Colorado Master Plumber Exam Preparation

Below are a few questions from your upcoming PSI state exam:

(1) How many DFUs are permitted to be added to an apartment building with an existing 1,200 DFUs already installed? Assume the building drainage piping is 8-inch diameter at slope of 1/8″ per foot?

• • • IPC – TABLE 710.1(1) Row for DIAMETER OF PIPE (inches) “8 inches”, Column for DIAMETER OF PIPE (inches) 1/8-inch Slope per foot lists “1,600” DFUs. Therefore, subtract; Allowable = 1,600 – 1,200 DFUs = 400 DFUs

(2) Where smoke is utilized for drainage and vent final test of a plumbing system, it shall be made by filling all traps with water and then introducing into the entire system a pungent, thick smoke produced by one or more smoke machines. When the smoke appears at stack openings on the roof, the stack openings shall be closed and a pressure equivalent to?

• • • Correct Answer: IPC – 312.4, pressure equivalent to a “1-inch water column” shall be held for a test period of not less than 15 minutes.

(3) According to the IPC, cast-iron pipe must be supported by hangers at a maximum interval of how many feet between the hangers if vertically installed?

• • • Correct Answer: IPC – Table 308.5, 15 feet.