Maine (ME) Plant Operator Authority
Practice Exam Questions With 100%
Correct Answers.
1. What is the primary purpose of the Maine Plant Operator endorsement?
A. To authorize residential electrical work
B. To authorize work at a propane bulk plant involving propane and propane equipment
C. To authorize installation of municipal water systems
D. To authorize operation of steam locomotives
Correct Answer: B
Explanation: The Plant Operator endorsement is intended for persons who work at a bulk plant
and handle propane and propane equipment. It does not generally authorize unrelated trades such
as electrical or plumbing work. The scope of the endorsement should always be distinguished
from other Maine Fuel Board authorities.
2. Which organization administers licensing requirements for Maine propane and natural
gas technicians?
A. Maine Fuel Board
B. Maine Department of Transportation
C. Maine Water Resources Board
D. Maine Labor Relations Board
Correct Answer: A
Explanation: The Maine Fuel Board regulates propane and natural gas technician licensing. Its
licensing system includes several authorities, including Plant Operator, Delivery Technician,
Tank Setter and Outside Piping Technician, and appliance-related authorities. Understanding
which board governs the activity is essential for determining licensing requirements.
3. A person working at a bulk propane plant wants to perform duties involving propane
handling. Which authority is specifically associated with this work?
A. Delivery Technician only
B. Plant Operator
,C. Oil Burner Technician
D. Plumber's Apprentice
Correct Answer: B
Explanation: Maine identifies the Plant Operator endorsement as the authority required for
persons working at a bulk plant and handling propane and propane equipment. Delivery
Technician authority concerns propane delivery activities and is distinct from bulk-plant
operating authority.
4. Which code is particularly important for propane plant operator preparation?
A. NFPA 13
B. NFPA 58
C. NFPA 72
D. NFPA 101 only
Correct Answer: B
Explanation: NFPA 58, the Liquefied Petroleum Gas Code, is a central reference for propane
operations. The Maine examination bulletin specifically identifies NFPA 58 as part of the Plant
Operator Authority examination content.
5. What does LP-Gas commonly mean?
A. Low-pressure gasoline
B. Liquefied petroleum gas
C. Liquid plumbing gas
D. Licensed plant gas
Correct Answer: B
Explanation: LP-Gas means liquefied petroleum gas. Propane is a common LP-Gas used for
heating, appliances, industrial applications, and other purposes. Its behavior as a liquefied,
pressurized fuel is fundamental to safe plant operation.
6. Why is propane stored under pressure?
A. To convert it permanently into gasoline
B. To keep it in liquid form within the container
C. To eliminate vapor formation completely
D. To make the container lighter
Correct Answer: B
,Explanation: Propane can be stored economically as a liquid when sufficient pressure is
maintained. When pressure is released, some liquid propane vaporizes. This liquid-vapor
relationship is one of the most important concepts for plant operators.
7. What happens when liquid propane is released from a pressurized container?
A. It immediately becomes solid
B. It can rapidly vaporize and expand
C. It becomes water
D. It loses all flammability
Correct Answer: B
Explanation: Liquid propane undergoes rapid vaporization when pressure is reduced. The
resulting vapor can occupy a much larger volume than the original liquid. This creates serious
fire and explosion hazards if the release occurs near an ignition source.
8. Which property makes propane particularly hazardous in a poorly ventilated low area?
A. Propane vapor is heavier than air
B. Propane vapor is lighter than oxygen
C. Propane is nonflammable
D. Propane vapor always rises rapidly
Correct Answer: A
Explanation: Propane vapor has a relative vapor density greater than air, so it can collect in low
areas. A plant operator must therefore consider pits, drains, trenches, and other low points when
evaluating a suspected release.
9. What is the most important immediate concern during a significant propane leak?
A. Product accounting
B. Ignition and uncontrolled vapor accumulation
C. Paint damage
D. Equipment appearance
Correct Answer: B
Explanation: A propane leak can produce a flammable vapor cloud. Preventing ignition and
protecting personnel are the immediate priorities. Inventory calculations and equipment repairs
come later after the area is made safe.
10. Why is an odorant added to propane?
, A. To increase its octane rating
B. To make leaks easier to detect by smell
C. To reduce vapor pressure
D. To prevent all corrosion
Correct Answer: B
Explanation: Commercial propane is normally odorized so that people can detect a potential
leak by smell. Odorization is an important safety feature, although odor should never be
considered a substitute for approved gas-detection and leak-testing procedures.
11. Which characteristic describes propane vapor?
A. It is always visible
B. It can form a flammable mixture with air
C. It cannot travel away from a leak
D. It is harmless when concentrated
Correct Answer: B
Explanation: Propane vapor can mix with air within its flammable range and ignite if an
ignition source is present. Vapor may also travel considerable distances from the original leak
before reaching an ignition source.
12. Why should ignition sources be controlled around propane facilities?
A. Propane cannot burn without electricity
B. A spark or flame can ignite propane-air mixtures
C. Ignition sources only affect gasoline
D. Propane becomes nonflammable near flames
Correct Answer: B
Explanation: Propane requires an ignition source when the propane-air mixture is within its
flammable range. Sparks, open flames, hot surfaces, electrical equipment, and static discharge
can potentially provide ignition energy.
13. What is one reason propane containers are not normally filled completely with liquid?
A. Liquid propane does not expand
B. Space is needed for thermal expansion
C. Full containers produce no pressure
D. Containers must remain empty at night
Correct Answer: B
Practice Exam Questions With 100%
Correct Answers.
