Document mbrpK22nNMbbwVRJRxd9ZzxOB

HEATING VENTILATING AIR CONDITIONING GUIDE 1941 K a jo !ssr gs !! 4 W h Co s . Sjs >c c4J _ I" %3Eoo-a*-ooKcfTMgohS. e *Sfw*ctJ>tC,3.VOoco3.*ci): *o a *<fc .Xre3c5t c^oou*0^0sS Pg is WO 8*| Ss ^3 EP=tl> tf 8o*?j fe Jl5| .tB.5 ?=t f I'll f|s sjg Sg* ISilPfbsS-3??. 6-3 g !"-1Is%?=csSp gS8-5gp-Sj.8||"j &*3.g? c:<S4 '- mv tHiCri 2u V--r o^.oO cc< fc-f_ ll3cH'OiMaE1 a5 S5 3 G2o g g^3*5-o ef 2=b3 .oc3"*i*S3 atg. ^g5^~j *- v C 3n O J.`cJ u g : %> &a.Sa *3,y`3Z*0, hu$EMB E0> i**an** ^IPEH"i22iSo;|l! ` -S' c8s*'ig"o"<?s; D etailed Requirements for F uel Oils js= jjji 5"3 tt ss.5QS.5| *}3 **-3 vctt v i . ' <31o0plOc>ts5. OZZo c jo E3 s-s 56 Hi*3 CO < : -1 V 3; c H 5 *-5 3*.E|8 JSjo--c --s*i0s* S,,s 2S9 see J4OJ/ Ct4) 4XG) cws'v.si: -30(7 T3 I '51 a -=.s- Bsai ouZo Z6 Zo 6ZoZ: s. -O>c * 160 CHAPTER 7. COMBUSTION AND FUELS losses, if not accompanied by unburned products of combustion (satu rated and unsaturated hydrocarbons, hydrogen, etc.) may be offset some what by increasing the secondary heating surfaces of the heat absorbing medium boiler or furnace. Oil is a highly concentrated fuel composed mainly of hydrogen and carbon. In its liquid form oil cannot bum. It must be converted into a gas or vapor by some means. If the excess air is to be kept within efficient limits it means that air must be supplied in carefully regulated quantities. The air and oil vapor must be vigorously mixed to get a rapid and com plete chemical reaction. The better the mixing, the less excess air that will be needed. The combustion must take place in a space that maintains the temperatures high so the reaction will not be stopped before com pletion. When equipped with a means of igniting the oil and safety devices to guard against mishaps, the oil burner possesses all of the elements to be efficient and automatic. Table 8. Approximate Gravity and Calorific Value of Standard Grades of Fuel Oil COMMERCIAL Standard Ko. i 2 3 5 6 Approximate Gratttt, Range Baume 38-40 34-36 28-32 18-22 14-16 Calorific Value Btu Per Gallon 136,000 138,500 141,000 148,500 152,000 CLASSIFICATION OF GAS Gas is broadly classified as being either natural or manufactured. Natural gas is a mechanical mixture of several combustible and inert gases rather than a chemical compound. Manufactured gas as dis tributed is usually a combination of certain proportions of gases produced by two or more processes. Representative properties of gaseous fuels commonly used in domestic heating are presented in Table 9. Natural gas is the richest of the gases and contains from 80 to 95 per cent methane, with small percentages of the other combustible hydrocarbons. In addition, it contains from 0.5 to 5.0 per cent of COz, and from 1 to 12 or 14 per cent of nitrogen. The heat value varies from 1000 to 1200 Btu per cubic foot, the majority of natural gases averaging about 1000 Btu per cubic foot. Table 9 shows typical values for the four main oil fields, although values from any one field vary materially. Table 9 also gives the calorific values of the more common types of manufactured gas. Most states have legislation which controls the distri bution of gas and fixes a minimum limit to its heat content. The gross or higher calorific value usually ranges between 520 and 545 Btu per cubic foot, with an average of 535. A given heat value may be maintained and yet leave considerable latitude in the composition of the gas so that as distributed the composition is not necessarily'the same in different dis tricts, nor at successive times in the same district. However, in any community the variations in gas composition are held within suitable 161