Heat Steam Steam Ga 00 New y Rich

7/27/2019 Heat Steam Steam Ga 00 New y Rich

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7 B 3 025 7D1MACHINERY'S DATA SHEETSREVISED AND RE-ARRANGED IN LIBRARY FORM

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No. 1 5

Heat and SteamSteam and Gas Engines

PRICE 25 CENTSCONTENTS

Comparison of Thermometer Scales 4Weight of Water per Cubic Foot and Heat Units in Water at VariousTemperatures 5

Properties of Saturated Steam . . .Steam Pipe Sizes. ... . . 8Weight of Steam Discharged by Safety Valves 12Diameters of Steam Pipes and Areas of Steam Ports 13Steam Engine Design 14Volume of Cylinders for Different Diameters and Strokes 18Dimensions of Piston Rings 21Dimensions of Stuffing Boxes and Glands 22Piteh of Bolts in Water and Steam Joints 23Setting Corliss Engine Valve Gears 24Condenser and Air Pump Data . . . 28Direct-connected Engine and Generator BasesHorsepower of Gasoline EnginesProportions of Automobile Crankshafts.. ..36

The Industrial Press, 49-55 Lafayette Sheet, New YorkPublishers of MACHINERY

COPYRIGHT, 1910, TH-: INDUSTRIAL PRESS, NEW YORK


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MACHINERY'S DATA SHEET SERIESCOMPILED FROM MACHINERY'S MONTHLY DATASHEETS AND ARRANGED WITHEXPLANATORY NOTES

I j' No. 15 ^

Heat and SteamSteam and Gas Engines

CONTENTSComparison of Thermometer Scales 4Weight of Water per Cubic Foot and Heat Units in Water at VariousTemperatures 5

Properties of Saturated Steam 6Steam Pipe Sizes 8Weight of Steam Discharged by Safety Valves 12Diameters of Steam Pipes and Areas of Steam Ports 13Steam Engine Design 14Volume of Cylinders for Different Diameters and Strokes 18Dimensions of Piston Rings 21Dimensions of Stuffing Boxes and Glands

" 22Pitch of Bolts in Water and Steam Joints : 23Setting Corliss Engine Valve Gears 24Condenser and Air Pump Data 28Direct-connected Engine and Generator Bases 33Horsepower of Gasoline Engines 34Proportions of Automobile Crankshafts 36

Copyright. 1910, The Industrial Press, Publishers of MACHINERY,49-55 Lafayette Street, New York City


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In the following pages are compiled a number of diagrams and con-cise tables relating to heat, steam, steam and gas engines, carefullyselected from MACHINEEY'S monthly Data Sheets, issued as supplementsto the Engineering and Railway editions of MACHINERY since Septem-ber, 1898. Additional tables also are included which are published herefor the first time. In order to enhance the value of the tables and dia-grams, brief explanatory notes have been provided wherever necessary.In a note at the foot of the tables, reference is made to the page onwhich the explanatory note relating to the table appears.


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STEAM AND GAS ENGINESComparison of ThermometerScales

There are three thermometers in com-mon use, the Fahrenheit, the Celsius,and the Reaumur. The Fahrenheit ther-mometer is in general use in the UnitedStates and Great Britain, and in otherEnglish-speaking countries. The Cel-sius thermometer, commonly known asthe Centigrade, is used for most scien-tific purposes, and in nearly all of thecountries on the European continent.The Reaumur thermometer is largelyused in Germany. On the scale of theFahrenheit thermometer, the freezingpoint of water is taken at 32 degrees,and the boiling point at 212 degrees.On the scale of the Celsius or Centi-grade thermometer, the freezing pointis taken at zero (0 degree) and theboiling point at 100 degrees. On thescale of the Reaumur thermometer, thefreezing point is taken at zero and theboiling point at 80 degrees.The following rules may prove help-ful in transferring temperatures in Cen-tigrade and Reaumur to degrees Fahr-enheit.

1. To change a temperature given indegrees Centigrade to degrees Fahren-heit, multiply the number of degreesCentigrade by nine-fifths, and add 32degrees. The sum is the temperaturein degrees Fahrenheit.

