Filter Backwash Expansion BED Height Term Tool

Description

Return expandedHeight = settledHeight*(1+expansionFraction), freeboard = vesselHeight-expandedHeight and fits = expandedHeight <= vesselHeight.

Nominal hydraulic ratios connect flow to area, length, volume or travel time. These local terms depend on active geometry and steady conditions; they do not describe a full distribution of velocities, residence times or treatment performance.

Return expandedHeight = settledHeight*(1+expansionFraction), freeboard = vesselHeight-expandedHeight and fits = expandedHeight <= vesselHeight.

When to use this tool

Use Filter Backwash Expansion BED Height Term when checking one supplied hydraulic loading, clearance, volume or travel-time term.

How to use the tool and how it works

Enter settledHeight, expansionFraction, vesselHeight. Use the units and conventions below.
Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
Read expandedHeight, freeboard, fits. Inspect fits before interpreting the associated values.

Require nonnegative settledHeight, expansionFraction and vesselHeight. Return expandedHeight = settledHeight*(1+expansionFraction), freeboard = vesselHeight-expandedHeight and fits = expandedHeight <= vesselHeight.^[1]

Input field	Meaning and units	Accepted input
settledHeight	Settled Height	Required. Finite number; minimum 0.
expansionFraction	Expansion Fraction	Required. Finite number; minimum 0.
vesselHeight	Vessel Height	Required. Finite number; minimum 0.

Output field	Interpretation	Returned shape
expandedHeight	Expanded Height	Required. Finite number.
freeboard	Freeboard	Required. Finite number.
fits	Fits	Required. Boolean.

json

{
  "input": {
    "settledHeight": 1,
    "expansionFraction": 0.4,
    "vesselHeight": 2
  },
  "output": {
    "expandedHeight": 1.4,
    "freeboard": 0.6000000000000001,
    "fits": true
  }
}

Limitations and assumptions

An exact fit returns true and zero freeboard. This variant reserves no additional headspace; negative freeboard remains visible. Expansion is supplied, not derived from backwash hydraulics or media properties.
Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.

Alternative or Complementary methods

Use a complete hydraulic and treatment model when changing flows, turbulence, media behavior or safety margins matter.

References

Calculation and input contract: environmental-engineering/filter-backwash-expansion-bed-height-term — tool.io

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