10
Minimum detection levels
see Table 1
The nozzle when fitted provides automatic 10-fold dilution of the gas stream entering the Gas Check
TCD, except when the ppm display is selected. The Gas Check nozzle should always be removed for
assessing gas concentration levels in volume spaces smaller than about 1 litre when you are using
the ppm display.
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
0
Positive
1.5x 10
-5
ml/sec
He
0
Positive
2.0 x 10
-5
ml/sec
R12
1
Negative
5.4 x 10
-5
ml/sec
R1301
1
Positive
4.9 x 10
-5
ml/sec
R134a
1
Negative
2.1 x 10
-4
ml/sec
R22
1
Negative
5.1 x 10
-5
ml/sec
SF
6
1
Negative
4.4 x 10
-5
ml/sec
CO
2
2
Negative
8.0 x 10
-5
ml/sec
CH
4
2
Positive
5.8 x 10
-5
ml/sec
Ar
2
Negative
7.0 x 10
-5
ml/sec
R11
3
Positive
6.3 x 10
-5
ml/sec
O
2
4
Positive
5.7 x 10
-4
ml/sec
