A lot has been added to this post since I first made it. Please read it again for more clarification and comparison.
Before I get started, I'd like to point out that the Tygon I got was thinwaill ID 1/2" OD 5/8" and the silicone tubing I have is thickwall ID 1/2" OD 3/4". This is of importance because of the fact that thinwall will kink much more easily.
Now, because I'm a n00b and I can never get pictures to work right, I'm going to tell you that you can see the tygon at
http://pictures.zoson.net/tygon. You should find all the pictures you want there.
Appearance:
Just by looking at the Tygon, you would think it's vinyl. It looks like vinyl, and is completely clear. Compared to the milky white color of silicone, this stuff is beautiful.
Flex and Softness:
Tygon is EASILY more flexible than silicone. It will bend and turn without problems given that you have enough tubing. Tygon IS very soft and will squish under very little pressure, which makes clamping effective. It also stretches very well.
Elasticity and Barbs:
I was easily able to get the tubing to fit over the large barb on my eheim 1250 pump. I'm not sure how big the barb is, but it's bigger than a 5/8" ID barb. Due to it's elasticity this stuff is EXTREMELY hard to pull off of barbs that are ID 1/2". It is easier to remove from brass barbs than plastic barbs though. For properly sized 1/2" OD barbs, you will not require any clamps. But on my Black Ice Xtreme radiator, I did need to clamp it (I had to clamp my silicone tubing as well on the radiator).
Tygon IS very soft and will squish under very little pressure, which makes clamping effective.
Kinks:
As far as kinks go, tygon tends to sort of flatten out, but the channel inside remains open, up to a fairly far point. If you look at the picture of me holding the tubing up and flexing it. That was about as far as I could bend it without it actually kinking. It does kink sooner than silicone tubing, but that may be because the tubing is thinwall.
Freezer test:
Per Una's request, I stuck some of the tubing in the freezer before I started working on my computer. I took it out after about an hour, and started to play with it. The tubing remained flexible, but was a little more stiff. It was NOT brittle.
Chemical Absorbtion:
One thing that is a huge mark for Tygon and against silicone is the fact that silicone is a porous material, and absorbs compounds like Water Wetter, dyelite, and antifreeze. The laboratory grade Tygon is designed to do exactly the opposite of this. It resists absorption of chemicals, and will not discolor because of them. Silicone discolors heavily after a little use. Because of the discoloration associated with silicone absorbing the water wetter in my coolant, UV light was unable to penetrate the silicone, and my coolant would not glow. This will not be a problem with Tygon.
Memory:
Contrary to popular belief, Tygon does not have a "memory" like vinyl has, and will not get stuck in a shape like vinyl will. When my tubing arrived, It had been rolled up, and vacuum packed. So it had probably been like that for awhile. Also counting that it took over a week to get to me. Also in my experience, silicone DOES have a memory. I have a picture of this on my website above.
Price:
It does run a little more expensive than silicone. Tygon is about $2 per foot. You can get it at
http://www.vwrsp.com/catalog/product...ect_id=0013719 in both the 3/8" ID and 1/2" ID flavors.
Conclusion:
Hands down, I think this stuff beats silicone. It's more flexible. It kinks at about the same point of flex. It's completely clear. It doesn't get messed up if it's frozen. It fits snugly on barbs without need of clamps. While it is a little more expensive than silicone, I think that the appearance of this stuff alone makes it worth the extra $.
Enjoy!
-Zoson