Journeyman Plumbers Exam Isometric Analysis and Math 5

Question 1

A sanitary drain must run 40 feet at a slope of 1/4 inch per foot. How much lower is the downstream end compared to the upstream end?

Accepted Answer

10 inches

Answer

Total drop = 40 feet × 0.25 inches/foot = 10 inches.

Question 2

When using 60-degree fittings to make an offset, the set constant (ratio of set to travel) is approximately:

Accepted Answer

0.866

Answer

For a 60-degree offset, set = travel × 0.866 (the cosine of 30 degrees, since the fitting angle is 60 degrees).

Question 3

In isometric pipe drawing, how is a tee fitting typically shown when one branch comes toward the viewer?

Accepted Answer

As a line branching along the front 30-degree axis toward the viewer

Answer

In isometric drawing, branches are drawn along the appropriate isometric axis, including the front 30-degree axis for pipes coming toward the viewer.

Question 4

A plumber must offset a 3-inch pipe around a structural beam using two 45-degree elbows. The set required is 9 inches. What is the face-to-face pipe length between the two elbows?

Accepted Answer

12.73 inches minus the two elbow take-outs

Answer

Travel = 9 × 1.414 = 12.73 inches total center-to-center; the cut pipe = 12.73 minus the take-outs of both elbows.

Question 5

Which formula correctly calculates the true length of a pipe in a rolling offset if the horizontal offset is H and the vertical rise is V?

Accepted Answer

True offset = √(H² + V²), then travel = true offset × offset constant

Answer

First find the true (diagonal) offset using the Pythagorean theorem: √(H² + V²), then multiply by the appropriate travel constant for the fitting angle.

Journeyman Plumbers Exam Practice Test

Journeyman Plumbers Exam Practice Test

Journeyman Plumbers Exam Isometric Analysis and Math 5