Column Flow Rate Calculator

Volumetric Flow Rate Formula:

\[ \text{Volumetric flow (mL/min)} = \frac{\text{Linear velocity (cm/h)} \times \text{Cross-section (cm²)}}{60} \]

Volumetric Flow:

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What Is Column Flow Rate?

Column flow rate calculation converts linear flow velocity to volumetric flow rate in chromatography systems. This is essential for optimizing separation efficiency and maintaining consistent performance in liquid chromatography applications.

2. How Does The Calculator Work?

The calculator uses the volumetric flow rate formula:

\[ \text{Volumetric flow (mL/min)} = \frac{\text{Linear velocity (cm/h)} \times \text{Cross-section (cm²)}}{60} \]

Where:

\( \text{Linear velocity} \) — Flow velocity through the column (cm/h)
\( \text{Cross-section} \) — Cross-sectional area of the column (cm²)
\( 60 \) — Conversion factor from hours to minutes

Explanation: This formula converts the linear speed of mobile phase movement through the column to the actual volumetric flow rate delivered by the pump.

3. Importance Of Flow Rate Calculation

Details: Accurate flow rate calculation is crucial for method development, scaling between different column sizes, maintaining optimal backpressure, and ensuring reproducible chromatographic separations.

4. Using The Calculator

Tips: Enter linear velocity in cm/h and cross-sectional area in cm². Both values must be positive numbers. The cross-sectional area can be calculated as π × (column radius)².

5. Frequently Asked Questions (FAQ)

Q1: Why convert linear velocity to volumetric flow?
A: Linear velocity determines separation efficiency, while volumetric flow is what HPLC pumps deliver. Conversion ensures methods work correctly on different instruments.

Q2: How do I calculate cross-sectional area?
A: For cylindrical columns, use π × r² where r is the column inner radius in cm. Standard column diameters are typically 4.6mm, 3.0mm, or 2.1mm.

Q3: What are typical linear velocity values?
A: For reversed-phase HPLC, typical linear velocities range from 10-30 cm/h, depending on particle size and column dimensions.

Q4: Can I use this for UHPLC systems?
A: Yes, the same formula applies to UHPLC, though linear velocities are typically higher due to smaller particle sizes and higher pressure capabilities.

Q5: How does flow rate affect backpressure?
A: Backpressure increases linearly with flow rate and inversely with the square of column diameter. Higher flow rates generate higher backpressure.