RHODE ISLAND JOURNEYMAN PLUMBER EXAM – QUESTIONS
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1. A journeyman plumber is sizing a horizontal sanitary drainage branch in a commercial
building. According to standard plumbing engineering standards, what is the minimum
required slope for a 3-inch horizontal drainage pipe to ensure self-scouring velocity?
A. 1/16 inch per foot
B. 1/4 inch per foot
C. 1 inch per foot
D. Completely flat with zero slope
ANSWER: B. 1/4 inch per foot
A slope of 1/4 inch per foot provides the necessary hydraulic velocity for 3-inch pipes to
transport suspended organic solids successfully without allowing them to settle and create
blockages. Steeper slopes cause water to run away too fast, while flatter slopes lack scouring
velocity.
2. When installing a domestic water distribution system using copper tubing in a
commercial retrofit, a plumber is evaluating the compatibility of joining methods. Under
standard mechanical code, what joining method requires an open flame or induction heat
source and alloy filler material melting above $840^\circ\text{F}$?
A. Soft soldering
B. Brazing
C. Push-fit mechanical coupling
D. Threaded dielectric union
ANSWER: B. Brazing
Brazing utilizes filler metals that melt at temperatures exceeding $840^\circ\text{F}$, creating
high-strength structural joints suitable for high-pressure or medical gas piping systems,
whereas soft soldering melts at significantly lower temperatures.
3. A plumber is designing a drainage system for a building where fixtures are located below
the crown level of the municipal street sewer. What specialized device must be installed on
the building drain to protect these lower-level fixtures from raw sewage surcharging?
A. A roof storm drain leader
B. A backwater valve
C. A thermal expansion tank
,D. An atmospheric vacuum breaker
Answer: B. A backwater valve
A backwater valve features an internal flapper or gate mechanism that permits normal
outward flow while closing automatically to prevent municipal sewer backups from flooding
basement fixtures during heavy surcharge events.
4. While installing a commercial kitchen grease interceptor, a journeyman notices that the
unintercepted waste line run from the fixture trap to the interceptor inlet is excessively
long. Why does code limit this developed length?
A. To prevent fats, oils, and greases from cooling, solidifying, and clogging the unintercepted
pipe run before reaching the trap chamber
B. To increase municipal water pressure to the faucets
C. To allow wastewater to boil before separation
D. Length limits are purely aesthetic and have no functional purpose
Answer: A. To prevent fats, oils, and greases from cooling, solidifying, and clogging the
unintercepted pipe run before reaching the trap chamber
Fats, oils, and greases (FOG) remain liquid only at elevated temperatures. Long unintercepted
runs cause rapid cooling and congealing, resulting in stubborn pipe blockages upstream of the
grease interceptor.
5. An apprentice asks why a water heater installation requires a thermal expansion tank on
a closed domestic water supply system equipped with a backflow preventer. How should
the journeyman explain this?
A. The expansion tank adds extra hot water storage capacity for large families
B. Backflow preventers create a closed loop, and thermal expansion during heating cycles
increases system pressure that must be absorbed to protect piping and components
C. It acts as an electrical ground for the water heater elements
D. It prevents the cold water supply pipe from freezing in winter
Answer: B. Backflow preventers create a closed loop, and thermal expansion during heating
cycles increases system pressure that must be absorbed to protect piping and components
When water is heated, it expands volumetrically. In an open system, excess pressure pushes
back into the municipal main; backflow preventers block this relief, requiring an expansion
tank cushion to prevent tank ruptures or pipe leaks.
6. A journeyman is testing a newly installed fuel gas piping system in a commercial
structure. The local code mandates a pneumatic test pressure of 10 psi. What type of test
gauge must be utilized to verify this low-pressure gas test accurately?
, A. A high-range industrial gauge scaled up to 500 psi
B. A finely graduated pressure gauge scaled in increments of 0.1 psi or less, or a mercury
manometer
C. A standard automotive tire pressure gauge
D. An electrical digital timer
Answer: B. A finely graduated pressure gauge scaled in increments of 0.1 psi or less, or a
mercury manometer
Low-pressure pneumatic tests require sensitive gauges capable of registering minute pressure
drops or micro-leaks that would be entirely invisible on high-range rough pressure gauges.
7. A plumber is routing a 4-inch vertical cast-iron soil stack through multiple floors of an
apartment complex. According to standard structural support rules, how frequently must
vertical cast-iron stacks be secured?
A. At every floor level or at least at every alternate floor level and at the base of the stack to
support total dead weight
B. Only at the roof penetration point
C. Once every 500 feet
D. No vertical support is required if the pipe touches the dirt floor
Answer: A. At every floor level or at least at every alternate floor level and at the base of
the stack to support total dead weight
Vertical cast-iron stacks carry substantial dead load weight. Securing them with heavy-duty
riser clamps at structural floor levels prevents joint separation, sagging, and structural
overstressing.
8. During a service call, a customer complains of a loud banging noise in the copper water
supply lines every time the automatic washing machine solenoid valve snaps shut. What
mechanical device solves this issue?
A. A sanitary backwater valve
B. A certified water hammer arrestor meeting ASSE 1010 standards
C. A reduced pressure principle backflow preventer
D. A chemical neutralization tank
Answer: B. A certified water hammer arrestor meeting ASSE 1010 standards
Quick-closing valves create hydraulic shock waves (water hammer). Water hammer arrestors
use trapped air cushions or internal pistons to absorb this kinetic energy shock instantly.
9. A plumber is preparing to install a commercial dishwashing machine that discharges
directly into a food prep sink drainage network. Why does code mandate an air gap or air
break on this indirect waste connection?
