Air Permeability in the USA is normally expressed as follows:

Cubic feet per square foot per minute (ft3 / ft2 / min)@125Pa

When sending results to European customers, send the results in 2 additional ways:

Litres per square meter per second ( L / m2 / sec )
Factor: (ft3 /ft2 /min) x 5.08 = (L/m2 /sec)@125Pa

Cubic centimeters per square centimeter per second (cm3 / cm2 / sec)
Factor: ( ft3 / ft2 / min) x .508 = (cm3 / cm2 / sec)@125Pa

When converting air permeability results from metric system:

Metric results x .197= (ft3 /ft2 /min)
Metric results / 5.08 = (ft3 /ft2 /min)
(Use the pressure conversions also, if one is necessary)

Pressure conversion factors

• In some countries the reading is taken at 200Pa instead of at 125Pa. The conversion can be assumed to be linear.

To convert from an air permeability value taken at one pressure to one taken at a different pressure (This conversion factor may be used in combination others.):

(Value@125Pa) x 1.6 = (Value@200)
(Value@200Pa) x 0.625 = (Value@125)

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