1. Measurement Systems and Conversion Procedures
Chapter 3
Measurement Systems and Conversion Procedures

2. © 2010 Delmar, Cengage Learning.
Objectives
Interpret the systems of measurement
Simplify units using dimensional analysis
Perform metric system conversions
Perform conversions between metric and nonmetric systems
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3. © 2010 Delmar, Cengage Learning.
Objectives (cont’d.)
Perform conversions between apothecary and household systems
Perform temperature conversions between Celsius, Fahrenheit and Kelvin
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4. Systems of Measurement
United States Customary System of Measurement:
Distance:
1 ft = 12 in
1 yd = 3 ft
1 mi = 5280 ft
Volume:
8 fl oz = 1 cup
1 pt = 2 cups
1 qt = 2 pt
4 qt = 1 gal
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5. Systems of Measurement (cont’d.)
Metric system:
m → meter → Length
l or L → liter → Volume
g → gram → Weight
0.91 m = 1 yd
3.79 L = 1 gal
28.3 g = 1 oz
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6. Systems of Measurement (cont’d.)
Table 3.1 Metric Prefixes and Values
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7. Basic Dimensional Analysis
Algebraically changing or converting units of measure .
Grams per liter
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8. Conversions Within the Metric Systems
Horizontal format:
1. Identify decimal location in the number being converted
2. Identify prefix location on horizontal diagram
3. Find the difference between the two exponents associated with each prefix
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9. Conversions Within the Metric Systems (cont’d.)
Horizontal format:
4. Conversion is moving right on the diagram:
Move decimal to the right by the amount calculated in step 3
5. Conversion is moving left on the diagram:
Move the decimal to the left by the amount calculated in step 3
Figure 3.1 Horizontal format for metric prefixes and values
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10. Conversions Within the Metric Systems (cont’d.)
Horizontal format: (cont’d.)
Convert 12 mL to microliters
Identify decimal: 12.0
Identify prefixes in diagram
Difference is -3 –(-6) = 3
12 mL = 12,000 μL
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11. Conversions Within the Metric Systems (cont’d.)
Dimensional analysis:
1 will always be placed with two-letter unit
Convert: 12μL to mL .
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12. Conversions Between Metric and Nonmetric
Table 3.2 Relationships between the U.S. System and the Metric System
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13. Conversions Between Metric and Nonmetric (cont’d.)
Convert 5 kg to oz:
Convert kg to lbs
Convert lbs to oz
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Apothecary Systems
Apothecary equivalents:
1 fl oz = 8 fl dr
4 mL = 1 fl dr
60 minims = 1 fl dr
1 g = 15 gr
1 gr = 60 mg
1 mL = 16 minims
1 pt = 16 fl oz
1 qt = 2 pt
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15. Apothecary Systems (cont’d.)
50mg is how many grains? .
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16. Apothecary Systems (cont’d.)
250 fl dr equals how many milliliters? .
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Household Systems
Household equivalents:
60 drops (gtt) = 1 tsp
1 fl oz = 30 mL
2 tbs = 1 oz
6 fl oz = 1 teacup
8 fl oz = 1 glass
16 oz = 1 lb
1 cup = 8 fl oz
5 mL = 1 tsp
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18. Household Systems (cont’d.)
You drank 3 ½ glasses of water
How many ounces did you consume? .
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19. Household Systems (cont’d.)
How many tablespoons are in 12oz? .
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20. Household, Apothecary, and Metric Equivalents
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21. Temperature Conversions
Three scales to measure temperature:
Fahrenheit
Celsius
Kelvin
Converting Celsius to Fahrenheit: or
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22. Temperature Conversions (cont’d.)
0°C equals how many °F?
°F = (0° × 1.8) + 32°= 0° + 32° = 32°
75°F equals how many °C? .
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23. Temperature Conversions (cont’d.)
Converting Celsius to Kelvin:
K = °C
100°C
K = 100° ° = °
Converting Kelvin to Fahrenheit:
°F = 1.8K − °
300K
°F = 1.8(300°) − ° = 80.33°
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24. © 2010 Delmar, Cengage Learning.
Summary
To perform metric conversions, we must be familiar with Table 3.1
Conversions within the metric system can be done using the horizontal format
Apothecary system: used in calculating drug dosages
Household system: used when administering medications in the home
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25. © 2010 Delmar, Cengage Learning.
Summary (cont’d.)
The three main temperature formulas:
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