VESDA VFT-15 Product Guide
VESDA by Xtralis
18
www.xtralis.com
3.3
Air Sampling Network
The VESDA VFT detector uses Microbore tubing to provide air sampling points.
For reliable smoke detection and flow monitoring performance, the detector must be connected to a balanced
network comprised of between 1 and 15 equal length tubes. Two types of Microbore tube can be used, as
listed below in Table 3-7. Normal diameter tubes are used in the default configuration detailed in Section 3.3.1,
while a combination of normal and reduced diameter tubes can be used in the alternate configurations detailed
in Section 3.3.2.
Microbore Tube
Outer Diameter
Inner Diameter
Normal diameter
6 mm (0.25 in)
4 mm (0.17 in)
Reduced diameter
4 mm (0.17 in)
2.5 mm (0.096 in)
Table 3-7: Microbore Tube Properties
Caution:
Do not insert ANY object into the inlet ports other than the normal diameter tube. This is to avoid
damage to delicate electronic flow sensor components mounted just inside each port opening.
Attention :
N'insérez PAS d'objets dans les orifices d'entrée autres que le tube de diamètre normal afin de
ne pas endommager les composants, fragiles, du capteur de débit électronique montés juste à
l'intérieur de chaque ouverture.
Ensure that Microbore tubes are never glued to the inlets of the detector.
Note:
For more details refer to the VESDA Pipe Installation Guide or Appendix B.
3.3.1
Default Microbore Tube Configuration
The default configuration requires between 1 and 15 normal diameter Microbore tubes, each 50 meters (164
feet) in length. It is recommended that excess tubing be coiled close to the sampling point end.
10.0
PROGRAM
0.01
0.1
1.0
4.0
SCAN
ISOLATE
F1 . . . Fn
SOUNDER
SILENCE
ACCEPT
CODE REQUIRED
20.0
000 .. . 999
STOP
TEST
MENU
RESET
?
000
FIRE 1
ALERT
ACTION
FIRE 2
FAULT
ALARM
SECTOR
1
3
2
4
5
6
8
10
9
7
ALL
12
15
13
14
11
B
A
Legend
A
Detector
B
Normal diameter Microbore tube with
excess coiled close to the sampling
point end.
Total length: 50 m (164 ft)
Figure 3-5: Default configuration with coiled normal diameter Microbore tube
Unused inputs on the detector should be looped to one another using short lengths of normal diameter
Microbore tube. For example, if the VFT-15 detector has unused inputs 9 to 15, one way of connecting the
unused inputs would be to use short pieces of microbore to connect inputs 9 to 12, 10 to 13, 11 to 14 and have
input 15 capped off.
3.3.2
Alternate Microbore Tube Configurations
A set of alternate Microbore tube configurations is provided below to reduce or eliminate coiling of excess
tubing while maintaining a balanced network for reliable and consistent detector performance.
These tube configurations use a shorter length normal diameter Microbore tube connected to reduced
diameter Microbore tube using a reducer connector, as shown in Figure 3-6. These configurations have shorter
overall length but impose the same airflow impedance as the default configuration that uses 50 m (164 ft)
length tubes.
