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Instruction Manual
5 Using the gauge with different gases
The measurement value is gas dependent. The pressure reading applies to dry air, O
gases, the measurements have to be corrected.
Indication range below 1.0 x 10
-5
In the range below 10
determined by means of the following conversion formula:
where: Gas type
K
Air (N
, O
, CO)
1.0
2
2
Xe
0.4
Kr
0.5
Ar
0.8
H
2.4
2
Ne
4.1
He
5.9
These conversion factors are average values.
Example: If the gas in use is argon (Ar) and the CCM502 indicates a measured pressure of 7.6 x 10
-6
p
0.8 X 7.60 X 10
= 6 X 10
eff =
A mixture of gases and vapors is often involved. In this case, accurate determination is only possible with a
partial pressure measurement instrument, e.g. a quadrupole mass spectrometer.
InstruTech
Indicated pressure (gauge calibrated for air)
p [Torr]
4
2
–3
10
8
6
4
2
10
–4
8
6
4
2
–5
10
8
6
4
2
–6
10
8
6
4
2
10
–7
10
–7
10
–6
2
4 6
2
-5
Torr
the pressure indication is linear. For gases other than air, the pressure can be
p
= K × indicated pressure
eff
-6
Torr true pressure of argon gas
Air
O
2
CO
Xe Kr
Ar
N
2
10
–5
10
–4
10
–3
4 6
2
4 6
2
4 6
p
[Torr]
eff
CCM502 Hornet
, CO and N
2
H
Ne He
2
10
–2
2
4 6
. For other
2
-6
Torr,
Page 15
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