High noise levels produced during operation of fans and compressors can be reduced by using__________________?

Related Mcqs:

1. Noise produced by cooling fans (employed in air cooled heat exchangers or cooling tower) is mainly caused due to the turbulence created by blade passage through air. It can be reduced by use of a slower fan_________________?

   A. With greater number of blades
   B. Of increased diameter
   C. Both A. & B.
   D. Neither A. nor B.

2. Major sources of noise in furnace operation arises from air inspirators, combustion, side wall vibrations and fluctuation in the process heat load. A 50% increase in fuel firing rate may increase the furnace noise level by about ____________ decibels?

   A. 3
   B. 30
   C. 7
   D. 70

3. The major reason of hydrodynamic noise (i.e., noise resulting from liquid flow) is_________________?

   A. Pipe vibrations
   B. Cavitation
   C. Boundary layer separation
   D. Fluctuation in liquid flow

4. Aerodynamic noise resulting from turbulent gas flow is the most prevalent source of valve noise in fluid flow control. It is caused due to_________________?

   A. Reynold stresses
   B. Shear forces
   C. Both A. & B.
   D. Neither A. nor B.

5. High noise level in a chemical plant can be controlled by the_________________?

   A. Suppression of noise at the source itself
   B. Path control of noise
   C. Protection of operating personnel
   D. All A., B. & C.

6. Noise level audible to audience sitting in the 5th row from the stage during a large orchestra show corresponds to about _______________ decibels?

   A. 105
   B. 135
   C. 160
   D. 185

7. Noise level during normal conversation among men is about ______________ decibels?

   A. 10
   B. 45
   C. 90
   D. 115

8. Foaming and priming in boiler operation can be reduced by reduction in ______________ in feed water?

   A. Turbidity
   B. Color (Hazen)
   C. Total solids
   D. All A., B. & C.

9. A man exposed to excessive noise level in the working environment may suffer from____________________?

   A. Hearing loss
   B. Rupture of ear drum
   C. Nervousness & fatigue
   D. All A., B. & C.

10. ______________ cannot control the noise pollution ?

    A. Use of silencers
    B. Green house gases
    C. Vibration damping
    D. Tree plantation