Industrial Scientific Ventis 17154524-1, Полевой руководство

Страница: 7 / 17

3
Guidelines for using a motorized pump and sampling line
When sampling with a motorized pump and sampling line, Industrial Scientific recommends the following:
•
Choose the tubing type based on the target gases. If the target gases are known, use Teflon-lined
tubing when sampling for these gases: chlorine (Cl
2
), chlorine dioxide (ClO
2
), hydrogen chloride (HCl),
and volatile organic compounds (VOCs). For other known target gases, urethane tubing or Teflon-
lined tubing may be used.
When the target gases are unknown, use Teflon-lined tubing.
•
Know the length of the sample line as it is a factor in determining sampling time. A sample line may
consist of tubing, a probe, or a probe and tubing. It should also have a dust filter–water stop installed
at the line's end that will extend into the sample area. Sample-line length is defined as the distance
from the dust filter–water stop opening to the point where the line connects to the pump's inlet. Ensure
sample-line length does not exceed the pump's maximum draw.
• Before and after each air sample, perform a test of the full sampling line.
o
Use a thumb to block the end of the sampling line at the water-stop opening. This should
cause a pump-fault alarm.
o
Remove the thumb from the water-stop opening. After the alarm cycle completes, the pump
should resume normal operation.
Note: If a pump fault does not occur, check and correct for cracks or other damage, debris, and proper installation in
these areas: the sampling line and its connections, the pump's inlet cap and inlet barrel, and the dust filter-water stop
items at the end of the sampling line and inside the pump inlet barrel.
•
Based on sample-line length, calculate the minimum time recommended for the air sample to reach
the instrument's sensors. As shown in Table 3, use a base time of 2 minutes, and add 2 seconds for
each 30 cm (1 ') of line length. Watch the display screen for gas readings and, if present, allow them
to stabilize to determine the reading.
Table 1.3 Minimum sample time for common sample-line lengths
Sample-line
length
Base time
(minutes)
+ Sample-line-length
factor
= Minimum sample time
(mm:ss)
3.05 m (10 ') 2 min
+
(10 ' x 2 s) = 02:20
6.10 m (20 ') 2 min
+
(20 ' x 2 s) = 02:40
9.14 m (30 ') 2 min
+
(30 ' x 2 s) = 03:00
12.10 m (40 ') 2 min
+
(40 ' x 2 s) = 03:20
15.24 m (50 ') 2 min
+
(50 ' x 2 s) = 03:40
18.29 m (60 ') 2 min
+
(60 ' x 2 s) = 04:00
21.34 m (70 ') 2 min
+
(70 ' x 2 s) = 04:20
24.38 m (80 ') 2 min
+
(80 ' x 2 s) = 04:40
27.43 m (90 ') 2 min
+
(90 ' x 2 s) = 05:00
30.48 m (100 ') 2 min
+
(100 ' x 2 s) = 05:20