Mining industry usually employs following motive power :
A. A.C. electric motor
B. compressed air
C. petrol engine
D. diesel engine
In multistage compressor, the isothermal compression is achieved by :
A. employing intercooler
B. by constantly cooling the cylinder
C. by running compressor at very slow speed
D. by insulating the cylinder
The capacity of compressor will be highest when its intake temperature is :
A. lowest
B. highest
C. anything.
D. atmospheric
Reciprocating air compressor is best suited for :
A. large quantity of air at high pressure
B. small quantity of air at high pressure
C. small quantity of air at low pressure
D. large quantity of air at low pressure
After-cooler is used to :
A. cool the air
B. decrease the delivery temperature
C. cause moisture and oil vapour to drop out
D. reduce volume
During base load operation, the best method of controlling compressor is :
A. start-stop motor
B. constant speed unloader
C. relief valve
D. variable speed
The volumetric efficiency of a compressor is calculated on the basis of :
A. volume of air inhaled at working conditions
B. volume of air inhaled at N.T.P. conditions
C. volume at 0°C and 1 kg/cm2
D. volume at 20°C and 1 kg/cm2
The compressor efficiency is the :
A. isothermal H.P/indicated H.R
B. isothermal H.P./shaft H.R
C. total output/air input
D. compression work/motor input
For a compressor, least work will be done if the compression is :
A. isentropic
B. isothermal
C. polytrophic
D. somewhere in between isentropic and isothermal
