Modern Plumbing, 8th Edition Page 81 (95 of 624)

Common metric units that are used in plumbing are: • Meter—For long distances. • Centimeter—For short distances. • Millimeter—For very small measurements, such as certain pipe diameters and nut sizes. • Liter or the cubic centimeter (cm3)—For liquid volume. • Cubic meter (m3)—For dry volume. • Pascal—For pressure. One Pascal is equal to 1 newton per square meter. The newton is the metric unit for force. A newton is the amount of force needed to accelerate a weight of 1 kilogram one meter per second. • Degrees Kelvin or degrees Celsius—For temperature. The degree Celsius is equal to 14⁄5 Fahrenheit degree. Kelvin is in the Celsius scale and measures temperatures in the super- cold range (–273° and up). Figure 4-27 illustrates the comparative dry volume measurements and provides factors for converting between the US customary and metric Metric Measurement Some industries have adopted the metric system of measurement. Since many construction trades, such as plumbing, are not involved in international commerce, there is less pressure for them to change. However, some fixtures, faucets, and valves are now available in metric sizes. The base unit of length measurement in the metric system is shown in Figure 4-26, along with comparable US customary units. One of the chief advantages of using the metric system is the ease of changing from one metric unit to another simply by multiplying or dividing by multiples of 10. This is easier than using the various conversion factors required in the conventional inch-pound system. Unlike US customary measure, where dimen- sions are often expressed in both feet and inches (2′-3″), the metric system does not mix its units. A distance of 2 meters and 3 centimeters, for example, will be written as 2.03 m or 203 cm, never as 2 m-3 cm. Goodheart-Willcox Publisher Figure 4-24. Converting cubic inches and cubic feet to gallons. To Convert To Procedure Example Cubic inches Cubic feet Gallons Gallons Divide by 231 Multiply by 7.48 376 cu. in. = 376 ÷ 231 = 1.63 gal. 6 cu. ft. = 6 × 7.48 = 44.88 gal. Total slope = Slope per foot × Feet of run = 1⁄8″ × 50 = 50⁄8″ = 61⁄4″ 50′ Total slope Outlet Flow Inlet Line of sight Builder’s level or transit Goodheart-Willcox Publisher Figure 4-25. If a 50-foot horizontal run of building sewer is to be installed, what is the total slope of the run if a slope of ⅛ inch per foot is to be established? Chapter 4 Mathematics for Plumbers 81 Copyright Goodheart-Willcox Co., Inc.

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Common metric units that are used in plumbing are: • Meter—For long distances. • Centimeter—For short distances. • Millimeter—For very small measurements, such as certain pipe diameters and nut sizes. • Liter or the cubic centimeter (cm3)—For liquid volume. • Cubic meter (m3)—For dry volume. • Pascal—For pressure. One Pascal is equal to 1 newton per square meter. The newton is the metric unit for force. A newton is the amount of force needed to accelerate a weight of 1 kilogram one meter per second. • Degrees Kelvin or degrees Celsius—For temperature. The degree Celsius is equal to 14⁄5 Fahrenheit degree. Kelvin is in the Celsius scale and measures temperatures in the super- cold range (–273° and up). Figure 4-27 illustrates the comparative dry volume measurements and provides factors for converting between the US customary and metric Metric Measurement Some industries have adopted the metric system of measurement. Since many construction trades, such as plumbing, are not involved in international commerce, there is less pressure for them to change. However, some fixtures, faucets, and valves are now available in metric sizes. The base unit of length measurement in the metric system is shown in Figure 4-26, along with comparable US customary units. One of the chief advantages of using the metric system is the ease of changing from one metric unit to another simply by multiplying or dividing by multiples of 10. This is easier than using the various conversion factors required in the conventional inch-pound system. Unlike US customary measure, where dimen- sions are often expressed in both feet and inches (2′-3″), the metric system does not mix its units. A distance of 2 meters and 3 centimeters, for example, will be written as 2.03 m or 203 cm, never as 2 m-3 cm. Goodheart-Willcox Publisher Figure 4-24. Converting cubic inches and cubic feet to gallons. To Convert To Procedure Example Cubic inches Cubic feet Gallons Gallons Divide by 231 Multiply by 7.48 376 cu. in. = 376 ÷ 231 = 1.63 gal. 6 cu. ft. = 6 × 7.48 = 44.88 gal. Total slope = Slope per foot × Feet of run = 1⁄8″ × 50 = 50⁄8″ = 61⁄4″ 50′ Total slope Outlet Flow Inlet Line of sight Builder’s level or transit Goodheart-Willcox Publisher Figure 4-25. If a 50-foot horizontal run of building sewer is to be installed, what is the total slope of the run if a slope of ⅛ inch per foot is to be established? Chapter 4 Mathematics for Plumbers 81 Copyright Goodheart-Willcox Co., Inc.

