Arizona C 37CR37 Plumbing Commercial
Practice exam for Plumber Licensing Exams under Plumber Licensing Exams (Licensing Exams). 5 sample questions.
Sample Questions
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Question 1
Mechanically formed water supply tee fittings shall be constructed by
Correct Answer: B
Rationale: Brazing joins copper or brass fittings using a filler metal with a melting point above 840°F, creating a strong, leak-proof joint suitable for water supply tees under pressure. Soldering uses lower temperatures and is not permitted for mechanically formed tees in potable water systems due to weaker bonds. Flaring expands the pipe end to fit over a fitting but does not form a tee. Chemically bonding applies to plastics like PVC, not copper or brass water supply systems.
Rationale: Brazing joins copper or brass fittings using a filler metal with a melting point above 840°F, creating a strong, leak-proof joint suitable for water supply tees under pressure. Soldering uses lower temperatures and is not permitted for mechanically formed tees in potable water systems due to weaker bonds. Flaring expands the pipe end to fit over a fitting but does not form a tee. Chemically bonding applies to plastics like PVC, not copper or brass water supply systems.
Question 2
What is the purpose of installing a check valve on each zone when piping a multi-zone heating system using multiple circulators
Correct Answer: B
Rationale: Check valves allow flow in one direction only, stopping warm water from a running zone from migrating backward through inactive circulators into other zones, which would cause ghost flow and uneven heating. Cool water prevention is not the primary issue—warm water backflow is. Air scoops remove air, not affected by check valves. Circulator efficiency depends on flow design, not check valves.
Rationale: Check valves allow flow in one direction only, stopping warm water from a running zone from migrating backward through inactive circulators into other zones, which would cause ghost flow and uneven heating. Cool water prevention is not the primary issue—warm water backflow is. Air scoops remove air, not affected by check valves. Circulator efficiency depends on flow design, not check valves.
Question 3
A potable water system is being disinfected with a water-chlorine solution containing 50 parts per million of chlorine. The solution MUST remain in the system for
Correct Answer: C
Rationale: At 50 ppm chlorine, the International Plumbing Code requires a minimum contact time of 24 hours to effectively kill bacteria and pathogens throughout the system. 8 or 12 hours is insufficient for full disinfection at this concentration. 36 hours exceeds the minimum requirement and is unnecessary unless specified by local authority.
Rationale: At 50 ppm chlorine, the International Plumbing Code requires a minimum contact time of 24 hours to effectively kill bacteria and pathogens throughout the system. 8 or 12 hours is insufficient for full disinfection at this concentration. 36 hours exceeds the minimum requirement and is unnecessary unless specified by local authority.
Question 4
What is the temperature rating for a sprinkler with a blue color code
Correct Answer: B
Rationale: NFPA 13 standardizes sprinkler color coding: blue indicates an ordinary temperature rating of 175–225°F, suitable for most commercial and residential environments. 135–170°F is unclassified or ordinary (white or uncolored). 250–300°F is high temperature (green). 325–375°F is very high (orange).
Rationale: NFPA 13 standardizes sprinkler color coding: blue indicates an ordinary temperature rating of 175–225°F, suitable for most commercial and residential environments. 135–170°F is unclassified or ordinary (white or uncolored). 250–300°F is high temperature (green). 325–375°F is very high (orange).
Question 5
Pressure relief valves on hot water tanks MUST open before the water pressure in the tank exceeds
Correct Answer: A
Rationale: ASME and IPC require temperature and pressure relief (TPR) valves on water heaters to open at 150 psi to protect the tank from overpressurization before vessel failure. Tanks are tested to 300 psi, but relief must activate well below that. 180, 210, and 212 psi exceed the safe activation threshold.
Rationale: ASME and IPC require temperature and pressure relief (TPR) valves on water heaters to open at 150 psi to protect the tank from overpressurization before vessel failure. Tanks are tested to 300 psi, but relief must activate well below that. 180, 210, and 212 psi exceed the safe activation threshold.