Certification Exam (Second Period)
Practice (Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A| Instant Download Pdf
1. What is the developed length of a 90° long-radius elbow?
A. 150 mm
B. 305 mm
C. 230 mm
D. 120 mm
The long-radius 90° elbow commonly uses a developed length based on its
centerline radius, typically around 305 mm for standard trade sizing.
2. What type of valve provides the best throttling control?
A. Gate valve
B. Globe valve
C. Needle valve
D. Ball valve
Needle valves allow very fine adjustments to flow, making them ideal for
throttling.
3. The minimum size of a building drain for a residence is:
A. 2 in.
B. 3 in.
C. 4 in.
D. 1½ in.
Residential building drains must not be smaller than 3 inches according to
plumbing code.
,4. The purpose of a trap weir is to:
A. Support pipe
B. Increase velocity
C. Maintain the trap seal
D. Provide pressure relief
The trap weir retains water, ensuring the trap seal prevents sewer gas entry.
5. What is the function of a check valve?
A. Increase pressure
B. Reduce friction loss
C. Prevent reverse flow
D. Measure flow rate
Check valves are designed to stop backflow automatically.
6. Copper tube type L is identified by what color?
A. Yellow
B. Blue
C. Red
D. Green
Type L copper is marked with blue for medium-duty use.
7. Which fitting is used to join three sections of pipe at 90° angles?
A. Tee-wye
B. Wye
C. Coupling
D. Tee
A tee fitting connects one branch at 90° to the run.
8. A backwater valve is installed to protect against:
A. Low pressure
B. High pressure
C. Sewer backup
D. Pipe collapse
Backwater valves stop sewage from flowing back into a building.
, 9. The minimum slope for a 3-inch horizontal drainage pipe is:
A. 1%
B. 2%
C. 0%
D. 5%
3 in. pipe requires 1:50 slope = 2%.
10. Solder used for potable water must not contain:
A. Tin
B. Copper
C. Lead
D. Silver
Potable water joints must use lead-free solder for health and code
compliance.
11. Which device prevents siphonage?
A. Gate valve
B. Pressure gauge
C. Air admittance valve
D. Ball valve
AAVs let air enter to balance pressure and prevent siphonage.
12. What is the name of the vertical pipe that carries wastewater to the
building drain?
A. Branch line
B. Soil stack
C. Vent stack
D. Leader
A soil stack conveys waste vertically.
13. The maximum vertical distance from trap weir to vent is known as:
A. Vent rise
B. Trap arm length
C. Stack offset