IPC - International Plumbing Code Sanitary Drainage Systems Questions and Answers — Questions and Answers
Question 1: According to the IPC, what is the minimum required slope for a 4-inch horizontal sanitary drainage pipe?
- 1/16 inch per foot
- 1/4 inch per foot
- 1/8 inch per foot (Correct answer)
- 1/2 inch per foot
Correct answer: 1/8 inch per foot
IPC Table 704.1 specifies the minimum slope for horizontal drainage piping. For pipes with a diameter of 3 to 6 inches, the minimum slope required is 1/8 inch per foot (1-percent slope).
Question 2: A plumber is installing a new building sewer. According to the IPC, a cleanout is required at intervals of not more than:
- 50 feet
- 150 feet
- 75 feet
- 100 feet (Correct answer)
Correct answer: 100 feet
IPC Section 708.3.2 states that building sewers shall be provided with cleanouts located not more than 100 feet apart. This allows for proper access for cleaning and maintenance of the sewer line.
Question 3: Which of the following fittings is generally prohibited for use in a sanitary drainage system to connect a horizontal drain to another horizontal drain?
- Wye fitting
- Sanitary tee (Correct answer)
- Combination wye and 1/8 bend
- Long-sweep quarter bend
Correct answer: Sanitary tee
According to IPC Section 706.3 and associated tables, a sanitary tee is restricted to connecting a horizontal drain to a vertical drain. Using it in a horizontal-to-horizontal application can impede flow and lead to stoppages.
Question 4: In a multistory building, a cleanout is required at the base of each waste or soil stack. The IPC requires the size of this cleanout for a 3-inch stack to be:
- Not less than 4 inches
- The same nominal size as the pipe it serves (Correct answer)
- One pipe size smaller than the stack
- At least 1 1/2 inches
Correct answer: The same nominal size as the pipe it serves
IPC Section 708.7 specifies that cleanouts shall be the same nominal size as the pipe they serve up to 4 inches. Therefore, a 3-inch stack requires a 3-inch cleanout.
Question 5: A horizontal wet vent is being installed to serve two bathroom groups on the same floor. According to the IPC, which of the following statements is correct?
- The wet vent can serve fixtures on multiple floors.
- Any fixture can connect to the wet-vented section.
- The wet vent portion of the pipe is sized smaller than a standard drain.
- Each wet-vented fixture drain must connect independently to the horizontal wet vent. (Correct answer)
Correct answer: Each wet-vented fixture drain must connect independently to the horizontal wet vent.
IPC Section 912.1 requires that each fixture drain connecting to a horizontal wet vent does so independently. This ensures that the discharge from one fixture does not interfere with the venting of another.
Question 6: A plumber needs to install a horizontal drainage branch that will carry a total of 30 Drainage Fixture Units (DFUs). The pipe will be installed with a slope of 1/4 inch per foot. Based on IPC Table 710.1(2), what is the minimum required size for this horizontal branch?
- 2 inches
- 4 inches
- 3 inches (Correct answer)
- 2 1/2 inches
Correct answer: 3 inches
According to IPC Table 710.1(2), a 3-inch horizontal branch pipe with a 1/4-inch-per-foot slope can handle a maximum of 42 DFUs. Since 30 DFUs is less than 42, a 3-inch pipe is the minimum required size. A 2 1/2-inch pipe at the same slope can only handle 21 DFUs, which is insufficient.
IPC - International Plumbing Code Sanitary Drainage Systems Questions and Answers
According to the IPC, what is the minimum required slope for a 4-inch horizontal sanitary drainage pipe?