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Seymour is committed to providing the highest level of support for their product and services. The information contained in our Frequently Asked Questions section is intended to provide you with a quick reference to common question you may have. If the question you are looking for is not answered here, please contact us for more information.
What is PEX?
PEX is cross-linked polyethylene. Through one of several available processes, links between polyethylene macro-molecules are formed to create essentially one large molecule of polyethylene. This three-dimensional molecule is more resistant to temperature extremes, chemical attack and creep deformation which makes PEX ideal for use in hot water applications. Typical cross-linking levels in pipe are 65%-89%. For more than three decades, PEX (or XLPE) has been used extensively in Europe for hot water heating and plumbing applications.

How is PEX made?
The process starts with medium to high density polyethylene (MDPE or HDPE) resin. In some of the cross-linking methods, chemicals are added to the base resin which, either during extrusion or in a post-extrusion process, create the molecular cross-links through chemical reaction. These chemical methods can be compared to the vulcanization of rubber. Another method, radiation (nuclear or electron beam), uses high energy irradiation of the extruded pipe to form the molecular links. Finished properties of cross-linked material from these commercial methods are very similar.

What cross-linking method is used to make CANPEX™?
Seymour uses the silane method of chemical cross-linking. This process uses HDPE resin with additives that react when the extruded pipe is exposed to heat and moisture. The chemical reaction stops when cross-linking reaches 70-80%. Even with further exposure, no additional reaction will take place. CANPEX is tested to check the degree of cross-link before it leaves the factory. The silane method provides advantages such as aging and abrasion resistance, higher long term strength, re-inforced memory effect, and excellent rapid crack propogation (RCP) resistance as well as outstanding resistance to slow crack-growth (SCG) at high temperatures.

What sizes is CANPEX™ available in?
CANPEX tubing is made in 1/4", 3/8", 1/2", 5/8", 3/4", 1", 1 1/4", 1 1/2", and 2" sizes. The tubing is copper tube size, meaning that the actual outside diameter of the PEX is the same nominal size of copper tubing. CANPEX has a wall thickness corresponding to SDR9 (Standard Dimension Ratio 9) meaning that the wall thickness is 1/9th of the outside diameter and is proportionate for each size maintaining the same pressure ratings for all sizes.

What about freeze-break resistance?
CANPEX tubing will stretch slightly to accommodate the expansion of frozen water, then return to its original size when the water thaws. This memory is a feature of cross-linked material, giving it thermo-elastic behaviour. Although freeze-break resistant, no pipe is freeze-break proof under all circumstances. Insulation of plumbing pipes as required by local codes is still recommended.

What about flexibility and fewer fittings for changes in direction?
CANPEX is flexible and requires fewer fittings to install since most changes in direction can be accomplished without the need for elbows. CANPEX is simply curved around obstructions unlike rigid piping materials. Compared to branch and main plumbing systems with rigid piping, a CANPEX plumbed system uses only about half the fittings.

What about the use temperatures and pressures ratings and approvals?
CANPEX tubing is rated for 100 psi @ 180° F and 160 psi @ 73° F. CANPEX tubing is manufactured, sampled, tested, marked and third-party-listed in accordance with ASTM standards F876 and F877 and CSA (Canadian Standards Association) standard B137.5. For more information on ratings and approvals, download any of the available Tech Data Sheets.

Can I use CANPEX™ tubing in Hydronic Heating Systems?
Yes, CANPEX tubing is perfectly suited for hydronic heating loops. An oxygen-barrier version of the tubing and a complete line of heating system components are also available