How to Guide

118
Plastics Technical Manual
SUPPLEMENTAL INFORMATION
R-Values and Thermal Conduc-
tivity
Thermal Conductivity
R-Value is a measure of the thermal resistance of a material.
Thermal resistance is an index of a material’s resistance to
the flow of heat. K-Value is a measure of a material’s thermal
conductivity measured in BTU’s and is the reciprocal of the
R-Value. The thermal resistances for PVC and CPVC remain
constant as C-Values. They are as follows:
PVC Thermal Conductivity C = 1.2 BTU in/Hr Sq Ft °F
CPVC Thermal Conductivity C = .96 BTU in/Hr Sq Ft °F
R-Value can be viewed as an equation when calculating for
various thickness of pipe.
R = Pipe Wall Thickness divided by C
The table below represents the R-Values for PVC Schedule 40
& 80 and CPVC CTS FlowGuard Gold.
Note: Always follow local code requirements for insulation
installation. Some code jurisdictions require insulation to be
installed in accordance with the International Energy Con-
servation Code.
Condensation and Sweating
Due to its low coefficient of thermal conductivity, it is often not
necessary to insulate FlowGuard Gold CPVC against condensa-
tion within conditioned buildings. Two conditions that control
sweating of a pipe are (1) the pipe surface temperature, which
depends on the temperature of the water inside the pipe and
(2) the relative humidity of the air around the pipe. Because
each of the factors can vary greatly, it is possible that condi-
tions exist that can cause CPVC pipe to sweat. Under most
conditions that cause copper pipe to sweat and drip, FlowGuard
Gold pipe will remain free of condensation.
1
⁄4” 0.119 0.099
3
⁄8” 0.126 0.105
1
⁄2” 0.109 0.091 0.147 0.123 0.068 0.071
3
⁄4” 0.113 0.094 0.154 0.128 0.080 0.083
1” 0.133 0.111 0.179 0.149 0.102 0.106
1
1
⁄4” 0.140 0.117 0.191 0.159 0.125 0.130
1
1
⁄2” 0.145 0.121 0.200 0.167 0.148 0.154
2” 0.154 0.128 0.218 0.182 0.193 0.201
2
1
⁄2” 0.203 0.169 0.276 0.230
3” 0.216 0.180 0.300 0.250
4” 0.237 0.198 0.337 0.281
5” 0.258 0.215 0.375 0.313
6” 0.280 0.233 0.432 0.360
8” 0.322 0.268 0.500 0.417
10” 0.365 0.304 0.593 0.494
12” 0.406 0.338 0.687 0.573
14” 0.437 0.364 0.750 0.625
16” 0.500 0.417 0.843 0.703
SDR 11 CTS
Wall
Thickness
PVC
Schedule 80
R-Value
Schedule 80
Wall
Thickness
PVC
Schedule 40
R-Value
Schedule 40
Wall
Thickness
Nominal
Pipe
Size
CPVC
SDR 11
R-Value