I’d argue that the EOR, designer, and installer should be aware of and account
for this possibility. CPVC manufacturers do provide this information. For
instance, Harvel Plastics, Inc. HFS-3 CPVC Fire Sprinkler Piping Products
Installation Instructions dated 1/1/09, provides the following direction:
* Thermal Expansion: HARVEL® CPVC Fire Sprinkler Products, like all piping
materials, expand and contract with changes in temperature. The coefficient of
linear expansion is 0.000034 inch/inch °F. A 25°F change in temperature will
cause an expansion of 1/2 inch for a 50 foot straight length. For most
operating and installation conditions, the effects of thermal expansion and
contraction are usually absorbed by the system at changes in direction in the
piping. However, long straight runs of piping are more susceptible to
experiencing measurable movement with changes in temperature (i.e. pipe
installed in unheated building during the winter, then brought under heat as
construction progresses). The installation of expansion loops, off-sets, or
bends is required on long straight runs to compensate for this movement. This
will allow the piping system to absorb forces generated by
expansion/contraction without damage. For Additional Thermal Expansion
information, please refer to Tables III and IV in the Reference Tables section.
* It has the following to say regarding Trenching Snaking of Pipe: After
CPVC pipe has been solvent welded, it is advisable to snake the pipe according
to the following recommendations beside the trench during its required drying
time. BE ESPECIALLY CAREFUL NOT TO APPLY ANY STRESS THAT WILL DISTURB THE
UNDRIED JOINT. This snaking is necessary in order to allow for any anticipated
thermal contraction that will take place in the newly joined pipeline.
Snaking is particularly necessary on the lengths that have been solvent welded
during the late afternoon or a hot summer’s day, because their drying time will
extend through the cool of the night when thermal contraction of the pipe could
stress the joints to the point of pull out. This snaking is also especially
necessary with pipe that is laid in its trench (necessitating wider trenches
than recommended) and is backfilled with cool earth before the joints are
thoroughly dry.
(There is a loop offset per temperature variation table given in this section
which provides the needed for 20, 50, and 100 ft for temp deltas of 10° though
100°F in 10° increments. The snaking concept can be used above grade to
accommodate anticipated thermal expansion/contraction once the system’s ambient
environment becomes controlled and the corresponding temperature delta that
exists between the two.)
* Other Design Criteria: CAUTION When drilling holes in solid wood joists
and in studs (wood or metal) to route the pipe the structural integrity must be
maintained. Consult the Authority Having
Jurisdiction (AHJ) or building code for requirements. When routing pipe
through metal studs, holes drilled must be oversized to allow for movement
caused by expansion and contraction.
* Reference Tables Section:
* Provides the following to determine change in length of due to thermal
expansion or contraction and includes an example calculation:
The change in length caused by thermal expansion or contraction can be
calculated as follows:
∆L = 12 eL (∆T)
e = 3.4 x 10-5 in./in. °F (Coefficient of Linear Expansion – Table II.)
L = Length of Run in Feet
∆T = Temperature Change in °F (difference between lowest system temperature and
maximum system temperature – whichever is greatest.
* Tables III provides thermal expansion in inches
* Table IV provides expansion loop length in inches
In short, it is my believe that proper review of and attention to the
manufacturer’s installation instructions prior to installation will provide you
with the information necessary to install a system properly even when the
installation temperature is significantly different than that of the finished
product and that knowledgeable contractors can design the system so locations
which should not move (sprinklers) – remain stationary in the temperature
changes while the system is still allowed the necessary flexibility to expand
or contract without exceeding manufacturers’ limitations.
I would think that if one looks hard enough, one will find that all CPVC
manufacturers provide similar guidance.
Hope this helps,
Ryan L. Hinson, PE*, SET** \ Burns & McDonnell
Senior Fire Protection Engineer
O 952-656-3662 \ M 320-250-5404 \ F 952-229-2923
[email protected] \ burnsmcd.com<http://www.burnsmcd.com/>
8201 Norman Center Drive, Suite 300 \ Bloomington, MN 55437
*Registered in: MD, MN, PA, & TX
**NICET IV - Water-Based Systems Layout
From: Sprinklerforum [mailto:[email protected]] On
Behalf Of Ed Kramer
Sent: Friday, June 09, 2017 1:18 PM
To: [email protected]
Subject: RE: CPVC Piping
I’ll throw in a twist – for those of us who live in either cold or hot
climates. Had a CPVC system installed during the winter prior to the structure
being heated (long cure time). After the heat was turned on, many of the
recessed pendents shifted. I never visited the project, but I’m guessing there
was significant stress put on the pipe at hangers, offsets, etc. Similar thing
could happen if installed in really hot weather.
Ed Kramer
Bamford Fire Sprinkler
From: Sprinklerforum [mailto:[email protected]] On
Behalf Of Mike Stossel
Sent: Friday, June 09, 2017 12:52 PM
To:
[email protected]<mailto:[email protected]>
Subject: RE: CPVC Piping
I totally agree with you on all the points you made. The space is conditioned
so the thermal expansion would be almost none existent. I could not find
anything establishing an allowable limit, is it merely up to the installer to
decide what the allowable expansion is?
Mike Stossel SET
[400dpiLogoCropped]
36 Barren Road
East Stroudsburg, PA 18302
Office: 973-670-2627
[email protected]<mailto:[email protected]>
From: Sprinklerforum [mailto:[email protected]] On
Behalf Of Hinson, Ryan
Sent: Friday, June 9, 2017 1:43 PM
To:
[email protected]<mailto:[email protected]>
Subject: RE: CPVC Piping
What is your expected temperature delta? Since CPVC is installed in heated
spaces, is there going to be that significant of a change in temperature?
Where is the water supply coming from? In a conditioned space, CPVC piping
system with no flow is going to have negligible thermal expansion IMO.
Ryan L. Hinson, PE*, SET** \ Burns & McDonnell
Senior Fire Protection Engineer
O 952-656-3662 \ M 320-250-5404 \ F 952-229-2923
[email protected]<mailto:[email protected]> \
burnsmcd.com<http://www.burnsmcd.com/>
8201 Norman Center Drive, Suite 300 \ Bloomington, MN 55437
*Registered in: MD, MN, PA, & TX
**NICET IV - Water-Based Systems Layout
From: Sprinklerforum [mailto:[email protected]] On
Behalf Of Mike Stossel
Sent: Friday, June 09, 2017 11:57 AM
To:
[email protected]<mailto:[email protected]>
Subject: CPVC Piping
I just recently had the question asked of me of, when do you need to install a
thermal expansion loop in CPVC piping? I searched all of the manufacturers
that I could think of and they all appear to say basically the same thing, in
long straight runs of pipe. No one specifically defines what that length would
be and likewise I could not find an allowable expansion amount. For instance
an expansion of ½” or 1” is acceptable or at 1” expansion you will need one.
I can understand not defining a specific length of run since each geographic
area has different temperature changes which would affect the expansion, but I
would have thought that they would define an expansion threshold. Any guidance
that can be given would be greatly appreciated.
Best regards,
Mike Stossel SET
[400dpiLogoCropped]
36 Barren Road
East Stroudsburg, PA 18302
Office: 973-670-2627
[email protected]<mailto:[email protected]>
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