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330 8' > <o92_ofa" I IS isa fa ?s Z 9 W(g PD Pj 5o5. e2sso Q j| 6O$.So ~*fa CHAPTER 14 1953, Guide 33 SO' E gg a a ja S'l. J0S J3 O 3*0V-2 KS J-g s sa |. .2 : S|3 fro m"Ifsls,0_ J>Q 0- g ii i* IS-rj 2s 8. *" ii |s is5 la"' &| 5"aa1a3; i** .8s|g'jS"i?2l; J*is"0of3g"|*s2>| f3lj3ag.Snj. >.3|*-52 "3 fe*S3--SS:-S>-gg"SH.92 2 0** &-S p o- ftOS8So^fl3fl SW^f-o^g-Slgs ^JSg s1- ao Qii. J" MNrsC--^Ro. >; =-a 8 S.9 2s. s^-iSa'-oS" 6 S6* oH.ges*S3 s8s.iI . -b3Sa*- I8- "os 1.2 . D e ta ile d R equirements fob F u e l Oils 1 |1t 3SS5B e^ S8g &< afc hs .. foa S2 ' o fa H2 ''ft3. S0 ' O S1 ~s iti' ac s. bi8! a U_ 2*1 gg6, s i- J** - S.( 5T^3O-AS3.id"S ** ft. rr,." Ec 'Sa * 2U r? 0 IP ao ga 3>i ao_.'S> SkS H 2 3 So3 " S-** 2 J'a a-- . 11 2 c' .3** 55 13 rsja c P-0 a-f II IsO <5 55* 0a > '~JS &.-Sa? 2c t* 3.2 is .2 a 1 sj `S A3 Jd Jg >oS Pa * SS0J> t5*?-2&atg>_ 8 "3 3 .sgSS I sf-f 0 8 | 85 3^ Sfi 5 80 3^ *3 q ~ij III 3co*0 2 *ga -- 0*0 0 * 0 III! 1 |l| J l$2 iai--?; | ll? a 55s o^S H.M2K0Z IggIH, .5 O 41 D ^ 0M C.33fa. J3. .0. l .Sa| S33J "3I u ! 2 *5 Sg c O' |3 i So o s= g I 3 -sa Fuels and Combustion 331 Table 5. Approximate Gravity and Calorific Value of Standard Grades of Fuel Oil Commercial Standard No. Approximate Gravity Range A.P.1. Calorific Value Btu Per Gallon 1 35-45 138,800-132,900 2 26-40 . 144,300-135,800 4 12-25 153,000-145,000 5 10-23 . 154,600-146,200 6 8-17.5 156,000-149,700 Grade Classification of Fuel Oils Fuel oils are most commonly classified by dividing them into grades in accordance with the Commercial Standard (CS12-48) entitled Fuel Oil published by the U. S. Department of Commerce. These specifications, given in Table 4, conform to ASTM Materials Tentative Specifications for Fuel Oils D 396 - 48 T. Oils may be classified roughly by specific gravity but it is not an adequate index of the suitability of an oil for a given purpose. Other characteristics of fuel oils which determine their grade classification in the Commercial Standard, and their suitability for given uses are the flash point, pour point, water and sediment content, carbon residue, ash, sulfur content, distillation characteristics, and vis cosity. The flash point of an oil is important with regard to safety in storage and ease of ignition in systems employing automatic ignition. The distil lation characteristics determine whether or not the oil can be completely evaporated in some types of burners, and whether cracking will be likely to occur prior to combustion. A low pour point and low water content are desirable for outdoor storage in cold climates. Sediment, carbon residue, and ash should be low to prevent clogging of strainers and the accumulation of unbumed material in the burner. A low viscosity allows the fuel oil to flow through supply lines readily and to be broken up into small droplets in atomizing type burners. The sulfur content is of importance because sulfur compounds corrode the burner and heating system or because un desirable compounds of. sulfur may be formed in certain industrial processes. Some of these characteristics of a fuel oil are required to he within certain limits for each of the grades of fuel oil listed in Commercial Standard CS12-48. Some fuel oils do not fall into any of the grade classifications of the Commercial Standard because failure to comply with all of the re quirements of one grade does not automatically place the fuel oil in the next lower grade, unless it meets all of the requirements of the lower grade. By ultimate analysis the No. 1 and No. 2 fuel oils contain 84 to 86 per cent carbon, 12.0 to 13.5 percent hydrogen, one to three percent oxygen and nitrogen, and 0.5 percent or less of sulfur. The heavier grades of fuel oil, Nos. 4, 5 and 6, may contain as much as 88 percent carbon, as low as 11 percent hydrogen, and considerably more sulfur than is permissible in the domestic grades. Due to variation in the constituents of different fuel oils and the differ ent refining methods used, the API gravities and calorific values of the different grades of fuel oil cover a range in each grade with some overlapping between domestic grades and between commercial and industrial grades. The relation between the API gravity of fuel oils and their calorific value is shown in Table 5. Grades No. 1 and No. 2 are used predominantly in domestic heating equipment whereas grades 5 and 6 are used in commercial