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Nitrogen Review Exercise

Nitrogen Physiological Effects and Hazards

1. The most critical effect associated with a nitrogen exposures is (are)

a. Tumor induction

b. Asphyxiation

c. Cirrhosis of the liver

d. All the above


2. O2 deprivation effects resulting from elevated nitrogen levels include which of the following?

a. Strength impairment

b. Judgement

c. Coordination

d. All of the above


3. Which of the following are correct statements regarding nitrogen-induced asphyxiation?

a. There is no warning prior to being overcome

b. Nitrogen rapidly overcomes the victim

c. O2 deficient atmospheres may exist immediately outside a confined space especially if the space has nitrogen in it under pressure

d. All the above

e. b and c


4. The most likely physiological effect from exposure to liquid nitrogen is

a. No effect

b. Thermal burn

c. Severe frostbite

d. None of the above


5. The DOT label code for nitrogen is 2.2. This means that nitrogen is a

a. Flammable gas

b. Non-flammable, non-toxic gas

c. Toxic gas

d. a or b depending on the state of origin


6.What risks can negative side effects can quickly occur if there is exposure in a confined space?

a. Tingling sensation in the extremities

b. Asphyxiation

c. Nausea and vomiting

d. Rash


7. According to the Parker Hannifin Corporation safety data sheet, which of the following exposure methods require first aid measures in regard to nitrogen gas exposure?

a. Ingestion

b. Inhalation

c. Skin contact

d. Eye contact

e. b, c, and d

f. All of the above


8. Which are symptoms of exposure to an oxygen-deficient atmosphere?

a. Dizziness

b. Salivation

c. Nausea

d. Vomiting

e. Loss of mobility/consciousness

f. All of the above


9. What rating do the NFPA and HMIS systems assign to the health effects of nitrogen?

a. 0

b. 1

c. 2

d. 3

e. 4


10. Is this rating given by NFPA and HMIS systems near the top or bottom of the scale in terms of hazard to human health?


11. The Air Products Safety Data Sheet (SDS) for nitrogen notes that asphyxiation may occur with little to no warning.

a. True

b. False


12. An atmosphere of only 4 to 6 percent oxygen causes the victim to fall into a coma in approximately how many seconds?

a. 20

b. 40

c. 60

d. 90


13. How soon must oxygen be administered to a victim in order to offer a chance of survival?

a. A few minutes

b. Half an hour

c. An hour


Gaseous Nitrogen Properties

14. The molecular weight of nitrogen is 28 g/mol. In the event of a container failure and the release of liquid nitrogen 100% concentration, it would be reasonable to expect the nitrogen gas to:

a. Seek out the lowest points in the facility

b. Rise to the highest points

c. Be dispersed throughout the area


15. Which of the following are characteristics of nitrogen?

a. Colorless

b. Odorless

c. Chemically unreactive/inert

d. All of the above

e. a and b


16. Combination of nitrogen with halogens and sulfur gives rise to very explosive compounds including

a. Halogen azides

b. Sulfur nitride

c. Both of the above


17. Nitrogen is the main constituent of air comprising ____% of air

a. 62

b. 93

c. 78


18. Nitrogen changes from a gas to a liquid at ______ degrees F

a. 32

b. 100

c. -320

d. -460


19. At a constant temperature, the volume of a given quantity of any gas varies inversely as the pressure to which it is subjected is a statement of:

