

Useful Conversionss » Conversion Calculators
Who needs to know anything about pumps? You do!
Mechanical pumps are the second most common machine in the world, after electric motors.


Metric to U.S. System Conversions, Calculations, Equations and Formulas:
 Millimeters (mm) x 0.03937 = inches (")(in)
 Centimeters (cm) x 0.3937 = inches (")(in)
 Meters (m) x 39.37 = inches (")(in)
 Meters (m) x 3.281 = feet (')(ft)
 Meters (m) x 1.094 = yards (yds)
 Kilometers (km) x 0.62137 = miles (mi)
 Kilometers (km) x 3280.87 = feet (')(ft)
 Liters (l) x 0.2642 = gallons (U.S.)(gals)
 Liters (l) x 0.0353 = cubic feet
 Bars x 14.5038 = pounds per square inch (PSI)
 Kilograms (kg) x 2.205 = Pounds (P)
 Kilometers (km) x 1093.62 = yards (yds)
 Square centimeters x 0.155 = square inches
 Square meters x 10.76 = square feet
 Square kilometers x 0.386 = square miles
 Cubic centimeters x 0.06102 = cubic inches
 Cubic meters x 35.315 = cubic feet


U.S. to Metric Conversions, Formulas, Calculations and Equations:
 Inches (")(in) x 25.4 = millimeters (mm)
 Inches (")(in) x 2.54 = centimeters (cm)
 Inches (")(in) x 0.0254 = meters (m)
 Feet (')(ft) x 0.3048 = meters (m)
 Yards (yds) x 0.9144 = meters (m)
 Miles (mi) x 1.6093 = kilometers (km)
 Feet (')(ft) x 0.0003048 = kilometers (km)
 Gallons (gals) x 3.78 = liters (l)
 Cubic feet x 28.316 = liters (l)
 Pounds (P) x 0.4536 = kilograms (kg)
 Square inches x 6.452 = square centimeters
 Square feet x 0.0929 = square meters
 Square miles x 2.59 = square kilometers
 Acres x 4046.85 = square meters
 Cubic inches x 16.39 = cubic centimeters
 Cubic feet x 0.0283 = cubic meters


Area and Distance Conversions, Equations, Calculations and Formulas:
 Acre x 43560 = square feet
 Inches x 0.0833 = feet
 Feet x 12 = inches
 Square mile ("Sections") x 640 = Acres
 Miles x 5280 = feet
 Circumference of circle x 0.3183 = Diameter of the circle
 Diameter of circle x 3.14 = Circumference of circle
 Diameter squared x 0.7854 = Area of circle
 Radius squared x 3.14 = Area of circle
 Miles x 1760 = yards
 Square Miles x 259 = hectares
 Square kilometers x 100 = hectares
 Acres x 40.47 = areas
 Hectares x 100 = areas
 Areas x 100 = square meters
 Yards x 3 = feet
 Acres x 4840 = square yards


Water Pressure Equations, Conversions, Formulas and Calculations:
 Feet head (of water) x .433 = Pounds per square inch (PSI)
 Feet head (of water) x 0.3049 = meters head (of water)
 Feet head (of water) x 0.0295 = atmospheres
 Feet head (of water) x 2.988 = kiloPascals
 Meters head (of water) x 3.28 = feet head (of water)
 atmosphere (Atm) x 1.013 = 1 bar (b)
 atmosphere x 14.696 = Pounds per square inch (PSI)
 bars x 1.033 = kilograms per square centimeter
 bars x 14.67 = Pounds per square inch (PSI)
 bars x 100 = kiloPascals
 Kilograms per square centimeter x 14.223 = pounds per square inch (PSI)
 Pounds per square inch (PSI) x 2.31 = feet head (ft. hd.)
 Pounds per square inch (PSI) x 0.0703 = kilograms per square centimeter
 Pounds per square inch (PSI) x 0.06895 = bars
 Pounds per square inch (PSI) x 0.06805 = atmospheres
 Pounds per square inch (PSI) x 2.31 = feet head (of water)
 Pounds per square inch (PSI) x 6.896 = kiloPascals
 kiloPascal x 0.145 = Pounds per square inch (PSI)
 kiloPascal x 0.01 = bars
 kiloPascal x 0.334 = feet head (of water)


