Tedlar, FEP and PVC are widely used to make gas sample bags. But what, exactly, are their differences? Discover what makes them unique materials, and which thermoplastic is best suited to your application, from VOC testing to fuel emission testing, chemical sampling and breath collection.
Commonly used for VOC, breath, landfill, odour and automotive emission testing, Tedlar® gas sampling bags are extremely robust and durable, and ensure sample integrity. In addition to being tougher and more economical, Tedlar® is also chemically inert, abrasion resistant and temperature resistant.
FEP gas sample bags offer the highest purity, guarantee no leeching from the material and give the ultimate in low contamination and easy cleaning. FEP is also the most chemically inert material and is resistant to extreme temperatures. FEP gas bags are normally specified for odour sampling and applications where a very low ppm are involved.
Widely used for non-critical testing as a cheaper alternative to more expensive materials, PVC sampling bags are quick and easy to produce, and extremely durable. However, PVC contains plasticisers and as such, could leach and contaminate samples. PVC is abrasion resistant and enjoys dielectric strength. Similar materials also used for cheaper gas sampling bags are PU, E-CTFE and PET.
In this particular application, Tedlar® sample bags were used for VOC testing of in-cabin automotive components at elevated temperatures. Widely used for testing of VOC's, Tedlar® film was chosen as the film is robust, contains no plasticisers, has excellent aging properties and remains tough and flexible over a broad temperature range.
Used for testing fuel emissions, Tedlar® sampling bags were chosen for their robustness and sample integrity. The sampling bags were made with crinkle film and no internal pipe work, so the film did not block when the samples were evacuated. In addition, the Tedlar® bags were enclosed in a black PVC outer and a black FEP tube feed was used to ensure the light did not affect the samples.
In this particular application, FEP gas sample bags were used for the liquid sampling of chemicals. FEP was chosen as it is the most inert material known to man. Holding liquid, this bag was made with thicker film so it was more robust. A Kapton reinforcement was also included at the section where the customer’s free issue fitting attached to the bag, again to ensure robustness.
Used for collecting the breath of visitors at a music festival, PVC sampling bags were chosen for their low cost. The visitors’ breath was collected to create an art installation for the event and used to play an instrument. A simple PVC bag was designed with a tube connector and a sealing clip, so it was easy for the public to blow into the bag and seal the breath within the bag.