a. Avogadro’s Law

b. Boyle’s Law

c. Charles’ Law

d. Graham’s Law


20. Which of these statements are true?

a. A gas is a substance that boils between absolute zero and ambient temperature

b. A vapor is formed from evaporating liquids

c. A fume is formed from molten metal or welding

d. All of the above


21. What is the composite molecular weight of air?

a. 8

b. 18

c. 25

d. 29


22. A _____ is usually shipped at higher pressure at 70℉ in heavy steel cylinders.

a. Gas

b. Fume

c. Vapor

d. Non-liquified gas


23. The scientific definition of a gas is a material that boils between _____ and _____ degrees ℉.

a. Absolute zero, 0

b. Absolute zero, 80

c. 0, 32

d. 32, 100


24. Nitrogen is a(n) _____ gas

a. Toxic

b. Inert

c. Flammable


25. Gaseous nitrogen is typically stored in

a. High-pressure tube trailers

b. Plastic cylinders

c. Plexiglass tube trailers


26. What happens to nitrogen when it's exposed to high temperatures?

a. It shrinks

b. It expands

c. Nothing happens


27. What QVL (grade) in nitrogen is specified for general industrial usage, inerting, and heat treatment applications?

a. R

b. B

c. M

d. L


28. What is the nitrogen min. % for QVL grade B?

a. 98.3%

b. 27.5%

c. 99.0%

d. 99.998%


29. Nitrogen has an odor

a. True

b. False


30. What is the odor threshold for nitrogen?


31. If a nitrogen leak were to occur, would the leak most probably be found:

a. At the ceiling

b. At the floor

c. Dispersed throughout the room


32. At what temperature does nitrogen auto ignite?


33. Nitrogen is likely to cause ground pollution.

a. True

b. False


34. Which of the following can be contacted to determine proper methods of disposal for nitrogen gas?

a. Local environmental agency

b. State environmental agency

c. Provincial environmental agency

d. Federal environmental agency

e. All of the above


35. Have you been trained to recognize the hazards associated with gaseous nitrogen?


36. Who provided the training?


37.Which of the following hazard pictures is associated with nitrogen?


Liquid Nitrogen Properties

38. Satisfactory materials for use with liquid nitrogen include

a. 18-8 stainless steel

b. Copper

c. Monel

d. Brass

e. Aluminum

f. Carbon steel

g. a-e


39. Appropriate clothing for use with liquid nitrogen includes which of the following?

a. Non-absorbent loose-fitting leather gloves that can be easily removed if liquid should splash onto, or into them.

b. Non-woven materials to minimize becoming saturated with cold liquid.

c. Goggles and face shields to protect the eyes and face where spraying or splashing of liquid may occur.

d. Overalls, or similar clothing made without open pockets or turn-ups where liquid could collect and worn outside boots.

e. All of the above


40. OSHA standard 29 CFR 1910.151(c) requires an eyewash and safety shower be in close proximity to storage and handling locations for injurious corrosive chemicals. This standard then requires an eyewash and safety shower be located in close proximity to the storage and handling areas for liquid nitrogen.

a. True

b. False


41. If liquid nitrogen enters an enclosed flask that is then warmed to room temperature, it could vaporize and in doing so would expand 696:1 possibly resulting in an over-pressurization of the flask and a subsequent explosion.

a. True

b. False


42. The cold boil-off vapor of cryogenic liquids rapidly freezes human tissue. Most metals become stronger upon exposure to cold temperatures, but materials such as carbon steel, plastics and rubber become brittle or even fracture under stress at these temperatures.

a. True

b. False


43. Atmospheric air that comes into contact with the outside of a pipe or metal surface that is at or below liquid nitrogen’s boiling point (-320F) may condense into a liquid. Since O2 has a higher boiling point (-297F) than the N2 in the air, the condensed air may be

a. O2 enriched

b. O2 deficient

c. In a vacuum

d. Pressurized


44. If you chewed frozen graham crackers and then emitted “smoke” from your mouth and nostrils it was the result of

a. Cigarette smoke the instructor had previously inhaled being crystallized and expunged by the LN2

b. Exponential warming of the carbohydrates in the crackers

c. Frozen water vapor emitted from the instructor’s mouth and nostrils

d. Nitrogen gas becoming visible after contacting saliva in the instructor’s mouth and being released as a vapor


