The Uk's number 1
Paraglider Service center

Porosity Test

£25

Measurements are taken in 3 places on the top surface, 10 – 20cm in from the leading edge using a JDC porosimeter. If readings are low or inconsistent, further readings are taken.

The porosity is checked using a JDC porosimeter, this instrument does not directly measure porosity but instead measures the time for a fixed volume of air to pass through a circle of cloth, the reading in seconds can then be converted into real porosity values. ( 9 divided by reading in seconds = cm3 per cm2 per second)Measurements are taken within 15cm of the leading edge on the top surface, with the readings in the centre being more important than the tips. Wings with very low overall readings can suffer from deep stall. Manufacturers set their own limits for porosity readings and we follow these, but for a guideline –

  Canopy Condition    Time (Seconds)  
As NewAbove 200
Good50-200
Fair10-50
Acceptable5-10
Poor1-5