1. Air passes through a 1.5m-diameter ventilation duct at a velocity of 3.0 m/s. Calculate the volumetric flow rate and the mass flow rate assuming that the air has a density of 1.12 kg/m3.
2. During a ventilation survey the cross-sectional area of a mine airway is measured to be 25 m2. Anemometer traverses of the airway have been undertaken and the results from four such traverses at the area measuring site indicated that on the first pass a total of 231 m of air was registered on the anemometer. In the second traverse 245 m was measured, in the third 238m and in the final traverse 228m. Given that each anemometer traverse was timed over 100 s, determine the average flow velocity of the air and the air quantity flowing.
3. Measurements of gas concentration at a particular site underground indicate that the concentration of methane in the general body of the air is 0.85%. If 33.5 m3/s of air is flowing at the site determine the volume of methane present in the airstream?
4. A Pitot-static tube is used to measure air velocity as part of a ventilation survey. At a particular measuring site a velocity pressure of 950 Pa is measured, assuming the air has a density of 1.12 kg/m3 what is the air velocity at that point?
5. Describe the method of undertaking an anemometer traverse for a mine airway, what particular precautions have to be taken when undertaking such a traverse?
6. Describe the gauge and tube method of undertaking a pressure survey in a mine. What advantages and disadvantages does this method have?
7. Describe a method of undertaking a point measurement traverse for airflow in a circular duct using a pitot static tube, are there any standards avialble for such a traverse?
8. Measurements of an airway show that the height is 4.5m and the width is 5m. What is the cross-sectional area of the airway and what is the perimeter?
9. An explosion occurs when a pre-mixed cloud of gas and air (or other oxidiser) combusts resulting in a rapid increase in pressure. Four conditions must exist underground for an explosion to occur. Name the four conditions and give a brief description thereof.