Case mods, tools, techniques, water-cooling gear and everything to do with PC modding
PETG vs acrylic tubing
I’ve been dabbling with rigid tubing for a few years now, and while installation does take a lot more effort compared with flexible tubing, both clear and metal rigid tubing look fantastic. The straight lines create a super cleanlooking loop, while clear rigid tubing really allows your coolant to shine. It can be trickier to work with metal tubing, and it’s more expensive too, but it can also look even better.
Plastic-based tubing offers another perk, of course, which is that it can be bent to shape to create a completely custom loop. This tubing can be useful for creating a loop that works specifically with your hardware or case, or for simply creating a great-looking loop design. There’s a couple of downsides to acrylic tubing, though, which was the first plastic-based tubing to become popular with watercooling enthusiasts. It’s very brittle and can crack easily. It’s not an issue most of the time, but if your system is moved, or sometimes if a fitting is tightened too much, the acrylic tube can crack. There are obvious consequences to this problem if your system is filled with coolant at the time.
Acrylic tubing has a relatively high melting point too, which not only results in its brittleness at room temperature, but makes it tricky to heat and bend, requiring lots of practice. There is a new kid on the block, though, in the form of polyethylene terephthalate glycol-modified (PETG) tubing. In short, PETG tubing looks mostly the same as acrylic tubing and comes in the same sizes. However, it has one key property that makes working with it much easier – it has a lower melting temperature, which means you can heat and bend it far more easily.
More importantly, though, early tests showed what appeared to be an incredible resistance to shattering compared with acrylic tubing. The latter will easily shatter using a hammer, but by contrast, a hammer will likely bounce off an identical piece of tubing made from PETG. The lower melting point not only means it’s easier to bend, but also that it’s closer to a liquid state at room temperature than acrylic tubing, making it more elastic and crackproof as a result.
It’s no wonder, then, that many manufacturers have focused on PETG tubing as their primary tubing, including Thermaltake, which has been busy releasing its own large range of water-cooling gear recently. For the most part, it was a wise decision. It’s easier to work with PETG tubing, and of course it’s far more shatterproof.
However, you’ll note that I don’t say that it’s stronger than acrylic tubing, which is true. It doesn’t have a
molecular structure that’s physically stronger or stiffer, its benefits are purely down to its lower melting point and the fact that it’s closer to being a liquid at room temperature.
Unfortunately, the lower melting point does pose one significant issue. At room temperature, PETG tubing is tough enough to handle any job a liquid-cooling loop can throw at it. However, horrific photos have appeared online of the tubing seemingly bent out of shape and compressed, even inside the compression fittings themselves.
It’s a situation that has led to leaks, but it’s important to understand why the tubing acted in this way. In each case, or at least certainly the ones I’ve read about anyway, there has been a fairly clear reason for this behaviour. A failure in the system, specifically a pump or fans, will see the coolant temperature skyrocket, but it might then take several minutes before your PC actually crashes. By then, the damage will have been done.
Much more worryingly, the coolant temperature can get too high even in a working, stable system. Linustechtips forum user Smollie1 revealed that his small form factor water-cooled PC, built into a Fractal Design Node 202 case, suddenly sprung a leak. On closer inspection, his PETG tubing had become compressed in the fittings due to high coolant temperatures. This compression was simply caused by a lack of airflow in a small, cramped
system, but the issue is that the CPU and GPU temperatures were well away from their thermal limits.
Their temperatures were very high for a custom water-cooled PC, though, with the GPU approaching 70°C under load, instead of a more typical temperature of 40-50°C for a watercooled GPU, and the CPU temperature being even higher. For normal flexible tubing, and probably acrylic tubing too, these temperatures would likely be fine, but unfortunately, PETG tubing can start to lose its shape at these temperatures, whereas acrylic tubing generally isn’t affected in this way.
It’s not just a case of avoiding pump or fan failure, which isn’t common but far from a rare occurrence, especially with Laing DDC-based pumps. It’s mainly down to being aware if your PC’s water-cooling system will be operating at higher temperatures than usual – for example, in a small form factor PC. There’s a bit of forethought required if you plan to use bendable, plastic-based tubing. It’s trickier to
work with acrylic tubing, and it’s more prone to shattering, although it will be fine in 99.9 per cent of situations.
However, if you’ve seen the various hammer-test videos online, which compare PETG with acrylic tubing, it’s important to realise that PETG isn’t stronger, and the lower melting point means you need to be aware of your coolant temperature as well. If you have a normal tower PC with ample radiator cooling capacity, you need to have an active warning system for pump or fan failure.
In addition, in systems that might be operating at higher coolant temperatures (such as small form factor rigs), it would be wise to invest in a fan controller such as Lamptron’s CW611, which has the ability to monitor coolant temperature and ramp up fan speeds when required. Thermaltake states that its PETG tubing will start to become malleable at 62°C, so you’ll want to keep your coolant at least 15°C below this temperature under load if you use PETG tubing.
Our recent dream PC build used PETG tubing, and working with it was comparatively easy
A fan controller that reacts to coolant temperature would be a wise investment if you’re using PETG tubing
PETG tubing can end up becoming compressed in tube fittings at high coolant temperatures, causing leaks, as shown in this photo from Linustechtips forum user Smollie1
Rigid tubing uses similar compression fittings to normal tubing