Mechanical Engineering Measurements
40 Questions
5 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary factor used to measure the velocity of air in a drift?

  • Average time of wet and dry bulbs
  • Dry bulb temperature
  • Wet bulb temperature
  • Velocity pressure (correct)

    • What is the range of measurement for an inclined water gauge?

  • Less than 50 mm
  • Less than 200 mm (correct)
  • Greater than 50 mm
  • Greater than 200 mm

    • What is the minimum reading that an inclined water gauge can take?

  • 2 mm
  • 0.2 mm (correct)
  • 1.5 mm
  • 1 mm

    • What is the purpose of the spiral casing in a centrifugal fan?

    <p>To prevent reentry of discharged air</p> Signup and view all the answers

    What is the primary factor that affects the efficiency of a centrifugal fan?

    <p>Well-designed blades of the fan</p> Signup and view all the answers

    What is the maximum permissible speed of an axial flow fan?

    <p>4200 m/min</p> Signup and view all the answers

    What is the maximum water gauge developed in an axial flow fan?

    <p>15 cm</p> Signup and view all the answers

    What factors affect the water gauge developed and quantity circulated with an axial flow fan?

    <p>Quantity of air and velocity</p> Signup and view all the answers

    What is the minimum pressure required for a refrigerant circulation system?

    <p>more than 250 pa</p> Signup and view all the answers

    Which of the following refrigerants is considered good and harmless?

    <p>Freon-12</p> Signup and view all the answers

    What is the purpose of a profilometer?

    <p>Measuring cross section of irregular shape</p> Signup and view all the answers

    Why should ammonia not be used in underground mines?

    <p>It forms an explosive mixture with air at 20% concentration</p> Signup and view all the answers

    What type of extinguisher is best suited for fires involving live electrical equipment?

    <p>CO2 type</p> Signup and view all the answers

    What is the recommended width of a trench to separate coal and overburden dumps in an abandoned quarry?

    <p>3-5 m</p> Signup and view all the answers

    What is the maximum height allowed for a coal stock?

    <p>1.5-3 m</p> Signup and view all the answers

    What is the minimum quantity of coal that should be maintained in a stock?

    <p>200 te</p> Signup and view all the answers

    What is the minimum thickness of isolation stoping in deg I and II gassy coal mine?

    <p>2 m</p> Signup and view all the answers

    At what minimum percentage of CH4 behind the stoping should the isolation stoping be explosion proof?

    <p>2 %</p> Signup and view all the answers

    What is the minimum thickness of explosion proof isolation stoping?

    <p>3 m</p> Signup and view all the answers

    What is the minimum depth of locking in shale required for isolation stoping?

    <p>75 cm</p> Signup and view all the answers

    How much gypsum is required for every cu.m of stoping volume?

    <p>1.3</p> Signup and view all the answers

    How far beyond the temporary stoping should the sample pipe extend?

    <p>3 m</p> Signup and view all the answers

    What type of stopings are isolation stopings?

    <p>Preparatory stopings</p> Signup and view all the answers

    How often should the atmosphere near the stoing be tested for during the process of seaming fire area below ground?

    <p>Frequently</p> Signup and view all the answers

    What is the height of the temporary dam?

    <p>10 m</p> Signup and view all the answers

    What is the thickness of the permanent water dam?

    <p>3 m</p> Signup and view all the answers

    What type of safety lamp is the electric cap lamp?

    <p>Both 1 and 2</p> Signup and view all the answers

    At what percentage of CH4 does the flame of a flame safety lamp show spires of jumps?

    <p>3 %</p> Signup and view all the answers

    What percentage of inflammable gas triggers an alarm in automatic detectors?

    <p>2 %</p> Signup and view all the answers

    What is the cause of Tuberculosis?

    <p>None of the above</p> Signup and view all the answers

    What is the method of dealing with fire in mine where heating is in the initial stages and its exact location is known?

    <p>Digging out and extinguishing</p> Signup and view all the answers

    What is the term for spraying the surface with liquid cement sand mixture (1:3) in dealing with fire?

    <p>Guniting</p> Signup and view all the answers

    What is the ideal ratio of ore to waste in open stope mining?

    <p>1:4</p> Signup and view all the answers

    What type of ore is most suited to the open stope method?

