PEX PIPING INFORMATION - CONTENTS: properties, installation, safey. What is PEX pipe, where is it used, & how is it installed. PEX properties, PEX history & key dates, PEX failure class action information, PEX compared with copper piping, PlumbPex class action settlement, Kitec class action settlement. PEX piping leaks, reliability, & PEX used for building water supply piping, radiant floor heating & other heating applications. Update on Pex fitting de-zincification problems reported from the field. Pex dezincification research citations.
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PEX cross linked polyethylene piping guide:
This article describes the properties of Pex Tubing or Piping, Cross-Linked Polyethylene (PEX). We discuss the uses of PEX tubing for water supply & in heating applications.
We describe the several differnt types of PEX tubing connector systems used including PEX crimp fittings, PEX compression fittings, PEX expander fittings, PEX Press-Fit connectors, and PEX Shark-Bite fittings and connectors.
We also discuss the ongoing debate of Pex versus Copper or other piping choices, with the pros and cons of each, and we include a literature review of and comment on the question is PEX tubing or piping safe to use or does it leach contaminants into our water supply. This article also includes the history of the development, use, & standards for PEX piping.
Pex Tubing or Piping, Cross-Linked Polyethylene (PEX)
PEX and PB plastic pipe are used for water supply in buildings use mechanical fittings (crimp and compression type) and we have found some installers using PEX tubing in low temperature heating applications (see below). PEX piping is also referred to as "cross-linked polyethylene" piping or just "PEX".
Our photo (left) illustrates PEX water supply piping being installed in a New York home.
Installing both building water supply piping and heating supply piping (and radiant heating) can be significantly faster using PEX tubing because of its ability to bend around turns, avoiding some elbows, 45's and other fittings.
PEX piping is used in both hot and cold water applications (see the blue and red colors below). By convention the builder uses blue PEX for cold water and red PEX for hot water supply piping lines.
Generally you will find PEX piping or tubing marked with the nominal pipe size, wall thickness, and pressure rating and other information (see the illustration just below).
Temperature and pressure ratings for PEX, according to Zurn Manufacturing's engineering specifications is 160 PSI at 73°F, 100 PSI at 180°F, and 80 PSI at 200°F.
Illustration of PEX tubing markings - courtesy Zurn Manufacturing (permission requested 12/2010). [Click any image or table to see an enlarged, detailed version.]
When installing PEX piping, care must be taken that the pipe does not contact heating ducts.
If the pipe freezes, it is less likely to burst than and copper piping. Also, most types of plastic water pipe tend to sag and should be well supported by hangers
Watch out: PEX plastic water piping should not be installed outdoors or exposed to sunlight for long periods. The red and blue PEX piping shown below (right) were delivering hot and cold water in a newly-constructed home. The larger black ABS plastic pipe is probably a drain line.
Watch out: do not use plastic piping nor any other type of piping in applications for which it was not intended, or the result could be dangerous. For example, do not use PEX tubing for LP or natural gas piping.
PEX Tubing Connectors: Types, Tools, Requirements
Watch out: a variety of patented PEX tubing push-fit and clamp connecting fittings (at least six types) and connector crimping tools are on the market. You may not obtain a proper and secure PEX connection if you mix tubing connector fittings and crimping tools improperly. We recommend choosing a specific connector type and crimping tool and using it consistently at a given plumbing installation.
Examples & Photographs of the various types of PEX fittings and the special tools used include:
Clamp type PEX fittings (photo at left) using a brass connector and stainless steel clamp-rings (e.g. Hydro-Pex clamping tool). These connectors were in use in our PEX installation photograph above. Popular, easy to use.
Note in our PEX photo at left that on the cold water (blue) Tee fitting one of the clamp fittings remains to be completed. (Photo courtesy Galow Homes).
Crimp type PEX fittings (photo at left - Crimp type PEX fittings in a Haddonfield New Jersey home) (e.g. Watts Radiant PEX cramping tool) using Hydro-Pex fittings.
The copper crimp rings are used with most PEX connectors.
Compression type PEX fittings (photo at left) (radiant heating and other applications) uses three parts (connector, compression ring or ferrule, threaded nut) to connect PEX tubing to a radiant heating manifold.
Threaded nut and ferrule are used with an insert to prepare the tubing for connection to the manifold.
No special tools are needed and compression type PEX fittings work with standard and Pex tubing.
