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Chromatography Bed, Flow & Residence Time

Calculate nominal bed residence time from linear flow velocity or cylindrical bed dimensions and volumetric flow.

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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

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Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

A 100 mm bed with linear flow velocity 300 cm/h has a nominal residence time of 2 minutes.

Time = bed height / superficial velocity = cylindrical bed volume / volumetric flow

Worked example

Enter these known values and leave the other values blank.

Known flow measurement
Linear flow
Bed height for linear calculation
100 mm
Superficial linear flow velocity
300 cm/h
Nominal time from linear velocity
2 min

Assumptions and limitations

  • Dimensions, flow rates and times are positive. The volumetric mode assumes a cylindrical bed with a constant cross section.
  • Nominal residence time uses the full packed-bed volume or superficial velocity. It does not correct for void fraction or determine a solute’s chromatographic retention time.
  • The two flow modes have separate inputs. Switching modes does not automatically transfer a bed height or compute the corresponding flow velocity.

Common questions

Is this the elution time of a retained molecule?

No. Chromatographic retention also depends on interactions with the stationary phase. This is a nominal bed-volume turnover time.

Does bed porosity enter the calculation?

No. The full geometrical bed volume is used. A void-volume or interstitial-velocity calculation would need an appropriate porosity.

References

Volumetric flow rates use exact US or imperial fluid-volume definitions and exact seconds per minute, hour and day.

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