Ion Science GasCheck IS - Manual (Page 10)

GASCHECK 3000 & 3000IS MANUAL Ion Science Ltd
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Technical data
Performance
Detector type:
Dual micro-volume thermal conductivity cell
Gases Detected:
All gases and vapours having a different thermal conductivity to the ambient air on which it was zeroed. The
larger the difference the greater the sensitivity, so that GasCheck is not highly sensitive to the gases
normally found in large concentrations in the ambient air, e.g. N2 (nitrogen) and O2 (oxygen).
For ease of use the GasCheck groups gases having similar thermal conductivity into one of the 5 gas groups
shown in Table 1. Each group has a calibration curve stored in memory. Although the GasCheck will detect
ALL gases with a different thermal conductivity to air, Table 1 lists those 12 common tracer gases that have
been tested and assigned gas groups. If the gas or gas mixture that you seek is not included in these
groups, select group 0 (which is the most sensitive). The Gas Check will then still find leaks quickly even
though the measured values will not be displayed accurately.
Some gases give a negative response, among them argon (Ar) carbon dioxide (CO
2
) and R134a.
Minimum response time:
Short probe fitted Less than 1 second
Long probe fitted About 9 seconds
Recovery time
About 1 second
Maximum detection level with the
short probe and nozzle fitted
20 ml/sec
The nozzle when fitted provides automatic 10-fold dilution of the gas stream entering the detector cell.
Smallest leak detection levels: see Table 1
(below)
Note1: the minimum detection levels given in Table 1 apply when the Gas Check is used in clean laboratory
air conditions. When used in conditions where the ambient atmosphere contains clouds of the gas for which
you leak test, the minimum detection levels may be obscured.
Note2: An offset of up to 10 times the detection levels given in Table 1 may be experienced in the presence
of electromagnetic interference @ 320 +- 30 MHz at the levels specified in EN 50082-1.
Table 1- Smallest Leak Detection Levels
Gas
Gas Group
Positive/Negative
Smallest Leak Detection Level in ml/sec
H
2
1.5 x 10 -5 ml/sec
He 2.0 x 10 -5 ml/sec
R12 5.4 x 10 -5 ml/sec
R1301 4.9 x 10 -5 ml/sec
R134a 2.1 x 10 -4 ml/sec
R22 5.1 x 10 -5 ml/sec
SF
6
4.4 x 10 -5 ml/sec
CO
2
8.0 x 10 -5 ml/sec
CH
4
5.8 x 10 -5 ml/sec
Ar 7.0 x 10
-5
ml/sec
R11 6.3 x 10 -5 ml/sec
O
2
5.7 x 10
-4
ml/sec