wall ternperature low enou 9h to perm it ope ratingunder adve rseweath er conditions without trouble.The lifeis4,000 hours which is double that ofthe 150 watt PAR-38lamp. Among their many applications are display lighting,garden lighting, architectural l ighting, patio lighting, andsecu rity Iighting.Other Sylvania lamps that use krypton are the K105 andK205, 12,000 hour types for street lighting service and theSuperSaver family of 2500 hour bulbs. Krypton fill in theK105 and K205 provides a means of improving the lumenoutput where extra long life is required. The SuperSaverA-17Slimlite types can be used to replace a higher wattage Excel-line lamp and still maintain the same lumen andlife ratings. For example, the 34 watt SuperSaver XL typeprovides the same 420 lumens and 2500 hours life givenby the 40 watt Excel-line (2500 hour) bulb. Wattage savings provided by the SuperSaver lamps range from 15%for the 34 watt to 5% for the 135 watt when compared tothe equivalent lumen Excel-line bulb.

DECORATIVE LAMPSSylvania's line of decorative incandescent lamps includesDecor Lites. This family of light bulbs offers bulbs of candie flame shape in several finishes with both candelabraand medium bases. A SuperSaver reduced wattage version of many 8-10 and C-11decor types is available witha 4,000 hour life. Interesting variations in design arepresented by straight top bulbs and twist top bulbs witha curled tip that looks likea realcandle flame.A bulb shapedlikethe old fashioned lamp chimney isalso available intwobulb sizes and four wattage ratings. Sylvania's Excel Lineincludes Decor Lites with 2500-hour lifefor commercial applications. G40 Globe lamps with clear and white finishesare frequently recommended by architects and interiodesigners lor various lighting applications in restaurantshotel ballrooms, cocktail lounges, reception areas, corridors, recreation rooms, and many other commercial andresidential areas.Complete information and data on all ofthe preceding major types of incandescent lamps and many others will befound inother buIletins, catalog pages and the Large LamCatalog.

1


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TUNGSTEN HALOGEN LAMPSAnother member of the growing incandescent lamp fami-ly is the Tungsten Halogen lamp. This source makes useof the halogen regenerative cycle. Halogen is the nameapplied to the classification of elements including bromine,chlorine, fluorine, iodine and cyanogen. The regenerativecycle minimizes lamp blackening by causing most of theevaporated tungsten not to settle on the bulb.Because of the high temperatures required for the opera-tion of the cycle, Tungsten Halogen lamps are made withtungsten filaments in tubular quartz, or hard glass env-elopes. A halogen gas, such as iodine, is introduced intothe lamp during manufacture. While the lamp is burning,the tungsten particles which evaporate from the filamentcombine withthe halogen gas inthe lamp. Thisnew materialiscarried to the tube wall by convection currents but doesnot deposit because of the high temperature and returnsto the filament. Here the extremely high heat liberates thehalogen gas, and the tungsten particle isdeposited on thefilament. This cycle is repeated over and over, resulting ina self-cleaning lamp that darkens very slightly and producesmaximum light output for its entire life. Theoretically, thelamp should last forever if the tungsten could beredeposited evenly on the filament. In actual practice,however, the deposit of tungsten is heavier on some spotsthan others, resulting in thinner sections of wire that even-tually break.Formore detailed information and data on types ofTungstenHalogen lamps now available see other bulletins, and theLarge Lamp Catalog.

C AP SY LlTE LA MP SState-of-the-art Capsylite PAR and incandescent typelamps are the result of continuing leadership by Sylvaniain "lamp-within-a-lamp" tungsten halogen technology.These years-ahead lamps are a major advance in lighting;they offer long life, durable design, excellent color rendi-tion, a more precise and whiter light-and substantialenergy savings!Capsylite PAR lamps offer a wider selection of beam pat-terns and provide a more evenly distributed light patternwith better beam control than standard PAR lamps. Theyactually deliver more usable light per watt! Moreover, theben efits oftheir tungste n halogen desig n mean the Iampsretain 97% of their whiter, b righter light throughout Iifecom-pared to standard filament incandescent lamps.Advanced Sylvania Capsylite Incandescents, in three wat-tages, replace standard and long life (2500 hours) in-candescent lamps. They offer up to 30% energy savingsand a long 3,SOO-hourrated life. The advanced Capsyliteincandescent lamp quickly pays dividends in energy sav-ings and lamp-changing labor costs.

16

THE HIGH QUALITY OFSYLVANIA LAMPSGTESylvania is proud of its quality and uses only the finestmaterials handled by skilled workers to make lamps ofthehighest quality. Although most of the lamp makingmachines are automatic or semi-automatic, they are preciseand very delicately adjusted. Experienced engineers andforemen must make the initial adjustments on the machinesand carefully inspect the first group of finished lamps todetermine if the machines are operating properly.But the best machinery and employee effort cannot makea high quality lamp unless the 'parts that are fed into themachine are free from defects. All glass bulbs and basesfor Sylvania lamps are manufactured to the most rigidspecifications. Quality control begins here through an in-coming material inspection departmentProbably the most vital part of an incandescent lamp isthe tungsten wire filament. Insome of the lowwattage lampsit is so fine that it is visible only to the best of eyes, and itisdifficult to measure its diameter byconventional methods.Since the life and efficacy of a lamp depend largely uponthe diameter and length of the filament, it is essential thatthese items be kept within extremely close limits. For ex-ample, a variation of only 1/100,OOathof an inch in thediameter of certain filaments may affect the life ofthe lampby more than 50 percent. Sylvania weighs accuratelymeasured lengths of fi lament wire to within 40 millionthsof a pound as acheck on the diameter. The sizeolthe man-drel on which the filament is wound isalso carefully deter-mined since a change of only 1/10,00Oth of an inch indiameter may decrease life by as much as 75 percent Theaccuracy of the spacing of coils is closely checked toeliminate errors which may vary the lamp's life by similaramounts.In the lamp plants Statistical Process Control is a vital fac-tor inthe assurance of a uniform and high quality finishedlamp. Wherever possible, Sylvania has equipped itsautomatic equipment and processes with automatic con-trols and gauges such as photocells, continuity and cur-rent detecting units. These units will automatically rejectdefective parts or signal responsible personnel that theequipment is not running within processing specifications.In addition to these devices, established process controlsampling plans are maintained in each process for dimen-sion and other visible defects.Shaping and molding glass for the stem and lamp seal isa very critical process in lamp making. By periodic sampl-ing of each machine and the use of a polariscope andpolarimeter, glass strain patterns are controlled withinspecified limits during processing.Every Sylvania lamp is lighted and inspected asa final stepin itsmanufactu reoItmay seem that no lurther checks, testsor inspections are necessary after the lamps have beenlighted and placed in cartons. But it is possible for a lampto light properly at this point and appear to be without a


