Deck 10: Environmental Control and Noise

Question 1

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
D)an indication that a worker's hearing has been damaged

Answer 1

D

Question 2

17.A "threshold shift" is a barrier to continued attenuation of a noise source.

Answer 2

False

Question 3

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").

Answer 3

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.

Question 4

2.Ventilation is considered which of the following strategies to hazard control?

A)Engineering
B)Administrative
C)Work practice
D)Personal protective equipment

Question 5

21.Gamma rays and X rays typify which of the two primary classes of radiation?

Question 6

19.Hearing damage at what noise frequency is viewed as typical of industrial exposures?

Question 7

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.
D)Provide ear protection that cuts the noise level by one half.

Question 8

3.For each of the following industrial materials,suggest substitutes that are feasible for some operations and that prevent certain hazards:
Silica (for blasting)

Question 9

18.List the elements of an effective hearing conservation program.

Question 10

12.What is a "threshold shift?"

Question 11

20.Which of the following noise frequencies is viewed as typical of industrial exposures?

A)1000 Hz
B)4000 Hz
C)10000 Hz
D)20000 Hz

Question 12

4.What is the name given to a type of ventilation system that can be likened to "sweeping dirt under the rug?"

Question 13

5.Which of the following types of ventilation most resembles sweeping dirt under the rug?

A)dilution ventilation
B)exhaust ventilation
C)push-pull ventilation
D)makeup air ventilation
E)ordinary heating and air conditioning systems

Question 14

16.A "threshold shift" is an administrative control for rotating employees exposed to excessive noise.

Question 15

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.

Question 16

14.A "threshold shift" is an indication that a worker's hearing has been damaged.

Question 17

1.What material is commonly substituted for silica sand to prevent silicosis in blasting workers?

Question 18

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%.
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.
D)Provide ear protection that cuts the noise level by one half.

Question 19

15.A "threshold shift" is a hazard of walking and working surfaces.

Question 20

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

Question 21

35.The device shown is identified as .

Question 22

40.Which (pressure vs.time)waveform represents a low pitched loud sound?

Question 23

30.The purpose of the device shown is

A)to remove particulates
B)to absorb toxic gases
C)to act as a heat exchanger
D)none of the above

Question 24

38.Which (pressure vs.time)waveform represents a low pitched soft sound?

Question 25

37.What is the specific purpose of the electric motor indicated by the large arrow?

Question 26

27.Identify the device indicated by the large arrow.What is its purpose?

Question 27

32.The purpose of the device shown is

A)to absorb toxic gases
B)to remove particulates
C)to act as a heat exchanger
D)none of the above

Question 28

25.Which is a

Question 29

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.

Question 30

28.The device shown is a

A)tornado
B)cyclone
C)hurricane
D)heat pump

Question 31

29.The purpose of the device shown is

A)to remove particulates
B)to absorb toxic gases
C)to act as a heat exchanger
D)none of the above

Question 32

26.Which is a

Question 33

31.The purpose of the device shown is

A)to act as a heat exchanger
B)to remove particulates
C)to absorb toxic gases
D)none of the above

Question 34

23.The best exhaust ventilation systems are the "push" types.

Question 35

39.Which (pressure vs.time)waveform represents a high pitched soft sound?

Question 36

33.The purpose of the device shown is to

A)reduce ionizing radiation
B)reduce non-ionizing radiation
C)charge particles
D)remove toxic gases

Question 37

1 X = 10⁶/1728 = 578.7 ft³/hr

Question 38

34.The purpose of the device shown is to

A)reduce ionizing radiation
B)reduce non-ionizing radiation
C)remove particulates
D)remove toxic gases

Question 39

22.Radio waves and microwave radiation typify which of the two primary classes of radiation?

Question 40

36.The device shown is known as a

A)packed tower wet scrubber
B)cyclone precipitator
C)electrostatic precipitator
D)fabric collector

Question 41

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.

Question 42

45.The diagram illustrates

A)absolute noise pressure and pitch
B)noise enclosure effectiveness
C)octave band analysis
D)none of the above

Question 43

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.

Question 44

44.The diagram illustrates

A)absolute noise pressure and pitch
B)noise enclosure effectiveness
C)octave band analysis
D)none of the above

Question 45

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.

Question 46

56.What organization is represented by the abbreviation ASHRAE?

Question 47

55.Explain why barrels are often found under filter baghouses.

Question 48

53.An operator is exposed to the following sources of noise:

Question 49

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

Question 50

59.Identify some of the problems associated with stale indoor air.

Question 51

50.Explain why it seems so difficult to reduce noise decibel levels even by a "small" amount,such as 5 or 6 decibels.

Question 52

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?

Question 53

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
D)carbon dioxide

Question 54

42.The diagram illustrates what device?

Question 55

57.What particular air contaminant is gaining recognition as a general benchmark for indoor air quality?

Question 56

60.In heating/ventilating terminology describe what is meant by a VAV air conditioning system.

Question 57

61.What advantages accrue from having a VAV air conditioning system?

Question 58

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.

Question 59

43.Assume the worker in the diagram is equidistant from each machine and compute noise exposure.

Question 60

7 = log₁₀ K