Expander type PEX fittings (photo at left, Expander type PEX fittings in a Tivoli NY home), e.g. ProPEX brass connecting fittings and the ProPEX expander tool from Uponor (formerly Wirsbo PEX fittings).
The expander tool actually expands or "stretches" the PEX tubing to accept the connecting fitting. A ProPEX ring of larger diameter covers and completes the expanded fitting connection. Popular with professional plumbers.
Our PEX tubing photo (left) illustrates three PEX installation details: use of expander-type PEX fittings, and at the photo bottom (blue cold water piping) a protective sleeve or bushing at the floor joist penetration, and a steel nail plate to protect the tubing from puncture by ceiling drywall (to be installed).
Watch out: use only with PEX A-quality fittings. lower quality tubing will not make secure PEX connections with this method.
Note: in best construction practices all holes drilled through structural floor joists (shown at left) would be made in the center of the joist, not near the bottom as in our photo.
Press-fit type PEX fittings from Wirsbo, Mr. PEX, and Viega. (do not assume you can mix fittings and tools among these three manufacturers). Use the Viega PEX press tool requires using Viega fittings, for example.
The Viega press PEX fittings are sold separately from the required stainless steel press PEX rings OR you can buy Viega pex press fittings that include the crimp ring already combined with the fitting.
When using the Viega method with the integrated fitting and crimp ring you'll need to look closely to assure that you have inserted the fitting fully into the tubing before crimping the sleeve using the Viega tool. Works with standard and Pex tubing.
SharkBite PEX push-fit fittings (photo at left) - push-in fittings (also work with copper and CPVC). No tools or rings are required.
We used the SharkBite fitting shown at left to temporarily cut and discontinue active hot and cold water plumbing lines during a building renovation/addition project. The fittings avoided having to drain piping and solder end caps onto pipes that were later to be further cut back, excavated, and permanently capped below the slab.
PEX Tubing cutter - used to make a clean end-cut, e.g. Wirsbo (now Uponor) PEX cutter
Types of PEX Cross-Linked Polyethylene Tubing
Four methods of creating cross-linked polyethylene, each possibly imparting different properties to the PEX piping or tubing, include
PE-Xa = using peroxide, developed by Engel, PAM, Frankische and others
PE-Xb = using silane, developed by DOW Corning / Sioplas
PE-Xc = using electronic irridiation
PE-xd = using AZO (Gustavsberg-Lobonyl) - not currently in production
- Bean (2007)
Standards, Listings and Approvals for PEX Plumbing Systems
The following standards and building codes list at least some elements of PEX plumbing systems.
ANSI/NSF Standard 14 (NSF International)
ANSI/NSF Standard 61
ASTM F876 (American Society for Testing & Materials)
CAN/CSA B137.5 (Canadian Standards Association)
California Plumbing Code - 2010
IPC (International Plumbing Code)
IRC (International Residential Code)
UPC (Uniform Plumbing and Mechanical Code)
U.S. State & Local Regulations or Canadian Provincial or Local Regulations
Pex Tubing / Plumbing use History & Dates
In the United States the use of PEX tubing in residential buildings for water supply & heating piping has been approved for use in all fifty states and in Canada in all of the provinces.
1933: (accidental) discovery of polyethylene following an explosion at Imperial Chemial Industries in England
1939: pilot plant production of polyethylene in the U.S.
1940's: BASF in Germany experiments with polyethylene tubing
1950: beginning research on cross-linked polyethylene plastics.
1954: Hoechst experiments with Hoestlan high density polyethylene & predicts very long life of the tubing (more than50 years). Early tubing needed further development to withstand high temperatures.
1965: Engel patents an economical process for successfully cross-linking polyethylene
1967: First licensed use of the Engel patent to produce Vernetzes polyethylene i.e. PEX
1970's: PEX formulation improved by Lenman, Agren et als.
1975: Golan produces PEX-a & PEX-c later sold to American & Canadian interests
1975-85: standards for PEX piping developed by Stufen, Liedelt, Stagge & Seydel et. als.
1980: PEX piping introduced for use in the United States & Canada. DIN 4726 created limiting Oxygen gas transmission rate, a factor in tubing success. (Oxygen permeation / outgassing created problems in hot water heating applicatyions.)
