HomeProtein PurificationConverting from Flow Velocity to Volumetric Flow Rates

# Converting from Flow Velocity to Volumetric Flow Rates

It is convenient when comparing results for columns of different sizes to express ﬂow as ﬂow velocity (cm/h). However, ﬂow is usually measured in volumetric ﬂow rate (ml/min). To convert between ﬂow velocity and volumetric ﬂow rate use one of the formulae below.

### From ﬂow velocity (cm/h) to volumetric ﬂow rate (ml/min)

 Volumetric ﬂow rate (ml/min) = Flow velocity (cm/h) 60 × column cross sectional area (cm2)

 Volumetric ﬂow rate (ml/min) = Y 60 × π × d2 4

where

Y = ﬂow velocity in cm/h
d = column inner diameter in cm

Example:

What is the volumetric ﬂow rate in an XK 16/70 column (i.d. 1.6 cm) when the ﬂow velocity is 150 cm/h?
Y = ﬂow velocity = 150 cm/h
d = inner diameter of the column = 1.6 cm

 Volumetric ﬂow rate (ml/min) = 150 × π × 1.6 × 1.6 60 × 4 = 5.03 ml/min

### From volumetric ﬂow rate (ml/min) to ﬂow velocity (cm/h)

 ﬂow velocity (cm/h) = Volumetric ﬂow rate (ml/min) × 60 column cross sectional area (cm2)

 ﬂow velocity (cm/h) = = Z × 60 × 4 π × d2

where
Z = volumetric ﬂow rate in ml/min
d = column inner diameter in cm

Example:

What is the linear ﬂow in a Tricorn 5/50 column (i.d. 0.5 cm) when the volumetric ﬂow rate is 1 ml/min?
Z = volumetric ﬂow rate = 1 ml/min
d = column inner diameter = 0.5 cm

 ﬂow velocity = 1 × 60 × 4 π × 0.5 × 0.5 = 305.6 cm/h

### From volumetric ﬂow rate (ml/min) to using a syringe

1 ml/min = approximately 30 drops/min on a HiTrap 1 ml column
5 ml/min = approximately 120 drops/min on a HiTrap 5 ml column

Materials