VESDA
®
Refrigerated Storage Design Guide
3.1 Sample
Pipe
Material
The choice of pipe material will depend on where the pipe is to be located. For instance, installation
of ceiling mounted pipes can be made easier by using long lengths of pipe material suited to coping
with low temperatures and internal temperature fluctuations. Such materials include the Halogen-
free Fire-retardant high Temperature (HFT) plastics, Acrylonitrile Butadiene Styrene (ABS) and
High Density Polyethylene (HDPE). Suitable materials and their properties are presented in Table 3
below.
Table 3 – Properties and recommended applications for pipe materials
[11-14]
.
Material
Operating Temperature
Thermal Contraction
Recommended
Applications
PVC
-18°C (-40 to 120°F)
7.0 mm per 10 m per 10°C
(0.28” per 32.8 ft per 18°F)
Above -18°C (0°F)
HFT
-40 to 140°C
(-40 to 284°F)
7.0 mm per 10 m per 10°C
(0.28” per 32.8 ft per 18°F)
Above –40°C (-40°F)
ABS
-40 to 80°C
(-40 to 176°F)
10.1 mm per 10 m per 10°C
(0.4” per 32.8 ft per 18°F)
Above –40°C (-40°F)
CPVC
-18 to 94°C
(0 to 201°F)
6.7 mm per 10 m per 10°C
(0.26” per 32.8 ft per 18°F)
Above -20°C (0°F)
PE-80
-50 to 60°C
(-58 to 140°F)
20 mm per 10 m per 10°C
(0.79” per 32.8 ft per 18°C)
Above –50°C (-58°F)
PE-100
-50 to 60°C
(-58 to 140°F)
13 mm per 10 m per 10°C
(0.52” per 32.8 ft per 18°F)
Above –50°C (-58°F)
An added advantage of using a continuous semi-flexible pipe material such as HDPE
[14]
is the
reduction in the number of pipe junctions required.
3.2
Positioning Pipes And Sample Holes
The various international codes and standards specify detection point spacing or maximum area of
coverage per detection point for a variety of different airflow rates, ceiling heights and structures
etc. In compliance with these prescriptive regulations, VESDA sample holes would be located in
the same positions as individual smoke detection devices. Alternatively, with reference to local
codes, the pipe and sample hole configuration can be determined by satisfying performance-based
design requirements.
Note:
For Factory Mutual (FM) approved, refrigerated storage, VESDA installations the sample
holes should be placed as for heat detectors as outlined in the latest edition of the FM 8-29
Datasheet and Memorandum 0805
[1, 15]
.
Sample hole locations are usually represented by a grid like that shown below (Figure 1). The letter
X represents the sample hole spacing required according to local codes and standards.
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