181. Mining industry usually employs following motive power___________________?
A. A.C. electric motor
B. compressed air
C. petrol engine
D. diesel engine
E. D.C. electric motor

182. Separators in compressor installations are located_____________________?
A. before intercooler
B. after intercooler
C. after receiver
D. between after-cooler and air receiver
E. before suction

183. An air compressor may be controlled by____________________?
A. throttle control B. clearance control
C. blow-off control
D. any one of the above
E. none of the above

184. During peak load periods, the best method of controlling compressors is___________________?
A. start-stop motor
B. constant speed unloader
C. relief valve
D. variable speed
E. none of the above

185. The compressor performance at higher altitude compared to sea level will be _______________?
A. same
B. higher
C. lower
D. dependent on other factors
E. none of the above

186. A centrifugal compressor works on the principle of__________________?
A. conversion of pressure energy into kinetic energy
B. conversion of kinetic energy into presĀ¬sure energy
C. centripetal action
D. generating pressure directly
E. combination of A. and D.

187. A compressor at high altitude will draw________________?
A. more power
B. less power
C. same power
D. more/less power depending on other factors
E. none of the above

188. The thrust on the rotor in a centrifugal compressor is produced by________________?
A. radial component
B. axial component
C. tangential component
D. resultant component

189. The area of actual indicator diagram on an air compressor as compared to area of ideal indicator diagram is_____________________?
A. less
B. more
C. same
D. more/less depending on compressor capacity
E. unpredictable

190. To aviod moisture troubles, the compressed air main line should __________________?
A. rise gradually towards the point of use
B. drop gradually towards the point of use
C. be laid vertically
D. be laid exactly horizontally
E. none of the above

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