英语翻译The two purposes of mine ventilation are:(1) to answer t

英语翻译
The two purposes of mine ventilation are:(1) to answer the requirements of the law in regard to suplying a stated quantity of fresh air per minute to each man in the mine,and to dilute,render harmless,and sweep away dangerous gases.① In coal mines the quantity of fresh air prescribed is generally from 100 to 150cu.ft/min/ man in the mine.② Some mining regulation specify a maximum limit to the quantity of methane permitted in the return air of coal mines,and some limit the amount of carbon dioxide permissible in the mine air.(2) to make working condintions more comfortable for miners.If conditions of humidity and air temperature are favourable,a decided cooling effect on the men is secured by giving the proper velocity to the air current,and the efficiency of the miners is increased.③ Dust and fumes from explosives are also removed.
Natural and Artificial Ventilation
Press differences required to cause air flow,may be produced by natural or mechanical forces.Flow caused by unequal densities or weights of air columns in or near the openings (due mainly to temperature differences) is “natural-draft” flow,and resulting pressure-differences are “natural draft” pressure.④The relatively feeble currents forming complete flow-circuits in undivided single openings,also due to equal densities,are separately termed “convection currents”.Many metal mines and some small coal mines are ventilated by natural draft alone,which also acts in conjunction with fan pressure in mechanically-ventilated mines;where its importance largely depends on depth of workings and mine resistance.⑤
In mines where the natural ventilation pressure is inadequate to supply the necessary air,fans are used.However,the effect of natural ventilation on the performance of the fan is important.Owing to the change in temperature from summer to winter conditions,natural ventilation may reverse its direction; in one case it assists the fan,in the other case it opposes it.⑥
Ventilation of coal mines is nowadays almost universally effected by use of the fans,of which there are many types.Such fans may either exhaust the air from the upcast shaft or blow or force the air down the downcast shaft.With few exceptions,exhausting fans at the top of the up-cast shaft are used in modern mines.
Although many types of fans are used for mine ventilation,they fall into two classes,viz,the centrifugal or wheel-type fan and the axial-flow or propeller type fan.

我的通风的这二个目的是:(1) 每分钟对矿的每个男人回答对 suplying 新鲜空气的决定了量的在关心的法律的需求,而且冲淡,提出无害处的,而且扫掉危险的瓦斯.在煤矿中的①通常被规定的新鲜空气的量是从 100 对 150cu.在矿中的 ft/最小/ 男人.②一些采矿规则叙述对在煤矿的回返空气中被允许的甲烷的量的一个最大的界限,而且一些界限大量的二氧化碳可允许的在矿中晾干制的.(2) 使矿工的工作 condintions 更舒服.如果湿气和空气温度的情况是有用的,确定的冷却效果在男人上被藉由把适当的速度给空气涌流保护,而且矿工的效率被增加.来自炸药的③灰尘和臭气也被移动.
天然和人造的通风
压必需引起气流的不同,可能被肉色或机械的军队生产.由不相等密度或者空气专栏的压重所引起的流程在或者在开口 (主要地由于温度不同) 的附近是流动的 " 肉色 - 草稿 " 、和产生的压力-不同是 " 天然的草稿 " 压力.④相对微弱的涌流形成完全的流程-未分开的单一开口的线路,也适当的等于密度,分开地被称 " 对流涌流 ".许多金属挖掘,而且一些小的煤矿独自地被天然草稿通风,哪一个也连同狂热者压力行动在机械通风的挖掘;它的重要性主要地仰赖工作和我的抵抗的深度地方.⑤
在挖掘哪里天然的通风压力不充分供应必需的空气,扇被用.然而,天然通风对狂热者的表现的效果很重要.由于从夏天到冬天的在温度方面的改变情况,天然的通风可能颠倒它的方向; 在一情况,它协助狂热者,在另一个情况,它反对它.⑥
煤矿的通风是几乎普遍地现在产生被狂热者的使用,其中有许多类型.如此的狂热者可能或用尽来自向上抛的桥的空气或者打击或者强迫空气 落气馁的桥.藉由少数例外,在向上-阵容桥的顶端用尽狂热者被用于现代的挖掘.
虽然狂热者的许多类型作为我的通风,但是,他们掉入二个班级、 viz 、离心或轮子-类型的狂热者和轴者-流程或螺旋桨类型狂热者.