1. What is the primary purpose of the Maine Plant Operator endorsement?
A. To authorize residential electrical work
B. To authorize work at a propane bulk plant involving propane and propane equipment
C. To authorize installation of municipal water systems
D. To authorize operation of steam locomotives
Correct Answer: B
Explanation: The Plant Operator endorsement is intended for persons who work at a bulk plant
and handle propane and propane equipment. It does not generally authorize unrelated trades such
as electrical or plumbing work. The scope of the endorsement should always be distinguished
from other Maine Fuel Board authorities.
2. Which organization administers licensing requirements for Maine propane and natural
gas technicians?
A. Maine Fuel Board
B. Maine Department of Transportation
C. Maine Water Resources Board
D. Maine Labor Relations Board
Correct Answer: A
Explanation: The Maine Fuel Board regulates propane and natural gas technician licensing. Its
licensing system includes several authorities, including Plant Operator, Delivery Technician,
Tank Setter and Outside Piping Technician, and appliance-related authorities. Understanding
which board governs the activity is essential for determining licensing requirements.
3. A person working at a bulk propane plant wants to perform duties involving propane
handling. Which authority is specifically associated with this work?
A. Delivery Technician only
B. Plant Operator
,C. Oil Burner Technician
D. Plumber's Apprentice
Correct Answer: B
Explanation: Maine identifies the Plant Operator endorsement as the authority required for
persons working at a bulk plant and handling propane and propane equipment. Delivery
Technician authority concerns propane delivery activities and is distinct from bulk-plant
operating authority.
4. Which code is particularly important for propane plant operator preparation?
A. NFPA 13
B. NFPA 58
C. NFPA 72
D. NFPA 101 only
Correct Answer: B
Explanation: NFPA 58, the Liquefied Petroleum Gas Code, is a central reference for propane
operations. The Maine examination bulletin specifically identifies NFPA 58 as part of the Plant
Operator Authority examination content.
5. What does LP-Gas commonly mean?
A. Low-pressure gasoline
B. Liquefied petroleum gas
C. Liquid plumbing gas
D. Licensed plant gas
Correct Answer: B
Explanation: LP-Gas means liquefied petroleum gas. Propane is a common LP-Gas used for
heating, appliances, industrial applications, and other purposes. Its behavior as a liquefied,
pressurized fuel is fundamental to safe plant operation.
6. Why is propane stored under pressure?
A. To convert it permanently into gasoline
B. To keep it in liquid form within the container
C. To eliminate vapor formation completely
D. To make the container lighter
Correct Answer: B
,Explanation: Propane can be stored economically as a liquid when sufficient pressure is
maintained. When pressure is released, some liquid propane vaporizes. This liquid-vapor
relationship is one of the most important concepts for plant operators.
7. What happens when liquid propane is released from a pressurized container?
A. It immediately becomes solid
B. It can rapidly vaporize and expand
C. It becomes water
D. It loses all flammability
Correct Answer: B
Explanation: Liquid propane undergoes rapid vaporization when pressure is reduced. The
resulting vapor can occupy a much larger volume than the original liquid. This creates serious
fire and explosion hazards if the release occurs near an ignition source.
8. Which property makes propane particularly hazardous in a poorly ventilated low area?
A. Propane vapor is heavier than air
B. Propane vapor is lighter than oxygen
C. Propane is nonflammable
D. Propane vapor always rises rapidly
Correct Answer: A
Explanation: Propane vapor has a relative vapor density greater than air, so it can collect in low
areas. A plant operator must therefore consider pits, drains, trenches, and other low points when
evaluating a suspected release.
9. What is the most important immediate concern during a significant propane leak?
A. Product accounting
B. Ignition and uncontrolled vapor accumulation
C. Paint damage
D. Equipment appearance
Correct Answer: B
Explanation: A propane leak can produce a flammable vapor cloud. Preventing ignition and
protecting personnel are the immediate priorities. Inventory calculations and equipment repairs
come later after the area is made safe.
10. Why is an odorant added to propane?
, A. To increase its octane rating
B. To make leaks easier to detect by smell
C. To reduce vapor pressure
D. To prevent all corrosion
Correct Answer: B
Explanation: Commercial propane is normally odorized so that people can detect a potential
leak by smell. Odorization is an important safety feature, although odor should never be
considered a substitute for approved gas-detection and leak-testing procedures.
11. Which characteristic describes propane vapor?
A. It is always visible
B. It can form a flammable mixture with air
C. It cannot travel away from a leak
D. It is harmless when concentrated
Correct Answer: B
Explanation: Propane vapor can mix with air within its flammable range and ignite if an
ignition source is present. Vapor may also travel considerable distances from the original leak
before reaching an ignition source.
12. Why should ignition sources be controlled around propane facilities?
A. Propane cannot burn without electricity
B. A spark or flame can ignite propane-air mixtures
C. Ignition sources only affect gasoline
D. Propane becomes nonflammable near flames
Correct Answer: B
Explanation: Propane requires an ignition source when the propane-air mixture is within its
flammable range. Sparks, open flames, hot surfaces, electrical equipment, and static discharge
can potentially provide ignition energy.
13. What is one reason propane containers are not normally filled completely with liquid?
A. Liquid propane does not expand
B. Space is needed for thermal expansion
C. Full containers produce no pressure
D. Containers must remain empty at night
Correct Answer: B
