Chemical Permeation Testing
Permeation is a process by which a chemical passes through a polymer by means of molecular diffusion. This occurs without there being any physical holes in the fabric.
How is permeation measured?
Permeation is measured by exposing the outer surface of a sample of fabric to the chemical against which it is being tested. The exposure is total and constant, and emulates total immersion conditions. The inner surface of the fabric is monitored analytically to determine the amount of chemical (if any) passing through the fabric.
What is the “breakthrough time”
The breakthrough time is the elapsed time between first exposure of the fabric to chemical and the rate of permeation reaching a target value. The target permeation rate for tests carried out according to BS EN ISO 6529 or BS EN 374-3 is one microgram of chemical passing through each square centimetre of fabric every minute. When measured according to a standard method, the breakthrough time is a value by which the performance of different fabrics can be compared.
We are accredited to perform chemical permeation testing to the following standards as detailed in Accreditation Schedule (see here):
· (BS) EN 16523
· ISO 6529 & BS EN ISO 6529:2001
· (BS) EN 374-3 (Withdrawn)
· ASTM F739
Classification can be provided according to EN 14325 and EN ISO 374-1 standards. When classification is required and the results fall close to the class boundary we apply Decision Rules which are also detailed in the test report. The Decision Rules we use can be found here.