Gurley to Air Permeance Converter (Bendtsen, Frazier)
Gurley to Air Permeance Converter (Bendtsen, Frazier): convert between 6 air permeance units, for example 1 s/100 mL = 127.0809506 µm/(Pa·s).
| Unit | Value |
|---|---|
| Gurley second to micrometre per pascal second | 127.0809506 µm/(Pa·s) |
| Gurley second (s/100 mL) | 1 s/100 mL |
| Gurley second to Bendtsen millilitre per minute | 11208.53984 mL/min (Bendtsen) |
| Gurley second to Frazier (cfm/ft² at 125 Pa) | 3.126991894 cfm/ft² @125 Pa |
| Gurley second to millimetre per second at 100 Pa | 12.70809506 mm/s @100 Pa |
| Gurley second to millimetre per second at 200 Pa | 25.41619011 mm/s @200 Pa |
Convert Gurley seconds to air permeance in µm/(Pa·s), Bendtsen mL/min and Frazier cfm/ft². Gurley is a time (s per 100 mL at 1.22 kPa), so a higher number means a less porous sheet: P ≈ 127.08 ÷ Gurley seconds.
Why the conversions are approximate
Each tester uses its own area and pressure: Gurley 6.45 cm² at 1.22 kPa, Bendtsen 10 cm² at 1.47 kPa, Frazier 125 Pa. Converting between them assumes the air flow is proportional to the pressure difference (viscous, Darcy flow), which holds well for paper and fine membranes but less so for very open fabrics. For contracts, test with the instrument the specification names.
Gurley and Frazier
Under the linear-flow assumption Frazier (cfm/ft² at 125 Pa) ≈ 3.13 ÷ Gurley seconds (100 mL). A filter medium of 10 cfm/ft² is therefore about 0.31 Gurley seconds, too open for a Gurley densometer, while a battery separator at 200 s is about 0.016 cfm/ft².
Air Permeance unit definitions
- micrometre per pascal second (µm/(Pa·s))
- The micrometre per pascal second is the SI unit of air permeance in the ISO 5636 series: the air flow through unit area of paper or board per unit pressure difference. Gurley, Bendtsen and Schopper readings all convert to it.
- Gurley second (s/100 mL)
- The Gurley second is the time, in seconds, for 100 mL of air to pass through 6.45 cm² (one square inch) of a sheet under a pressure difference of 1.22 kPa (TAPPI T 460, ISO 5636-5). It is an air resistance: the higher the number, the less porous the material. Battery separators, sack kraft, filter papers and membranes are specified in Gurley seconds. Reference: 100 mL through 6.45 cm² (1 in²) at 1.22 kPa (TAPPI T 460, ISO 5636-5); assumes air flow proportional to pressure difference.
- Frazier (cfm/ft² at 125 Pa) (cfm/ft² @125 Pa)
- Frazier air permeability is the face velocity, in cfm per square foot, through a fabric at 125 Pa (0.5 inH₂O), from ASTM D737. Expressing it as a permeance lets it be compared with Gurley seconds: Frazier ≈ 3.13 ÷ Gurley. Reference: Measured at 125 Pa (0.5 inH₂O) as in ASTM D737; assumes flow proportional to pressure difference.
- Bendtsen millilitre per minute (mL/min (Bendtsen))
- The Bendtsen tester measures the air flow, in mL/min, that leaks through 10 cm² of paper under 1.47 kPa (ISO 5636-3). It is common in Europe for printing and sack papers; unlike Gurley, a higher reading means a more open sheet. Reference: 10 cm² test area at 1.47 kPa (ISO 5636-3); assumes flow proportional to pressure difference.
- millimetre per second at 100 Pa (mm/s @100 Pa)
- Air permeability in mm/s measured at 100 Pa, the ISO 9237 condition for apparel fabrics. As a permeance it is 10 µm/(Pa·s) per mm/s. Reference: Test pressure 100 Pa (ISO 9237 apparel fabrics); assumes flow proportional to pressure difference.
- millimetre per second at 200 Pa (mm/s @200 Pa)
- Air permeability in mm/s at 200 Pa, the ISO 9237 condition used for industrial and filter fabrics. As a permeance it is 5 µm/(Pa·s) per mm/s. Reference: Test pressure 200 Pa (ISO 9237 industrial fabrics, EN filter media); assumes flow proportional to pressure difference.
Popular air permeance conversions
- micrometre per pascal second to Gurley second
- Gurley second to micrometre per pascal second
- Gurley second to Bendtsen
- Gurley second to Frazier
- Bendtsen to Gurley second
- Frazier to Gurley second
Show all 30 air permeance conversions
From micrometres per pascal second
From Gurley seconds
From Bendtsen millilitres per minute
From Frazier (cfm/ft² at 125 Pa)
From millimetres per second at 100 Pa
From millimetres per second at 200 Pa
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Sources
- ISO 5636 Paper and board — Determination of air permeance (Part 3: Bendtsen method; Part 5: Gurley method), International Organization for Standardization.
- TAPPI T 460 om-21 Air resistance of paper (Gurley method), TAPPI.
- ASTM D737 Standard Test Method for Air Permeability of Textile Fabrics, ASTM International.
- ISO 9237:1995 Textiles — Determination of the permeability of fabrics to air, International Organization for Standardization.
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