Transactions - American Society of Heating, Refrigerating and Air-Conditioning Engineers . t; rf y ^ N< M^ ~- y h w -^ -^ 1 sv -- ^ ^ pj rr> c E So •v^ ^ , ^ S \ ^ ^w ^ ?-r ^ , ?v ^ s. uj-^ ^ ^ v 2 /<: y , ^ ^, t ^ r ^ ^ X _. ^ ? S \ ^ ^^ / -1 ., U ^00 4000 6000 8000 1000012000 14000 16000 18000 20000 22000 24000^C^bic Test of a No. 8 Niagara Couoidal Fan, 450 IS. of openings. In this way, the quantity of air handled may be variedfrom nothing to the full capacity of the fan, and by this means theperformance of the fan at different capacities may be deter
Transactions - American Society of Heating, Refrigerating and Air-Conditioning Engineers . t; rf y ^ N< M^ ~- y h w -^ -^ 1 sv -- ^ ^ pj rr> c E So •v^ ^ , ^ S \ ^ ^w ^ ?-r ^ , ?v ^ s. uj-^ ^ ^ v 2 /<: y , ^ ^, t ^ r ^ ^ X _. ^ ? S \ ^ ^^ / -1 ., U ^00 4000 6000 8000 1000012000 14000 16000 18000 20000 22000 24000^C^bic Test of a No. 8 Niagara Couoidal Fan, 450 IS. of openings. In this way, the quantity of air handled may be variedfrom nothing to the full capacity of the fan, and by this means theperformance of the fan at different capacities may be fan is then operated at some constant speed, and by means ofa pitot tube in the discharge pipe about twenty diameters from thefan outlet the pressures developed with each outlet are noted. Atthe same time power readings are taken in order to compute thehorsepower and efficiency. These values are then plotted and curves drawn as in Fig. 18,. 60 80 100 120 MO 160 Per Cent of Rated Capacity Performance Curve of Bufifalo Niagara Conoidal Fans. Forward Curved Blade Type. Fig. 19. 62 THE CENTRIFUGAL FAN and by a study of these curves a certain capacity is selected asgiving for the widest range of conditions the most satisfactory per-formance characteristics for this type of fan. This point is thentermed the rating of this size of fan at the speed used. By redraw-ing these curves as shown in Fig. 19, in per cent, of the rated per-formance, the characteristics of this style of fan for any size maybe readily found for any other than the rated capacity. The ordi-nary fan capacity tables are evolved from the values selected aspoint of rating. It will be seen from this diagram, Fig. 19, that the pressure curvesfor a fan with forward curved blades are entirely different from theones already shown in Fig. 17 for the straight blade type. At noload the total pressure is 47 per cent, of the rated, while with thestraight blade fan the rat
Size: 1998px × 1251px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookidtransactions, bookyear1895
