Operation
Mini-Convectron Module Instruction Manual - 275513 45
3.6 Calibrate the Convectron Gauge at Vacuum Chamber Pressure
Periodic resets of the vacuum chamber calibration point improve the accuracy and repeatability of
the Convectron gauge.
Regardless of the process gas that is being used, always use N
2
or air to calibrate the Convectron
gauge at vacuum chamber pressure.
The procedure for calibrating the Convectron gauge at vacuum chamber pressure depends on
whether or not the module has the optional display.
3.6.1 If the module does not have a digital display:
1. Turn on the pump and, using N
2
or air, allow vacuum chamber pressure to descend to a pressure
that is lower than 10
–4
Torr (1.3 x 10
–5
kPa, 1.3 x 10
–4
mbar).
2. Use a high-precision, high-input impedance (Z
in
>1MΩ) DVM to measure the voltage across the
MONITOR ANALOG and MONITOR COMMON test points on the module front panel.
3. Use a flat-head instrument screwdriver to adjust the ADJUST VACUUM potentiometer to a
reading of 0.375 Vdc.
3.6.2 If the module has a digital display:
1. Turn on the pump and, using N
2
or air, allow vacuum chamber pressure to descend to a pressure
that is lower than 10
–4
Torr (1.3 x 10
–5
kPa, 1.3 x 10
–4
mbar).
2. When the display indicates pressure is 0.00 mTorr, use a flat-head instrument screwdriver to
adjust the ADJUST VAC potentiometer to a reading of 0.375 Vdc.
Table 3-8 Typical Atmospheric Pressures at Altitude/Pressure/Voltage Relationships
Altitude Above Sea Level Pressure of N
2
or Air
Analog Output
Voltage (Vdc)
Feet Meters Torr kPa mbar
0 0 760 101 1013 5.534
1000 305 733 97 977 5.513
2000 610 707 94 942 5.493
3000 914 681 90 908 5.473
4000 1219 656 87 874 5.454
5000 1524 632 84 842 5.435
6000 1829 609 81 812 5.417
7000 2134 586 78 781 5.399
8000 2438 564 75 752 5.382
9000 2743 543 72 724 5.366
10,000 3048 523 69 697 5.350
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