What is PE (as in
HDPE, MDPE, LDPE, LLDPE, etc.) and what are some of its uses?
Polyethylene
(PE) is a plastic material belonging to a group of polymers called polyolefins.
It is usually first categorized by its density as indicated in the abbreviations
e.g. HDPE (high density PE), MDPE (medium density PE), LDPE (low density PE) ,
LLDPE (linear low density PE). Depending on its specific grade and properties,
it is used in a wide range of plastic products from milk bottles and plastic
bags (lower end of properties and cost) to high performance plastic pipes (high
end of properties and cost).
What is used to make
PE or HDPE?
All polyethylenes are made from petroleum feedstocks also known as hydrocarbons.
Both the feedstocks (and raw materials) and polyethylene is composed of only
hydrogen and carbon (hydrocarbon).
What is a polymer?
A polymer by definition is poly (many) mer (parts). It is generally a very
simple molecule (mer) which is chemically combined (polymerized) many times
until it attains the final desired properties as a polymer.
What is a stabilizer (thermal vs. ultraviolet stabilizer)?
Stabilizers are added to polymers to enhance their ability to resist natural,
environmental, mechanisms which tend to shorten their useful lives. Antioxidants
retard oxidation ultraviolet stabilizers retard sunlight degradation, and
thermal stabilizers help buffer the degradation effects of high temperature
exposure.
What is TiO2?
TiO2, titanium dioxide is essentially an inert white pigment which whitens and
opacifies plastics.
What is carbon black?
Carbon black is a black pigment, which can also enhance mechanical properties as
well as act as an excellent UV stabilizer when properly compounded into a
plastic or rubber.
Are PE pipe and fittings safe for use in homes?
Yes, PE is safe for use in the home. As answered above it is a polymer composed
of only carbon and hydrogen atoms. PE is commonly used for food containers (milk
bottles, plastic food bags, etc.) when the plastic has received approval to NSF
International's standards health effects applications by a third party
certifying agency. Examples of such standards are NSF 14 and NSF 61.
What is ASTM?
ASTM (American Society for Testing & Materials) is an independent,
not-for-profit standards writing organization. It promulgates standards in many
diverse technical disciplines. ASTM is the forum for a majority of standards in
the USA, especially those related to plastic materials and products testing.
ASTM writes standards and conducts educational training seminars
(Specifications, Test Methods and Guides. ASTM does not conduct testing,
listing, certifying, or enforcement of its standards.
What is NSF?
NSF (NSF International) is an independent, private, not-for-profit, 3rd party
certification, testing, and standards writing organization. NSF is accredited by
ANSI, (the American National Standards Institute), RvA, (the Dutch Raad voor
Accreditatie), and SCC, (the Standards Council of Canada) for its testing,
standards writing, and certification programs. NSF writes consensus standards
for product, material, and system assessment. NSF provides an array of testing
services to many different industries. NSF provides the plumbing industry
services for items such as pipes, fittings, valves, pumps, water heaters, sinks,
showers, toilets, faucets, controllers, filters, materials, and ingredients. NSF
does conduct testing, listing, certifying, and enforcement of its standards.
What is PPI?
PPI (a.k.a. the Plastics Pipe Institute) is a trade organization whose members
include plastic manufacturing companies, plastic piping product manufacturing
companies, related equipment and chemical suppliers and educators and
consultants to the plastic pipe industry.
What is ASTM D 3350?
This is an ASTM Standard which provides a cell classification method for
classifying plastics. When classified under D 3350 the plastic material receives
an alphanumeric designation, which identifies its mechanical and chemical
properties. It is a shorthand method for describing a plastic material.
What is NSF Standard
14?
ANSI/NSF
Standard 14 Plastic Piping System Components and Related Materials is a
consensus standard promulgated by NSF International. This standard enables
comprehensive assessment of plumbing system products, materials, and ingredients
for health effects, quality control, quality assurance, marking, material
property requirements, long term strength evaluation via PPI TR-3, and short
term product performance to various standards such as ASME, ASTM, ASSE, etc.
What is NSF Standard 61?
