HELIX GRANVILLE-PHILLIPS Convectron ATM, Instruction Manual

Page: 64 / 98

Chapter 4
56
Convectron
®
ATM Vacuum Gauge Module Instruction Manual
4.7 Calibrating Convectron
gauge at atmospheric
pressure
An atmospheric pressure calibration is performed on the Convectron gauge,
using N
2
, at the factory before the module is shipped.
Because performance varies depending on the process gas, you may wish
to reset the atmospheric calibration point if a gas other than N
2
or air is
being used. Periodic resets of the atmospheric calibration point also
improve the accuracy and repeatability of the Convectron gauge near
atmospheric pressure, even if the process gas is N
2
or air.
• Regardless of the process gas that is being used, you should always use
N
2
or air to calibrate the Convectron gauge at atmospheric pressure.
• You must send the command in the pressure unit that has been
programmed for the module. See page 55.
1. Shut off the pump and, using N
2
or air, allow the vacuum chamber
pressure to increase to the atmospheric pressure. Atmospheric pressure
must be higher than 400 Torr (5.332 mbar, 533.2 Pa).
2. Send a calibration at system (TS) command such as the command in
the example command sequence, which sets the atmospheric
calibration point to 760 Torr:
Example TS command from host: #01TS7.60E+02
↵
Example response from module: *01 PROGM OK
↵
If the module returns a message other than “*01 PROGM OK
↵
” in response
to the TS command, the atmospheric calibration has failed. See page 64 to
troubleshoot the problem.
4.8 Calibrating 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, you should always use
N
2
or air to calibrate the Convectron gauge at vacuum chamber pressure.
• You must send the command in the pressure unit that has been
programmed for the module. See page 55.
• The highest allowable calibration pressure is 1 x 10 –1 Torr
(1.33 x 10 –1 mbar, 133.3 x 10 –1 Pa).
1. Turn on the pump and allow the vacuum chamber to decrease to the
pressure at which the vacuum chamber pressure point will be set.
Pressure must be lower than 1 x 10
–1 Torr.
2. Send a calibration at vacuum chamber pressure (TZ) command:
Example TZ command from host: #01TZ1.00E–4
↵
Example response from module: *01 PROGM OK
↵
If the module returns a message other than “*01 PROGM OK
↵
” in response
to the TZ command, the vacuum chamber pressure calibration has failed.
See page 64 to troubleshoot the problem.