CHAPTER 10 SAMPLE QUIZ QUESTIONS
10.1. What material is commonly substituted for silica sand to prevent silicosis in
blasting workers?
10.2. Ventilation is considered which of the following strategies to hazard control?
b. Administrative
c. Work practice
d. Personal protective equipment
ref. p. 231
10.3. For each of the following industrial materials, suggest substitutes that are
feasible for some operations and that prevent certain hazards:
10.4. What is the name given to a type of ventilation system that can be likened to
“sweeping dirt under the rug?”
10.5. Which of the following types of ventilation most resembles sweeping dirt under
the rug?
b. exhaust ventilation
c. push-pull ventilation
d. makeup air ventilation
e. ordinary heating and air conditioning systems
ref. p. 233-242
10.6. Which of the following solutions is preferred for the problem of toxic air
contaminants arising from the surface coatings of materials during the welding
process?
a. ventilation
b. removal of the coatings prior to welding
d. provision of respirators for the welder
ref. 231-232
10.7. One part of a manufacturing process for metal products involves tumbling the
parts in an abrasive, and the noise in the area of this operation is measured at
94 dBA. An acoustics engineering firm has designed a barrier for enclosing this
operation that engineers claim will attenuate the absolute sound pressure by
50%. If the claim is correct, calculate the new noise level in dBA generated by
this operation.
10.8. A particularly noisy process is operated by a single operator working at a control
console. The 8-hr TWA exposure level for this operator is 96 dBA. The
company has initiated an engineering project to alleviate the problem and has
two plans:
Plan A – Move the operator‘s control console from its current position 5 feet from
the source of the noise to a point 10 feet away.
Plan B – Enclose the noise source in an enclosure that would be effective in
reducing the absolute sound pressure level of the noise by 75%.
What would be the new decibel exposure level if
a. Plan A were carried out
b. Plan B were carried out
c. Both Plan A and Plan B were carried out
10.9. Which of the following would be most effective in dealing with a work-related
noise exposure problem?
a. Enclose the noise source with a barrier that reduces the noise level 50%.
noise.
c. Rotate personnel so that each worker is exposed to the noise source for only
one-half shift.
d. Provide ear protection that cuts the noise level by one half.
10.10. Which of the following would be least effective in dealing with a work-related
noise exposure problem?
a. Enclose the noise source with a barrier that reduces the noise level
by 50%.
b. Position the operator at a distance twice as far from the source of
the noise.
c. Rotate personnel so that each worker is exposed to the noise source
for only one-half shift.
10.11. From the perspective used by the federal enforcement agency, rank the following
solutions to a worker noise exposure problem (from most effective,”1“, to least
effective,”4″).
2 Enclose the noise source with a barrier that reduces the noise level by
50%.
1 Position the operator at a distance twice as far from the source of the
noise.
3 Rotate personnel so that each worker is exposed to the noise source for
only one-half shift.
4 Provide ear protection that cuts the noise level by one half.
ref. p. 244-248; also earlier chapters that emphasized the preference of engineering
and administrative controls over personal protective equipment.
10.12. What is a “threshold shift?”
10.13. A “threshold shift” is
a. a hazard of walking and working surfaces
b. an administrative control for rotating employees exposed to excessive
noise
c. a barrier to continued attenuation of a noise source
ref. p.256
10.14. A “threshold shift” is an indication that a worker’s hearing has been damaged.
10.15. A “threshold shift” is a hazard of walking and working surfaces.
10.16. A “threshold shift” is an administrative control for rotating employees exposed to
excessive noise.
10.17. A “threshold shift” is a barrier to continued attenuation of a noise source.
10.18. List the elements of an effective hearing conservation program.
10.19. Hearing damage at what noise frequency is viewed as typical of industrial
exposures?
10.20. Which of the following noise frequencies is viewed as typical of industrial
exposures?
a. 1000 Hz
c. 10000 Hz
d. 20000 Hz
ref. p. 256
10.21. Gamma rays and X rays typify which of the two primary classes of radiation?
10.22. Radio waves and microwave radiation typify which of the two primary classes of
radiation?
10.23. The best exhaust ventilation systems are the “push” types.
9.24. You are requested to design a general exhaust ventilation system to
deal with a process that leaks bromine into the plant air at the rate of one cubic
inch per hour. Calculate how much flow in cubic feet per hour is needed to keep
the bromine vapors within OSHA limits (PEL and AL). Show your calculations.
