- About Us
- Support Services
- Scientific Services
- Distributor Directory
- Garment Selector
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.
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.
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.
All samples are conditioned for 24 hours prior to testing.
In the case of gloves, homogeneity will be assigned if not already done so by a customer. Where gloves are of homogeneous design, three samples shall be taken from the palm area. In the case of non-homogeneous design, samples shall be taken from the palm, back and wrist of glove. Gloves made of multiple constructions and/or with seams will require additional testing and sampling will be agreed with the customer.
In the case of garments, samples may be taken from:
Neat challenge chemicals used i.e. at full concentration, in an undiluted state, will be of a minimum AR (analytical reagent) grade. The percentage purity of neat chemicals will be indicated on the test report.
Chemical solutions will either be purchased at the requested concentration or prepared in-house from neat chemicals and diluted using distilled water. The concentration of the solution will be indicated on the test report.
In the case of mixtures, please contact us directly for further information.
CP20 – Open loop system with dry nitrogen as the collecting medium. Fourier Transform Infrared (FT-IR) Spectroscopy is used as means of detection.
CP30 – Closed loop system with potassium chloride solution as the collecting medium. Conductivity by hydrogen ion selective electrode is used as means of detection.
CP40 – Closed loop system with TISAB:distilled water (1:1) as the collecting medium (Total Ionic Strength Adjustment Buffer). Conductivity by fluoride ion selective electrode is used as means of detection.
CP50 – Open loop system with dry air as the collecting medium. Photo ionisation Detection (PID) is used as means of detection.
Open loop – refers to a testing mode in which fresh collection medium flows continuously through the collection chamber of the test cell and is not reused or recycled.
Closed loop – refers to a testing mode in which the collection medium is fixed.
In some cases, only one combination of collection medium and detection technique would be appropriate, in some cases two or three options may be appropriate.
Where a chemical can be collected by more than one collection medium, it is widely acknowledged that results may differ depending on whether the medium is aqueous or gaseous.
Our office hours are between 9am and 5pm GMT/BST.
Fill in our enquiry form and we will get back to you ASAP.