Over time we have observed that Nafion™ can turn discolor to a brown hue over time when exposed to atmosphere or bright light. Our tests have shown that this discoloration has no effect on the water transfer properties of the material – so you can install the product and continue to use it without loss of performance. Similarly, we have found that as long as Nafion™ is kept in a clean area the performance should not degrade over time. In most applications the Nafion™ tubing lasts as long as the device, except when contaminants or dirt present in the sample stream block the water transfer chains on the inside surface of the tubing. In these cases, the product will have a lifetime in the application dependent on the amount of contaminants present.