2. To change a temperature givenin degrees Reaumur to degrees Fahren-heit, multiply the number of degreesReaumur by nine-fourths, and add 32degrees. The sum is the temperaturein degrees Fahrenheit.On page 4 is given a table for rapid

comparison of thermometer scales forordinary temperatures up to the boiling

point of water. For example, a tem-perature of 34 degrees Centigrade, itwill be seen from tnis table, correspondsto a temperature of 27.2 degrees Reau-mur and 93.2 degrees Fahrenheit.

Properties of Saturated SteamThe amount of heat required for rais-

ing water to any given temperature andfor transforming water into steam ismeasured in heat units or British ther-mal units. A British thermal unit isdefined as the quantity of heat requiredto raise the temperature of one poundof water one degree F., at or near thetemperature of maximum density ofwater (39.1 degrees F.).On page 5 is given a table of theweight of water per cubic foot, and ofheat units in water, for temperaturesbetween 32 and 212 degrees F. Thecolumn of heat units gives the numberof heat units required for raising thewater to any given temperature from32 degrees F.On pages 6 and 7 are given the mostcommonly required properties of satu-rated steam. The temperature of satu-rated steam depends upon the pres-sure under which it is generated, thetemperature being the same as that ofthe water from which it is generated.When steam is generated in a closedvessel, the pressure increases with theincreasing temperature of the waterwith which it is in contact, and fromwhich it is generated.The total heat in steam is made up

of three quantities:1. The heat required to raise the tem-

perature of the water to the tempera-ture of the steam.

2. The heat required to evaporate or(Continued on page 20.)

347506


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- ^ : MACHINERY'S DATA SHEETS No. 15COMPARiSCK OF THERMOMETER SCALES.


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No. 15 HEAT, STEAM, STEAM AND GAS ENGINESWeight of Water per Cubic Foot and Heat Units in Water between 32 and 2 12 F.


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MACHINERY'S DATA SHEETS No. 15PROPERTIES OF SATURATED STEAM.


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No. 15 HEAT, STEAM, STEAM AND GAS ENGINESPROPERTIES OF SATURATED STEAM (Continued).


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MACHINERY'S DATA SHEETS No. 15

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No. 15 HEAT, STEAM, STEAM AND GAS ENGINESSTEAM PIPE SIZES II


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10 MACHINERY'S DATA SHEETSSTEAM PIPE SIZES 111

No. 15


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No. 15 HEAT, STEAM, STEAM AND GAS ENGINES 11

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12 MACHINERY'S DATA SHEETSWEIGHT OF STEAM DISCHARGED BY SAFETY VALVES

No. 15


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14 MACHINERY'S DATA SHEETS No. 15STEAM ENGINE DESIGN I

Cylinder:- /n proportioning fhe cyfinder for any g/'renpower ofengine f/?efollowing date is usually furnished the designer: bo/farpressure, backpressure, cut-off, cfecrrctnce and piston speecf.

First, find the mean effect/re pressure (M. E. P.) for the g/Ven cond/f/onsby Me formu/a M.E.R - '9P(l 'h^3 losr R) -O.3p, /n whichP=boiler pressure (abso/ufe), R = "actual "ratio of expansion

* clearance and cvf-otf areclearanee cui--o *as a percentage of the jfroke, jo*= back pressure (abso/ufe)Area of P/sfon :- A- speed > /n h'ch * = area ofp^sfon /nsquare inches. The d/crmefer /s usvcr//(/ made eren /ncnes and fr?episfon speed changed fo g/r.e f/?e same H. P. Tnis /'s atone by f/?e fo//o#-in? emotion ^^fon dfn *rea .In ca/cu/cffincf the effective p/sfon area we must cr/fow for rne crr0ct

of the. p/sfon rod upon one side of ffie p/sfon X/ = ~^^ > in whichAi = effective area of p/'sfon, A = acfucr/ areor ofp/sfon, cr = area ofpiston rod. dffer assuming a p/'sfon d/'amefer of eren inches wemusf substifufe its "effecf/re"area in the equaf/on for f/'nc/ing ffonew p/'sfon speed.Thickness of Cy/inder She//'- f - 0.0003pd + O.3, in wh/'ch

f - thickness of she// /'n inches, cf diameter of cu//'nc/er /'n /nches,p * boi/er pressure per square /'ncn. The fh/'ckness of f/anc/es maybe made /.3t; the mefa/ of the sfecrm chesf ancf passages O.3f;and the vci/re secrf abouf /. 2S f.Counterbore i- Depth of counterbore shou/der -fc /nch in ct///'ncfers

/2 fo I inches in d/crmefer. The /engfh shou/cf be sue/? fharf j ofpacking rincf of p/sfon passes over edge of counterbore af endof stroke.

