Copyright Goodheart-Willcox Co., Inc. 101 C H A P T ER 6 Mathematics for Plumbers OBJECTIVES After studying this chapter, you will be able to: ■ ■■ Read a rule accurately to the nearest 1/16″. ■■ Add and subtract fractions and whole numbers. ■■ Compute pipe offsets using the Pythagorean theorem and trigonometric functions. ■■ Apply the formulas for finding area and volume. ■■ Compute the total slope of a run of drainpipe. ■■ Explain and apply SI metric measure in finding length, area, volume, and temperature. ■ Convert customary measure to metric measure. TECHNICAL TERMS laying length plumber’s rule Pythagorean theorem trigonometric functions Pume lumbers need to make accurate measurements and calculations. They need to add and subtract dimensions, compute pipe offsets, and determine the vol- of tanks. This chapter provides the basic information needed to master these skills. In addition, metric measurement is introduced. Workplace Skills Helping a New Team Member Your company obtained a major contract to install the plumbing system for a dozen homes being built in a new subdivision. You are assigned to work with a new team of four people to install the DWV piping in these homes. One person assigned to the team is a new employee who previously worked for a concrete company. At the jobsite, the supervisor walks the team through the building, indicating where DWV piping should be installed on the first floor. The supervisor instructs you and the new team member to move tools and materials from the truck into the house, set up lights on the first floor, add a set of lights in the basement, and bring select- ed tools and materials to the basement and first floor. What can you do to help the new employee feel part of the team? How should you handle questions that arise? What do you do if the new employee does something that is incorrect or dangerous? These suggestions should help. ■ ■ Suggest a location where the two of you can safely store your food. ■ ■ As you take lights to the basement and first floor, consider what routes will be best for moving tools and materials into the desired location. For example, it may be easier for one of you to hand ten-foot lengths of pipe through a window opening. ■ ■ Check the route you are going to use to avoid hazardous situations. ■ ■ Ask the new employee about their previous work experience. ■ ■ Get to know the new employee. Try talking about hobbies, family, or sports. Respond to the following questions: ■ ■■ What can you do to encourage the new employee? ■ What can you share about the plumbing company with your coworker? ■ ■ How would you help the new employee stop rushing and risking injury? ■ ■ What can you do if the new employee is not getting enough work done?