Permeability Conversion
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Popular Permeability Converters:
What is a Permeability Converter?
A permeability converter is a tool that converts between units of water vapor permeability such as perms, perm-inches, and kg/(Pa·s·m²). It is used in building science, packaging engineering, and materials testing to evaluate moisture barriers and vapor retarders.
How to Convert Permeability Units
Select the permeability unit you want to convert from and the target unit using the dropdown menus. Enter your value in the input field and the converter instantly calculates the equivalent permeability. Note that 0°C and 23°C variants have slightly different conversion factors.
Permeability Conversion Formulas
History of Permeability Measurement
Water vapor permeability measurement became important with modern building science in the mid-20th century. The perm was defined as one grain of water vapor per hour per square foot per inch of mercury. Different reference temperatures (0°C and 23°C) exist because vapor properties change with temperature.
About This Permeability Converter
This permeability converter supports 5 units including kg/pascal/second/square meter, permeability at 0°C, permeability at 23°C, permeability inches at 0°C, and permeability inches at 23°C. It handles temperature-specific conversion factors.
Frequently Asked Questions
What is a perm in building science?
A perm measures how easily water vapor passes through a material. One perm equals one grain of water vapor per hour per square foot per inch of mercury pressure difference. Lower perm ratings mean better vapor barriers.
What is the difference between perm at 0°C and 23°C?
The two reference temperatures give slightly different conversion factors because water vapor properties change with temperature. The 23°C value is about 0.4% higher than the 0°C value.
What perm rating is a vapor barrier?
Materials with a perm rating below 0.1 are considered vapor barriers (impermeable). Materials rated 0.1-1.0 perm are vapor retarders. Materials above 10 perms are considered vapor permeable.
What is perm-inch?
Perm-inch (or permeance-inch) measures the permeability of a material per unit thickness. It allows comparison of materials regardless of their thickness, unlike perms which measure a specific assembly.
How is permeability different from permeance?
Permeability is an intrinsic material property (per unit thickness), while permeance is the vapor transmission rate of a specific thickness of material. Permeability = permeance × thickness.
Metric Conversion Factor Tables for Permeability Converter
| Units to convert | Multiply By The Number | Convert as Unit |
|---|---|---|
| Permeability (0°C) | 5.72135e-11 | kg/(Pa·s·m²) |
| Permeability (23°C) | 5.74525e-11 | kg/(Pa·s·m²) |
| Permeability inches (0°C) | 1.45322e-12 | kg/(Pa·s·m²) |
| Permeability inches (23°C) | 1.45929e-12 | kg/(Pa·s·m²) |
Permeabilityconverters & it's abbreviations
| Unit | Abbreviation | Unit | Abbreviation | Unit | Abbreviation |
|---|---|---|---|---|---|
| kilogram/pascal/second/square meter | kg/(Pa·s·m²) | permeability (0°C) | perm (0°C) | permeability (23°C) | perm (23°C) |
| permeability inches (0°C) | perm·in (0°C) | permeability inches (23°C) | perm·in (23°C) |
Complete list of Permeability conversion units and its conversion.
- 1 permeability (0°C) = 5.72135E-11 kg/(Pa·s·m²)
perm (0°C) to kg/(Pa·s·m²) → - 1 permeability (23°C) = 5.74525E-11 kg/(Pa·s·m²)
perm (23°C) to kg/(Pa·s·m²) → - 1 permeability inches (0°C) = 1.45322E-12 kg/(Pa·s·m²)
perm·in (0°C) to kg/(Pa·s·m²) →
- 1 permeability inches (23°C) = 1.45929E-12 kg/(Pa·s·m²)
perm·in (23°C) to kg/(Pa·s·m²) →