Contributed by Chas. L. Hubbard, MACHINERY'S Data Sheet No. 120. Explanatory note : Page 38.


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No. 15 HEAT, STEAM, STEAM AND GAS ENGINES 15STEAM ENGINE DESIGN II

Cylinder Heads ;- The fhicknes^ mat/ be /. 2ff C^ee ^heef I),stiffening ribs depending on diamefer.Cylinder Head Bo/fsi- /?= O.7OS df + 2. /8, //? which rr - number of

bo/fs, d,= diamefer of counterbore. The size ofbo/fs. shou/dbese/chfhctf fhe fofa/ foad due fo sfeam pressure and screwing up'shcf//nofexceed 7000 pounds per square inch, for m//d sfee/-

Tofal pressure on head - p (^^ )> in wh/ch p = betterpressure persquare inch, d - diamefer of counferbore . The pressure due fe screw-ing up may be faffen &s 2-ffoo pounds upon each 3fact.Diamefer of Bo/f Circ/e . D, - df + 2? t d, }n wh/'cfy &/ - a'/cfmerer

ofbo/f circfe, d = d/amefer of counferbore, f - f/j/c/fr?esjwa/f, d** cf/'amefer ofbo/fs. D/arr?efer of ct///rrder bead^ D, / cf+drea of Porte :- These are based on fhe ve/oc/ft/ of *sfecrm

fhrouafy them, as fo//ows :- 5fearn Porfs sooo feef perPorfs^ sooo feef per m/nufe.

Piston :- For horizonfa/ eng/nee fhe fh/ckness efp/sfos? mat/ befound bu fhe formu/a T=J~L~x~b /n wh/cf? T= fh/ckness ofphfortin inches, L lenc/fh of sfrake /'n //7cf?e*s, 0~ Gf/'crmefer ofpisfon /n inches.

Pisfon Pod:- The area of mefaf fhrouafy fhe weafresf parf /sfound by fhe formu/a cr= -j^ x Dzx p , /n which a- crrectofmefcflin weafresf parf of rod, f'- /oooo for wrougfrf /ron, and /30oo forsfeef, D~ d/amefer of pf&fon /n /nches, p- difference /npressureper square /nch acfing upon fhe fwo s/'des of fhe ptefo/7 .Stiffness of Pisfon ffod:- The required s/ze of fhe bode/ of fhe

pisfon rod mat/ be deferm/'ned b(/ fhe fbrmc//cr d~ 'K x D x*/p ', towhich d= d/amefer of rod, K- 0.0/03, fo O.O/8Z for $horf sfrofreengines, and 0.02 fo 0.0224 for moderafe/y /or?# sfrofre bor/zo/?fcr/engines, p difference in pressure per square inch acfingf upe/7fhe fwo sides of pisfon .

Contributed by Chas. L. Hubbard, MACHINERY'S Data Sheet No. 120. Explanatory note : Page 38-


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16 MACHINERY'S DATA SHEETS No. 15STEAM ENGINE DESIGN III

Connecting f?od-- The connecting rod /$ common/g made from twoto four fimes fhe /engfh ofstroke. Two and or?e-ha/f to three is 0n averageFor round rods fhe diameter at fhe center may be taken crsc/= cfJDLJp / O f in which' d- diameter of rod in inches, D = d/'ameferof cy/inder in inches, L = /engfh ofrod in feeft p~ boi/er pressureper square inch, ct= O./S for high speed, and O./S formoderate speed,C= J inch for high speed, and % inch for moderate speed.The diamefer at fhe necks mag be made about /./ f/me


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No. 15 HEAT, STEAM, STEAM AND GAS ENGINES 17STEAM ENGINE DESIGN IV

fa/re 5fern . d- V -j= , in which d- diameter of rod in inches, I' /engfnof ra/ve in inches, b- width of ra/re in inches, p- pressure per sat/areinch on va/ve, F - /SOOO for Jong sfee/ rod& and /4S~oo for &ftcrf sfee/rods.

