Document B8O6R7E7Eqm0MjQrkmgQYv7BL

HEATING VENTILATING AIR CONDITIONING GUIDE 1943 factors in the increased susceptibility to gastrointestinal disorders in hot summer weather. In warm atmospheres, particularly during physical work, a considerable amount of chloride is lost from the system through sweating. The loss of this substance may lead to attacks of cramps, unless the salts are replaced in the drinking water. In order to relieve both cramps and fatigue, it Table 3. Relation Between Metabolic Rate and Activity3 ActrvrrT HOUBLT Metabolic Rate for Avo Person or Total Heat Dissipated, Btu per hour Hourly Hourly Sensible Latent Heat Dis Heat Dis sipated, sipated, at 79 F, at 79 F, Btu per Btu per Hour - Hour Moisture Dissipated per Hour Grains Pounds Basal.................... -........................... -...... -................ 291 Seated at Rest..................................._...................... 384 Reading Aloud (Seated).-....................................... 420 Standing at Rest....................................-................. 431 Hand Sewing (Seated) .....................__............... 441 Knitting 23 stitches per minute on Sweater___ 462 Dressing and Undressing...... ............................ ...... 468 Tailor........ ................... ................................................ 482, Singing........ ................. -.............. -...............-............ 486 Office Worker Moderately Active...... .................. . 490 Light Work Standing............................... ............... 549 Typewriting Rapidly................................................ 558 Ironing with 5 Id iron._............................................ 570 Dishwashing--Plates, Bowls, Cups and Saucers 600 Clerk Moderately Active Standing at Counter.. 600 Book Binder.-......................... .................-................ 626 Shoemaker.......... ............................. ............ .............. 661 Sweeping Bare Floor 38 Strokes per Minute.... 672 Pool Player.--........................... ................................. 680 Walking 2 mph, Light Dancing.......... .................. 761 Light Metal Worker (at Bench)............................ 862 Painter of Furniture (at Bench)........................... 876 Carpenter..................................... ............................... 954 Restaurant Serving................................................... 1000 Pulling Weight--...................................................... 1041 Walking 3 mph.......... ..............................-......... . 1050 Walking 4 mph, Active Dancing, Roller Skating 1390 Walking Down Stairs............... ............................... 1444 Stone Mason____ ...................................................... 1490 Bowling................. ....................................................... 1500 Man Sawing Wood................................................... 1800 Swimming............................ ....................................... 1986 Running 5.3 mph.....................................-............ . 2268 Walking 5 mph.......... ................................................ 2330 Walking Very Fast 5.3 mph.......... ........................ 2580 Walking Up Stairs...... .............................................. . 4365 Maximum Exertion Different People.--.............. 3000-4800 145 225 225 225 225 225 225 225 225 .225 225 225 225 225 225 225 225 229 230 250 277 280 307 325 335 339 452 467 485 490 590 145 159 195 206 216 237 243 257 261 265 324 333 345 375 375 401 436 443 450 511 585 596 647 675 70S 711 938. 977 1005 1010 1210 978 1072 1315 1389 1457 1598 1639 1733 1760 1787 2185 2246 2326 2529 2529 2704 2940 2987 3055 3446 3945 4019 4363 4552 4774 4795 6325 6588 6777 6811 8_1_6_0 ...V.... 0.140 0.153 0.188 0.198 0.2080.228 0.234 0.248 0.251 0.255 0.312 0.321 0.332 0.361 0.361 0.386 0.420 0.427 0.434 0.492 0.564 0.574 0.623 0.650 0.682 0.685 0.904 0.941 0.968 0.973 _1._1_66 ___ -- aThese metabolic rates were compiled by the A.S.H.V.E. Research Laboratory from actual tests, from other authoritative sources, and from estimates based upon various considerations. Division of the total heat dissipation into latent and sensible rates is based on actual test data and on various considerations for metabolic rates up to 1250 Btu per hour, and extrapolated for higher rates.. Values for total heat dissipa tion for a person at rest apply for a dry-bulb temperature range from, approximately 60 to 90 F; for'other than rest conditions the values apply for a similar but lower temperature range. Below these temperature ranges metabolic rates and total rates of heat dissipation increase, while above these ranges metabolic rates increase slightly and total heat dissipation rates decrease rapidly. Division of total dissipation rates into sensible and latent heat holds only for a dry-bulb temperature of 79 F. For lower temperatures, sensible heat dissipation increases and latent heat decreases, while for higher temperatures the reverse is'true. 52 CHAPTER 2. PHYSIOLOGICAL PRINCIPLES is recommended that 6 g of sodium chloride and 4 g of potassium chloride be added to a gallon of water22. _ The deleterious physiologic effects of high temperatures exert a power ful influence upon physical activity, accidents, sickness and mortality. Both laboratory and field data show that physical work in warm atmos pheres is a great effort, and that production falls progressively as the tem perature rises. The incidence of industrial accidents reaches a minimum at about 68 F, increasing above and below that temperature. Sickness and mortality rates increase progressively as the temperature rises. The need of air conditioning for workers in hot industries is growing rapidly and this should become an important field for the air conditioning engineer. The hot conditions may be remedied by any of the recognized comfort cooling applications. The choice of the type of system and cycle to be used in a given instance must be determined by the air conditioning engineer after a study of surrounding conditions. Recently it has been shown that in some hot industries where a small number of workers are engaged in spaces of large volumetric capacity the worker himself, rather than the entire environment, can be cooled by either placing him in a small cooled and ventilated booth, by blowing cooled air over him, or by circulating cooled air through a loose-fitting suit23. RELATION OF AIR CONDITIONING NEEDS TO METABOLISM The major objective of heating and ventilation is to balance heat losses from the human body. The basic factor is metabolism. The desirable environment, from the standpoint of heat loss, depends directly on the heat.produced in the body and this heat may be over ten times as great when a man is exercising violently as when he is reclining and at rest. Therefore, there is no absolute optimum of air temperature or other environmental conditions, which will meet all cases. With moderate, (45 per cent) relative humidity and minimum air movement, an air tem perature of 80 F has been found ideal for the lightly clothed subject at rest in a semi-reclining position, while normally clothed, healthy persons have been found comfortable at 72 and 77 F with 45 per cent relative humidity (or 67 and 71 deg ET, respectively) for winter and summer conditions. In factories where light work is performed in summer time, the ideal has been found to be about 76 F. For children (who have a high metabolism) at school, in winter clothing, 70 F has been considered correct; while in a gymnasium, 55 F has been recommended. The wide variations in metabolic activities with which the engineer must be prepared to cope and the influence of such variations in metabo lism on the heat load contributed by the human body to the environment are given in Table 3 and in Figs. 2, 3 and 4. It should be noted that metabolism and heat dissipation values are proportional to the body surface areas of the persons considered; and that the data referred to are ----------- . tJSome Effects of High Air Temperatures Upon the Miner, by K. N. Moss (Transactions Institute of Mtntng Engineers, Vol. 66. 1924, p. 284). "A.S.H.V.E. Research Report No. 118S-t--Local Cooling of Workers in Hot Industry, by F. C. Houghten, M. B. Ferderber and Carl Gutberlet (A.S.H.V.E. Transactions, Vol. 47, 1941, p. 403). 53br