User Guide

88 l uponorengineering.com
Painting Uponor
AquaPEX
It is acceptable to use latex
and acrylic-based paint, such
as 100 percent acrylic exterior
latex house paint, with Uponor
AquaPEX. These products
will not harm the molecular
structure or integrity of the
PEX piping.
Termiticides/pesticides
Liquid termiticides/pesticides
are often applied to treat the
soil below the concrete slabs
of slab-on-grade structures.
The treatment creates a
barrier to prevent termites and
pests from inltrating the oor
of the structure. PEX piping for
plumbing applications is often
installed within slabs or below
slabs (in trenches in the soil)
below the soil that is treated.
Liquid termiticides/pesticides
use a liquid solvent to carry
the active ingredients. These
solvents can be categorized
as one of two types: organic
solvent-based (also known
as petroleum solvent-based)
and water-based (water
solvent-based).
The type of solvent used in
a termiticide/pesticide will
affect its ability to permeate
through various materials.
Organic-based termiticides/
pesticides have largely
disappeared from the North
American marketplace for this
application, and the majority
of products available today
are water-based. Water-based
products are generally safer
for the environment and pose
less risk of inltration into PEX
piping.
Available data indicates
the solvents used in liquid
termiticides/pesticides will
soak into the ground and/
or evaporate before they
can pass through the wall
of polyethylene piping. The
data also indicates these
solvents are prevented from
passing through the wall of
polyethylene piping because
of the large size of the water-
or organic-solvent molecules,
relative to the size of the
molecules in the piping itself.
Once liquid solvents have
dissipated or evaporated,
the solids that remain behind
cannot permeate through
the walls of polyethylene or
PEX piping because of the
molecular size.
Additional research shows
that water-based termiticides/
pesticides are of sufciently
large molecular size to
completely prevent permeation
through polyethylene and
PEX piping. Instances of
water-based termiticides/
pesticides permeating through
polyethylene or PEX piping
are not known. Pesticides
have not been found to be
corrosive or have polymer
degradation.
Although all research data
and anecdotal evidence
strongly suggest there are
no permeation issues with
water-based termiticides/
pesticides and PEX, take
extra caution to ensure safe
installation of PEX piping and
to prevent misapplication or
pooling/puddling of the liquid
termiticides/pesticides around
PEX piping.
Supporting research
A study done in 2001 in
Australia, titled “Investigating
the Possible Permeation
of Organic Chemicals
Commonly Used in Termiticide
Barrier Treatments through
Polyethylene Water Pipes,”
indicated that “migration of
pesticide constituents and
their associated solvents,
through the polyethylene pipe,
did not occur, indicating that
the concentration of solvents
(even in the saturated soil)
was not high enough to cause
permeation of the solvents
through the polyethylene
pipe wall (within the 16-week
period of study).” The study
also stated “this indicates that
the concentration of these
constituents in the soil in
contact with the pipes was
not high enough to develop
a positive diffusion pressure
and cause the constituents
to be detected in the water.”
The study was conducted
using organic solvent-based
pesticides, which are known
to be more aggressive than
water-based pesticides.
Therefore, the results are valid
for organic solvent-based
pesticides and water-based
pesticides.
Research conducted by
Dr. Michael R. Hoffman of
the California Institute of
Technology (2005) indicates
that the ability of a chemical
compound to permeate
a material is correlated
directly with the octanol-
water partition coefcients
of the individual organic
chemicals. The octanol-
water partition coefcient
is a relative measure of the
hydrophobic nature of the
organic compounds. In spite
of a measurable tendency to
partition into plastic material,
the ability of these compounds
is retarded substantially given
the low measured diffusion
coefcients for selected
chemicals. For example, a
PEX piping wall thickness of
5mm and a typical diffusion
coefcient for organic
compound migration of 1.0
x 10-12 cm2/s, the time to
permeate through the walls,
would be 2.5 x 1,011 seconds
or approximately 8,000 years.
If the wall thickness was
reduced to 2mm, then the
time to permeate completely
through the pipe wall would be
reduced to 1,300 years.
Note: Crosslinked
polyethylene (PEX) piping is
assumed to behave similarly
to polyethylene water piping.