安全工程專業(yè)英語翻譯-展示頁
2024-11-12 09:33本頁面
【正文】 he pressure must be exerted. CREATING THE PRESSURE There are two main types of fan: 2 ? Axial: these are generally highvolume, lowpressure fans, either directly driven by the motor shaft (with the motor inside the tube body) or remotely driven using belts (with the motor outside the tube body). These are generally adjustable for volume by setting the pitch of the adjustable blades on the rotor and, in some cases, motor speed can be tailored to adjust volume and pressure. ? Centrifugal: these are generally highpressure, lowvolume fans that consist of a multibladed, squirrelcage wheel in which the leading edge of the fan blades curves toward the direction of rotation. These fans have low space requirements, low tip speeds and are relatively quiet. AUXILIARY VENTILATION The ventilation of deadend workplaces is the most frequent and Important application of auxiliary ventilation. It is used for both development and exploration work, as well as for production headings with only one entrance. A major inconvenience with any method of auxiliary ventilation during development is the necessity of frequent extension. The auxiliary airstream must be delivered as dose to the face as possible so that it can sweep away any impurities that have been generated. The two main methods of ventilating the faces of deadend workplaces are erecting linebrattice (air entering on one side of the brattice and returning In the other side) and the installation of a fan, coupled with ventilation tubing. The practice of redirecting the main ventilation system with smaller, local fans is used where a line brattice is not adequate. Tubing, often suspended from timbers or roof bolts (if approved), carries the air to, or away from, the working face (tubing is rigid for exhaust systems and collapsible for forcing systems). This auxiliary
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