45. Immersing a rose into a dewar of LN2 and then crushing it by hand is indicative of the risks of LN2 to

a. Quickly freeze human tissue

b. Allow frozen human tissue to be shattered

c. Both of the above


46. If a frozen tennis ball shattered and emitted a loud bang when thrown against the floor, it was the result of the

a. Impact of the frozen ball striking the floor

b. Expansion of the air inside the ball when it struck the floor

c. Both of the above


47. If LN2 were tossed across the floor and gathered the dust from the floor and deposited it at the wall it was an indication of

a. The new FDA and JHAC standards for cleanliness measurements

b. The ability of LN2 to solidify dust and move it in the direction that it was flowing

c. Neither of the above

d. ________ (fill in the blank)


48. Cooking an egg to a hard-boiled state in LN2 and then shattering it and then watching it return to a liquid state demonstrates that LN2

a. Can freeze and then allow the frozen materials to be shattered

b. Eggs are one class of material not susceptible to being permanently altered by LN2 exposure

c. Both the above

d. Neither the above


49. A match re-ignited into a flame from an ember when exposed to the condensation on the outside of the metal cup containing LN2 is the result of

a. LN2 being ignitable under specific conditions

b. O2 in the air being frozen and since it has a boiling point less than of N2, sliding down the cup and contacting the ember of the match

c. Neither of the above


50. Placing the LN2 into a metal tube, inserting a rubber stopper, then activating the spark plug before the rubber stopper was ejected, is possible due to

a. Ignition of the N2 by the spark plug

b. Rapid expansion of the N2 in the tube and an increased pressure above atmospheric in the tube

c. Both the above

d. Neither of the above


51. Freezing an orange and banana and then using them to drive a 16d nail into a 2 x 4 is an example of LN2’s ability to make solid and liquid objects rigid.

a. True

b. False


52. Cryogenic liquids have a boiling point below ___ ℉.

a. 212

b. 32

c. 0

d. -150


53. A _____ will not recondense into a liquid except at very low temperatures


54. When liquified gases under pressure are released they can

a. Vaporize rapidly and cool to temperatures that can cause frostbite

b. Cause an explosion

c. Vaporize slowly and will take time before affecting employees

d. Vaporize slowly and then explode


55. Recommended materials for transporting liquid nitrogen are

a. 18-8 stainless steel

b. Nickel-chromium alloys

c. Copper

d. All of the above


56. Have you been trained to recognize the hazards associated with liquid nitrogen?


57. Who provided the training?


Respirator Use

58. A self contained breathing apparatus should be used in instances where exposure levels are not known.

a. True

b. False


59. What type of respiratory protection equipment does the safety data sheet supplied by Air Products specify to be used in an oxygen deficient environment?


60. Air-purifying respirators will provide protection in an oxygen deficient environment.

a. True

b. False


61. Are persons who use breathing apparatus required to be trained by the OSHA standards?

a. Yes

b. No


62. What does a comprehensive management system for supplied air include?

a. Continuous monitoring of air supply

b. Routine inspection and replacement of supplied-air hoses

c. Restriction of vehicular traffic in the area of supply hoses

d. All of the above


63. When using supplied air, a worker should carry a small backup cylinder/escape pack, attached to a different supplied-air system, with enough breathing air to last how many minutes?

a. 1 to 2 minutes

b. 5 to 10 minutes

c. 20 to 30 minutes


Nitrogen Workplace Incidents

64. According to CSB data, over 60% of workplace fatalities and injuries from breathing nitrogen- enriched air involved victims who were working in or next to a confined space.

a. True

b. False


65. What percent of fatalities from CSB data were due to attempts to rescue injured persons in confined spaces?

a. 2

b. 5

c. 10

d. 20


66. Data shows that employees and contractors are often both victims of nitrogen asphyxiation in the workplace

a. True

b. False


67. 13 percent of nitrogen asphyxiation incidents involved maintenance activities

a. True

b. False


68. 14 percent of nitrogen asphyxiation incidents involved trenches and manholes.

