FREE Journeyman Plumbers Drain, Waste, Vent Systems Questions and Answers

Question 1

According to most plumbing codes, what is the maximum allowable distance between cleanouts on a 4-inch horizontal drainage line?

Accepted Answer

100 feet

Answer

Both the International Plumbing Code (IPC) and the Uniform Plumbing Code (UPC) generally require cleanouts on horizontal drains to be installed at intervals not exceeding 100 feet. Some local codes might have slight variations, but 100 feet is the most common standard.

Question 2

A plumber is installing a wet vent for a single bathroom group. Which of the following is a universal requirement for this type of installation?

Accepted Answer

All fixtures served by the wet vent must be on the same floor level.

Answer

A key rule for both horizontal and vertical wet venting, according to major plumbing codes, is that all the fixtures connecting to the wet vent must be located on the same story or floor level. While other rules apply regarding pipe sizing and fixture order, the same-floor requirement is fundamental.

Question 3

What is the minimum required clearance in front of a cleanout for a 3-inch drain pipe to allow for proper rodding and servicing?

Accepted Answer

18 inches

Answer

The International Plumbing Code (IPC) specifies that cleanouts on 6-inch and smaller pipes must have a clearance of not less than 18 inches for rodding. The Uniform Plumbing Code (UPC) has similar requirements, stating that pipes over 2 inches need at least 24 inches, but 18 inches is a widely accepted minimum for smaller pipes.

Question 4

A residential bathroom group consists of a standard water closet (1.6 GPF), a lavatory, and a bathtub. What is the total Drainage Fixture Unit (DFU) load for this group that should be used for sizing the branch drain?

Accepted Answer

6 DFU

Answer

Individually, a 1.6 GPF water closet is typically 4 DFU, a lavatory is 1 DFU, and a bathtub is 2 DFU, totaling 7 DFU. However, plumbing codes recognize that not all fixtures are used simultaneously. Therefore, when calculating the load for a bathroom group on a branch, a lower value is often assigned. Adding them up: Lavatory (1 DFU) + Bathtub (2 DFU) + Water Closet (3-4 DFU) would be 6-7 DFU. Different codes may vary slightly, but 6 DFU is a common value. For example, some codes value a 1.6 GPF toilet at 3 DFU, making the total 6.

Question 5

Which of the following describes the minimum required length for a trap arm, as measured from the trap weir to the inner edge of the vent?

Accepted Answer

It must be at least two times the diameter of the trap arm.

Answer

To prevent crown-venting, where the vent opening becomes fouled by waste, and to ensure proper function, the trap arm must have a minimum length. The code specifies this minimum length to be no less than two times the nominal pipe diameter of the trap arm itself.

Journeyman Plumbers Exam Practice Test

Journeyman Plumbers Exam Practice Test

FREE Journeyman Plumbers Drain, Waste, Vent Systems Questions and Answers