Fogging On Time Humidity Band

Calculate constant-temperature closed-room fog on-time from a supplied saturation vapor density, evaporation yield and other vapor sources; ventilation, condensation and cooling are excluded, so not a controller setting guarantee.

Description

Relative humidity can be raised by adding water vapor to a closed room at fixed temperature.

Relative humidity can be raised by adding water vapor to a closed room at fixed temperature. The required vapor mass depends on saturation density and room volume.^[1]

When to use Fogging On Time Humidity Band

Use this tool to calculate constant-temperature closed-room fog on-time from a supplied saturation vapor density, evaporation yield and other vapor sources; ventilation, condensation and cooling are excluded, so not a controller setting guarantee.

Prepare the plant, nutrient, light or scheduling measurements for the intended crop and period. Keep paired records aligned and confirm units and supplied target values.

How to use Fogging On Time Humidity Band and understand its results

Prepare the plant, nutrient, light or scheduling measurements for the intended crop and period. Keep paired records aligned and confirm units and supplied target values.
Enter roomVolumeM3, saturationVaporDensityGramsPerM3, initialRhPercent, targetRhPercent, fogWaterGramsPerSecond, evaporatedFraction, otherVaporSourcesGramsPerSecond using the field table and calculation rules, then run the tool.
Read modelFogOnSeconds, evaporatedWaterGrams. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
roomVolumeM3	Room volume m3	number	Required
saturationVaporDensityGramsPerM3	Saturation vapor density grams per m3	number	Required
initialRhPercent	Initial rh percent	number	Required
targetRhPercent	Target rh percent	number	Required
fogWaterGramsPerSecond	Fog water grams per second	number	Required
evaporatedFraction	Evaporated fraction	number	Required
otherVaporSourcesGramsPerSecond	Other vapor sources grams per second	number	Required

Use positive room volume, saturation density and fog rate, evaporation fraction in (0,1], nonnegative other sources and ordered RH percentages within [0,100]. Return modeled on-time and vaporized fog mass. Equal initial/target RH gives zero time.

required vapor=volume × saturation density × (target RH−initial RH)/100; time=required vapor/(fog evaporation rate+other sources)

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
modelFogOnSeconds	Model fog on seconds	number
evaporatedWaterGrams	Evaporated water grams	number

json

{
  "input": {
    "roomVolumeM3": 100,
    "saturationVaporDensityGramsPerM3": 20,
    "initialRhPercent": 40,
    "targetRhPercent": 60,
    "fogWaterGramsPerSecond": 10,
    "evaporatedFraction": 0.5,
    "otherVaporSourcesGramsPerSecond": 0
  },
  "output": {
    "modelFogOnSeconds": 80,
    "evaporatedWaterGrams": 400
  }
}

Limitations and assumptions

Ventilation, condensation and cooling are excluded. This is not a guaranteed controller setting.

Numeric inputs and returned numeric values must be finite; an unrepresentable returned value produces an error. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Pad Fan Cooling Degree Drop: Model pad cooling from supplied wet bulb and saturation efficiency, then downstream sensible reheating; not a duplicate wet-bulb psychrometric solver or cooling-performance guarantee. For a complementary task, use Virtual Temperature Correction: Compute exact ideal moist-air virtual temperature with vapor and suspended-liquid specific mass fractions relative to total mixture; differs from vapor mixing-ratio approximations and excludes ice unless caller independently models it.

References

Fogging On Time Humidity Band — tool.io

Similar or alternative tools

Pad Fan Cooling Degree Drop
Model pad cooling from supplied wet bulb and saturation efficiency, then downstream sensible reheating; not a duplicate wet-bulb psychrometric solver or cooling-performance guarantee.
Virtual Temperature Correction
Compute exact ideal moist-air virtual temperature with vapor and suspended-liquid specific mass fractions relative to total mixture; differs from vapor mixing-ratio approximations and excludes ice unless caller independently models it.