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Meter Yard Foot Decimeter Inch Inch Actual Centimeter Actual Millimeter Actual Goodheart-Willcox Publisher Figure 4-26. The above illustration compares relative lengths of metric and customary units. 1″ = 25.40 mm To convert inches to millimeters, multiply by 25.4 Example 3″ = 3 × 25.4 = 76.2 mm 1″ = 2.54 cm To convert inches to centimeters, multiply inches by 2.54 16″ = 16 × 2.54 = 40.64 cm 1′ = 0.3048 m To convert feet to meters, multiply feet by 0.3048 3′ = 3 × 0.3048 = 0.9144 m Polymetric Services, Inc., Tarzana, CA 91356 Goodheart-Willcox Publisher Figure 4-27. Metric and customary dry volume measurements and conversion factors. To convert from cubic inches to: Multiply by: Example: Gallons Cubic feet Liters 0.004 0.00058 0.016 3674 cu in = ____ gal 4677 cu in = ____ cu ft 286 cu in = ____ liters 3674 × .004 = 14.7 gal 4677 × .00058 = 2.712 cu ft 286 × .016 = 4.576 liters To convert from cubic feet to: Multiply by: Example: Gallons Cubic inches Liters Cubic meters Cubic yards 7.48 1728.0 28.32 0.028 0.037 6.5 cu ft = ____ gal 3 cu ft = ____ cu in 1.5 cu ft = ____ liters 278 cu ft = ____ cu meters 5687 cu ft = ____ cu yards 6.5 × 7.48 = 48.62 gal 3 × 1728.0 = 5184.0 cu in 1.5 × 28.32 = 42.48 liters 278 × .028 = 7.784 cu meters 5687 × .037 = 210.42 cu yards Cubic inch Cubic centimeter Cubic foot Cubic decimeter 82 Section 1 Introduction to Plumbing Copyright Goodheart-Willcox Co., Inc.

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Finding the volume of cylindrical tanks requires the use of the formula: Volume = πr2h This is read: “volume equals pi times the radius squared times the height.” Figure 4-23 illustrates the use of this formula. After calculating volume in some convenient units of cubic measure, it may be necessary to convert the cubic units of measure to a volume measure, such as gallons. The most common conver- sion factors and examples of their use are given in Figure 4-24. English-metric conversion factors are provided in the Useful Information section. Computing Slope of Pipe Horizontal runs of sewer and drain pipe must slope to permit flow and prevent blockage. Computing the total amount of slope for a hori- zontal run of pipe permits the builder’s level to be used to accurately position the run of pipe, Figure 4-25. Generally, horizontal pipe runs in sewers and drains are required to slope ⅛ ″ to ¼″ per foot of run. 8′ Area = πr2 πr2 = 3.14 r = Radius = 1⁄2 diameter Since the diameter is 8′, the radius is 4′. Therefore, Area = 3.14 × (4)2 = 3.14 × 16 square feet = 50.24 square feet or Area = .7854d2 Area = .7854 × (8)2 = .7854 × 64 square feet = 50.24 square feet Goodheart-Willcox Publisher Figure 4-21. Formula for computing the area of a circle. 6′ 12′ 4′ Volume = Length (L) × Width (W) × Height (H) This formula is frequently written V = LWH Substituting the dimensions from the above drawing V = 12′ × 4′ × 6′ V = 288 cubic feet Goodheart-Willcox Publisher Figure 4-22. Determining the volume of a rectangular tank. 6′ 2′ Volume = Pi × Radius squared × Height This formula may be written: V = πr2h Substituting from the above drawing: V = 3.14 × (2′)2 × 6′ V = 75.36 cubic feet Goodheart-Willcox Publisher Figure 4-23. Determining the volume of a cylindrical tank. 80 Section 1 Introduction to Plumbing Copyright Goodheart-Willcox Co., Inc.

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Page 2Section 1 Introduction to Plumbing click to expand contents

Page 148Section 2 Plumbing Systems click to expand contents

Page 252Section 3 Plumbing System Design and Installation click to expand contents

Page 440Section 4 Plumbing Services click to expand contents

Page 494Section 5 Career Development and Plumbing History click to expand contents

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