Modern Plumbing, 7th Edition Page 368 (368 of 641)

Some manufacturers use fittings that are
installed by first expanding the end of the tube
with a special tool. The fitting is inserted and
the PEX contracts around the fitting. The crimp
ring is installed in the same way as shown in
Figure 20-25.
Supporting PEX
It is recommended that horizontal runs of
PEX be supported every 32″. Vertical runs
should be secured at least every 5 feet. Local
code may include more stringent support
requirements.
Chapter 20 Installing Water Supply Piping
367
Figure 20-25. Care must be taken when installing PEX fittings. (NIBCO Inc.)
1. Cut tubing square and remove burrs. 2. Slide crimp ring on tube.
3. Insert fitting into tubing all the way to the
shoulder. Position crimp ring 1⁄8″ to 1⁄4″
from end of tubing.
4. Position jaws squarely over the crimp
ring. Crimp the ring by completely closing
the jaws of the crimping tool firmly. Check
the crimp ring with the gauge.

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Some manufacturers use fittings that are
installed by first expanding the end of the tube
with a special tool. The fitting is inserted and
the PEX contracts around the fitting. The crimp
ring is installed in the same way as shown in
Figure 20-25.
Supporting PEX
It is recommended that horizontal runs of
PEX be supported every 32″. Vertical runs
should be secured at least every 5 feet. Local
code may include more stringent support
requirements.
Chapter 20 Installing Water Supply Piping
367
Figure 20-25. Care must be taken when installing PEX fittings. (NIBCO Inc.)
1. Cut tubing square and remove burrs. 2. Slide crimp ring on tube.
3. Insert fitting into tubing all the way to the
shoulder. Position crimp ring 1⁄8″ to 1⁄4″
from end of tubing.
4. Position jaws squarely over the crimp
ring. Crimp the ring by completely closing
the jaws of the crimping tool firmly. Check
the crimp ring with the gauge.

Help

Test Your Knowledge
Write your answers on a separate sheet of paper.
Do not write in this book.
1. Installation of all piping within the walls,
floors, and ceilings of a finished building is
called _____.
A. first rough
B. fixture installation
C. rough-in
D. second rough
2. When measuring to determine the length of
pipe required to connect two fittings, the
method that requires an allowance be made
for laying length is _____.
A. center-to-center
B. face-to-face
C. shoulder-to-shoulder
D. None of the above.
3. Water hammer arrestors should be installed
near the stub-out for fixtures or appliances
with _____ valves.
A. ball
B. gate
C. compression
D. quick-closing
4. If the outlet of a T/P relief valve is nomi-
nally 3⁄4″, the discharge pipe joined to it
must be _____.
A. 3⁄4″
B. 1″
C. 1⁄2″
D. 1⁄8″
5. When facing the location of a fixture, the
hot water pipe should be installed _____ the
cold water pipe.
A. to the left of
B. to the right of
C. above
D. below
6. If the face-to-face distance between a 3⁄4″
CPVC tee and a 3⁄4″ elbow is 18″, what
length of 3⁄4″ CPVC pipe is required to prop-
erly connect the two fittings?
A. 19″
B. 191⁄8″
C. 191⁄4″
D. 191⁄2″
7. The first step in the process of joining
plastic pipe is to _____ the pipe and fitting.
A. clean
B. apply solvent cement to
C. caulk
D. apply joint tape to
8. When making cemented connections in
plastic piping, what practice ensures even
distribution of the solvent cement?
A. Cleaning the inside of the fitting.
B. Twisting the fitting 1⁄4 turn as it is
installed.
C. Applying a thick coating of cement on
the inside of the joint.
D. Applying a thick coating of cement on
the end of the pipe.
9. The plumber can be assured that a
cemented plastic pipe joint is correctly
made if a(n)___ of cement forms completely
around the fitting.
10. If the face-to-face distance between a 1⁄2″
copper ell and a 1⁄2″ copper tee is 61⁄2″, the
length of the connecting copper pipe is
_____.
A. 61⁄2″
B. 7″
C. 71⁄4″
D. 71⁄2″
11. The minimum recommended bend radius
in PEX is _____ times the outside diameter
of the tube.
A. 18
B. 4
C. 10
D. 8
12. Horizontal runs of PEX should be
supported every _____ inches.
A. 16
B. 24
C. 32
D. 48
368
Section 3 Plumbing System Design and Installation

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and work backward along the run to establish
bends and secure the tube to the frame of the
building. When at the point where the next
fitting is to be installed, cut the tube and install
the fitting. This greatly reduces the need to use
a rule.
Making Bends in PEX
A major concern when bending PEX is how
small of a radius it can bend without causing
the inside of the tube to begin closing. The rule
of thumb is that the bend should not be smaller
than 8 times the actual outside diameter of the
tube, Figure 20-23.
Special bend supports, Figure 20-24, are
available to hold the tube in the correct radius
bend. The bend support also eliminates much
of the pressure that would otherwise be placed
on the fitting by the tube’s natural tendency to
straighten. If a smaller radius bend is required,
an ell must be installed. Larger radius bends
can be secured with straps near each end of
the bend.
Cutting and Joining PEX
1. Cut the PEX tube to the desired length. A
tube cutter makes achieving a square cut on
PEX tube very easy. See Figure 20-25.
2. Once the tube is cut, a crimp ring is slipped
onto the tube.
3. Insert the fitting inside the tube
4. Use the crimping tool to secure the crimp
ring.
5. Check every crimp ring with a crimp gauge to
determine if it has been sufficiently crimped.
If the gauge will not slip over the ring, the ring
and fitting must be removed and new ones
installed. Recrimping does not work.
366
Section 3 Plumbing System Design and Installation
PEX was developed in the late 1950s by
scientists working on the molecular structure
of polyvinyl chloride to produce a more heat
resistant product. Three different manufactur-
ing processes have been developed for PEX.
All three produce materials that are approved
for plumbing.
History Brief
Figure 20-23. Bends in PEX tube should not be smaller
than shown in this table.
Bend radius
Tube Size Bend Radius
1⁄2 5″
3⁄4 7″
1 9″
Figure 20-24. Bend supports maintain the correct
bend radius and relieve stress on fittings.

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Page 16Section 1 Introduction to Plumbing click to expand contents

Page 168Section 2 Plumbing Systems click to expand contents

Page 272Section 3 Plumbing System Design and Installation click to expand contents

Page 465Section 4 Plumbing Services click to expand contents

Page 523Section 5 Career Development and Plumbing History click to expand contents

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