Cross Head :- The pressure on the guides may be taken as 4O to 00pounds per square inch for ordinary fabrication, and 3O to toopoundswith good /ubr/cafion . W~ dp tern a, in which W-fofa/presst/reon guides in pounds , /I * area of pisfon />?, square inches, p*> press-ure on pis fon in pounds per square inch, a- the ang/e between f/?econnecting rod and fhe center /ine ofpiston rod extended, w/?en connecf--ing rod and crank are at righf ang/es.

Wrist Pin > d= O.O3


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18 MACHINERY'S DATA SHEETS No. 15VOLUME OF CYLINDERS, IN CUBIC FEET.


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20 MACHINERY'S DATA SHEETS No. 15transform water at that temperature intosteam, this heat quantity being termedthe internal latent heat.

3. The heat corresponding to the ex-ternal work done by the steam in mak-ing room for itself against the pressureof the atmosphere, or against the sur-rounding steam, if enclosed in a vessel.The sum of the two last quantities iscalled the latent heat of steam.

Referring to the tables on pages 6and 7 it will be seen that these tablesgive the temperature of the steam forvarious pressures, the weight in poundsper cubic foot of steam at given pres-sures, the volume in cubic feet ofone pound of steam at a given pressure,and the heat units in the water and inthe steam, together with the latent heatin the steam. These tables will be foundconvenient in calculations relating tosteam and steam engines.Assume as an example that it is re-

quired to find the various properties ofsaturated steam for 115.3 poundsgage pressure. Referring to the tableon page 6 we find that steam at thispressure has a temperature of 347.1 de-grees P., that it weighs 0.294 poundper cubic foot, and that the volume ofone pound of the steam is 3.41 cubicfeet. The total number of heat unitsin the water is 319.1, and in the steam1,187.8, the number of latent heat unitsin the steam being 868.7.

Steam Pipe SizesThe problem of determining the size

required for steam pipes under varyingconditions is one which often confrontsthe engineer, and the difficulty of obtain-ing reliable data is well known. In or-der to facilitate work of this character,the tables given on pages 8 to 11, inclu-sive, have been computed. Tables I,II and III (pages 8 and 9) are com-puted from D'Arcy's formulas for flowof steam in pipes, which are given onpage 10. Table IV gives the values ofthe constants used in these formulas for

various diameters of pipe.Table I, on page 8, gives the flow of

steam in pounds per minute throughpipes 100 feet in length, for initial pres-sures of *4 to 5 pounds, assuming thatthe pressure in each case drops to zero;that is, the drop in pressure equals theinitial pressure. It is seen from thetable, for example, that a 2-inch pipewill discharge 2.9 pounds of steam perminute under a pressure of 14 poundper square inch, or 14.9 pounds under apressure of 5 pounds, the terminal pres-sure dropping to zero in each case. Thetable is sufficiently accurate for anyinitial pressure less than 10 pounds forthe drops in pressure noted at the headsof the columns, regardless of whetherthe pressure falls to zero or not. Forexample, a 4-inch pipe, 100 feet long,will discharge approximately 18.1 poundsof steam per minute with a drop in pres-sure of ]4 pound, or 91.9 pounds witha drop of 5 pounds, for any initial pres-sure up to 10 pounds.As the initial pressure increases, the

quantity of steam discharged for a givendrop in pressure becomes greater thangiven in Table I. Table II, page 9,gives correction factors for higher initialpressures. For example: The factorfor a drop of 5 pounds at an initial pres-sure of 80 pounds is 2.09, so that underthese conditions a 4-inch pipe will dis-charge 91.9 X 2.09= 192 pounds of steamper minute, the value 91.9 having beenobtained from Table I.The figures given in Table I are forpipe runs of 100 feet only. For differ-ent lengths, the results should be cor-rected by the factors given in Table III,page 9. For example: A 4-inch pipe,100 feet in length, will discharge 91.9pounds of steam per minute with a dropin pressure of 5 pounds at the dischargeend; if the pipe is only 50 feet in length,it will discharge 91.9X1.41 = 129.5pounds, or if it is 500 feet in length, itwill discharge 91.9 X 0.45= 41.4 pounds.

(Continued on page 32.)


