Plumbing Pipe Systems & Materials 2 — Questions and Answers
Question 1: What is the nominal pipe size (NPS) measurement based on?
- Exact outer diameter
- Approximate inner diameter (Correct answer)
- Wall thickness
- Flow rate capacity
Correct answer: Approximate inner diameter
Nominal pipe size (NPS) is an approximate measurement of the inner diameter, not an exact measurement of any physical dimension.
Question 2: Which pipe material is best suited for underground sewer lines due to its chemical resistance?
- Copper
- PEX
- Schedule 40 PVC (Correct answer)
- Galvanized steel
Correct answer: Schedule 40 PVC
Schedule 40 PVC is widely used for underground sewer lines because of its excellent chemical resistance and durability in soil environments.
Question 3: What does 'Schedule' refer to in pipe specifications (e.g., Schedule 40)?
- The pipe's installation timeline
- The pipe's wall thickness (Correct answer)
- The pipe's pressure rating
- The pipe's diameter
Correct answer: The pipe's wall thickness
Schedule refers to the wall thickness of a pipe, with higher schedule numbers indicating thicker walls and greater pressure ratings.
Question 4: Which type of copper pipe has the thinnest wall and is used for interior supply lines?
- Type K
- Type L
- Type M (Correct answer)
- Type DWV
Correct answer: Type M
Type M copper has the thinnest walls among the three pressure-rated copper types and is commonly used for interior supply lines in residential applications.
Question 5: What is the purpose of a dielectric union?
- To allow pipe expansion
- To prevent galvanic corrosion between dissimilar metals (Correct answer)
- To reduce pipe diameter
- To allow pipe rotation
Correct answer: To prevent galvanic corrosion between dissimilar metals
A dielectric union prevents galvanic corrosion by electrically isolating two dissimilar metal pipes, such as copper and galvanized steel.
Question 6: What is the maximum operating temperature for standard PVC pipe?
- 60°F
- 100°F
- 140°F (Correct answer)
- 180°F
Correct answer: 140°F
Standard PVC pipe has a maximum operating temperature of 140°F (60°C), which is why it cannot be used for hot water supply lines.
Plumbing Pipe Systems & Materials 2
What is the nominal pipe size (NPS) measurement based on?