    <p>Low grade</p> Signup and view all the answers

    What is the term for the pillar left to support the upper level in open stope mining?

    <p>Crown pillar</p> Signup and view all the answers

    What is the typical thickness of the bed in open stope mining?

    <p>2 to 3 m</p> Signup and view all the answers

    What method of stoping is best suited to low-grade deposits of horizontal or mild dip and of thickness up to 5m?

    <p>Sublevel stoping</p> Signup and view all the answers

    Breast stoping is employed for stoping ore bodies not more than what thickness?

    <p>1 m</p> Signup and view all the answers

    Among the methods of open stoping, which method lends to large-scale mechanization in drilling, blasting, loading, and transporting?

    <p>Breast stoping</p> Signup and view all the answers

    What is the maximum thickness of the ore body that can be worked with the room and piller method?

    <p>4 to 6 m</p> Signup and view all the answers

    Study Notes

    Thermometry and Psychrometry

    • Dry bulb temperature measures the air temperature
    • Wet bulb temperature measures the temperature of the air when it is fully saturated with water vapor
    • Inclined water gauge is used to measure water pressure less than 200 mm

    Centrifugal Fans

    • Smooth flow of air and conversion of velocity energy into pressure energy takes place in the spiral casing
    • Re-entry of discharged air is prevented by the spiral casing
    • Efficiency of the fan and reduction in power cost can be obtained with well-designed blades

    Axial Flow Fans

    • Maximum permissible speed is 5200 m/min
    • Maximum water gauge developed is 13.5 cm
    • Water gauge developed and quantity circulated depend on more than 250 pa

    Refrigeration

    • Refrigerant used in refrigerant circulation system is Freon-12
    • Harmless refrigerant is Carbon dioxide
    • Profilometer is used to measure the cross-section of irregular shapes

    Safety and Extinguishers

    • Ammonia should not be used in underground mines as it forms an explosive mixture with air if present above 20% by volume
    • The best extinguisher for fires involved in live electrical equipment is CO2 type
    • The best extinguisher for fires due to oil is Foam type
    • The best extinguisher for gaseous fires is CO2 type

    Mining and Quarrying

    • When a quarry is abandoned, the coal and OB dump should be separated by digging a trench 3-5 m wide
    • Coal stock should not exceed 100 te
    • The height of the coal stock should not exceed 1.5 to 3 m
    • The ignition temperature of bituminous coal is 20°C

    Isolation Stopping

    • Isolation stopping in degree I and II gassy coal mines should have a minimum thickness of 2 m
    • The isolation stopping should be explosion-proof if the minimum CH4% behind the stopping is 2%
    • The minimum thickness of the explosion-proof isolation stopping is 4.5 m
    • Isolation stopping should have a minimum depth of locking in shale of 75 cm

    Stoping and Mining Methods

    • Temporary stoping is constructed before depillaring is undertaken
    • Stoping should always be kept white washed on the surface and at the roof, floor, and sides for 1 m outbye for every detection of cracks
    • During the process of sealing a fire area below ground, the atmosphere near the stoping should be tested frequently for 20 m

    Dams

    • The thickness and height of the temporary dam are 1 m and 2 m, respectively
    • The thickness of the permanent water dam is 6 m

    Electric Cap Lamp

    • The electric cap lamp is intrinsically safe
    • The flame of a flame safety lamp while testing for CH4 spires of jumps at 3%

    Automatic Detectors

    • Automatic detectors give either audio or visual alarm when the percentage of inflammable gas exceeds 2%

    Health Hazards

    • Tuberculosis is caused due to inhalation of quartz dust

    Fire Fighting

    • The method of dealing with fire in a mine where heating is in the initial stages and its exact location is known is digging out and extinguishing
    • Spraying the surface with a liquid cement sand mixture (1:3) in dealing with fire is known as plastering

    Stone Dust Barrier

    • A stone dust barrier may fail to arrest an explosion if there is a crack in the roof of the roadway over the barrier

    Open Stope Method

    • Open stope method is used for ore of high grade
    • The thickness of the bed in open stoping is 2 to 3 m

    Pillar Left

    • The pillar left to support the upper level is called the sill pillar

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Mining Exam Paper PDF

    Description

    This quiz assesses knowledge of measurement instruments and techniques in mechanical engineering, including temperature and water gauge measurements.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser