Copyright Goodheart-Willcox Co., Inc. May not be reproduced or posted to a publicly accessible website. Chapter 5 Measurement 85 For a conversion of ounces to grams, the conversion chart multiplier is 28.349. To convert 12 ounces to grams, the calculation would be as shown here: 12 oz × 28.349 = 340.188 g Thus, 12 ounces equals 340.188 grams. To convert grams to ounces, use the multiplier 0.03527. 340.188 grams × .03527 = 11.998 oz Thus, 340.188 g equals 11.998 oz, which can be rounded up to 12 oz. 5.9.4 Temperature Measurement Conversions While temperatures in the United States are most often measured and recorded in Fahrenheit, Celsius temperatures are used by HVACR technicians in many instances, especially when working on food production, research, or medical equipment. To convert from Fahrenheit to Celsius, use the following formula. Remember to perform operations within the parentheses first. (°F – 32) × __5 9 = °C For example, a temperature of 70°F can be converted to Celsius: 70° – 32 = 38°F 38°F × 5 __ 9 = ____901 9 190 ÷ 9 = 21.1 Seeing that the remainder of 1 would continue on endlessly in this division equation, the calculation can stop at one decimal place. Thus, 70°F equals 21.1°C. To convert from Celsius to Fahrenheit, the formula is as shown: (°C × __9 5 ) + 32 = °F A temperature of 21.1°C would convert to Fahrenheit as: 21.1°C × __9 5 = 37.98°C 21.1°C × 1.8 = 37.98°C 37.98°C + 32 = 69.98°F Thus, 21.1°C equals 69.98°F, which can be rounded up to 70°F. The scientifi scales of Kelvin and Rankine are seldom used in the trades, but fic they are commonly used in laboratory settings and may be encountered in ultra-low temperature applications. To convert from Fahrenheit to Rankine, add 460° to the Fahrenheit value. To convert from Celsius to Kelvin, add 273° to the Celsius value. 5.9.5 Heat Measurement Conversions Heating and cooling systems in the United States may be rated in Btu per hour, therms, tons, horsepower, pounds per hour, calories, joules, or kilojoules. It is often necessary to convert from one unit to another. 5