Maryland Master Plumber/Gas Fitter
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationale 2026 Q&A| Instant Download
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1. A master plumber is reviewing plans for a commercial installation
where a water distribution system must prevent contamination from
backflow. Which device provides the highest level of protection against
backsiphonage and backpressure conditions involving health hazards?
A. Double check valve assembly
B. Pressure vacuum breaker
C. Reduced pressure principle backflow preventer
D. Atmospheric vacuum breaker
C. Reduced pressure principle backflow preventer
A reduced pressure principle backflow preventer provides the greatest level
of protection for high-hazard cross-connections because it protects against
both backsiphonage and backpressure through the use of independently
acting check valves and a relief valve.
2. In a drainage system, what is the primary purpose of a plumbing trap?
,A. To increase flow velocity
B. To prevent sewer gases from entering occupied spaces
C. To separate solids from liquids
D. To reduce water pressure fluctuations
B. To prevent sewer gases from entering occupied spaces
A plumbing trap retains a water seal that blocks sewer gases, vermin, and
odors from entering the building through fixture drains while still allowing
wastewater to flow through the system.
3. A gas fitter is sizing a natural gas piping system for a building supplied
with 0.5 psi gas pressure. Which factor is most critical when
determining pipe sizing?
A. Pipe color coding
B. Length of run and total connected load
C. Type of insulation on the pipe
D. Number of shutoff valves installed
B. Length of run and total connected load
Gas pipe sizing depends primarily on the total demand in cubic feet per
hour and the developed length of the piping system because pressure loss
increases with both flow and distance.
4. When testing a newly installed drainage and vent system with water,
what is the minimum requirement for the test head in most plumbing
codes?
A. 5-foot head above the highest fitting
B. 10-foot head above the highest fitting
C. 15-foot head above the lowest cleanout
D. 20-foot head above the building drain
B. 10-foot head above the highest fitting
,A water test typically requires the system to be filled to produce at least a
10-foot head above the highest fitting to ensure that joints and
connections are watertight under pressure.
5. Which type of copper tubing is commonly identified by a green
marking and approved for underground water service applications?
A. Type K
B. Type L
C. Type M
D. DWV copper tubing
A. Type K
Type K copper tubing has the thickest wall among common copper tubing
types and is commonly approved for underground water services due to its
durability and corrosion resistance.
6. A plumbing contractor is installing a cleanout on a horizontal drainage
pipe. Where should the cleanout opening normally be directed?
A. Upstream only
B. Downstream only
C. In the direction of flow or at right angles thereto
D. Toward the nearest wall
C. In the direction of flow or at right angles thereto
Cleanouts are intended to facilitate drain cleaning equipment access and
are generally required to open in the direction of flow or at right angles to
it for effective maintenance.
7. Which statement about vent terminals is correct?
A. Vent terminals may terminate inside attics
B. Vent terminals must terminate below all windows
, C. Vent terminals must extend outdoors to open air
D. Vent terminals may connect directly to chimney flues
C. Vent terminals must extend outdoors to open air
Vent terminals are required to terminate outdoors so sewer gases can
disperse safely into the atmosphere without entering occupied portions of
the structure.
8. What is the primary purpose of a thermal expansion tank installed on
a domestic hot water system?
A. To increase water heater recovery rate
B. To absorb pressure increases caused by heated water expansion
C. To reduce sediment accumulation
D. To increase hot water temperature
B. To absorb pressure increases caused by heated water expansion
A thermal expansion tank accommodates the increased volume of heated
water in a closed system, preventing excessive pressure that could damage
piping or fixtures.
9. Which piping material is prohibited for use as a gas vent connector
because of rapid corrosion potential?
A. Stainless steel
B. Aluminum in certain high-efficiency appliance applications
C. Schedule 40 steel
D. Cast iron
B. Aluminum in certain high-efficiency appliance applications
High-efficiency gas appliances can produce acidic condensate that rapidly
corrodes aluminum vent connectors, making them unsuitable in many
condensing applications.