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defect and yet have a major flaw or blemish which will af-fect its efficiency, life or strength. An example of this is a"leaker" which may light satisfactorily when itis first takenfrom the machine and then burn out immediately when itis illuminated only a few hours later due to the presenceof air which has seeped into the bulb through a fine crackor hole. Tokeep the number of major defects at a minimum,sample lamps are selected from the production of eachshift for further tests and inspecti ons. Enough sampies aretaken to be a representative cross-section of the entireproduction.All these sample lamps are subjected to numerous testsand inspections following each day's production, They areexamined for mechanical and structural defects andrelighted to find out if defects detrimental to good perfor-mance are present. Each year Sylvania inspectors handlemillions of lamps for these tests alone.In checking the quality of lamps, Sylvania also makesphotometric and life tests of tens of thousands of lamps

each year.Each year many lamps are used up in life,shoand bump tests, and in other quality tests. The resultsthese tests show that Sylvania incandescent lamps exceethe requirements of the GSA specifications for life anefficiency.Sylvania's efforts to supply itscustomers wrththe best lammoney can buy are not relaxed even after the lamps aplaced in warehouses. Larg.e quantities of lamps aselected from warehouse stocks to be relighted, inspecteand tested.Sylvania has always tried to serve the best interests ofcustomers and the lamp industry through research deelopments to give the user more light for his money. TCompany spends hundreds of thousands of dollars eayear in research and testing to guarantee that Sylvanlamps willmeet the most exacting requirements for strenghigh efficiency and long life.Great care istaken to manufature a quality lamp. and these tests and inspections amade to maintain this high quality.


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SylvaniaLighting CenterDanvers, MA 01923508 777-1900

Sales OfficesAtlanta, Georgia2115 Sylvan Road, SWAtlanta, Georgia 30344404-762-1781Boston, Massachusetts (Salem)60 Boston StreetSalem, Massachusetts 01970508-777-1900 Ex. 3473Buffalo, 'New York25 Dewberry LaneGardenvil le Ind. ParkBuffalo. New York 14224716-668-7555Charlotte, North Carolina3811 North Davidson StreetPO. Box 5246Charlotte. North Carolina 28225704-334-4671Chicago, Illinois (Elk Grove Village)800 Devon AvenueElk Grove Village. Illinois 60007312-593-3400Cincinnati, Ohio5480 Creek RoadCincinnati. Ohio 45242513-793-6440Cleveland, Ohio4848 West 130th StreetCleveland. Ohio 44135216-267-6800Dallas, Texas (Carrollton)2040 McKenzie DrivePO. Box 5018Carrollton. Texas 75011-5018214-247-7800Denver, Colorado4675 Holly StreetDenver. Colorado 80216303-399-1760

Detroit, Michigan (Dearborn)10800 Ford RoadDearborn, Michigan 48126313-582-8754Hartford, Connecticut100 Constitution PlazaHartford, Connecticut 06103203-249-5823Honolulu, Hawaii770 Kapiolani Blvd.Suite 513808-536-5267Houston, Texas1440 Greengrass DriveHouston, Texas 77008713-869-8671Kansas City, Kansas450 Funston RoadKansas City. Kansas 66115913-371-3773Los Angeles, California6505 East Gayhart StreetP.O.Box 2795Los Angeles. California 90051213-726-1666Minneapolis, Minnesota (Fridley)5330 Industrial Blvd., N.E.Fridley, Minnesota 55421612-571-9400New Orleans, Louisiana5510 Jefferson HighwayNew Orleans. Louisiana 701835047336970New York, New York237 Park Avenue, 9th FloorNew York. New York 10017212-503-1010

Orlando, Florida7492 Chancellor DrivePO. Box 13327AOrlando, Florida 32859407-859-6220'Philadelphia, Pennsylvania (Devon)465 Devon Park DrivePO Box 500Devon, Pennsylvania 19333215-2939330Pittsburgh, Pennsylvania450 Butler StreetP.O.Box 9544Pittsburgh, Pennsylvania 15223412-781-4533St. Louis, Missouri (Hazelwood)5656 Campus ParkwayHazelwood. Missouri 63042314-731-5515San Francisco, California (Burlingame)1811Adrian RoadBurlingame. California 94010415-6973500Seattle, Washington750 South Michigan StreetSeattle, Washington 98108206-763-2660Teterboro, New Jersey1000 Huyler StreetTeterboro, New Jersey 07608201-288-9484Washington, D.C. (Springfield. Va.)6610 Electronic DriveSpringfield, Virginia 22151703-354-3100

Ind ustrial/Commercial

Documents

Sylvania Engineering Bulletin - Incandescent Lamps 1988