Journeyman Plumber ExamFixtures, Faucets, and Other AppliancesHard
A plumber is installing a water softener in a residential application. The local plumbing code, based on the UPC, requires a minimum of 6 feet of developed length between the water softener discharge and the building drain or branch drain. If the discharge pipe is 1.5 inches in diameter, what is the maximum number of 90-degree elbows allowed within this 6-foot developed length, assuming each 90-degree elbow is equivalent to 5 feet of straight pipe for friction loss calculations?
- A1
- B2
- C3
- D0
Show answer & explanationAnswer & explanation
Correct answer: A. 1
The developed length required is 6 feet. If each 90-degree elbow is equivalent to 5 feet of straight pipe, then with one elbow, you would have 5 feet (for the elbow) + 1 foot (for actual straight pipe) = 6 feet of developed length. Therefore, a maximum of 1 elbow is allowed.
Why the other options are wrong
- B. 2 elbows would equate to 10 feet (2 * 5 feet), exceeding the 6-foot developed length limit.
- C. 3 elbows would equate to 15 feet, significantly exceeding the limit.
- D. 0 elbows would mean the entire 6 feet must be straight pipe, which is too restrictive if elbows are allowed at all.
Developed Length
The length of a pipeline measured along the centerline of the pipe and fittings, representing the total friction loss equivalent length.
- Includes length of straight pipe and equivalent length of fittings.
- Used in drainage and water distribution sizing calculations.
- Critical for proper flow and drainage performance.
Memory trick: Pipe's real length plus fitting's fiction, equals the developed length's total friction.