PEX (Cross-linked Polyethylene): Definition and General Description.

January 31, 2014 • Radiant Floor Heating, Radiant Heating • Views: 242

PEX (Cross-linked Polyethylene): definition and general description. 

PEX, also known as Cross-linked Polyethylene is a plastic material made from medium- or high-density polyethylene. It has been modified in order to improve its properties, such as enhanced heat resistance, long term strength and stability. This makes PEX an excellent choice for use in service lines, hot- and cold-potable water distribution systems, residential fire-sprinkler systems and hydronic radiant heating applications. PEX tubing is produced to meet the Buy Cheap Cialis online from Certified an… following requirements: ASTM F876, ASTM F877, AWWA C904 and/or CSA B137.5.

PEX tubing has been used in hot- and cold-water distribution systems and for hydronic radiant heating for decades. It has been introduced into the United States from Europe in the 1980’s, At the present day, PEX is the most widely-used flexible plumbing piping for plumbing and radiatn floor heating applications. Increasingly, metal pipes in residential and commercial plumbing needs are being replaced by PEX.

PEX coil

PEX tubing is manufactured by extrusion in sizes raging from Πinch up to 3 inch in diameter. It is controlled to meet Outside Diameter (OD) dimensions commonly called CTS (copper tube size). The wall thickness is based on a SDR 9 (Standard Dimension Ratio 9), indicating that the ratio of the OD to the wall thickness of the tubing is 9:1. It is available in straight lengths and coils of various lengths.

Environmentally friendly (Green building and sustainable development)
A significant benefit of PEX and other plastic pipe is its small environmental impact compared to other materials used for similar applications. The PPFA (Plastic Pipe and Fittings Association) encourage the development of sustainable building. Standards and rating systems for sustainable and green building are developed using an ANSI accredited process. These standards and rating systems utilize LCA (Life Cycle Assessment) to set up criteria that cover the broad range of construction materials and techniques.

Applications 
PEX tubing is used in service lines or potable water distribution systems, as long as it has been tested in accordance with the governing standard, meeting the requirements of ANSI/NSF Standard 61, and bearing proper certification from an established testing agency.
PEX tubing is also used for heat transfer applications, in low-temperature applications, including radiant floor heating and cooling, snow melting, turf conditioning and permafrost protection. It is also used for distribution piping for temperatures up to 200°F, such as hot-water baseboard, convectors, radiators, and some type of PEX is approved for residential fire-sprinkler systems.

Building Codes 
PEX tubing is accepted and recognized for water distribution piping in all major model plumbing codes.

Availability 
PEX tubing is available from plumbing wholesalers, building centers, and manufacturers such as GTGlobe, throughout the U.S.A. and Canada.

Marking 
PEX tubing must be labeled as follows:
The manufacturer’s name or trademark
The standard to which it conforms (ASTM F876, F877, AWWA C904 and/or CSA B137.5)
Tube size and CTS
Material designation code (PEX0006 or similar)
Pressure/temperature rating(s)
SDR9
If the tubing is for potable applications, a laboratory seal or mark attesting its suitability for potable water must be added
ASTM fittings designations approved for use by the tubing manufacturer
The marking interval on the tube is required to be no more than five feet.

Additional Resources 
The Online Piping & Usage Specification by the Mechanical Contracting Education & Research Foundation  provides information concerning users on pipe types, materials, applications and joining methods.

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