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Instruction Manual
7.4
Log 0-7; Log-Linear Analog Output Equation & Table - mbar
Log-Linear 0 to 7 V analog output for selected gases - Engineering units in mbar
True
Pressure
N2
Ar
(mBar)
0.0001
0.000
0.000
0.0002
0.301
0.301
0.0005
0.699
0.699
0.0010
1.000
0.903
0.0020
1.301
1.146
0.0050
1.699
1.524
0.0100
2.000
1.820
0.0200
2.301
2.188
0.0500
2.699
2.512
0.1000
3.000
2.809
0.2000
3.301
3.103
0.5000
3.699
3.495
1.0000
4.000
3.784
2.0000
4.301
4.064
5.0000
4.699
4.404
10.0000
5.000
4.633
20.0000
5.301
4.815
50.0000
5.699
4.969
100.0000
6.000
5.045
200.0000
6.301
5.093
300.0000
6.477
5.131
400.0000
6.602
5.178
500.0000
6.699
5.237
600.0000
6.778
5.295
700.0000
6.845
5.349
760.0000
6.881
5.380
800.0000
6.903
5.399
900.0000
6.954
5.488
1000.0000
7.000
5.494
1100.0000
7.041
5.539
1200.0000
7.079
5.580
1300.0000
7.114
5.624
1333.0000
7.125
5.636
The log-linear output signal and pressure are related by the following formulas:
(V - 4)
P = 10
V = log
An analog output of 10 volts indicates a faulty convection gauge or unplugged gauge cable.
The chart on the following page shows the graphical results of the table and formulas given above for nitrogen.
True pressure (N
) is plotted on the X-axis with a log scale. The output is plotted on the Y-axis on a linear scale.
2
Note - when using the units of pascals and LOG 0-7 is selected , the same equation of P = 10
applies. This results in a log-linear analog output range of 0 to 9.12 Vdc for 1.30E-02 pascals to 133 kpa.
InstruTech, Inc.
He
O2
CO2
0.000
0.000
0.000
0.301
0.301
0.301
0.699
0.699
0.699
0.938
1.000
1.028
1.204
1.301
1.355
1.602
1.699
1.672
1.908
1.991
2.012
2.208
2.294
2.345
2.607
2.693
2.741
2.928
2.989
3.033
3.217
3.288
3.325
3.634
3.686
3.696
3.962
3.987
3.982
4.324
4.288
4.249
5.070
4.695
4.550
7.125
5.008
4.743
7.125
5.337
4.886
7.125
5.862
5.002
7.125
6.282
5.065
7.125
6.526
5.157
7.125
6.625
5.253
7.125
6.705
5.353
7.125
6.786
5.448
7.125
6.861
5.532
7.125
6.928
5.611
7.125
6.965
5.658
7.125
6.988
5.687
7.125
7.042
5.766
7.125
7.092
5.847
7.125
7.125
5.936
7.125
7.125
6.028
7.125
7.125
6.140
7.125
7.125
6.169
Values listed under each gas type are in volts.
(P) + 4 where P is the pressure in mbar, and V is the output signal in volts.
10
KR
Freon12
Freon22
0.000
0.000
0.000
0.301
0.301
0.301
0.523
0.699
0.699
0.668
1.125
1.125
0.970
1.487
1.487
1.370
1.883
1.855
1.675
2.172
2.136
1.979
2.473
2.434
2.372
2.863
2.837
2.671
3.157
3.136
2.963
3.445
3.424
3.341
3.798
3.783
3.614
4.044
4.037
3.865
4.250
4.255
4.141
4.447
4.471
4.309
4.556
4.602
4.433
4.621
4.675
4.514
4.680
4.722
4.548
4.751
4.780
4.606
4.851
4.877
4.654
4.918
4.950
4.679
4.962
5.000
4.710
4.996
5.038
4.734
5.025
5.070
4.754
5.050
5.097
4.765
5.063
5.112
4.772
5.072
5.122
4.787
5.092
5.146
4.799
5.111
5.167
4.812
5.128
5.187
4.822
5.146
5.204
4.828
5.164
5.222
4.830
5.169
5.228
VGC301 Controller
D2
Ne
CH4
0.000
0.000
0.000
0.301
0.301
0.301
0.699
0.699
0.699
1.080
0.903
1.167
1.392
1.166
1.523
1.778
1.551
1.893
2.082
1.849
2.186
2.385
2.150
2.484
2.779
2.543
2.886
3.082
2.844
3.197
3.393
3.148
3.500
3.828
3.553
3.893
4.174
3.867
4.201
4.579
4.192
4.517
6.288
4.696
4.877
7.125
5.252
5.374
7.125
6.608
6.409
7.125
7.125
6.930
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
7.125
(V - 4)
listed above
Page 28
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