It’s not often that we see a new product take over a specific sector of the construction industry. Much like poly-woven materials appeared in the 1990’s as competition to common building paper, PEX plumbing products has emerged to give copper tubing a run for the money. Contractors enjoy working with this product primarily because of cost and ease of installation, and for that reason, I believe we will continue to see this product used more and more in both commercial and residential construction.
So, what is PEX? PEX is a product made out of HDPE or High Density Polyethylene. The PEX tubing we are now seeing more and more in both residential and commercial products first began it’s life as little bb sized plastic pellets. Those pellets are heated to a liquid state and then forced through a die under high pressure. The result is an extruded section of PEX tube.
PEX can be labeled as PEX-A, PEX-B or PEX-C. The letter designation defines the manufacturing process in which the product was made, and has no bearing on quality or performance ratings. I won’t go into the scientific difference of each manufacturing process at this time, but it’s important to know that all PEX, regardless of the letter designation must comply with ASTM F876 or ASTMF877 standards.
There are now several large manufacturers of PEX, such as; Uponor, Watts, Zurn, JM Eagle, Rehau and Viega to name a few. Important information regarding the manufacturers name, product name, ASTM designation, ICC-ES evaluation number, etc., can be found stamped on the tubing at specific increments.
PEX tubing is manufactured in several colors including, white, black, purple, red, blue and brown. According to several manufacturers, there is no difference between colors in regards to use, but generally installers will use blue for cold lines, red for hot water and white for fire systems. A word of warning, while these color assignments may appear to be common sense, I have seen colors installed and mismatched with no regards to hot, cold or other uses.
Ease of installation is one desirable aspect of PEX tubing and unlike copper pipe which requires soldering, PEX can be joined in a number of ways. There are numerous types of fittings used to joint the tubing; however, all styles are not compatible with all brands. Some examples of fittings include; shark bite, compression, expansion, crimp, clamp and press, and all require specialized tools depending on fastening method. Most if not all manufacturers only allow certain fittings to be used with their product, which is why it’s best to stay with fittings made by the same manufacturer as the tubing.
Here are some general guidelines when installing PEX tubing. These guidelines are from Uponor, but are similar to requirements from the other major manufacturers.
Do not install where pressures exceed the rating
Maximum exposure to direct sunlight (White) 30 days
Maximum exposure to direct sunlight (Red & Blue) 90 days
Do not weld, glue or use adhesives
Do not apply flame
Do not install within 6” of any gas appliance
Exception; Double wall B-vents or plastic vents w/ 1” min. clearance
Do not install within 18” of a connection to a water heater
Do not install within 12” of recessed light fixture
Exception: unless tubing is protected by insulation or can light is I.C. rated
Do not install within 5’ direct view from fluorescent lighting without UV-blocking material
Do not solder within 18”
Do not install between the tub/shower valve and tub spout
Do not allow contact with chemicals, pesticides or strong acids
Do not subject to impact
PEX tubing can be an economical and convenient way to install plumbing in lieu of copper tubing; however professional installers as well as do-it-yourselfers need to pay attention to guidelines and installation requirements set forth by the various manufacturers.
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