Pira Consulting
Proficiency Services
Permeability
The Permeability Proficiency Service (PermPS) provides film samples for checking water vapour and oxygen permeability equipment. It is a bi-annual service; samples of film are prepared every six months at Pira and sent to each subscriber in April and October, accompanied by a statistical analysis report of the previous round results.
For each round and test condition, two different types of film are provided, to give two levels of permeability. Subscribers can choose to take samples for water vapour and/or Oxygen Permeability. For WVTR, two conditions are available: 25°C, 75% rh. and 38°C, 90% rh. and again you can choose one or the other or both. Samples are identified by film number and an indicative value that enables an immediate check on results (see table below).
| Test condition | Level 1 |
Level 2 |
|---|---|---|
| WVTR 38°C, 90% rh | 3.0 g/m²,day |
9.0 g/m²,day |
| WVTR 25°C, 75% rh | 1.2 g/m²,day |
2.3 g/m²,day |
| Oxygen | 13 cc/m²,day |
55 cc/m²,day |
Costs
The costs vary for each laboratory, as subscribers can choose whether to take samples for both parts of the service, and as mentioned earlier, there are two conditions for WVTR. It is also possible to only participate in one of the two rounds. The subscription costs are currently based on the number of samples taken and each sample is £188 (GBP). Each sample comprises two different levels with four replicates for each. If a client wishes to submit results for more than one instrument from a single set of samples, each additional instrument is charged £60 (GBP).