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationale 2026 Q&A| Instant Download
1. A master plumber is reviewing plans for a commercial installation
where a water distribution system must prevent contamination from
backflow. Which device provides the highest level of protection against
backsiphonage and backpressure conditions involving health hazards?
A. Double check valve assembly
B. Pressure vacuum breaker
C. Reduced pressure principle backflow preventer
D. Atmospheric vacuum breaker
C. Reduced pressure principle backflow preventer
A reduced pressure principle backflow preventer provides the greatest level
of protection for high-hazard cross-connections because it protects against
both backsiphonage and backpressure through the use of independently
acting check valves and a relief valve.
2. In a drainage system, what is the primary purpose of a plumbing trap?
,A. To increase flow velocity
B. To prevent sewer gases from entering occupied spaces
C. To separate solids from liquids
D. To reduce water pressure fluctuations
B. To prevent sewer gases from entering occupied spaces
A plumbing trap retains a water seal that blocks sewer gases, vermin, and
odors from entering the building through fixture drains while still allowing
wastewater to flow through the system.
3. A gas fitter is sizing a natural gas piping system for a building supplied
with 0.5 psi gas pressure. Which factor is most critical when
determining pipe sizing?
A. Pipe color coding
B. Length of run and total connected load
C. Type of insulation on the pipe
D. Number of shutoff valves installed
B. Length of run and total connected load
Gas pipe sizing depends primarily on the total demand in cubic feet per
hour and the developed length of the piping system because pressure loss
increases with both flow and distance.
4. When testing a newly installed drainage and vent system with water,
what is the minimum requirement for the test head in most plumbing
codes?
A. 5-foot head above the highest fitting
B. 10-foot head above the highest fitting
C. 15-foot head above the lowest cleanout
D. 20-foot head above the building drain
B. 10-foot head above the highest fitting
,A water test typically requires the system to be filled to produce at least a
10-foot head above the highest fitting to ensure that joints and
connections are watertight under pressure.
5. Which type of copper tubing is commonly identified by a green
marking and approved for underground water service applications?
A. Type K
B. Type L
C. Type M
D. DWV copper tubing
A. Type K
Type K copper tubing has the thickest wall among common copper tubing
types and is commonly approved for underground water services due to its
durability and corrosion resistance.
6. A plumbing contractor is installing a cleanout on a horizontal drainage
pipe. Where should the cleanout opening normally be directed?
A. Upstream only
B. Downstream only
C. In the direction of flow or at right angles thereto
D. Toward the nearest wall
C. In the direction of flow or at right angles thereto
Cleanouts are intended to facilitate drain cleaning equipment access and
are generally required to open in the direction of flow or at right angles to
it for effective maintenance.
7. Which statement about vent terminals is correct?
A. Vent terminals may terminate inside attics
B. Vent terminals must terminate below all windows
, C. Vent terminals must extend outdoors to open air
D. Vent terminals may connect directly to chimney flues
C. Vent terminals must extend outdoors to open air
Vent terminals are required to terminate outdoors so sewer gases can
disperse safely into the atmosphere without entering occupied portions of
the structure.
8. What is the primary purpose of a thermal expansion tank installed on
a domestic hot water system?
A. To increase water heater recovery rate
B. To absorb pressure increases caused by heated water expansion
C. To reduce sediment accumulation
D. To increase hot water temperature
B. To absorb pressure increases caused by heated water expansion
A thermal expansion tank accommodates the increased volume of heated
water in a closed system, preventing excessive pressure that could damage
piping or fixtures.
9. Which piping material is prohibited for use as a gas vent connector
because of rapid corrosion potential?
A. Stainless steel
B. Aluminum in certain high-efficiency appliance applications
C. Schedule 40 steel
D. Cast iron
B. Aluminum in certain high-efficiency appliance applications
High-efficiency gas appliances can produce acidic condensate that rapidly
corrodes aluminum vent connectors, making them unsuitable in many
condensing applications.
