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Moisture Content

Reference data and engineering information about moisture content for miscellaneous applications.

moisturecontent

Overview

Engineering reference data for Moisture Content in miscellaneous.

Key Formulas

Unit Conversion

y=x⋅ky = x \cdot k

Multiply by conversion factor.

Linear Interpolation

y=y1+(x−x1)(y2−y1)x2−x1y = y_1 + \frac{(x - x_1)(y_2 - y_1)}{x_2 - x_1}

Estimate between two known points.

Percentage

p=partwhole×100%p = \frac{\text{part}}{\text{whole}} \times 100\%

Part as fraction of whole.

Variables

SymbolDescriptionUnit
xxInput value—
yyOutput value—
kkConversion factor—

Moisture Content on Wet Basis

The water content on a wet basis is the ratio of the mass of water to the total mass of the moist sample:

MCw=mH2Omw=mH2OmH2O+mdMC_w = \frac{m_{H_2O}}{m_w} = \frac{m_{H_2O}}{m_{H_2O} + m_d}

where:

  • MCwMC_w = moisture content on wet basis
  • mH2Om_{H_2O} = mass of water (kg, lb)
  • mwm_w = total mass of the moist (wet) sample, i.e., mass of solid plus mass of water (kg, lb)
  • mdm_d = mass of dry solid (kg, lb)

This basis is commonly used in soil science and food processing.

Conversion Between Bases

The formulas can be rearranged to solve for mass components or to convert between bases.

Given a known total mass mm and dry basis moisture content MCdMC_d, the mass of water can be calculated as:

mH2O=MCd⋅m1+MCdm_{H_2O} = \frac{MC_d \cdot m}{1 + MC_d}

The corresponding mass of dry solid is:

md=m−mH2Om_d = m - m_{H_2O}

Practical Application

Example: Water Content in Birch on Wet Basis Given air-dried Birch with a density of 705 kg/m³ and a 20% (0.2) water content on a wet basis, the mass of water per unit volume is:

mH2O=mw⋅MCw=(705 kg/m3)(0.2)=141 kg/m3m_{H_2O} = m_w \cdot MC_w = (705\ \text{kg/m}^3)(0.2) = 141\ \text{kg/m}^3

Example: Moisture Content in Birch on Dry Basis For the same Birch with a 20% moisture content on a dry basis, the mass of water per unit volume is calculated using the transformed formula:

mH2O=MCd⋅m1+MCd=(0.2)(705 kg/m3)1+0.2=117.5 kg/m3m_{H_2O} = \frac{MC_d \cdot m}{1 + MC_d} = \frac{(0.2)(705\ \text{kg/m}^3)}{1 + 0.2} = 117.5\ \text{kg/m}^3

Key Considerations

  • Industrial Convention: Moisture content values on a dry basis are often multiplied by 100% for reporting (e.g., 20% instead of 0.2).
  • Density Relationship: The density of a moist material is the total mass per unit volume, encompassing both water and solid components.

References

Source: engineeringtoolbox.com