AMIE Study Circle Blog

The analysis of a sample of air from old workings is reported to be O 2 – 19.3%, CO 2 – 0.4%, N 2 = 79.8%, CH 4 – 0.5%. Find the percentage of air and black damp in the sample, as well as composition of black damp. Standard composition is not given. These values can be taken as CO 2 – 0.03, O 2 – 20.93 and N 2 – 79.04 respectively (if not given). CO 2 eq = CO 2 wrt O 2 \( = \left( {\frac{{C{O_{2,std}}}}{{{O_{2,std}}}}} \right){O_{2,ret}} = \left( {\frac{{0.03}}{{20.93}}} \right)x19.3\) = 0.028 N 2 eq = N 2 wrt O 2 \( = \left( {\frac{{{N_{2,std}}}}{{{O_{2,std}}}}} \right){O_{2,ret}} = \left( {\frac{{79.04}}{{20.93}}} \right)x19.3\) = 72.88 --- The study material for AMIE/BTech/Junior Engineer exams is available at https://amiestudycircle.com

Explain homotropal and antitropal ventilation. Homotropal ventilation  Ventilation by a current of air travelling in the same direction as the flow of mineral out of a mine. Antitropal ventilation  Ventilation by a current of air travelling in the opposite direction to that of the flow of mineral out of the mine. What do you understand by flame-proof apparatus? The equipment is simply contained in a heavy protective enclosure, usually made of die-cast steel, occasionally plastic. If heat or sparks from faulty equipment within the enclosure ignite flammable gas present with it the resulting explosion is contained within the enclosure.  Advantage – simple to design the system, suitable for high power equipment Disadvantage – equipment becomes extremely heavy & expensive; opening the enclosure while powered is not permitted Name the fittings on an explosion-proof fire stopping. A fire-stopping should have the following fittings Water gauge, Thermometer, A sampling pipe, ...

Each question carries 2 marks. What is glare? Enumerate the steps to control it. The human eye is sensitive to a particular range of luminance, which is determined by the average adaptive luminance in the visual field. This range at the lower end is determined by the threshold of vision, the point at which an object can just barely be seen. By increasing the luminance level the clarity improves but beyond a certain luminance level, even though we go on increasing the luminance, there won’t be any further improvement in the clarity with which we see the object. This we call the upper range of luminance. The effects of this unwanted light on visual performance is classified into two types, (i) discomfort glare, which increases eye fatigue, causes distraction and generally plays havoc with the human factor. (ii) disability glare, which reduces the task visibility What are the major sources of noise in underground mining, highlighting the permissible levels of noise in those? The ambient n...