a. True

b. False


69. There were 85 nitrogen-related accidents in the U.S. from 1992—2002 documented by the U.S. Chemical Safety Board that resulted in the deaths of 80 persons.

a. True

b. False


Nitrogen Cylinders

70. What is a requirement for nitrogen gas cylinders?


71. Nitrogen cylinders should be stored in a:

a. Cool, dry place

b. Warm, dry place

c. Cool, damp place

d. Warm, damp place


72. What is the maximum amount of time a nitrogen cylinder should be stored for?

a. 2 weeks

b. 1 month

c. 6 months

d. 1 year

e. 3 years


73. How large of a container can nitrogen be shipped in?

a. 100 mL

b. 125 mL

c. 550 mL

d. 1 L

e. 1350 mL


74. What is the maximum gross mass vessel in which nitrogen can be shipped?

a. 30 kg

b. 100 kg

c. 5 kg

d. 20 kg


75. Cylinders for nitrogen, industrial grade air, and breathing-quality air should have distinct and incompatible fittings that cannot be cross connected.

a. True

b. False


76. Liquified gases in cylinders are kept liquid by:

a. High pressure

b. Low temperature

c. Vapor pressure

d. Adiabatic pressure


Workplace Air Quality Standards

77. Ventilation systems should be equipped with:

a. Emergency shutoff valves

b. Sprinklers

c. Malfunction alarms

d. “On” Button


78. What is a warning property that there is too much nitrogen in the atmosphere?

a. Burning eye sensation

b. There are no warning signs

c. Rotten egg smell

d. Sweet smell


79. Oxygen must be kept at _____ or above in buildings where nitrogen is stored/used.

a. 19.5%

b. 21.5%

c. 67.8%

d. 32.9%


80. What is required if a worker is in an area with less than 19.5% oxygen concentration?

a. They are only allowed to be in the area for 30 minutes before they must take a break

b. Must be wearing special breathing equipment

c. Must be with a partner in case something goes wrong

d. None of the above


81. Which one(s) of the following actions(s) should be undertaken if a nitrogen leak is discovered or if an alarm sounds?

a. Evacuate personnel to safe areas

b. If possible to do so safely, shut off the source of the leak

c. Monitor oxygen levels and provide maximum ventilation

d. Initiate the emergency plan and make the required emergency contacts

e. All of the above


82. In testing for atmospheric hazards, what is the order in which the tests would be performed?

a. Combustible gases and vapors, oxygen, toxic gases and vapors

b. Oxygen, combustible gases and vapors, toxic gases and vapors

c. Oxygen, toxic gases and vapors, combustible gases and vapors

d. Toxic gases and vapors, oxygen, combustible gases and vapors


83. Is the order in which the tests are performed regulated by the OSHA Standards?


84. If so, which standards are applicable?


85. Ventilation is not required in rooms or chambers into which nitrogen may leak or vent.

a. True

b. False


86. How should a nitrogen leak be cleaned up?

a. Wait 1 hour for it to dissipate

b. Ventilate the area

c. Nothing needs to be done


87. The DOT Emergency Response Guidebook, 2012 edition, recommends that as an immediate precautionary measure, one should isolate the spill or leak area for _______ meters ( ____ feet) in all directions.

a. 25, 75

b. 50, 150

c. 100, 330


88. When should a valve be closed?

a. After each use

b. When piping is empty

c. Valves should never be closed

d. b and c


89. What type of oxygen monitoring system did your firm provide for your use in indoor areas where nitrogen is stored or used?


