VESDA
®
Refrigerated Storage Design Guide
7.
Appendix – Heat Tracing
There are several techniques for warming sampled air including water heaters, electrically heated
tape and passing the pipe through an area that has been heated to 5-10
°
C (41-50
°
F). Electrically
heated tape is preferred as it is easy to install. An example of a pipe covered with heat tape is
shown below (Figure 17). If the surface temperature is over 30
°
C (86
°
F), the pipe must be
insulated.
Figure 17 – Example of heat tracing
with heat tape.
Raychem heat tape 5BTV2-CT or 3BTV1-CR can be used.
The following charts provide estimates of copper pipe and heat tape lengths required for heat
tracing. Variations in ambient temperature are assumed to be negligible due to pipe insulation. The
surface of the pipe is kept at a temperature of 35°C (95°F) and the tape is wound around it at 100
mm (4”) intervals along its length.
0
0.5
1
1.5
2
-40 / -40
-30 / -22
-20 / -4
-10 / 14
0 / 32
10 / 50
Sampled Air Temperature (deg C / F)
Cu Pipe Length (m
)
0
2
4
6
Cu Pipe Length (ft
)
20 l/min
30 l/min
40 l/min
Figure 18 – Estimates of copper pipe length for heat tape.
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