Document ZB1ppD4RkG60brOeZkOjZdw3O

i I American Society of Heating and Ventilating Engineers Guide, 1929 Table. 2. Areas of Standard Size Pipes of Standard Weight Nomina! See of Pipe Inches 1M 1mM 2 2M 3 3M 4 5 6 8 10 12 Area of Pipe 8q. In. 0.192 0.305 0.533 0.863 1.496 2.038 3.356 4.784 7.388 9.887 12.73 19.99 28.89 50.04 78.84 113.10 , not usually the case to find much attention given to complicated formulae and curves; this is for the reason that the saving on installations involving only a few hundred dollars is so small as not to justify elaborate engi neering calculation besides which the work itself is generally installed by a competition contractor and no funds are available for which a proper designer could be employed. As a general rule the contractor himself does all the designing which is necessary and he doesn't want to be bothered with any complication which can in any way be avoided. Probably the simplest way of determining hot-water pipe sizes in the ordinary small gravity system is the old method of taking the area of each radiator connection or valve and adding these areas together where the lines join, making the area of combined line practically equal to the sum of all the areas which the line supplies. Thus if a pipe is feeding three radiators, one with a %-in. connection, one with a 1-in. connection and the third with a lj^-in. connection the sum of these areas is as follows: 1 in......................... 0.863 sq. in. 1H in......... -.......... 2.038 Min....... ,............0.533 3.434 sq. in. Referring back to. the table it will be found that the pipe which has practically the same area is a 2-in. pipe which has an area of 3.356 sq. in. For jobs of somewhat larger character where too much refinement is Table 3. Square Feet of Radiation Allowable on Risers up to 100 Ft. Height Nominal Pips Sra Distance above the Boileb m Feet 10 20 30 40 50 .60 70 80 90 100 M---------------------- 40 .. 50 60 .70 80 . 90 100 no 120 130 l....................... ....... 70 80 90 100 110 120 130 140 150 160 1M---------------------- no . 120 135 150 160 175 185 200 210 225 1J4------------- --- - 180 185 210 230 250 265 285 300 315 330 300 350 400 500 575 625 700 . 775 825 900 128 Chapter IV--Hot Water Heating Systems and Piping unnecessary but at the same time closer results than that given in the above are desired, the table given below which takes into the consideration the heig;ht of the riser available to circulate the line may be recommended. The risers are then connected up to the mains on the basis of allowing a factor for each size of pipe and then adding these factors to obtain the factor corresponding to the proper size of basement main. These factors are as follows: Table 4. Factors for Various Sizes of Pipe in Gravity Hot Water Heating Nominal Size of Pipe. laches M l 1M 2 2M 3 3 y2 4 5 6 8 10 12 Factor 5 10 20 30 60 110 175 260 380 650 1050 2250 Thus, if the. three radiators previously Considered were set and sized as follows; the %-in. radiator with 20 sq.. ft., and located 40 ft. above the boiler; the 1-in. radiator with 40 sq. ft. and set 20 ft. above the boiler and the 1 J^-in. radiator with 75'sq. ft., and set 10 ft. above the boiler all being on the same riser, the riser size would be as follows: Riser for 20 sq. ft. radiator 40 ft. above............................. M in. Riser for 40 sq. ft. radiator 20 ft. above. .....................--. M in. Riser for 75 sq. ft. radiator 10 ft. above............................ 1M in. To combine into one riser take the factors and add; M in---......... M in............... ..... 5 1M in............... ..... 20 Total....... ...... 30 arid the factor 30 is equivalent to a lj^-in. riser. ': Even if these radiators had all beeri placed on the first floor (or 10 ft. above the boiler), the riser size of lJ/-in. would still have been sufficient for the three or their equivalent in one radiator. This indicates that the method of combining valve areas gives about one pipe size larger than when more accurately figured. AIR SEALED OR CLOSED HOT WATER SYSTEMS* For many years the closed system of hot-water heating iri some form has been used successfully abroad, but there has been little thought given to and no research work done in connection with the a'r sealed system in this country, so that available data is meagre. For design 2Prepared from data submitted by R. H. Feltwell, Philadelphia and H. A. Thrush, Peru. Iud. 129