. Transactions. g, 18-Ft. American Fan, Blade-Tips Bent Forward to Radial. This method of testing has many advantages over any testmade directly on the mine, for the reason that it avoids all com-plications and uncertainties due to natural ventilation. Anydesired condition can be established almost instantaneously,maintained as long as desired, and re-established if necessaryto verify results. The temperature and barometric correctionsare simpler. Any fan can be tested under identical conditions, Op cit. 460 CENTRIFUGAL VENTILATORS. without regard to its particular mine; and there is no interf
. Transactions. g, 18-Ft. American Fan, Blade-Tips Bent Forward to Radial. This method of testing has many advantages over any testmade directly on the mine, for the reason that it avoids all com-plications and uncertainties due to natural ventilation. Anydesired condition can be established almost instantaneously,maintained as long as desired, and re-established if necessaryto verify results. The temperature and barometric correctionsare simpler. Any fan can be tested under identical conditions, Op cit. 460 CENTRIFUGAL VENTILATORS. without regard to its particular mine; and there is no interfer-ence with the regular ventilation of the mine. The water-gauge was taken close to the inlet hy means of apipe extending nearly to the outer end of the shaft, the endbeing protected hy flannel so as to avoid variations due to theimpact of the air. The air was necessarily measured in thechimney, at the point marked in Fig. 1, plane of air-measure-ment. The area of the chimney at this point was divided by Fig. 6. Guibal Spiral Casing of a 36-Ft. English Fan. wires into 16 equal rectangles, and the anemometer, mountedon a rod, was held in the center of each rectangle for a giveninterval, usually one minute, timed with a stop-watch. Theanemometer was then moved to the center of the next square,and so on until all had been covered, the total reading for the16 squares being used in determining the average velocity ofthe air-current. All the measurements were checked by the use of two ane- CEN l i:il i •. \l. \ l \ I I l. \ rORS. 161 >.- •5s 5 : - 8g Y pi 1 T^ ~^ O : ~? •~ O ~ * 1k I X - 00 vpnoJO)tK>ipu] ; MM jo .1 H 1 •MV HI .1 II 1S •••M* -uo itraivAfiiDa II. » J,*i .11V .1 l\\ uuojj iw 11.) oo\ [VQUOJ] jwuil-^ ;<! Jiy •ainiiij*; jad*y yaodg£iaqdfJd(] no•A3H Jad Jiy
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
