. The principles of hygiene; a practical manual for students, physicians, and health-officers . FlG. 19.—Apparatus for removing dust in manufacturing establishments:a, emery weeel; b, hood over emery wheel; c, exhaust shaft. absence of air currents, from which it may be removedby means of a damp Fig. 20.—Apparatus for removing dust in manufacturing establishmentsa, blower; b, dust-collecting chamber; c, water-sprays. REMOVAL OF,DUST. 81 Comparison of Extraction and Propulsion Methods The extraction method is less costly and utilizes thenaturally high temperature of the vitiated air to
. The principles of hygiene; a practical manual for students, physicians, and health-officers . FlG. 19.—Apparatus for removing dust in manufacturing establishments:a, emery weeel; b, hood over emery wheel; c, exhaust shaft. absence of air currents, from which it may be removedby means of a damp Fig. 20.—Apparatus for removing dust in manufacturing establishmentsa, blower; b, dust-collecting chamber; c, water-sprays. REMOVAL OF,DUST. 81 Comparison of Extraction and Propulsion Methods The extraction method is less costly and utilizes thenaturally high temperature of the vitiated air to assist inthe ventilation. Its disadvantages are that the source ofthe incoming air is not under control, and, consequently,impure air may be admitted and there is greater liabilityto draught. In the propulsion method the inlets areentirely under control if properly arranged, and thepurity of the air can be assured, as well as its suitabletemperature and velocity, so as to avoid draughts. Aproper diffusion of the incoming air throughout the roomis more easily effected in the propulsion than in the ex-traction method. The disadvantage of propulsion is itsgreater cost. A combination of the two methods is fre-quently employed, and meets all the requirements. Comparison of Natural and Artificial Me
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Keywords: ., bookcentury1900, bookdecade1900, booksubjecthygiene, bookyear1901
