MKS Granville-Phillips Mini-Convectron 275 series - Adjustment of Gauge Readings

4 Operation
38
Series 275 Mini-Convectron Module with DeviceNet
Instruction Manual - 275563
4.8 Adjustment of Convectron Gauge Zero and Atmospheric Pressure Indications
Each Convectron Gauge has a stable, temperature compensated design and is individually
computer calibrated for N
2
. Zero adjustment of the gauge should not be necessary unless readout
accuracy is required below 1 x 10
-3
Torr or the gauge has been contaminated. Adjustment of the
atmospheric indication should not be necessary unless compensating for variations in mounting
orientation, or contamination.
For accurate readout, the adjustments must be made at vacuum, followed by adjustment at
atmosphere. Atmosphere adjustment will not effect the vacuum setting, but vacuum adjustment will
effect the atmosphere setting. The REAL data is an unassigned 32 bit floating point number.
4.8.1 Calibrate the Vacuum Reading
1. Evacuate the Convectron Gauge to a pressure known to be less than 1 x 10
-4
Torr of N
2
for at
least 15 minutes.
2. If the pressure less than 1 x 10
-4
send the data listed in Table 4-8 to adjust Zero.
The example in Table 4-9 sets the pressure to a value of 1 x 10
-2
Torr.
4.8.2 Calibrate the Atmosphere Reading
1. Allow the system pressure to increase to atmospheric pressure.
2. Use Table 4-10 to determine the atmospheric pressure (Torr) and data for your altitude and
enter the data value for the atmospheric adjust service.
NOTE: For units of measure other than Torr, or for other atmospheric pressures,
use decimal to floating point Hex conversion to find the REAL float format.
Using the N
2
calibration to pressurize a vacuum system above about 1
Torr with certain other gases can cause dangerously high pressures which
may cause explosion of the system. See Section 4.7 before using with
other gases.
Table 4-8
<1 x 10
-4
Vacuum Adjust Example
Parameter Service Class Instance REAL Data
Zero Adjust 4B
hex
31
hex
1 None
Table 4-9
1 x 10
-2
Vacuum Adjust Example
Parameter Service Class Instance REAL Data
Zero Adjust 4B
hex
31
hex
1 0A D7 23 3C
hex