AND ANSWERS | VERIFIED AND WELL DETAILED ANSWERS |
PLUS RATIONALES | GUARANTEED PASS | LATEST EXAM
UPDATE | EXAM PREP | STUDY GUIDE | PRACTICE TEST
1. A journeyman plumber is sizing a horizontal sanitary drainage branch in a commercial
building. According to standard plumbing engineering standards, what is the minimum
required slope for a 3-inch horizontal drainage pipe to ensure self-scouring velocity?
A. 1/16 inch per foot
B. 1/4 inch per foot
C. 1 inch per foot
D. Completely flat with zero slope
ANSWER: B. 1/4 inch per foot
A slope of 1/4 inch per foot provides the necessary hydraulic velocity for 3-inch pipes to
transport suspended organic solids successfully without allowing them to settle and create
blockages. Steeper slopes cause water to run away too fast, while flatter slopes lack scouring
velocity.
2. When installing a domestic water distribution system using copper tubing in a
commercial retrofit, a plumber is evaluating the compatibility of joining methods. Under
standard mechanical code, what joining method requires an open flame or induction heat
source and alloy filler material melting above $840^\circ\text{F}$?
A. Soft soldering
B. Brazing
C. Push-fit mechanical coupling
D. Threaded dielectric union
ANSWER: B. Brazing
Brazing utilizes filler metals that melt at temperatures exceeding $840^\circ\text{F}$, creating
high-strength structural joints suitable for high-pressure or medical gas piping systems,
whereas soft soldering melts at significantly lower temperatures.
3. A plumber is designing a drainage system for a building where fixtures are located below
the crown level of the municipal street sewer. What specialized device must be installed on
the building drain to protect these lower-level fixtures from raw sewage surcharging?
A. A roof storm drain leader
B. A backwater valve
C. A thermal expansion tank
,D. An atmospheric vacuum breaker
Answer: B. A backwater valve
A backwater valve features an internal flapper or gate mechanism that permits normal
outward flow while closing automatically to prevent municipal sewer backups from flooding
basement fixtures during heavy surcharge events.
4. While installing a commercial kitchen grease interceptor, a journeyman notices that the
unintercepted waste line run from the fixture trap to the interceptor inlet is excessively
long. Why does code limit this developed length?
A. To prevent fats, oils, and greases from cooling, solidifying, and clogging the unintercepted
pipe run before reaching the trap chamber
B. To increase municipal water pressure to the faucets
C. To allow wastewater to boil before separation
D. Length limits are purely aesthetic and have no functional purpose
Answer: A. To prevent fats, oils, and greases from cooling, solidifying, and clogging the
unintercepted pipe run before reaching the trap chamber
Fats, oils, and greases (FOG) remain liquid only at elevated temperatures. Long unintercepted
runs cause rapid cooling and congealing, resulting in stubborn pipe blockages upstream of the
grease interceptor.
5. An apprentice asks why a water heater installation requires a thermal expansion tank on
a closed domestic water supply system equipped with a backflow preventer. How should
the journeyman explain this?
A. The expansion tank adds extra hot water storage capacity for large families
B. Backflow preventers create a closed loop, and thermal expansion during heating cycles
increases system pressure that must be absorbed to protect piping and components
C. It acts as an electrical ground for the water heater elements
D. It prevents the cold water supply pipe from freezing in winter
Answer: B. Backflow preventers create a closed loop, and thermal expansion during heating
cycles increases system pressure that must be absorbed to protect piping and components
When water is heated, it expands volumetrically. In an open system, excess pressure pushes
back into the municipal main; backflow preventers block this relief, requiring an expansion
tank cushion to prevent tank ruptures or pipe leaks.
6. A journeyman is testing a newly installed fuel gas piping system in a commercial
structure. The local code mandates a pneumatic test pressure of 10 psi. What type of test
gauge must be utilized to verify this low-pressure gas test accurately?
, A. A high-range industrial gauge scaled up to 500 psi
B. A finely graduated pressure gauge scaled in increments of 0.1 psi or less, or a mercury
manometer
C. A standard automotive tire pressure gauge
D. An electrical digital timer
Answer: B. A finely graduated pressure gauge scaled in increments of 0.1 psi or less, or a
mercury manometer
Low-pressure pneumatic tests require sensitive gauges capable of registering minute pressure
drops or micro-leaks that would be entirely invisible on high-range rough pressure gauges.
7. A plumber is routing a 4-inch vertical cast-iron soil stack through multiple floors of an
apartment complex. According to standard structural support rules, how frequently must
vertical cast-iron stacks be secured?
A. At every floor level or at least at every alternate floor level and at the base of the stack to
support total dead weight
B. Only at the roof penetration point
C. Once every 500 feet
D. No vertical support is required if the pipe touches the dirt floor
Answer: A. At every floor level or at least at every alternate floor level and at the base of
the stack to support total dead weight
Vertical cast-iron stacks carry substantial dead load weight. Securing them with heavy-duty
riser clamps at structural floor levels prevents joint separation, sagging, and structural
overstressing.
8. During a service call, a customer complains of a loud banging noise in the copper water
supply lines every time the automatic washing machine solenoid valve snaps shut. What
mechanical device solves this issue?
A. A sanitary backwater valve
B. A certified water hammer arrestor meeting ASSE 1010 standards
C. A reduced pressure principle backflow preventer
D. A chemical neutralization tank
Answer: B. A certified water hammer arrestor meeting ASSE 1010 standards
Quick-closing valves create hydraulic shock waves (water hammer). Water hammer arrestors
use trapped air cushions or internal pistons to absorb this kinetic energy shock instantly.
9. A plumber is preparing to install a commercial dishwashing machine that discharges
directly into a food prep sink drainage network. Why does code mandate an air gap or air
break on this indirect waste connection?
