Process Manufacturing worked example

Tank Empty Time at 11% heel, rinse, and delay allowance: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop heel, rinse, and delay allowance to 11%, then walk the calculation through step by step. Estimate tank empty or drain time from transfer volume, pump-out rate, and operating allowance.

The inputs for this scenario

  • Volume to empty: 2,800 gal (held at the documented default)
  • Pump-out or gravity drain rate: 70 gal / min (held at the documented default)
  • Heel, rinse, and delay allowance: 11 % (the input this scenario stresses; the baseline uses 15)

Working through the calculation

  • The calculation starts from the formula this tool documents: Base empty time = volume to empty รท pump-out or drain rate.
  • required tank empty time works out to 44.4 min at these inputs, and this is the headline figure for the scenario.
  • base tank empty time works out to 40 min at these inputs.
  • emptying allowance applied works out to 11 % at these inputs.
  • pump-out or drain rate works out to 70 pieces / min at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where heel, rinse, and delay allowance sits at 15% and the headline result is 46 min, this scenario comes in 3.48% below the baseline at 44.4 min.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to heel, rinse, and delay allowance, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It uses one average rate, but real drain rate falls sharply as head decreases, and the final heel can take disproportionately long; treat it as a planning estimate.

Results at a glance

  • required tank empty time: 44.4 min (headline result)
  • base tank empty time: 40 min
  • emptying allowance applied: 11 %
  • pump-out or drain rate: 70 pieces / min

Run it with your numbers

  • To rerun this with your own numbers, open the live Tank Empty Time calculator, set heel, rinse, and delay allowance to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.