0.1 X = 106/1728 = 578.7 ft3/hr
X = 5787 ft 3
/hr
The AL is 1/2 PEL and would require a ventilation system of double the capacity
required to meet the PEL.
for AL:
x = 2 x 5787 = 11574 ft 3
/hr
ref. p.236-237
10.25. Which is a preferred design for exhaust ventilation systems?
(a) (b)
10.26. Which is a preferred design for exhaust ventilation systems?
10.27. Identify the device indicated by the large arrow. What is its purpose?
10.28. The device shown is a
a. tornado
c. hurricane
d. heat pump
ref. p. 237
10.29. The purpose of the device shown is
b. to absorb toxic gases
c. to act as a heat exchanger
d. none of the above
ref. p. 237
10.30. The purpose of the device shown is
b. to absorb toxic gases
c. to act as a heat exchanger
d. none of the above
ref. p. 237
10.31. The purpose of the device shown is
a. to act as a heat exchanger
c. to absorb toxic gases
d. none of the above
ref. p. 237
10.32. The purpose of the device shown is
a. to absorb toxic gases
c. to act as a heat exchanger
d. none of the above
ref. p. 237
10.33. The purpose of the device shown is to
a. reduce ionizing radiation
b. reduce non-ionizing radiation
d. remove toxic gases
ref. p. 238
10.34. The purpose of the device shown is to
a. reduce ionizing radiation
b. reduce non-ionizing radiation
d. remove toxic gases
ref. p. 238
10.35. The device shown is identified as .
10.36. The device shown is known as a
b. cyclone precipitator
c. electrostatic precipitator
d. fabric collector
ref. p. 239
10.37. What is the specific purpose of the electric motor indicated by the large arrow?
10.38. Which (pressure vs. time) waveform represents a low pitched soft sound?
a b c D
10.39. Which (pressure vs. time) waveform represents a high pitched soft sound?
a b c D
10.40. Which (pressure vs. time) waveform represents a low pitched loud sound?
a b c D
10.41. Which (pressure vs. time) waveform represents a high pitched loud sound?
a b c D
10.42. The diagram illustrates what device?
10.43. Assume the worker in the diagram is equidistant from each machine and
compute noise exposure.
10.1, a difference of 12 dB between sources would represent a combined noise
level of 89.8 + 0.2 = 90 dBA
ref. p. 245-247
10.44. The diagram illustrates
a. absolute noise pressure and pitch
b. noise enclosure effectiveness
d. none of the above
ref. p. 251
10.45. The diagram illustrates
a. absolute noise pressure and pitch
c. octave band analysis
d. none of the above
ref. p. 255
10.46. An air sample bag is needed at the PEL for carbon disulfide (20 ppm). The
smallest quantity of carbon disulfide available for this experiment is 5 ml. Calculate the
minimum capacity air sample bag necessary for this experiment. Show your
calculations.
10.47. You are requested to design a general exhaust ventilation system to deal with a
process that leaks hexachloroethane into the plant air at the rate of one cubic
inch per hour. How much flow in cubic feet per hour is needed to keep the
hexachloroethane vapors within OSHA limits (PEL and AL)? The PEL is 1 ppm.
10.48. Noise Source A has a sound power level of 99 dB, and noise Source B has a
sound power level of 82 decibels. Compute the ratio of absolute sound power
between Source A and Source B.
NOTE TO INSTRUCTOR: This examination question goes beyond the scope of
the text. It is a technical question intended for students who have an engineering
or science background. Supporting lecture notes for instructors who desire to
teach this technical extension of Chapter 10 topics are available from the author.
1.7 = log10 K
K = 50.12
10.49. A certain drying process produces 5 cubic feet of methanol vapors per hour. The
PEL for methanol is 200 ppm. If general exhaust ventilation is used, calculate
how much flow in cubic feet per hour is needed to keep the methanol vapors
within OSHA limits. Show your calculations.
10.50. Explain why it seems so difficult to reduce noise decibel levels even by a “small”
amount, such as 5 or 6 decibels.
10.51. Explain, in terms easily understood by workers and managers, the following
physical characteristics of occupational noise:
a. the physical characteristic of noise that gives rise to the sensation of pitch.
b. the physical characteristic of noise that gives rise to the sensation of loudness.
c. how noise is affected by the distance to the source (in what way and at what
proportional rate).
d. how doubling the absolute sound pressure affects decibel level (in what way and by
how much).
10.52. Describe some engineering solutions to the problem of toxic air contaminants
arising from surface coatings during the welding process. Indicate a priority to
rank the preference for the solutions to the problem.
10.53. An operator is exposed to the following sources of noise:
Source A: 81 dBA
Source B: 83 dBA
Source C: 85 dBA
Perform calculations to determine the approximate overall noise exposure to the
worker. Show your work.
10.54. An operator working an 8-hour shift is exposed to 85 dbA the first half of the shift
and 92 dbA the second half. Calculate the noise dose. Does the total dose
exposure exceed the OSHA PEL? Does it exceed the AL?
10.55. Explain why barrels are often found under filter baghouses.
10.56. What organization is represented by the abbreviation ASHRAE?
10.57. What particular air contaminant is gaining recognition as a general benchmark
for indoor air quality?
10.58. Which of the following air contaminants is recognized by ASHRAE engineers as
a benchmark for general indoor air quality?
a. carbon disulfide
b. carbon monoxide
c. hydrogen sulfide
ref. p. 240
10.59. Identify some of the problems associated with stale indoor air.
10.60. In heating/ventilating terminology describe what is meant by a VAV air
conditioning system.
10.61. What advantages accrue from having a VAV air conditioning system?