Document 2RNDxryKxj2wE7QGjEkRaRJEr

American Society of Heating and Ventilating Engineers Guide, 1928 condensate returns counter to the steam and where only the condensate from the riser so returns) are given in Tables 4 and 5. Investigation of limiting velocities for horizontal pipe with varying degrees of pitch has not yet been carried to a conclusion but the limiting velocities given in Table 17 are. offered as safe. Further study of the subject may allow them to be increased. Where the velocity of steam is the limiting factor of the capacity of a pipe, care must be taken that this velocity'is not exceeded in any part of the pipe or fittings by a constriction, since the velocity at any one con striction will limit the whole system. For this reason, particular care must be taken to ream such pipe and guard against dope constricting jN om ber zof RldC r 4 L_ J____a______ bottom Ttpc dfCihunu A Squared Enfom S % I1 D"Tioopmt1LiB+uettromc1i1 fToPo ipi1 A IT A 0 c_ A 0 c Sr 3* 3 t5 3 of tsltom A i. <; 33 Point 1 Too * & i s. bottom I | Too A r> c_ u 3 3 <2 L! ftomtd j 2 1 i5 i 5 3 j I 3 3 3 3 33 3 3 3 3 K I Bounded 5 if 3 3 SmqkwMhltltr Three W 3 a jS V & T IS 3 D------- --D _ j, h--A--- 6odared Entrance >--c--- h H-- * -- Reamed Cntimncc *--H I&ukoed Entrance ^inolc^ThrecWkeelCuttc/? w Fig. 9. w jrk=vrRESEARCH LAD ourcau or MINES PtTTMitrt PA. PATC>CTtf-te ' PnWft HO. Effect of Reaming Entrance to One-Pipe Risers it at joints. Iron pipe should also be examined for constricting blisters, Fig. 9 and Table 18, from the Laboratory reports show the importance of these factors. N Table 20 shows variation in capacity of a pipe as affected by variation of . size and smoothness of pipe generally found on the market. The maximum and minimum results were obtained by picking out very smooth and very rough pipe from the stock room of a large manufacturer. Free area of valves, unions, and other fittings as found on the market are not always equal to the inside area of pipe of the same nominal'size. Globe valves show a maximum capacity below that of pipe of the same nominal size. . The maximum capacity of such valves in a hori zontal pipe depends upon whether the stem is vertical or horizontal. Table .19 shows capacities found for valves picked at random from the stock of a large supply house. .* 110 Chapter III--Steam Heating Systems and Piping Table 17- Comparative Capacity of Steam Lines at Various Pitches* Pitch of Pipe in Inches per 101 Ft._______________ ________________- Pitch or Pipe-- 1 IN. Pipe Site s sSq. Ft Rad. Baaed on 240 B.t.u. > i Sq. Ft Rad. Based on 240 B.t.u. > s Sq. Ft Rad. Based on 240 B.tu. M a x .V e l. M a x .V e l. 1J4 m. 2 IN. 3 IN. SSq. Ft. Rad. Based on 240 B.tu. "3 > 5 Sq. Ft. Rad. Based on 240 B.tu. Sq. Ft > Rad. i. 2 Based on 240 B.tu. 4 IN. 5 IN. Sq. Ft Sq. Ft. Rad. Based on 240 B.tu. > 1 2 Rad. Based on 240 B.tu. 5 2 12 30.3 14 37.3 18 40.4 19 42.5 20 46.1 21 47.5 22 49.3 23 12 52.6 15 63.0 17 70.0 20 75.2 22 83.0 23 87.9 25 90.2 26 18 117.2 20 133.0 23 144.5 25 154.0 27 165.0 28 172.6 29 178.2 31 18 159.0 21 181.0 23 196.5 25 209.3 27 224.0 28 234.8 30 242.6 31 r 236.0 19 263.5 20 299.5 23 325.5 25 346.5 27 371.5 28 388.4 29 401.1 30 Table 18. Effect of Reaming Entrance to One-Pipe Risers* See Fig. 9 Maximum Capacity of Riser Reamed entrances..................... ......... Rounded entrances.. -......................... - Squared entrances................ .............. Three wheel cutter.............................. 24.7. lb. per hr. 23.9 lb. per hr. 22.2 lb. per hr. 19.2 lb. per hr. Single wheel cutter.................. ........... 17.6 lb. per hr. Per Cent Decrease 0.0 3.2 10.1. 22.2 28.7 Table 19. Results of Tests on Angle and Globe Valves* Nominal Size of Pipe In. x i 1M IX Area of Pipe Sq. in. 0.537 0.835 1.459 1.927 Area Valve Seat Opening Sq. In. Per Cent of Area of Pipe 0.4418 0.822 1.258 1.773 82.2 98.4 86.2 92.2 Maximum Pipe and Valve 9.68 22.10 30.00 46.13 Capacity Pipe Alone Per Cent of Capacity of Pipe Alone 13.52 23.30 47.5 68.5 71.6 95.0 63.1 67.4 Nominal Size In. . X' i m 1H Valve Stem--Vertical Capacity of Pipe and Valve Lb. per Hr. 1.38 7.73 13.20 18.81 Per Cent of Capacity of Pipe Alone 11.8 35.7 31.2 33.0 Valve Stem--Horizontal Capacity of Pipe and Valve Lb. per Hr. 8.83 14.06 22.88 32.00 Per Cent of Capacity of Pipe Alone 76.3 66.1 54.3 56.7 Table 20. Per Cent Difference in Capacity Due to Variation of Pipe Size and Smoothness* Maximum Condensation, Lb. per Hr. Capacity of Pipe...... Minimum. Maximum__ Per Cent Variation X" 14.00 15.20 8.6 1" 24.89 30.08 20.8 IX' 45.42 52.08 14.7 IX' 70.50 82.00 16.3 Data from American Society op Heating and Ventilating Engineers Research Laboratory.