For anyone who is interested, I contacted the guy at:
http://hydro-tubes.com/ and got a reply. Here was my question:
"My main question is what is the pvc material you use for the tubes? Is it standard plumbing pvc? I understand standard pvc pipe degrades over time with exposure to UV radiation, but I have not found any information about how long this actually takes. Do these stand up well to relatively high levels of UV radiation, and are they painted? What kind of lifetime is expected of the tubes, pumps, and sprayers? Basically I need to know what kind of maintanence costs can be expected for a system over a several year period. Obviously this will vary depending on what system is used, but if you could give me a general idea it would really help me."
And his reply:
"Hello *flow*, The PVC pipe that we use will last 20 years or more. Their are two different types of PVC pipe that is standard in the plumbing industry, solid wall and cellular core. We only use solid wall. The cellular core is not a good choice for hydroponics. It will not last as long. The pipe is not painted. UV radiation will not have any effect on the PVC pipe that we use. The pumps are high quality mag-drive pumps.
they have a 3 year warranty, but we have pumps that are over 15 years old and they are still in operation. The pumps can be used inline or submersed in the nutrient tank. The sprayers are very inexpensive, but our systems do not require sprayers unless you really want to use them. There is a feeder line inside the 6" PVC pipe that works without the need for sprayers. ALL sprayers will require cleaning or replacing as time passes. We have designed our systems to be as close to maintanence free as possible. Just a basic cleaning is all that is needed between growing cycles."