1984: ASTM F876/877 Lenman published for PEX Tubing
1984: oxygen-related boiler corrosion problems reported associated with "non-barriered" pipe used in heating systems leads to continued research on the oxygen diffusion problem
Latter 1980's: PEX tubing radiant heat applications developing in North America and elsewhere
1987: DIN 4726 standard finalized.
1989: CSA 137.5 for PEX published by Lenman
1990-2007: production of PEX a,b,c (various methods of producing cross-linked polyethylene tubing), PEX-AI-PEX, and PE-RT tubing.
1995: begin use of IPEX-manufactured Kitec fittings later found to fail & leak
15 May 1999: beginning of period of defective Plumb-Pex defective component installations in North America - for class action settlement purposes
2005: IPEX recalls Kitec®, or Kyetec brand of brass plumbing fittings
2009: California approved PEX for use in all homes.
2007: California, one of the last adopters, did not approve the use of PEX (cross-linked polyethylene tubing) for household plumbing until 2007 (on a case by case basis)
31 March 2012 - end date for filing claims re: Court ordered homeowner notification program for defective Plumb-PEX components
22 September 2013: ending date for filing claims for the Court ordered homeowner notification program for defective Plumb-PEX components
PEX Pipes vs Copper Piping: which is preferred?
Reader Question: Pex vs. Copper Water Supply Piping - which should I use?
Question: my daughter is doing extensive renovations on her house and the question has come up whether to use PEX or copper in the plumbing.
I did a google search and the informations is conflicted; see below. [We read & also expanded the writer's original four web link citations in the article below - Ed.] Do you have knowledge of, and opinions about, this controversy? Any thoughts would be helpful. Thanks. Elisha Fisch, New York 2/17/2013
Elisha I've moved this discussion on Pex pipes vs copper pipes to its own article at
Plumb-PEX Plumbing System Class Action Settlement - PEX piping leaks
In March 2012 people who own or previously owned a building where Plumb-PEX plumbing components were installed are notified of a proposed class action settlement involving Radiant Technology, Inc. and Uponor, Inc who sold Plumb-PEX insert fittings and stainless steel PEX tubing clamps.
Kitec Brass Fitting & Related IPEX Plastic Pipe Leaks: Class Action Settlement
The Kitec system was a collection of brass plumbing connectors intended for use with PEX type plastic piping. Kitec, also in some sources spelled Kyetec is a brand of brass plumbing fitting that was recalled in 2005 by its manufacturer, IPEX, due to its tendency to quickly corrode. - Wikipedia 
Kitec plastic pipe and fittings has agreed to settle class-action suits in the United States and Canada for $125 million. The piping system that is the subject of this action was used in roughly 292,000 U.S. and Canadian homes beginning in 1995.
Details about the Kitec plastic class action suit are given in a link just below.
Question: is PEX the same as Kitec® ?
Is PEX the same as Kitec? How does one tell distinguish between Kitec and PEX? - Anon
Reply: Kitec was an individual brand of PEX pipe subject of a class action settlement
PEX (cross-linked polyethylene piping) is a general term for a type of plastic piping used in water supply, heating, and other applications.
Kitec® is a specific brand of PEX tubing that was subject of a class action settlement with an end-date for filing claims of 31 March 2012.
Pex De-zincification Update & Research: field failure photographs of Brass PEX Pipe Fitting Corrosion & Leaks
[Click to enlarge any image]
Above left: brass tee corrosion appearing both on the Tee-fitting body (red arrow) and around the end of the PEX tubing (green arrow) on water piping in a 2009 home.
Details about corrosion, leaks, & possible dezincification problems at brass connectors used in PEX piping systems are
at PEX BRASS CONNECTOR LEAKS
Research on PEX Piping vs Drinking Water Contamination
Kelley, Keven M., Alexandra C. Stenson, Rajarashi Dey, and Andrew J. Whelton. "Release of drinking water contaminants and odor impacts caused by green building cross-linked polyethylene (PEX) plumbing systems." Water research 67 (2014): 19-32.
Continue reading at PEX BRASS CONNECTOR LEAKS (discussing de-zincification and leaks at PEX connectors) or select a topic from the More Reading links or topic ARTICLE INDEX shown below.
Try the search box below or CONTACT US by email if you cannot find the answer you need at InspectApedia.
installing PEX in concrete
(July 17, 2014) Anonymous said:
When putting pex in concrete do you need to pressurize the system before you pour the concrete?
