Minnesota Restricted Master Plumber
Exam Practice Questions And Correct
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Rationales 2026 Q&A | Instant
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1. A plumbing vent system is primarily designed to
A. Increase water pressure
B. Remove solids from wastewater
C. Protect trap seals from siphonage and backpressure
D. Heat water in the system
C. Protect trap seals from siphonage and backpressure
Vent systems maintain atmospheric pressure in drainage piping to
prevent trap seal loss due to siphoning or backpressure conditions.
2. The minimum slope for a 3-inch horizontal drainage pipe is typically
A. 1/16 inch per foot
B. 1/8 inch per foot
C. 1/4 inch per foot
, D. 1/2 inch per foot
C. 1/4 inch per foot
A 3-inch drain requires adequate slope to maintain self-scouring
velocity, and 1/4 inch per foot is the standard minimum.
3. A P-trap is installed to
A. Increase flow velocity
B. Prevent sewer gases from entering the building
C. Filter solids from wastewater
D. Increase pipe pressure
B. Prevent sewer gases from entering the building
A P-trap holds a water seal that blocks sewer gases from backing
into occupied spaces.
4. The minimum water seal depth in a trap is generally
A. 1 inch
B. 2 inches
C. 3 inches
D. 4 inches
B. 2 inches
Most plumbing codes require a minimum trap seal of about 2 inches
to ensure effective gas blockage.
5. A common material used for DWV systems is
A. Copper Type K
B. Cast iron soil pipe
, C. Aluminum tubing
D. Brass fittings
B. Cast iron soil pipe
Cast iron is widely used for DWV systems due to its durability, sound
dampening, and fire resistance.
6. Air admittance valves (AAVs) are used to
A. Increase water flow
B. Replace vent stacks in all conditions
C. Allow air into the system while preventing sewer gas escape
D. Increase pipe diameter
C. Allow air into the system while preventing sewer gas escape
AAVs admit air under negative pressure conditions while sealing
under positive pressure.
7. The purpose of a cleanout is to
A. Increase flow speed
B. Provide access for pipe inspection and cleaning
C. Reduce pipe diameter
D. Vent sewer gases
B. Provide access for pipe inspection and cleaning
Cleanouts allow maintenance equipment to access and clear
blockages in drainage piping.
8. A water hammer arrestor is installed to
A. Increase pressure
, B. Prevent pipe corrosion
C. Absorb pressure surges from fast-closing valves
D. Reduce water temperature
C. Absorb pressure surges from fast-closing valves
Water hammer arrestors protect piping systems from shock waves
caused by sudden valve closure.
9. The main function of a backflow preventer is to
A. Increase water flow rate
B. Prevent contamination of potable water
C. Filter sediment
D. Reduce pipe size
B. Prevent contamination of potable water
Backflow preventers stop reverse flow that could introduce
contaminants into potable systems.
10. A vent stack is best described as
A. A pipe carrying waste
B. A pipe carrying only rainwater
C. A vertical pipe that provides venting for the drainage system
D. A pipe used for water supply
C. A vertical pipe that provides venting for the drainage system
Vent stacks extend through the roof to equalize pressure in drainage
systems.
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. A plumbing vent system is primarily designed to
A. Increase water pressure
B. Remove solids from wastewater
C. Protect trap seals from siphonage and backpressure
D. Heat water in the system
C. Protect trap seals from siphonage and backpressure
Vent systems maintain atmospheric pressure in drainage piping to
prevent trap seal loss due to siphoning or backpressure conditions.
2. The minimum slope for a 3-inch horizontal drainage pipe is typically
A. 1/16 inch per foot
B. 1/8 inch per foot
C. 1/4 inch per foot
, D. 1/2 inch per foot
C. 1/4 inch per foot
A 3-inch drain requires adequate slope to maintain self-scouring
velocity, and 1/4 inch per foot is the standard minimum.
3. A P-trap is installed to
A. Increase flow velocity
B. Prevent sewer gases from entering the building
C. Filter solids from wastewater
D. Increase pipe pressure
B. Prevent sewer gases from entering the building
A P-trap holds a water seal that blocks sewer gases from backing
into occupied spaces.
4. The minimum water seal depth in a trap is generally
A. 1 inch
B. 2 inches
C. 3 inches
D. 4 inches
B. 2 inches
Most plumbing codes require a minimum trap seal of about 2 inches
to ensure effective gas blockage.
5. A common material used for DWV systems is
A. Copper Type K
B. Cast iron soil pipe
, C. Aluminum tubing
D. Brass fittings
B. Cast iron soil pipe
Cast iron is widely used for DWV systems due to its durability, sound
dampening, and fire resistance.
6. Air admittance valves (AAVs) are used to
A. Increase water flow
B. Replace vent stacks in all conditions
C. Allow air into the system while preventing sewer gas escape
D. Increase pipe diameter
C. Allow air into the system while preventing sewer gas escape
AAVs admit air under negative pressure conditions while sealing
under positive pressure.
7. The purpose of a cleanout is to
A. Increase flow speed
B. Provide access for pipe inspection and cleaning
C. Reduce pipe diameter
D. Vent sewer gases
B. Provide access for pipe inspection and cleaning
Cleanouts allow maintenance equipment to access and clear
blockages in drainage piping.
8. A water hammer arrestor is installed to
A. Increase pressure
, B. Prevent pipe corrosion
C. Absorb pressure surges from fast-closing valves
D. Reduce water temperature
C. Absorb pressure surges from fast-closing valves
Water hammer arrestors protect piping systems from shock waves
caused by sudden valve closure.
9. The main function of a backflow preventer is to
A. Increase water flow rate
B. Prevent contamination of potable water
C. Filter sediment
D. Reduce pipe size
B. Prevent contamination of potable water
Backflow preventers stop reverse flow that could introduce
contaminants into potable systems.
10. A vent stack is best described as
A. A pipe carrying waste
B. A pipe carrying only rainwater
C. A vertical pipe that provides venting for the drainage system
D. A pipe used for water supply
C. A vertical pipe that provides venting for the drainage system
Vent stacks extend through the roof to equalize pressure in drainage
systems.
