Basic Units of Measurement and Conversions - Basic Mathematics for Water and Wastewater Operators - page 62

TABLE 2.7 (continued)
Conversion Factors by Unit Category

Factor Metric (SI) or English Conversions

1 N-m (newton-meter) 1.00 J (joule)

2.78 × 10 -4 Wh (watt-hour)

1 Wh (watt-hour) 3.412 Btu (British thermal units)

859.8 cal (calories)
3600 J (joules)
35.53 L-atm (liter-atmospheres)

Units of Power

1 hp (horsepower) 745.7 J/sec (joules/second)

1 kW (kilowatt) 56.87 Btu/min (British thermal units/minute)

1.341 hp (horsepower)
1000 J/sec (joules/second)

1 W (watt) 3.41 Btu/hr (British thermal units/hour)

1.341 × 10 -3 hp (horsepower)
1.00 J/sec (joules/second)

Units of Pressure

1 atm (atmosphere) 1.013 bars

10.133 N/cm 2 (newtons/square centimeter)
33.90 ft H 2 O (feet of water)
101.325 kPa (kilopascals)
14.70 psia (pounds per square inch absolute)
760 torr
760 mmHg (millimeters of mercury)

1 bar 0.987 atm (atmosphere)

1 × 10 6 dynes/cm 2 (dynes/square centimeter)
33.45 ft H 2 O (feet of water)
1 × 10 5 Pa (pascal)
750.06 torr
750.06 mmHg (millimeters of mercury)

1 inch of water 1.86 mmHg (millimeters of mercury)

249.09 Pa (pascals)
0.0361 psi (lb/in. 2 )

1 mmHg (millimeter of mercury) 1.316 × 10 -3 atm (atmosphere)

0.535 in H 2 O (inches of water)
1.33 mb (millibars)
133.32 Pa (pascals)
1 torr
0.0193 psia (pounds per square inch absolute)

1 pascal 9.87 × 10 -6 atm (atmosphere)

4.015 × 10 -3 inch H 2 O (inches of water)
0.01 mb (millibar)
7.5 × 10 -3 mmHg (millimeters of mercury)