. A manual of practical hygiene. like a siphon, andsucks all the water out of the trap ; to avoidthis, the pipe should be large enough to pre-vent its running full, or the trap should be oflarger calibre than the rest of the pipe. This,however, will not always prevent it, as even6-inch pipes have sometimes sucked a siphon adry. The question has lately been very care-fully investigated in America, by Messrs. Phil-brick and Bowditch,1 whose report has shownthe danger of unsiphoning which small pipesare exposed to. The remedy appears to beto introduce an air-vent at the crown of the trap(see Fig.
. A manual of practical hygiene. like a siphon, andsucks all the water out of the trap ; to avoidthis, the pipe should be large enough to pre-vent its running full, or the trap should be oflarger calibre than the rest of the pipe. This,however, will not always prevent it, as even6-inch pipes have sometimes sucked a siphon adry. The question has lately been very care-fully investigated in America, by Messrs. Phil-brick and Bowditch,1 whose report has shownthe danger of unsiphoning which small pipesare exposed to. The remedy appears to beto introduce an air-vent at the crown of the trap(see Fig. 84), and not to have too small a pipe,especially when several pipes unite in one generalwaste. The experiments also showed how un-siphoning might take place from the pressure ofdescending water from upper floors, so that air might be forcibly driven 1 The Sanitary Engineer, vol. vi., p. 264, 1882 (New York). The Siphonage andVentilation of Traps, Report to the National Board of Health, by E. W. Bowditch andE. S. Philbrick, Fig. 84.—Siphon Closet Basins withventilating pipes. A, Soil pipe pass-ing up above the eaves, with opentop. B, Subsidiary VentilatingPipe (also passing up above eaves,with open top) to prevent suckingof the siphon. 26 PRACTICAL HYGIENE. into the house when upper closets or sinks were used. 5th, Traps mayperhaps be inefficient from the pressure of the sewer air, combined withthe aspirating force of the house displacing the water, and allowing theah uninterrupted communication between the sewer and the house. Theextent of the last danger cannot be precisely stated. From a long seriesof observations on the pressure of the air in the London sewers, Dr. Bur-don-Sanderson ascertained that in the main sewers, at any rate, thepressure of the sewer air, though greater than that of the atmosphere,could never displace the water in a good trap. In a long house drainwhich got clogged, and in which much development of gaseous effluviaoccurred, there might possibl
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Keywords: ., bookcentury1800, bookdecade1880, booksubjecthygiene, bookyear1883