Flow and Water Volume Formulas, Conversions, Calculations and Equations:
 U.S. Gallons per minute (gpm) x .1337 = Cubic feet per minute
 Cubic feet per minute x 7.48 = U.S. gallons per minute
 Cubic feet per second x 448.8 = U.S. gallons per minute
 U.S. gallons per minute x 0.00223 = Cubic feet per second
 Acre inches per hour x 453 = U.S. gallons per minute
 British Imperial gallons x 1.201 = U.S. gallons
 U.S. gallons x 0.833 = British Imperial gallons
 Acre feet x 325,850 = U.S. gallons
 Acre inches x 27154 = U.S. gallons
 Velocity in feet per second = (0.408 x GPM) / Inside diameter of pipe in inches, squared
 Q=AV (quantity = area x velocity) ("the basic equation of water flow")
(example: quantity in cubic feet per second = square feet of area x feet per second velocity)
 One inch of water depth = 0.62 gallons per square foot of area
 GPM x 226.8 = liters per hour
 cubic feet per minute x 1699 = liters per hour
 acre inches per hour x 1712.3 = liters per minute
 acre feet x 1231.7 = cubic meters
 acre inch x 102.64 = cubic meters
 velocity (feet/second) x 0.3047 = velocity (meters/second)
 velocity (meters/second) x 3.281 = velocity (feet/second)


Pump Calculations, Conversions, Equations and Formulas:
The following formulas assume 55% pump efficiency (the standard assumption).
Note: Horsepower is Brake horse power for an electric motor. Do not use for fuelpowered pump engines!
 GPM = (horsepower x 2178) / feet head
 Feet head = (2178 x horsepower) / GPM
 Efficiency of pump = (GPM x feet head) / (horsepower x 3960)
 Horse powers x 745.7 = watts (W)
 Water flow (in cubic meters per second) = 0.55 x pump power (watts) / pressure (pascals)
 Water flow (in liters per second) = 5.43 x pump power (kilowatts) / pressure (bars)


Miscellaneous Irrigation Formulas, Conversions, Equations and Calculations:
Sprinkler Precipitation Rate:
Note: "head spacing" is the distance between sprinkler heads. L = length between heads in the row, W = width between rows. Therefore "head spacing " = L x W. Use the GPM value for a full circle sprinkler. So if your sprinklers are all half circles, you need to double the GPM value so it is equivalent to a full circle value.
 Precipitation rate for square sprinkler spacing:
(GPM of full circle sprinkler x 96.3) / head spacing in feet = precipitation rate in inches per hour
 Precipitation rate for triangular sprinkler spacing:
(GPM of full circle sprinkler x 96.3) / (head spacing in feet x 0.866) = precipitation rate in inches per hour
Example: Rotors arranged in rows. The rows are 25 feet apart and the sprinklers are 30 feet apart in the row. The heads are arranged in a triangle pattern. The heads use 6 GPM.
(6 x 96.3) / [(25 x 30) x 0.866]
577.8 / [750] x 0.866
577.8 / 649.5
0.89 inches per hour


Friction Loss Calculators:
 Friction loss calculations are for standard PVC pipe.
 Cl 160 PVC pipe is not commonly available in 1/2" size, therefore the calculator assumes that Cl 315 pipe will be substituted.
 Cl 200 PVC pipe is not commonly available in 1/2" size, therefore the calculator assumes that Cl 315 pipe will be substituted.
 Cl 160 PVC pipe is not commonly available in 3/4" size, therefore the calculator assumes that Cl 200 pipe will be substituted.
 This calculator uses a contracted form of the HazenWilliams formula which is the industry standard for calculating friction loss.
 A conservative C coefficient of 140 is used for PVC pipe (many authorities use 150 which is risky as it leaves no margin for error).
 Velocities over 7 feet per second should not be allowed in PVC pipe.
 Velocities over 5 feet per second should be avoided, especially with pressures higher than 80 PSI, or in pipe larger than 2".






