1. What is a GC Linear Velocity to Flow Rate Calculator?

Definition: This calculator converts the linear velocity of carrier gas in a gas chromatography column to volumetric flow rate in mL/min.

Purpose: It helps chromatographers optimize and compare flow conditions between different GC systems and column dimensions.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q_{ml/min} \) — Volumetric flow rate (milliliters per minute)
• \( V \) — Linear velocity (centimeters per second)
• \( A \) — Column cross-sectional area (square centimeters)
• 60000 — Conversion factor (60 s/min × 1000 mL/L)

Explanation: The linear velocity is multiplied by the column's cross-sectional area and conversion factors to get volumetric flow rate.

3. Importance of Flow Rate Calculation in GC

Details: Proper flow rate calculation ensures optimal chromatographic separation, prevents column damage, and maintains consistent retention times.

4. Using the Calculator

Tips: Enter the linear velocity in cm/s and column cross-sectional area in cm². For capillary columns, area = π × (inner diameter/2)².

5. Frequently Asked Questions (FAQ)

Q1: Why is linear velocity important in GC?
A: Linear velocity directly affects peak shape, resolution, and analysis time in gas chromatography.

Q2: How do I find my column's cross-sectional area?
A: Measure the inner diameter (ID) and calculate using A = π × (ID/2)². Typical capillary columns have IDs of 0.1-0.53 mm.

Q3: What's a typical linear velocity for GC?
A: Common values range from 20-50 cm/s for capillary columns, depending on carrier gas and application.

Q4: Does this work for packed columns?
A: Yes, but packed columns have much larger cross-sectional areas, resulting in higher flow rates at the same linear velocity.

Q5: How does carrier gas type affect this calculation?
A: The calculation is independent of gas type, but optimal linear velocities vary by gas (higher for H₂ than He or N₂).