Conversion of pressure units



Conversion of volume units



Conversion of volume flow units

Pressure drop in a tube

When a medium is delivered through a tube, a pressure drop occurs. This pressure drop depends on the volume flow and the viscosity of the medium as well as the length and the inner diameter of the tube.

The volume flow Q of a liquid with dynamic viscosity η in a tube with length L and inner diameter D causes a pressure drop Δp

The pressure drop in laminar case is calculated as follows:



Calculation








m/s

Conversion


mm²/s
g/ml
mPas

Viscosity

Dynamic viscosity η: 1 mPas = 1 cP (P = Poise)
Kinematic viscosity ν: 1 mm²/s = 1 cSt (St = Stokes)

Examples of viscosities

Liquid η [mPas]
water, liquid, 0 °C 1,79
water, 20 °C 1
water, 50 °C 0,55
water, 80 °C 0,36
water, liquid, 100 °C 0,28
Liquid η [mPas]
Acetone0,36
Benzene0,65
Ethanol1,2
Methanol0,58
Toluene0,59