Pressure drops in air supply lines.
D P = L x 1,6 x 1012 x qv1.85 / d5 x Pa
Where: D P = pressure drop in kPa
L = length of line or hose in m
qv = air flow in m3/sec (i.e. the air consumption of the ejector)
d = inside diameter of line or hose in mm
Pa = Absolute air pressure at the beginning of the line in kPa.
SYMBOLS, UNITS AND CONVERSION FACTORS
Symbols
A = Area
D or f = Diameter
F = Force [Newton, N]
g = gravitational acceleration [kg/s2]
P = Pressure (SIunit is Pascal, Pa)(1 Pa = 1 N/m2)
D P = Pressure difference [kPa]
P = sub atmospheric pressure (kPa)
P+ = pressure above atmospheric pressure
Unit Conversion Factors
To convert from  To  Multiply by  or To  Multiply by
Pressure, stress (force per unit area)
Atmosphere
(normal,760 torr) Pa  1,013 x 105 kPa 101,3
Inch of mercury Pa 3,377 x 103 kPa 3,377
Kilogramforce/cm2 Pa 9,807 x 104 kPa 98,07
mm of mercury Pa 1,333 x 102 Pa 133,3
poundforce/sqFoot Pa 4,788 x 10 Pa 47,88
poundforce/sqInch Pa 6,895 x 103 kPa 6,895
bar Pa 1,0 x 105 kPa 100
torr Pa 133,322 kPa 0,133
Volume per unit time
foot3/ min (cfm) m3/s 4,719 x 104 dm3/s 0,4719
foot3/ sec m3/s 2,832 x 102 dm3/s 28,32
gallon/min m3/s 6,309 x 105 cm3/s 63,09
