Units Conversion and Constants

Units commonly used in renewable energy

Multiply                    By                                    To yield

Distance

Feet                        0.3048                        meters exactly

Area

2.471 acres in a hectare

Flow

1 cusec = 1 cubic meter per second

Mass

1 cubic foot = 62.4 pounds. 1 gallon fresh water = 7.48 pounds

Power

Horsepower            33 520                        Btu/hour

Pressure

1 psi = 2.31 ft = 0.704 meter of water head

Quantity

Barrels of oil            42                            Gallons, US

Cumecs    cubic meters per second of hydro flow

1 gallon/minute = 0.0166 gallons/second

Volume

Btus                3.927 x 10-4                    horsepower-hours

1 cubic meter = 1000 liters

Unsorted Miscellaneous but available

40000 gpm = 666 gpsecond = 2517 liter/sec = 2.517 m^3/sec

Constants

Earth Constants

Gravitational constant = 9.8 m s^-2 = 32.2 ft s^-2

Energy

3412 Btu = 1 kWh        1 horsepower = 33000 ft-lb/minute

Time

1 average year = 365.24 days = 8766 hours (including leap year)       1 day = 1440 minutes   

Other

1 atmosphere = 14.7 psi.

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Miscellaneous/units.htm updated 080326