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Operation
► Observe the constants for converting measuring signal and pressure.
► Convert measuring signal into pressure:
► Convert pressure into measuring signal:
6.2 Ascertaining effective pressure with calibration factors
The measuring signal is gas type dependent. The characteristics apply for nitrogen (N
dry air and carbon monoxide (CO).
p [hPa]
10
2
8
6
4
2
10
1
8
6
4
2
10
0
8
6
4
2
10
–1
8
6
4
2
10
–2
8
6
4
2
10
–3
10
Fig. 6:
Within the pressure range < 1 hPa, the display is linear.
Gas type
Air, oxygen (O
Hydrogen (H
Carbon dioxide (CO
Water vapor
Helium (He)
The calibration factors provided are mean values.
24/42
(U-c)
p = 10
U = c + log
p
10
Water vapor
–3
10
–2
2
4
6
2
4
6
Displayed pressure
Gas and vapor mixtures
Process gases are mostly mixtures of gas and vapor. Precise measuring of gas and vapor
mixtures is only possible using partial pressure measurement instruments, for example a
quadrupole mass spectrometer.
), carbon monoxide (CO), nitrogen (N
2
)
2
)
2
H
2
10
–1
10
0
2
4
6
2
4
)
2
), oxygen (O
2
He
Ne
Air
O
2
CO
N
2
CO
2
Ar
Freon 12
Kr
Xe
10
1
10
2
6
2
4
6
p
[hPa]
eff
Calibration factor (C)
1.0
0.5
0.9
0.5
0.8
),
2
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