AIR PERMEABILITY CONVERSION FACTORS

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)
(Or)
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.):

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