While I can't cite an authoritative reference, certainly I've never seen a system pressureized before installation. I do see that the pex tubing is capped and supported above the slab to keep it acessible and clean at its connection points.
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Bean, Robert, "The History and Influence of PEX Pipe on Indoor Environmental Quality", healthyheating online article (2007), Email: firstname.lastname@example.org, website: www.healthyheating.com, retrieve 6/25/2014, original source: http://www.healthyheating.com/History_of_Pex.htm
Bean, Robert, Bjarne W. Olesen, Ph.D., Kwang Woo Kim, Arch.D., "History of
Radiant Heating & Cooling Systems", ASHRAE Journal, January 2010, Website: ASHRAE.org
Eric Galow, Galow Homes, Lagrangeville, NY. Mr. Galow can be reached by email: email@example.com or by telephone: 914-474-6613. Mr. Galow specializes in residential construction including both new homes and repairs, renovations, and additions.
Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
John Cranor is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-747-7747 or by Email: firstname.lastname@example.org
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 PB (polybutylene with mechanical fittings) Piping leaks: especially in mobile homes and in the U.S. South, for example trailers and double-wides throughout Florida that were piped with this material - per M Cramer. See "Polybutylene Piping: Time Bomb?" Daniel Friedman, Journal of Light Construction, August 1996 [Technical Q&A].
 ABS Plastic Pipe: "All Black -hit," defective black ABS plastic waste pipe manufactured in the mid 1980's failed by cracking. Additional information: www.abspipes.com
 Polybutylene Plumbing (plastic pipes): gray plastic water supply piping cracked, leaked, and resulted in a class action and settlement.
Eric Galow, Galow Homes, Lagrangeville, NY. Mr. Galow can be reached by email: email@example.com or by telephone: 914-474-6613. Mr. Galow specializes in residential construction including both new homes and repairs, renovations, and additions.
 PB Technology Center (information about PB Pipes) Tel: 800-338-7732, also see the 1990 PB Pipe recommendations published by the Polybutylene Product Line Committee of the Plastic Pipe and Fittings Association.
 Zurn Manufacturing, Zurn Pex, Inc., Highway 11 East, Commerce, TX 75428, Tel: (903) 886-2580
provides information about installing and using PEX piping including Type b PEX through their website. Quoting from the company's website
Zurn was founded in 1900 in Erie, PA. It originally manufactured a patented backwater valve, and it now manufactures and distributes one of the largest plumbing products packages in the world! Zurn includes: the Specification Drainage Operation, AquaFlush flush valves, AquaSense sensor-operated plumbing products, AquaSpec commercial faucets, Wilkins, Zurn Light Commercial, Flo-Thru, the Chemical Drainage Systems, Zurn PEX Plumbing Systems and Zurn Radiant Heat.
 Zurn Pex Plumbing
Products Liability Litigation, United States Court of Appeals
FOR THE EIGHTH CIRCUIT, No. 10-2267, Filed 6 July 2011, Quoting:
Minnesota homeowners brought this action1 against Zurn Pex, Inc. and Zurn
Industries, Inc (Zurn) alleging that brass fittings used in the company's cross linked
polyethylene (PEX) plumbing systems are inherently defective. In pretrial motions
the homeowners sought class certification for their consumer protection, warranty, and
negligence claims, and Zurn moved to strike the testimony of two of the homeowners’
experts. After denying Zurn's motion to strike the expert testimony, the district court2
granted the homeowner requests for class certification for their warranty and
negligence claims, but denied it for their consumer protection claims. Zurn appeals
from the district court's certification order. We affirm.
