Download Polk County Master Mechanical Exam Questions and Answers and more Exams Technology in PDF only on Docsity!
Question 1. What is the primary purpose of a plumbing code in Polk County? A) To increase construction costs B) To ensure sanitary and safe installation of systems C) To speed up construction D) To promote advanced plumbing technologies Answer: B Explanation: The plumbing code exists to ensure all plumbing systems are installed safely and meet sanitary requirements to protect public health. Question 2. What is the minimum slope required for a horizontal drainage pipe 3 inches or less in diameter? A) 1/2 inch per foot B) 1/8 inch per foot C) 1/4 inch per foot D) 3/4 inch per foot Answer: C Explanation: A minimum slope of 1/4 inch per foot is required to ensure proper drainage and prevent solids from settling in the pipe.
Question 3. Which pipe material is NOT approved for natural gas distribution inside a building? A) Steel B) Copper (Type L, with approval) C) PVC D) CSST Answer: C Explanation: PVC is not approved for natural gas inside buildings due to its inability to safely contain gas under pressure and exposure to potential leaks. Question 4. What is the function of a trap in a plumbing system? A) Increase water flow B) Prevent sewer gases from entering occupied spaces C) Reduce water pressure D) Vent fixtures Answer: B Explanation: Traps contain water which acts as a barrier to stop sewer gases from entering buildings. Question 5. According to code, which of the following fixtures requires an air gap?
B) 20 psi C) 30 psi D) 40 psi Answer: C Explanation: A minimum pressure of 30 psi is required to ensure all fixtures operate properly. Question 8. What is the maximum allowable distance between a fixture trap and its vent in a 2” drain line? A) 18 inches B) 24 inches C) 5 feet D) 8 feet Answer: C Explanation: For a 2” drain, the maximum trap-to-vent distance is generally 5 feet to prevent siphonage. Question 9. Which of the following is considered an indirect waste connection? A) Lavatory B) Janitor sink
C) Refrigerator drain D) Water closet Answer: C Explanation: Refrigerator drains discharge indirectly to the drainage system, usually via an air gap. Question 10. What is the minimum burial depth for gas piping installed outdoors? A) 6 inches B) 12 inches C) 18 inches D) 24 inches Answer: C Explanation: Gas piping must be buried at least 18 inches deep to protect against accidental damage. Question 11. Which type of water heater venting system requires no chimney or vertical vent? A) Atmospheric B) Direct-vent C) Power-vent
Explanation: Stop-and-waste valves are not approved for use as main gas shutoff valves due to their design. Question 14. According to the plumbing code, what is the maximum allowable lead content in potable water pipe and fittings? A) 0.2% B) 0.5% C) 1.0% D) 2.0% Answer: B Explanation: Modern codes limit lead content to 0.25% weighted average, but 0.5% is a common exam choice and reflects older code standards. Question 15. What is the minimum size of a building sewer for a single-family dwelling? A) 2 inches B) 3 inches C) 4 inches D) 5 inches Answer: C
Explanation: A 4-inch minimum is required to handle the potential load from a single-family residence. Question 16. For a 40-gallon gas water heater, what is the typical minimum flue diameter? A) 2 inches B) 3 inches C) 4 inches D) 5 inches Answer: B Explanation: Most 40-gallon gas water heaters require a minimum 3” flue for safe venting. Question 17. What is the function of an expansion tank in a water heating system? A) Increase water temperature B) Store hot water C) Absorb increased pressure from thermal expansion D) Filter sediment Answer: C
Explanation: The stack vent extends from the highest point of the system to the outdoors. Question 20. What is the minimum size for a gas vent serving a single 40,000 BTU appliance? A) 2 inches B) 3 inches C) 4 inches D) 5 inches Answer: A Explanation: A 2-inch vent is typically adequate for a single 40,000 BTU gas appliance, but always check local code and manufacturer’s specs. Question 21. Which of the following materials is NOT permitted for use in potable water supply piping? A) Copper B) CPVC C) Galvanized steel D) Black steel Answer: D
Explanation: Black steel is not approved for potable water due to its susceptibility to corrosion. Question 22. What does a double check valve assembly protect against? A) Backpressure and backsiphonage B) Pipe freeze C) Water hammer D) Air in the line Answer: A Explanation: Double check valves protect against both backpressure and backsiphonage in non-health hazard situations. Question 23. When must a gas system be pressure tested? A) After painting B) Before being concealed C) After appliances are connected D) Only after final inspection Answer: B Explanation: Gas systems must be pressure tested before being concealed to ensure there are no leaks.
A) 3 feet B) 6 feet C) 10 feet D) 18 feet Answer: B Explanation: Water closets can be up to 6 feet from a vent, measured from the trap weir. Question 27. Which of the following is NOT considered a fixture unit? A) Water closet B) Lavatory C) Floor drain D) Hose bibb Answer: D Explanation: Hose bibbs are typically counted as multiple fixture units but are not a single fixture unit by themselves. Question 28. What is the minimum size for a gas drip leg (sediment trap)? A) 1/2 inch B) 3/4 inch
C) Same as the pipe size D) 2 inches Answer: C Explanation: The drip leg should be at least the same diameter as the gas pipe it serves. Question 29. Which type of joint is NOT permitted for gas piping? A) Threaded B) Welded C) Flanged D) Soldered Answer: D Explanation: Soldered joints are not permitted for gas piping due to heat and pressure concerns. Question 30. The minimum size of a trap for a bathtub is: A) 1-1/4 inch B) 1-1/2 inch C) 2 inch D) 3 inch
Explanation: Pilot safety devices stop gas flow if the pilot fails, preventing accidental ignition. Question 33. Which of the following is NOT part of a building drain system? A) Horizontal pipe inside the building B) Vertical stack C) Building sewer D) Branch drain Answer: C Explanation: The building sewer is outside the building, while the building drain is inside. Question 34. What is the minimum required air gap for a sink with a 1-inch water supply? A) 1 inch B) 1.5 inches C) 2 inches D) 3 inches Answer: C
Explanation: The air gap must be at least twice the diameter of the supply, so 2 inches for a 1-inch supply. Question 35. Which of the following is NOT a type of approved venting for gas appliances? A) Type B vent B) Single-wall vent C) Type C vent D) Direct vent Answer: C Explanation: There is no “Type C” vent recognized for gas appliances. Question 36. What is the maximum water temperature allowed at a public lavatory? A) 100°F B) 110°F C) 120°F D) 140°F Answer: B
Question 39. What is required for an exterior wall gas meter installation? A) Flexible connector B) Drip leg C) Bonding jumper D) All of the above Answer: D Explanation: All are typically required for safety and code compliance. Question 40. Which of the following is NOT a method for joining PEX piping? A) Crimp ring B) Solder C) Push-fit D) Expansion Answer: B Explanation: PEX piping cannot be soldered; it requires mechanical fittings. Question 41. Which fixture requires the largest trap size? A) Bathtub
B) Lavatory C) Floor drain D) Water closet Answer: D Explanation: The water closet has the largest trap, typically 3 inches. Question 42. What is the maximum developed length for a 3/4” gas pipe supplying a 75,000 BTU appliance (low pressure)? A) 10 feet B) 50 feet C) 100 feet D) 200 feet Answer: C Explanation: 3/4” pipe can typically supply up to 100 feet for this BTU load. Question 43. What is the minimum depth a building sewer must be laid below grade? A) 6 inches B) 12 inches C) Below frost line or 12 inches, whichever is greater
