systems. The comparison of liquid measurements in the customary and metric systems is shown in Figure 4-28. The Kelvin (absolute) or the Celsius scale is easier to understand if seen with the familiar Fahrenheit. Figure 4-29 shows how temperatures from one scale can be converted to a like temper- ature on other scales. Common Liquid Conversions Gallon Quarts Pints Cups Ounces Liters 1 1 4 1 2 8 1 2 4 16 8 16 32 128 0.237 0.473 0.946 3.785 Polymetric Services, Inc., Tarzana, CA 91356 Goodheart-Willcox Publisher Figure 4-28. Comparing common liquid measures. Examples To convert gallons to liters multiply gallons by 3.785 6 gal = ____ liters = 6 × 3.785 = 22.71 liters To convert quarts to liters multiply quarts by 0.946 3 qt = ____ liters = 3 × 0.946 = 2.838 liters LITER DECI LITER ONE ONE GALLON ONE PINT OUNCE 8 oz CUP ONE QUART 0 373.15 100 212 310.15 37 98.6 273.15 0 32 233.15 40 –40 0 –273.15 –459.67 Fahrenheit Celsius Kelvin Water boils Body temp. Water freezes Absolute zero To convert from degrees Celsius to degrees Kelvin, add 273.15. Example: 68°C = ______°K 68 + 273.15 = 341.15°K To convert from degrees Kelvin to degrees Celsius, subtract 273.15. Example: 351°K = ______°C 351 – 273.15 = 77.85°C To convert from degrees Fahrenheit to degrees Celsius, subtract 32 and multiply by 5⁄9. Example: 200°F = ______°C (200 – 32) × 5⁄9 = 93.33°C To convert from degrees Celsius to degrees Fahrenheit, multiply by 9⁄5 and add 32. Example: 75°C = ______°F (9⁄5 × 75) + 32 = 167°F Goodheart-Willcox Publisher Figure 4-29. Kelvin, Celsius, and Fahrenheit temperature measurement and conversion factors. Chapter 4 Mathematics for Plumbers 83 Copyright Goodheart-Willcox Co., Inc.