ANSI/NSF Standard 61 Drinking Water System Components-Health Effects is a
consensus standard promulgated by NSF International. This standard enables in
depth assessment of a variety of drinking water system products and materials
for health effects. This standard is used to evaluate a product for health
effect concerns only.
What is PPI TR3?
(Plastic Pipe Institute's Technical Report 3) PPI TR3 is a standard published by
PPI which describes, in depth the testing, calculations and
theory
by which plastic materials are tested to determine their long term strength
properties primarily for pressure piping applications. These long-term strength
properties (up to 50 years or more) are published, by material, in PPI TR4,
which lists this property as an HDB or hydrostatic design basis. These HDBs are
then used by engineers in designing plastic piping products for excellent long
term service.
What
are temperature limitations for PEX?
PEX tubing can be used up to 200° Fahrenheit for heating applications. For
plumbing, PEX is limited to 180° F. Temperature limitations are always noted on
the print line of the PEX tubing. Recommended 140 max for safety and
conservation
How are
PEX systems tested for leaks?
PEX plumbing and radiant heating systems can be pressure tested using either
water or air to check for leaks. Follow manufacturer's instructions.
How
soon after installation can you pressure test a PEX tubing installation?
PEX plumbing systems can generally be tested immediately after the installation
is complete. There is no wait time for glue to dry or joint to cool off. Weather
should be considered and manufacturer's instructions followed in cold weather.
Where
is PEX available?
PEX is available through almost all plumbing wholesale distributors throughout
the United States and Canada. Many retail building supply outlets also supply
PEX piping and fittings. Piping and fittings are commonly available in 1/4"
through 1" CTS (Copper Tube Size) with some manufacturers also supplying larger
sizes up to 2." Because the wall-thickness is proportionate for each size, the
pressure ratings are the same for all sizes.
What
sizes, lengths and packaging options of PEX are available?
PEX is available in 1/4" through 1" CTS (Copper Tube Size) and is packaged in
coils or 20' straight lengths. Some manufacturers tubing is color-coded for easy
identification of hot and cold lines. Coil lengths generally run to a maximum of
1000' and are available in a variety of shorter lengths.
Is
flexible PEX plumbed differently than rigid material plumbing systems?
Yes. The flexibility of PEX allows many directional changes to be made without
fittings, but, PEX systems are sized in the same fashion as copper or CPVC
plumbing systems. PEX piping is also used in high performance manifold plumbing
systems that takes advantage of the flexibility and economical cost of PEX
tubing.
What
are manifold plumbing systems?
Manifold or home run plumbing systems are much like a breaker box for the
electrical system in the home. The manifold provides a common location from
which all the plumbing fixtures are supplied. Some high-end manifolds also
feature fixture shut-off valves allowing the user to shut off the water to
individual fixtures from one location. Others are semi-home run manifolds or
termination manifolds, which may feed the plumbing requirements for a room or
set of rooms and reduce the number of fittings required in the plumbing system.
How are
PEX systems sized?
PEX systems are be sized just like other plumbing materials such as copper or
CPVC when used in a branch-and-main installation. To take advantage of utility
savings and system performance issues of branch-and-main systems, PEX can be
sized in manifold systems to meet the specific demands of each fixture, reducing
water and energy waste in the home.
Is the thermal expansion/contraction of PEX a problem?
No. While PEX expands more than other plumbing materials, directional changes
made with the tubing and some slack in the tubing during installation
accommodate the expansion and contraction of the system if properly installed.
Is PEX freeze-break resistant?
PEX piping is freeze damage resistant and can expand and contract as water
freezes and thaws within the tubing. No tubing material is freeze-break proof,
however, and PEX should be installed using the same locally-prescribed
insulation requirements to prevent freezing of any plumbing system.
How do
I thaw PEX lines?
When water freezes inside PEX tubing, it can be thawed using a hair dryer, warm
wet rags or heat tape, taking care not to overheat the tubing beyond it's
maximum recommended temperature.
Can PEX
be joined with solvent cement?
No. PEX cannot be joined with solvent cement, or heat fusion. PEX is installed
using only mechanical fittings either inserted in or around the tubing or by
compression fittings.
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