Web search 4/12/12, original source: www.ca8.uscourts.gov/opndir/11/07/102267P.pdf
 Uponor, Inc., F1807 Plumbing Court File No. - United States District Court, District of Minnesota, In Re: Uponor, Inc., F1807 Plumbing Court File No. 11-MD-2247 ADM/JJK
Fittings Products Liability Litigation, "
Order Granting Motion to Certify Class for Settlement Purposes and for Preliminary Approval of Class Action Settlement and Form and Dissemination of Notice to the Class" Quoting:
The Motion for Preliminary Approval of Class Action Settlement was heard on January 12, 2012. After review of pleadings and briefing, and having heard the arguments of counsel for good cause shown, it is hereby ORDERED that: (1) the Motion for Preliminary Approval of Nationwide Class Action Settlement Agreement; (2) preliminary and conditional certification of a settlement class; (3) approval of the form and content of Notice and Settlement; (4) an injunction and stay of all claims and actions against the RTI Defendants
Web search 4/12/12, original source: http://www.mnd.uscourts.gov/MDL-Uponor/
 Bonnie Ransom Stern & Gustavo Lagos, "Are There Health Risks from the Migration of Chemical Substances from Plastic Pipes into Drinking Water? A Review", Human and Ecological Risk Assessment: An International Journal
Volume 14, Issue 4, 2008, Abstract:
Plastic pipes used to convey hot and cold drinking water are synthetic polymers containing numerous additives that enhance durability, impact strength, and toughness, and resist material degradation. Although some research studies have been conducted to evaluate the type and levels of chemical substances migrating from polymeric materials into drinking water, the potential adverse health effects associated with these compounds in potable water have not been described. This review evaluates the literature on the occurrence of regulated and unregulated substances in drinking water related to the use of plastic pipes, characterizes potential health hazards, and describes uncertainties associated with human health and exposure in need of further research. Of particular public health concern is the potential for sensitive populations to be exposed to short-term elevations in leachates during critical periods, and for co-occurring leachates targeting the same organ(s) and/or sharing a common mode of toxic action to have additive or synergistic effects. Contaminants are measured in the distribution system, not at the tap where human exposure actually occurs. For increased health protection, it is important to identify compounds that migrate from plastic pipes into drinking water and to better quantify human exposures and health hazards to these substances and their degradates.
 Andrew J. Whelton, Andrea M. Dietrich, Daniel L. Gallagher, "Chapter 6 Impact of Chlorinated Water Exposure on Chemical Diffusivity and Solubility,
Surface and Bulk Properties of HDPE and PEX Potable Water Pipe", in Advancing Potable Water Infrastructure through an Improved Understanding of Polymer
Pipe Oxidation, Polymer–Contaminant Interactions, and Consumer Perception of Taste, Andrew James Whelton
Dissertation submitted to the Faculty of the
Virginia Polytechnic Institute and State University
In partial fulfillment of the requirements for the degree of
DOCTOR OF PHILOSOPHY
Andrea M. Dietrich, Chair
Daniel L. Gallagher
Marc A. Edwards
Brian J. Love
James M. Tanko, April 2, 2009
Blacksburg, Virginia. Abstract: While more than 100 years of research has focused on removing acute and chronic health
threats from water, substantially less study has focused on potable water infrastructure and water
quality deterioration, monitoring technologies, and relationships between water taste and
consumer health. These knowledge–gaps have left infrastructure users, owners, regulators, and
public health professionals largely unaware of how premise and buried polymer water pipes
deteriorate and sorb/ desorb organic contaminants during normal operations and following water
contamination events. These knowledge–gaps also prevent infrastructure managers from
producing drinking water that optimizes mineral content for both water taste and health benefits,
and employing a monitoring tool capable of immediately detecting water contamination or
Research was conducted to address these challenges using analytical chemistry,
environmental engineering, food science, polymer chemistry, public health, and material science
principles. This work was enhanced by collaborations with sixteen American water utilities and
the National Institute for Standards and Technology. These efforts were funded by the National
Science Foundation, American Water Works Association, and the Water Research Foundation.
Research results are unique and provide important scientific contributions to the public
health, potable water, and material science industries. Particular achievements include the: (1)
Evaluation of linkages between minerals, water palatability, and health useful for water
production and public health decisions; (2) Creation of a novel infrastructure and water quality
surveillance tool that has begun water utility implementation in the USA; (3) Development of an
accelerated chlorinated water aging method with stable water pH, free chlorine, and alkalinity
concentration that enables interpretation of polymer pipe surface and bulk characteristic changes;
(4) Discovery that polar compounds are 2–193% more soluble in PEX than HDPE water pipes;
(5) Finding that several polymer and contaminant properties can be used to predict contaminant diffusivity and solubility during sorption and desorption in new, lab aged, and water utility PE
pipes; and the (6) Discovery that chlorinated water exposure of HDPE and PEX pipes increases
polar contaminant diffusivity during sorption by 50–162% and decreases diffusivity during
desorption as much as 211%. Outcomes of this work have domestic and global significance, and
if engaged, can greatly improve public health protection, potable water infrastructure operations,
water quality, sustainability, and regulation.
