Not All Plastics are the Same

Understanding the Differences between CPVC and PE-X

If you’re like many professionals in the plumbing industry, you’re tired of paying the unpredictably high prices of copper pipe or hearing customer complaints about pitting, scaling and corrosion. If so, you have likely already made the decision to convert from metallic to plastic piping. But that’s not where the decision-making process ends. What type of plastic piping you choose can have a major impact on your company’s bottom line and your reputation. 

So before you make a final decision, consider the facts. Any way you look at it, FlowGuard Gold® CPVC outperforms cross-linked polyethylene (PE-X).

Proven Track Record 

CPVC has been used successfully for more than 50 years for potable water distribution systems in the U.S.  PE-X, in contrast, was first introduced in the U.S. in 1984. Although PE-X has a longer history in Europe, beginning with PE-Xa (peroxide-modified polyethylene) in the 1960s, the potable water supplies abroad are not treated the same as they are in the U.S. For example, Europe uses predominantly ozone and filtration techniques, whereas the U.S. primarily uses chemical treatments involving chlorine and chloramines. This means that PE-X materials have not proven to stand up to chlorine at the same performance levels that CPVC has achieved. 

Reliability 

FlowGuard Gold CPVC is a more durable alternative. Not only does it offer superior tensile strength – three times greater than PE-X—but it also resists even the most highly concentrated chlorine levels (in excess of 3,000 ppm) as a result of its unique molecular structure. The superior chemical resistance of CPVC is one reason why it is even specified for use with highly corrosive and aggressive industrial chemicals. In addition, its pressure-bearing capability does not diminish with UV exposure or age. 

PE-X, in contrast, is not recommended by some manufacturers for use in chlorine levels greater than 5 ppm, and for good reason. Worse is the fact that UV light will consume PE-X additives until they no longer protect the tubing from chlorine degradation. That’s a key reason why industry groups do not recommend PE-X for outdoor, above-ground use.

Further, because some PE-X products may not perform well in hot chlorinated water applications, such as might be seen in a typical hot water recirculation system in a home or commercial application, caution needs to be exercised regarding which PE-X material should be utilized in these applications. ASTM and NSF recognized this fact a number of years ago and have, as a result, created multi-tiered product performance levels for PE-X.

Ease of Installation and Design 

Both CPVC and PE-X plumbing systems can be installed significantly faster than copper and steel systems. The difference, however, is that a FlowGuard Gold CPVC system can be installed quickly and easily using inexpensive cutting tools and an ASTM- and NSF-approved solvent welding process that results in a joint that is actually stronger than the pipe or fitting alone. PE-X, on the other hand, requires expensive expansion or crimping tools, special fittings and expansion rings or crimp rings with the end result being a joint that is the weakest point of the system and the most vulnerable to failure. In addition, calibration of the tools is required before each installation. Once installed, FlowGuard Gold CPVC pipe provides a straight, professional appearance, unlike PE-X which is often described as “sloppy looking” and “spaghetti-like”.  CPVC, in fact, is the only rigid thermoplastic rated for hot and cold water service. As such, it is naturally kink resistant and requires fewer hangers and supports than similarly sized PE-X.

Designing a FlowGuard Gold CPVC system is also facilitated because its thermal expansion properties are three times less than PE-X. Plus, accommodations must be made when installing PE-X pipe because of the potential for reduced water flow that results from the PE-X system’s required insert style fittings.   

Health and Safety Considerations 

Today’s consumers are more educated about health factors than ever before. How a piping material impacts water quality is one important health consideration. While no piping material can actually improve water quality, some are better than others at maintaining it. When evaluating water quality, biofilm resistance is a key indicator. Biofilms that form naturally in aqueous environments can harbor potentially harmful bacteria and microorganisms, making them more resistant to disinfection technologies. CPVC has shown, through multiple international studies, to offer a superior performance over PE-X in the area of biofilm resistance. Polyethylene, in fact, has twice the potential of allowing biofilm formation than CPVC, and a greater variety of bacteria, as well.

Equally important as water quality is the overall safety of the piping material. Again, CPVC scores high marks in the area of safety. Unlike PE-X, it will not propagate a flame because it requires nearly three times more oxygen than what is in the Earth’s atmosphere in order to sustain combustion. Rather, it will simply char and stop burning as soon as the flame source is removed.  PE-X only requires everyday air to ignite, and will continue to burn much like a common household candle, dripping flaming plastic onto the structure beneath. 

Sustainability

Today, many building professionals prefer materials which have a low environmental impact relative to other choices. With so much focus on sustainability, it is only appropriate to compare piping materials using rigid scientific methods to measure their impact on the environment.  CPVC rates high in this area because, according to third-party environmental impact testing, it requires less energy to produce than any other piping material—metallic or non-metallic. In addition, as a thermoplastic material, it can be heated, formed and melted again for reuse and reshaping. PE-X, an irreversibly cross-linked thermoset, cannot be recycled. Plus, it requires a substantially larger amount of natural resources--namely petroleum--to produce than CPVC.

CPVC or PE-X? They are two different classes of polymers that perform very differently. Weighing the considerations can be confusing, but when you add up all the advantages, it’s easy to see why FlowGuard Gold CPVC is the smart choice.