Terms, Technology, and Formulas
Kirkwood Formula Converter
Mixing Fundamentals – Terminology and Formulas
AMPERE: A unit of intensity of electric current being produced in a conductor by the applied voltage.
FREQUENCY: The number of complete cycles per second of alternating current; e.g., 60 Hertz.
HORSEPOWER: The rate at which work is done. It is the result of work done (stated in foot-pounds) divided by the time involved.
INERTIA: The property of physical matter to remain at rest unless acted upon by some external force. Inertia usually concerns the driven load.
MOTOR EFFICIENCY: A measure of how effectively the motor turns electrical energy into mechanical energy. Motor efficiency is never 100% and is normally in the neighborhood of 85%.
POWER FACTOR: The ratio of the true power to the volt-amperes in an alternating current or circuit or apparatus.
SERVICE FACTOR: A safety factor in some motors which allows the motor, when necessary, to deliver greater than rated horsepower.
SYNCHRONOUS SPEED & SLIP: The speed of an a-e motor at which the motor would operate if the rotor turned at the exact speed of the rotating magnetic field. However in a-e induction motors, the rotor actually turns slightly slower. This difference is defined as slip and is expressed in percent of synchronous speed. Most induction motors have a slip of 1-3%.
TORQUE: That force which tends to produce torsion or rotation. In motors, it is considered to be the amount of force produced to turn the load. It is measured in lb.-ft.
VOLTAGE: A unit of electro-motive force. It is a force which, when applied to a conductor, will produce a current in the conductor.
Basic Formulae and Symbols
GPM = gallons per minute
Lb = pounds
Hr. = hour
Sp. Gr. = specific gravity
H = head in feet
psi = pounds per square inch
In. Hg. = inches in mercury
hv = velocity head in feet
V = velocity in feet per second
g = 32.16 ft./sec.2 (acceleration of gravity)
A = area in square inches
I.D. = inside diameter in inches
BHP = break horsepower
Eff. = pump efficiency expressed as a decimal
N = speed, RPM
Ns = specific speed
Nss = suction specific speed
D = impeller in inches
NPSH = net positive suction head
NPSH^ = net positive suction available
Pa = atmospheric pressure in psia
Pvp = vapor pressure in psia
w = specific weight of liquid in pounds/cu. ft.
hs = total suction head ft.
Q = capacity in GPM