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Process Design

Batch Tank Sizing Calculator

A batch tank is sized to hold one or more batches of liquid at a working fill level, plus any heel (dead) volume that stays in the tank between batches. This calculator estimates the working liquid volume from the batch size and number of batches, adds the heel, divides by the working fill fraction to get the geometric tank volume the vessel must provide, and applies an optional contingency allowance. It is a preliminary sizing estimate only — it is not a production schedule model, not a cleaning-validation model, and not a mechanical design.

TypeInteractive engineering calculator

Calculator

m³
%
m³
%
Result
Required working liquid volume20 m³
Heel / dead volume1 m³
Total required liquid capacity21 m³
Geometric tank volume required26.25 m³
Design tank volume (+10%)28.875 m³

Preliminary estimate only. Not a production schedule model, cleaning-validation model, or mechanical design. Does not model residence time, reaction completion, mixing time, heat-up/cool-down, filling/draining constraints, CIP, foam, or overflow. Final tank sizing requires the operating sequence, cleaning philosophy, site standards, mechanical design, and qualified engineering review.

Formulas

Working liquid volume
V_working = batch_volume × number_of_batches
Liquid required (with heel)
V_liquid = V_working + heel_volume
Geometric volume
V_geometric = V_liquid / fill_fraction
Design volume
V_design = V_geometric × (1 + allowance/100)

Diagram

V_geometric = (batches × V_batch + heel) / fillfreeboardbatches(working)heelV = (n·V_batch + heel) / fill

Worked example

A batch tank must hold 2 batches of 10.0 m³ each at an 80% working fill, with a 1.0 m³ heel and a 10% contingency allowance. What geometric tank volume is required?

  1. 01V_working = batch_volume × number_of_batches = 10.0 × 2 = 20.0 m³
  2. 02V_liquid = V_working + heel = 20.0 + 1.0 = 21.0 m³
  3. 03V_geometric = V_liquid / fill_fraction = 21.0 / 0.80 = 26.25 m³
  4. 04V_design = V_geometric × (1 + 10/100) = 26.25 × 1.10 = 28.875 m³
Result

Working liquid volume = 20.0 m³; liquid required incl. heel = 21.0 m³; geometric volume = 26.25 m³; design tank volume ≈ 28.88 m³.

FAQ

Why divide by the fill fraction?
The working fill fraction is the usable liquid level expressed as a fraction of the tank — the rest is freeboard for surge, foam, and overflow. Dividing the required liquid volume by the fill fraction grosses it up to the geometric (total) tank volume the vessel must physically provide.
What is the heel / dead volume?
The heel is the liquid that stays in the tank between batches — below the outlet, in the agitator zone, or as a deliberate working heel. It adds to the liquid the tank must hold but does not count as usable batch volume, so it is added before grossing up to the geometric volume.
Does this guarantee enough residence or reaction time?
No. This sizes the volume only. Whether a batch has enough time to react, mix, heat, or settle is a separate question that depends on kinetics, mixing, and the operating sequence — not on the tank volume alone.
Is the contingency allowance the same as freeboard?
No. Freeboard is already captured by the working fill fraction. The contingency allowance is an extra margin on the whole geometric volume for uncertainty in batch size, heel, number of batches, and future duty — a separate, optional design cushion.

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