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Master Plumber — Practical Problems

Master Plumber board reviewer: pipe sizing and computations.

Reviewer for Practical Plumbing Problems and computations for the Master Plumber board.

1

Fixture Units & Sizing

Pipes are sized using fixture units (FU) — each fixture has an FU value; total FU determines the required pipe diameter.

💡 Exam Hack

More fixture units → larger pipe. Use the code’s sizing tables to convert total FU to pipe size.

2

Flow and Pressure

Flow rate Q = Area × Velocity

Adequate pressure must reach the highest, farthest fixture. Friction loss increases with pipe length and fittings.

3

Slope of Drains

Horizontal drains need a minimum slope (commonly 2%, or 1/4 inch per foot) so waste flows by gravity without clogging.

4

Worked Example

A 100-ft drain at 2% slope drops how much?

Drop = 100 ft × 0.02 = 2 ft
📌 Quick Recap — Master These

Before your exam, make sure you can confidently explain and apply each of the following:

  • Fixture Units & Sizing
  • Flow and Pressure
  • Slope of Drains
  • Worked Example

Re-read any section above where you hesitate, then explain it aloud in your own words — if you can teach it simply, you understand it. Focus your final review on the tables, formulas, and the common-mistake warnings, since those are where most points are won or lost.