90. Do you have experience using personal or portable handheld oxygen monitors?


91. Have you received training in the use of either personal or portable handheld oxygen monitors?


Nitrogen Blanketing

92. What is nitrogen blanketing?


93. Why is nitrogen the gas most commonly used for blanketing?

a. Inert

b. Widely available

c. Relatively inexpensive

d. All of the above


94. What are the benefits of nitrogen blanketing?

a. Protect plant personnel, products, and plant assets by reducing the oxygen content in the vapor space of a storage tank/process vessel

b. Eliminate possibility of fire or explosion

c. Decreases evaporation

d. Protects tank from structural corrosion damage caused by air and moisture

e. Prevents air, moisture, and other contaminants from entering the vapor space and causing product degradation

f. All of the above


95. How does blanketing prevent air and other contaminants from infiltrating and causing oxygen degradation and spoilage of sensitive materials?

a. Increasing carbon dioxide levels inside storage containers

b. Increasing oxygen levels inside storage containers

c. Creating a slight positive pressure inside storage containers

d. Creating a slight negative pressure inside storage containers


96. Which is not an element needed to create a fire?

a. Oxygen

b. Fuel

c. Carbon dioxide

d. Ignition source


97. What are some ways that a storage tank can be made inert?

a. Reducing the oxygen content of a vapor space to a value that is less than the concentration that will support combustion

b. Reducing the fuel concentration in the vapor space to a value less than the minimum concentration that can support combustion

c. Increasing the fuel concentration in the vapor space to a value greater than the maximum concentration that can support combustion

d. All of the above


98. Floating roof tanks must be blanketed with nitrogen.

a. True

b. False


99. Fixed roof tanks must be blanketed with nitrogen.

a. True

b. False


100. Nitrogen blanketing systems are essential in spaces that are not sealed tight enough to hold a slight positive pressure.

a. True

b. False


101. Which is not a method commonly used for nitrogen control for use as an inert gas?

a. Continuous purge

b. Pressure control

c. Density control

d. Concentration control


102. What are some disadvantages of continuous purge systems?


103. Pressure-control systems can be employed for tanks that are not sealed.

a. True

b. False


104. The amount of nitrogen required to blanket a tank under pressure control is the sum of which two values?

a. Nitrogen required based on the tanks’ working throughput

b. Nitrogen required by thermal breathing

c. Nitrogen required by atmospheric levels

d. a and b

e. a and c

f. b and c


105. Concentration control is suitable for unsealed tanks.

a. True

b. False


106. Nitrogen usage is optimized when utilizing concentration control methods.

a. True

b. False


107. Which is not a basic plant nitrogen usage pattern?

a. Erratic

b. Constant baseline

c. Frequent

d. Periodic


Confined Spaces

108. What is a confined space in the workplace?


109. A worker should check air quality before entering a confined space.

a. True

b. False


110. If one were serving as the attendant as a member of a confined space entry team and was maintaining all parts of one’s body outside the plane of the opening to the confined space which contained nitrogen, then this would eliminate any exposure to the nitrogen.

a. True

b. False


111. If you were entering an area with a confined space, what components of the atmosphere would you want to test?


112. What are some warning and protection systems for confined spaces and their entry portals?

a. Flashing lights

b. Audible alarms

c. Auto-locking entryways to prevent access

d. All of the above


113. Which is not a reliable method of immediately retrieving immobilized workers in the event of continuous monitoring, ventilation failure, or another emergency condition?

a. Attaching a body harness and lifeline to personnel entering confined areas

b. Wristlets or anklets attached to a lifeline, along with a retrieval mechanism

c. Allowing personnel to enter the confined area with proper training, rescue equipment, and dependable breathing air

d. Allowing personnel to quickly enter the confined area without breathing in air


Outside Contractors

114. As an outside service or contractor, who is designated to be the representative responsible for determining their relationship, what are your responsibilities and obligations regarding hazardous energy control prior to starting work or providing services?


115. If a line has been marked nitrogen, would you feel that your firm has been notified of a potential hazard if you will be working on equipment that has pressurized nitrogen inside the equipment?


116. Prior to the beginning of the work, did your firm as an outside service contractor make the host employer aware of any activity or conditions you would be performing that might adversely affect the application of hazardous energy control or impact the normal operation of machines, equipment or processes?




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