If you are going for PEX as a plumbing material in your household, you will notice that many of the advice you listen to will include references like “A type is better than B and which is better than C”. It is like PEX has a grading system based on the alphabets.
Identifying the differences between the alternatives available in the market can be problematic, especially if one seeks to choose the most suitable pipe for a given project.
But don’t worry because this article will clear the confusion by highlighting the differences among these three types of PEX tubing.
You must remember that there are three common types of PEX: PEX-A, PEX-B, and PEX-C. These letters, which are used to identify types of PEX, can be misleading. There is an erroneous belief that the letters refer to the material’s quality grade so that PEX-A is better than PEX-B, which is superior to PEX-C.
This is not true. The letters are used to identify the different pipe manufacturing processes and have nothing to do with quality or performance. The classification refers to manufacturing the PEX, which is the primary difference between the three types.
PEX-A: Engel Method
PEX-A is produced by the Engel (peroxide) method. This method performs a “heated” crosslinking above the melting point.
However, the process is slightly longer than the other two methods as the polymer has to be held at elevated temperature and pressure for a long time during the extrusion.
The crosslink is between the carbon atoms, and ‘A’ type is obtained by introducing peroxide into HDPE before extruding it.
PEX-B: Silane Method
PEX-B is made by using the “moisture method.” In this method, crosslinking is carried out in a secondary post-extrusion process, producing crosslinks between crosslinking agents. The process is accelerated by heat and humidity.
PEX-C: Electron Beam Method
PEX-C is produced through the electron beam process in a “cold” crosslinking method (below the melting point). It offers a less uniform and less crosslinking degree than the Engel method, especially in tube diameters greater than 2.5 cm.
When the process is not properly controlled, the outer layer of the tube can become brittle.
The ASTM F876 Standards
PEX must meet ASTM F876 standards for pressure and temperature rates. Of course, this does not mean that all these types of PEX have identical requirements as per ASTM F876 standard,
- PEX-A must be up to 70% crosslinked to meet burst pressure requirements.
- PEX-B must be at least 65% crosslinked to meet burst pressure requirements.
- PEX-C must be at least 65% crosslinked to meet burst pressure requirements.
Flexibility is Better in PEX A
The most important advantage of the PEX-A is its great flexibility, which allows it to be bent and cold-bent with great simplicity and without the need for special tools. The flexibility allows you to make bends as its bending radius is better than PEX B and C types.
This flexibility means that the use of PEX-A pipes is very comfortable for plumbing and heating installations. Besides, this flexibility allows you to reduce the number of accessories needed to make the installations with a significant saving of time and money.
PEX- B and C are not flexible enough compared to PEX-A, because of their high bend radiuses.
On the other hand, lower bend radius, thermal memory, and elongation capacity make PEX-A pipes a product of recognized prestige in the plumbing and heating installation sector.
PEX-B has a high bend radius and PEX-C none at all. PEX-B can be used in bending but more prone to break, and PEX-C cannot be used in bends as it cracks or breaks immediately.
PEX-A’s “thermal memory” property allows correcting deformations with the application of hot air since the pipe structure can recover its original shape. This allows you to correct installation errors and repairing more easily.
The heating process to recover or repair is not recommended for PEX-B and PEX-C. They have no thermal memory and therefore need to replace rather than heat treated.
The Engel process uses various chemicals, and PEX A types are prone to chemical contamination. This contamination is harmful to water sources and, as a result, to human health. The MTBE and TBA chemicals are to be tested before the installation of type-A.
PEX-B, due to its resistance to chemical agents, low mechanical degradation, and the absence of corrosion, its physical properties remain practically unchanged over time, but PEX-C is the winner.
PEX-C is the most environmentally friendly of the three. It is not treated with chemicals and uses only high-energy electrons to separate the carbon-hydrogen bonds and facilitate crosslinking.
The most important advantage of the PEX-B pipes is their resistance to pressure and high temperatures. It shows durability and resistance to corrosion a tat better than PEX A. They are light tubes and easy to handle. It also reduces noise transmission in hydraulic networks.
If you are interested in fewer bends and more line installation, PEX B is the suitable choice. It has a low cost as compared to PEX A. The B types require less skill and bend, so it is cheap and easy to handle.
The B-type perfectly withstands blows, dragging, and of course, any type of erosion during its placement and installation.
The lack of flexibility means more connections and fittings, which is costly, and more skill is involved in its installation. These connections and fittings are prone to water leakage. The reduction of water pressure also results in external pollutants entering the water source.
So PEX-A is the cheaper of the lot. PEX-B is cheap in line installations, and PEX- C is not known for its flexibility or resistance. Because of its negligible usage and the reluctance of manufacturers to produce it, PEX-C has little value in installations. That said, PEX-C is also prone to cracking and kinking.
Read: PEX vs CPVC Comparison
Applications and Usage
The fundamental applications of PEX-A pipes are as follows:
- Medical Equipment likes Dialysis machines.
- Plumbing installations (hot and cold sanitary water).
- Radiator heating installations.
- Underfloor heating installations.
- Air conditioning installations.
PEX-B is utilized in:
- Offshore Oil Rigs
- Inline supply installation from a water source
PEX-C is used for temporary domestic purposes
- Outdoor Portable Pools
- Domestic Garden Pipes
To sum up, choosing between the types of PEX tubing can be difficult; therefore, the most important thing at this point is to remember that the benefits must be taken into account while choosing.
Moreover, to help you out, we have mentioned some of the differences between these three types of PEX which will help you decide.
We hope that the article has provided you with all the information you needed to differentiate between PEX-A, PEX-B, and PEX-C.