 Chemax, "Cross-Linked Polyethylene Tubing and Water Contamination", retrieved 2/17/2013, original source: http://www.chemaxx.com/polytube1.htm [copy on file as [Water Contamination chemical investigation.pdf]
 Ingun Skjevrak, Anne Due, Karl Olav Gjerstad, Hallgeir Herikstad "Volatile organic components migrating from plastic pipes (HDPE, PEX and PVC) into drinking water", Water Research Volume 37, Issue 8, April 2003, Pages 1912–1920
High-density polyethylene pipes (HDPE), crossbonded polyethylene pipes (PEX) and polyvinyl chloride (PVC) pipes for drinking water were tested with respect to migration of volatile organic components (VOC) to water. The odour of water in contact with plastic pipes was assessed according to the quantitative threshold odour number (TON) concept. A major migrating component from HDPE pipes was 2,4-di-tert-butyl-phenol (2,4-DTBP) which is a known degradation product from antioxidants such as Irgafos 168®. In addition, a range of esters, aldehydes, ketones, aromatic hydrocarbons and terpenoids were identified as migration products from HDPE pipes. Water in contact with HDPE pipes was assessed with respect to TON, and values ⩾4 were determined for five out of seven brands of HDPE pipes. The total amount of VOC released to water during three successive test periods were fairly constant for the HDPE pipes. Corresponding migration tests carried out for PEX pipes showed that VOC migrated in significant amounts into the test water, and TON ⩾5 of the test water were observed in all tests. Several of the migrated VOC were not identified. Oxygenates predominated the identified VOC in the test water from PEX pipes. Migration tests of PVC pipes revealed few volatile migrants in the test samples and no significant odour of the test water.
 Andrew J. Whelton, Ph.D., M.ASCE; Andrea M. Dietrich, Ph.D., Aff.ASCE; and Daniel L. Gallagher, Ph.D., P.E., M.ASCE, ”Contaminant Diffusion, Solubility, and Material Property Differences between HDPE and PEX Potable Water Pipes.” J. Environ. Eng., 136(2), 227–237.
Abstract: the objectives of this work were to identify differences between the composition, bulk properties, contaminant diffusivity and solubility for new high-density polyethylene (HDPE) pipe and crosslinked polyethylene (PEX) pipe, as well as determine which contaminant and polymer properties are useful for predicting contaminant fate in water pipe. Variations in PE pipe density (0.9371–0.9547 g/cm3) , crystallinity (69–72%), crosslinking (60 and 76%), and oxidative induction time (33 to >295 min .) were detected. While numerically these differences seem minor, results show that slight material differences have a notable effect on contaminant diffusivity and solubility. Nonpolar contaminant diffusivity and solubility were best predicted by bulk density. Polar contaminants were more soluble and diffused faster through PEX than HDPE pipes because PEX pipes contained a greater amount of oxygen. For all materials, dipole moment and Log Kow were good predictors of contaminant fate and molecular volume was only useful for predicting diffusivity and solubility values for haloalkane and nonpolar aromatic contaminants.
 Jia Tang, Daniel L. Gallagher, and Andrea M. Dietrich. (2013) Predicting Permeation of Organic Contaminants into Polyethylenes. Journal of Environmental Engineering 139:2, 205-212
Online publication date: 1-Feb-2013.
A model was developed and validated for predicting solubility and diffusion coefficients for contaminants permeating polyethylene (PE) materials used for water pipes and geomembranes. Model development was based on diffusivity and solubility of 13 contaminants and six PE materials that were new and/or aged in chlorinated water. Physical and chemical properties of the contaminants and PEs were included as variables in the model. Tree regression was used to select variables, and multiple linear regression was used to develop predictive equations for contaminant diffusivity and solubility in PE. Organic contaminant properties, especially dipole moment and octanol-water partition coefficient, had greater predictive capability than PE properties. Coefficients of determination (R2)>0.8 were obtained for the multiple linear regressions. Model coefficients changed slightly between new PE materials and chlorine-aged PE, but these changes were not statistically significant. Good agreement was demonstrated between model predictions and measured data from an independent data set. These results provide guidance for material selection for both water pipes and geomembranes and assessing contamination potential.