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No. 15 HEAT, STEAM, STEAM AND GAS ENGINESDIMENSIONS OF PISTON RINGS

21

Lap Cuf-^ D k-Tab/e of Dimensions for

Dimen- 8 Diameter of Cylinder in /nches10 13 A* /e /T-7F~3~ ~W32.76

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LapTab/e of D/'mens/ons for

Dimen-sions Diame fer of Cyf/ncter /r? /ncfre^s8 10 /2 /3 16 17A . 4 jfe 32.

/73Z 8~7JJ6_nwwrwrn /I 164 \ ' \ 're

Contributed by C. R. McGahey. Explanatory note : Page 38.


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22 MACHINERY'S DATA SHEETSDIMENSIONS OF STUFFING BOXES AND GLANDS

No. 15

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United States Navy Standard, MACHINERY'S Data Sheet No. 115. Explanatory note : Page. 38.


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No. 15 HEAT, STEAM, STEAM AND GAS ENGINESPITCH OF BOLTS IN WATER AND STEAM JOINTS

23


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24 MACHINERY'S DATA SHEETS No. 15


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26 MACHINERY'S DATA SHEETSSETTING CORLISS ENGINE VALVE GEARS III

No. 15

Contributed by F. Douglas Wilkes, MACHINERY'S Data Sheet No. 122. Explanatory note : Page 38.


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No. 15 HEAT, STEAM, STEAM AND GAS ENGINES 27SETTING CORLISS ENGINE VALVE GEARS IV

Explanatory Notes.Fig. /. Working edges of valves andports are shown &y ch/selmarks- onends of valves andchambersFt'g. 2. To Find Length'of ftods > Turn engine overby handunti/ eccen-tric stands vertical, as stoown atA; then adjust eccentric rodB unti/rockerstands vertical, asshown at G; then adjustreach rod D until wristp/dfestands vertical,as shown af E. See.marffS.on'hub as in F/g. 24.Fig. 3. To Set Valves:- Adjust rods Funtil steam vct/ves have' the re-quired lap, as. shown at H. Adjust rods G untilexhaust va/ves have therequired lap, as shown at- Her.Fig. 4. To 5ef Eccen trie - Putcrank on dead centerandmove eccentricaheadof crank un til. steam i/a/ves ^how requ/red fead,as at /


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28 MACHINERY'S DATA SHEETS No. 15CONDENSER AND AIR PUMP DATA I

To Find Amount of Wafer Required fo Condense One Pound'Jfeam.Lef //= fofal heaf/'n one poundsfeam afgiven pressure = (crbouf //so)

h =fofat hecrf/'n onepound wafer af femperafure offhe concfensedsfecrmf = temperafure of condensing wafer enfering condenserT-femperafure ofcondensing wafer tearing condenserQ=pounds wafer required fo condense one pound sfecrmr= temperafare of airpump discharge (= crpprox. h)

or Q= U9r (seePorjef condenser T= r hence g- 7 C-see Tab/e 2Z)

To Find Condensing Waferper H.P. in (US.) Gallons.One-pound wafer af condenser femperafune equate abouf 2d cubic inches

23~l~8~zs gallons, hence Q zj = U.S. gat/onsIf 5~pounds of sfeam requiredper H.P. per hour by engineW-pounds sfeam condensedper hour# =pounds condensing waferperpound sfeam

' * / / O y /O y ZThen condensing wafer in U.S. ga/fons per hour= ' 's ^ orcondensing wafer in u.S.ga/fons per m/nufe*~ ' '^g^-*

which is agoodpracficcrf a/fowcrnceSize of Injecff'on Pipe.

Ve/ocift/ of flow in injection pipe shou/dnofexceed 300ff.perminufe orSff. persecond/I close approximafior) /sDiometer ofpipe -] _

Contributed by F. Douglas Wilkes, MACHINERY'S Data Sheet No. 121. Explanatory note : Page 38.


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30 MACHINERY'S DATA SHEETSCONDENSER AND AIR PUMP DATA-IN

No. 15


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No. 15 HEAT, STEAM, STEAM AND GAS ENGINESCONDENSER AND AIR PUMP DATA IV

31


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32 MACHINERY'S DATA SHEETS No. 15Example 1. What weight of steam

will be discharged per minute througha 3^-inch pipe, 100 feet long, with aninitial pressure of 40 pounds, and a dropof 3 pounds?

47.8X1.70= 81.3 pounds.Example 2. What size of pipe will be

required to deliver 51.3 pounds of steama distance of 100 feet, with an initialpressure of 60 pounds, and a drop of 2pounds?The factor for 60 pounds initial pres-sure and 2 pounds drop is 2.02, and51.3 = 25.4, which in Table I corre-2.02sponds to a 3-inch pipe.Example 3. What weight of steamwill be discharged per minute througha 5-inch pipe, 600 feet long, with aninitial pressure of 5 pounds, and a dropof y2 pound?

45.7 X 0.40= 18.3 pounds.The tables given may be applied to

either power or heating work, or to anyconditions where the quantity of steamused can be reduced to pounds per min-ute. Engine ConnectionsSteam pipes for engine connections

are commonly based on a velocity of6,000 and 8,000 feet per minute for thesteam and exhaust pipes respectively,assuming the entire cylinder to be filledwith steam at each stroke. This givesapproximately 0.14 square inches inter-nal area per H. P. for the steam pipeand 0.20 square inches for the exhaust.For example, a 100 H. P. engine wouldrequire

100 X 0.14= 14 square inches, or a4-inch steam pipe; and100X0.20= 20 square inches, or a

5- inch exhaust pipe.Tables V, VI and VII, page 11, give

the diameters of pipe required for heat-ing purposes.

Weight of Steam Discharged bySafety ValvesOn page 12 a table is given of theweight of steam discharged per hour

by safety valves. The amount of steamdischarged by safety valves is a ratheruncertain quantity, but this table maybe considered as giving fair averagevalues. The weights are calculated fora valve lift of 0.1 inch. If the lift ofthe valve is changed, the values givenin the table should be multiplied by thefactors given beneath the table for dif-ferent valve lifts.

Diameters of Steam Pipes andAreas of Steam PortsOn page 13 is given a diagram by

means of which the diameters of steampipes and the areas of steam ports forengines with different piston speeds andvelocities of steam may be determined.The notes in the lower right-hand cor-ner of the diagram explain the signifi-cance of the various curves. The scalesat the top and bottom of the diagramindicate the port area in square inchesor the steam pipe diameter in inches,respectively.For example, assume that it is re-

quired to find the port area for a steamengine, when the piston speed is 500feet per minute, the piston area 20square inches and the velocity of steam6,000 feet per minute. Curve III givesthe port area when the piston areaequals 1, and the velocity of the steamis 6,000 feet per minute. In this caselocate 500 on the left-hand verticalscale, giving the piston speed in feetper minute. Follow the horizontal linefrom 500 until it intersects the diagonalmarked III. From the point of inter-section, follow vertically up or down tothe scale at top or bottom, where inthis case the approximate graduationwould be 0.085, which is the port areaexpressed in square inches for a pistonarea equal to one square inch. In thepresent case, where the piston areaequals 20 square inches, the port areamust be 20 X 0.085= 1.7 square inch.The steam pipe diameter for the sameconditions is found from curve VII, by

(Continued on page 38.)


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No. 15 HEAT, STEAM, STEAM AND GAS ENGINES 33DIRECT-CONNECTED ENGINE AND GENERATOR BASES


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34 MACHINERY'S DATA SHEETSHORSEPOWER OF GASOLINE ENGINES I

No. 15


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No. 15 HEAT, STEAM, STEAM AND GAS ENGINESHORSEPOWER OF GASOLINE ENGINES II


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36 MACHINERY'S DATA SHEETS No. 15PROPORTIONS OF AUTOMOBILE CRANK-SHAFTS I

Four Cf///ncfer 3Jot/mar/ Crank sftcrfte

B - Ci/f/ncfer BoreS/ - P/'sfon StrokeS Ter?s'//e Sfrengf/? ofSfee/ usecfP - Tofa/ Pressure on P/sfon />? Poustc/s

Z/ = Tofcf/ ordggrregrafe Crank Journcr/ j.errgrf/7/200X D

Four Ct///ncfer 3~'Jowrrta/ Crank

Secf/on A-BB= Cu//ncfer BoreS/= P/ston SfrofreP= Tofa/ Pressure on P/sfon /'s?

L/=Tofcr/or/Jgrg're^crfe Crcrr?t< ^/OLtrrrcr/ er?grfr,4/??? 3>%/ 43.4*1/S3OXD

/S/XP5 7=

Contributed by Herbert C. Snow, MACHINERY'S Data Sheet No. 79. Explanatory note : Page 40.


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No. 15 HEAT, STEAM, STEAM AND GAS ENGINESPROPORTIONS OF AUTOMOBILE CRANK-SHAFTS II

37


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38 MACHINERY'S DATA SHEETS No. 15following the horizontal line from 500feet piston speed until intersecting curveVII, and from the point of intersectionfollowing the vertical line upward, theapproximate reading on the upper scalebeing 0.29 inch. The piston diameter is5.05 inches for a piston area of 20 squareinches. Hence the steam pipe diameterrequired is 0.29 X 5.05= 1.46 inch.

Steam Engine DesignOn pages 14 to 17, inclusive, are given

a number of simple rules and formulasfor steam engine design, the details cov-ered being the cylinder, the cylinderheads, cylinder head bolts, piston, pis-ton rod, connecting-rod, crank-pin, valvestem, cross-head, wrist-pin and flywheel.For general guidance in steam enginedesign these rules and formulas willbe found of' considerable value to thesteam engine designer.

Volume of CylindersOn pages 18 and 19 are given two

tables by means of which the volume ofcylinders in cubic feet may be deter-mined when the diameter and the stroke,both in inches, are given. For exam-ple, assume that the diameter of anengine cylinder is 16 inches and thestroke 22 inches. Then we find fromthe lower table on page 18 that the vol-ume is 2.56 cubic feet. Of course, thetable is as conveniently used in thereverse direction. If a cylinder vol-ume of 4 cubic feet is required we findfrom the tables that a cylinder 18%.inches in diameter with a 26-inchstroke very closely fills the require-ments. We also find that the cylinder20 inches in diameter with a 22-inchstroke accurately answers the purpose.A number of other approximate com-binations can also be determined fromthe tables.

Dimensions of Piston Rings,Stuffing Boxes, etc.The table on page 21 gives dimen-

sions of equal section and eccentric

piston rings. These tables have beenin use for several years in a steam en-gine building plant and found to an-swer the requirements. Dimensions aregiven for both lap cut and pin cut typesof piston rings. On page 22 dimensionsare given of stuffing boxes and glands,and on page 23 a table for the pitch ofbolts in water and steam joints is pro-vided. These tables will be found ofvalue when designing steam engines andpower plant equipment.

Setting Corliss Engine ValveGearsOn pages 24 to 27 inclusive are

given directions for the setting of Cor-liss engine valve gears. The explana-tory notes on page 27 give all the re-quired information for the understand-ing of the illustrations on the three pre-vious pages. The directions should befollowed step by step, in order to obtainsatisfactory results.

Condenser and Air Pump DataOn pages 28 to 31 inclusive are givenformulas for the design of condensers

and air pumps, and tables for aid in thiswork. The quantities found from theformulas are the amount of water re-quired to condense one pound of steam,the amount of condensing water perhorsepower, the size of injection pipe,the size of air pump required for a jetcondenser, the size of air pump re-quired for a surface condenser, and therequired condensing surface. The ta-bles on pages 30 and 31, marked IIIand IV, respectively, give the amountof water required to condense one poundof steam, according to the formulasgiven on page 28.

Direct-connected Engine andGenerator BasesOn page 33 is given a table with a

diagrammatical illustration showing alay-out for direct-connected engine andgenerator bases, as arranged either for


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No. 15 HEAT, STEAM, STEAM AND GAS 'ENGINES 39horizontally or vertically parted gen-erators. In cases where the dimensionsgiven cannot be directly applied to thecase in hand, they will nevertheless beof value as guides in making similarlay-outs.

Horsepower of Gasoline EnginesThe horsepower of a gasoline engine

can, of course, be figured easily enoughfrom the well-known formulaPLAN

2 X 33,000in whichP= the mean effective pressure,L= the stroke in feet,A = the area of the piston or cylinderbore in square inches,N= the number of revolutions per

minute.In order, however, to save calculations

a table can be prepared, giving at aglance the horsepower of gasoline en-gines, when the bore and the strokeare known. Such a table is given onpage 34. This table shows the indicatedhorsepower or ideal power. To obtainthe actual horsepower from the indi-cated horsepower given in the table, thefigures stated must be multiplied by afactor based on the mechanical efficiencyof the mechanism, which may vary from94 to 70 per cent, and in some caseseven less. As a fair average, however,80 per cent may be used in the calcu-lations. In the table on page 34, thebore is given in the left-hand verticalcolumn, while the stroke is given in ahorizontal line at the top; beginningwith a stroke which is equal to thebore, which is found in the columnheaded "Bore + 0," the stroke increasesin each successive column by J/4 inchup to the final column, which is 2 incheslonger than the diameter of the bore.Thus the powers given are for enginesvarying from 2-inch diameter by 2-inchstroke, up to 6%-inch diameter by 7-inchstroke. The figures given, are, of course,for a single cylinder, and for multi-

cylinder engines all that is required isto multiply by the number of cylinders.In figuring the table on page 34 the for-mula stated in the preceding column wasused, the mean effective pressure beingtaken as 90 pounds per square inch, andthe number of revolutions as 1,000 perminute. Ninety pounds mean effectivepressure corresponds to a compressionpressure of 68% pounds. This may beverified by using Grover's well-knownformula:P= 2C 0.01C2,where C is the compression.This compression of 68% pounds is

taken as an average figure, but thecompression may in reality vary all theway from 60 to 100 pounds, and racingautomobiles have been built using acompression of 120 pounds.As cars using 60 pounds compression,we may mention the Franklin and Co-vert cars; the Thomas and Moline carsuse 65 pounds, while the Columbia carsuse 100, and the Acme, 102. For thesecases, the power corresponding may befound from the table by multiplying thefigures there given by the followingfactors :For 60 pounds comp., multiply by 0.933" 70 " " 1.011" 80 " ' " " " 1.066" 90 " " " " 1.100" 100 " ' 1.111As an example taken at random, illus-

trating the use of the table, let us findthe power of a 5%-inch bore, 6-inchstroke, 4-cylinder engine. In the lineof 5%-inch bore and in the^ column head-ed "Bore + % inch," we find the value16.2, which, multiplied by 4, gives 64.8,as the indicated horsepower. Assum-ing a mechanical efficiency of 80 percent, we get 51.8 H. P. as the actualhorsepower. In Table II, page 34, isgiven the direct or actual horsepowerof gasoline engines, as figured from theempirical formulaD 2 = horsepower

2.5


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40 MACHINERY'S DATA SHEETS No. 15which was recently adopted by the As-sociation of Licensed Automobile Man-ufacturers. This formula is based on apiston speed of 1,000 feet per minute,which gives 2,000 R. P. M. for a 3-inchstroke, 1,500 R. P. M. for a 4-inch stroke,1,200 R. P. M. for a 5-inch stroke, and1,000 R. P. M. for a 6-inch stroke. Thistable would then compare with TableI only on the basis of 1,000 R. P. M.,which would give a uniform stroke of6 inches for all engines, regardless ofdiameter. As an example, take thesame engine as above, 5^-inch diameterby 6-inch stroke, having 4 cylinders. Inthe table we find the horsepower givenas 12.10. This, multiplied by 4, givesus 48.4, which is reasonably near thefigure 51.8 for the horsepower, previous-ly found, to indicate that the empiricalformula previously given is approxi-mately correct.A more extended table of the horse-power of automobile engines as basedupon the formula of the Association of

Licensed Automobile Manufacturers, isgiven on page 35. The formula, in itscomplete form, is

D* XN2.5

in whichD= diameter of cylinder, andN == number of cylinders.The table gives the horsepower ofautomobile engines as calculated fromthis formula for engines having one,two, four and six cylinders, with thediameter of the cylinder varying from2% to 6 inches.

Proportions of AutomobileCrankshaftsOn pages 36 and 37 are given dia-

grams and a table for designing auto-mobile crankshafts. The formulas usedare given on page 36, and the values ofthe total pressure on the piston inpounds, P, for different compressions,are given in the table on page 37, forvarying bores.


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UNIVERSITY OF CALIFORNIA LIBRARYBERKELEYReturn to desk from which borrowed.

This book is DUE on the last date stamped below.

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