Practice Test: Question Set - 07
1. Rotary 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
2. The inter-cooler pressure, for minimum work required, for a two stage reciprocating air compressor, is given by (where p₁ = Intake pressure of air, p₂ = Inter-cooler pressure, and p₃ = Delivery pressure of air)
- (A) p₂ = p₁
× p₃
- (B) p₂ = p₁/p₃
- (C) p₂ = p₁
× p₂
- (D) p₂ = p₃/p₁
3. 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
4. The ratio of the net work obtained from the gas turbine plant to the turbine work is known as
- (A) Compression
ratio
- (B) Work
ratio
- (C) Pressure
ratio
- (D) None of
these
5. The thrust on the rotor in a centrifugal compressor is produced by
- (A) Radial component
- (B) Axial component
- (C) Tangential component
- (D) None of the above
6. In a centrifugal compressor, the highest Mach number leading to shock wave in the fluid flow occurs at
- (A) Diffuser
inlet radius
- (B) Diffuser
outlet radius
- (C) Impeller
inlet radius
- (D) Impeller
outlet radius
7. A compressor at high altitude will draw
- (A) More power
- (B) Less power
- (C) Same power
- (D) More/less power depending on other factors
8. In a single acting reciprocating air compressor, without clearance, the compression of air may be
- (A) Isothermal
- (B) Polytropic
- (C) Isentropic
- (D) Any one of
these
9. 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
10. The temperature of air at the beginning of the compression stroke is ________ the atmospheric temperature.
- (A) Equal to
- (B) Less than
- (C) More than
- (D) None of
these
11. A centrifugal compressor works on the principle of
- (A) Conversion of pressure energy into kinetic
energy
- (B) Conversion of kinetic
energy into pressure energy
- (C) Centripetal action
- (D) Generating pressure
directly
12. The air is delivered ________ in one revolution in case of a three lobbed rotor.
- (A) Two times
- (B) Three times
- (C) Four times
- (D) Six times
13. In a compressor, free air delivered is the actual volume delivered at the stated pressure reduced to
- (A) N.T.P. conditions
- (B) Intake temperature
and pressure conditions
- (C) 0°C and 1 kg/cm²
- (D) 20°C and 1 kg/cm²
14. The blades of gas turbine are made of
- (A) High nickel alloy
- (B) Stainless steel
- (C) Carbon steel
- (D) High alloy steel
15. The maximum delivery pressure in a rotary air compressor is
- (A) 10 bar
- (B) 20 bar
- (C) 30 bar
- (D) 50 bar
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