Journeyman Plumber ExamDrainage, Waste, and Venting (DWV) SystemsHard
A plumber is installing a combination waste and vent system for a series of floor drains in a commercial kitchen. This system uses a horizontal wet vent. What is the maximum number of drainage fixture units (DFUs) that a 3-inch horizontal wet vent can serve?
- A12 DFUs
- B20 DFUs
- C36 DFUs
- D8 DFUs
Show answer & explanationAnswer & explanation
Correct answer: B. 20 DFUs
For a horizontal wet vent, the maximum number of DFUs permitted is generally lower than for a dry vent or a vertical wet vent of the same size. A 3-inch horizontal wet vent is typically limited to 20 DFUs.
Why the other options are wrong
- A. This DFU count is often associated with a 2-inch horizontal wet vent.
- C. This DFU count is usually for larger pipes or dry vent applications.
- D. This DFU count is too low for a 3-inch horizontal wet vent.
Horizontal Wet Vent DFU Capacity
The maximum drainage fixture units allowed on a horizontal pipe that serves as both a drainage and vent pipe, subject to specific code limitations.
- Capacity is reduced compared to dry vents.
- Specific limits for each pipe size.
- Critical for proper air circulation and drainage.
Memory trick: Wet vents get weary, carry less load.