 Andrew J. Whelton, Andrea M. Dietrich, and Daniel L. Gallagher. (2011) Impact of Chlorinated Water Exposure on Contaminant Transport and Surface and Bulk Properties of High-Density Polyethylene and Cross-Linked Polyethylene Potable Water Pipes. Journal of Environmental Engineering 137:7, 559-568
Online publication date: 1-Jul-2011. Abstract:
The aim of this work was to determine if the aging of polyethylene (HDPE, PEX-A and PEX-B) water pipes by exposure to chlorinated water altered polar and nonpolar contaminant diffusivity and solubility by analyzing new, laboratory-aged, and exhumed water-distribution system polyethylene (PE) pipes. After 141 days of aging in pH 6.5 water with 45 mg/L free chlorine, the surface chemistry and bulk properties of PEX-A pipe were unaffected. Carbonyl bonds (σ=1,713 cm−1) were detected on the surfaces of HDPE and PEX-B pipe, and these oxygenated surfaces became more hydrophilic, resulting in statistically significant increases in diffusion rates. All 10 contaminant and four pipe material combinations had diffusivity increases on average of 50% for polar contaminants and 5% for nonpolar contaminants. Contaminant solubility was slightly increased for aged PEX-A and slightly decreased for PEX-B pipes. Toluene and trichloromethane diffusivity and solubility values for 7- to 25-year-old buried water utility pipes were similar to values for new and laboratory-aged HDPE-based materials. Because chlorinated water exposure alters how polar contaminants interact with aged PE pipes, results of this work should be considered in future health risk assessments, water quality modeling, pipe performance, and service-life considerations.
 ANDREW J. WHELTON & TINH NGUYEN, "Contaminant Migration from Polymeric Pipes used in Buried Potable Water Distribution Systems: A Review", Critical Reviews in Environmental Science and Technology, February 2012 posted online,
Abstract: Polymeric pipes are increasingly being installed in water distribution systems because of their many advantages. Contaminant migration from polymer pipes into drinking water is a growing concern in the United States and environmental engineers are evaluating the role of these materials on water quality, system operation, and regulatory compliance. To aid these efforts and serve as a source of background information, this paper critically reviews available literature on polymeric potable water pipes in use, known contaminants released from in–service and new piping, their perceived sources, and outlines future challenges in the U.S. and abroad.
 Andrew James Whelton, "Advancing Potable Water Infrastructure through an Improved Understanding of Polymer
Pipe Oxidation, Polymer–Contaminant Interactions, and Consumer Perception of Taste", Dissertation submitted to the Faculty of the
Virginia Polytechnic Institute and State University
In partial fulfillment of the requirements for the degree of
DOCTOR OF PHILOSOPHY
Civil Engineering, April 2, 2009
Blacksburg, Virginia, retrieved 2/17/2013, original source
http://scholar.lib.vt.edu/theses/ available/etd-04162009-113815/unrestricted/ FINALWheltonDissertationMay09.pdf#page=158
 Website: GreenBuildingAdvisor.com, "PEX vs Copper", retrieved 2/18/2013, original source: http://www.greenbuildingadvisor.com/ community/forum/green-products-and-materials/ 16256/pex-vs-copper [copy on file as PEX vs Copper _ GreenBuildingAdvisor.pdf]
 Website: GreenBuildingAdvisor.com," How Safe is PEX tubing?", retrieved 2/18/2013, original source: http://www.greenbuildingadvisor.com/ blogs/dept/qa-spotlight /how-safe-pex-tubing [copy on file as How Safe is PEX tubing_GreenBuildingAdvisor.pdf]
 Lauren Hunter, "California’s PEX Battle Continues", Remodeling Magazine, June 2010, Website: Builderonline.com, "x", retrieved 2/18/2013, original souirce: http://www.builderonline.com/legislation/californias-pex-battle-continues.aspx [copy on file as California’s PEX Battle Continues - Plumbing, Legal Issues, Legislation - Builder Magazine.pd]
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 Wikipedia provided background information about some topics discussed at this website provided this citation is also found in the same article along with a " retrieved on" date. NOTE: because Wikipedia entries are fluid and can be amended in real time, we cite the retrieval date of Wikipedia citations and we do not assert that the information found there is necessarily authoritative. Kitec web search retrieved 02/19/2013, original source: http://en.wikipedia.org/wiki/Kitec
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
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The ILLUSTRATED HOME illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The HOME REFERENCE BOOK - the ENCYCLOPEDIA of HOMES, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
The HORIZON SOFTWARE SYSTEM manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones