MGS-250 Manual
6490-9000 Revision 4
47
NOTE:
For improved accuracy and response, the gas
detector should be protected from excess drafts while
performing the adjustment. Excess air circulation may dilute
the applied calibration gas and lead to lower than expected
response.
Step
Adjustment Using Calibration Gas Cylinders
1
Connect the regulator to the test gas port using 3 mm or 1/8”
inside diameter tubing.
2
Enable parameter P.-17 Gas Test Mode (see Section 5).
When enabled, the display continuously cycles through the
following:
x
CAL is displayed briefly.
x
Next, the gas group number or gas type (based on
product code) is displayed.
x
Then four dashes (----) are displayed.
After gas is applied and the 75 PPM squelch level is
exceeded, the live concentration replaces the four dashes.
NOTE:
The analog outputs, relay activity, and RS-485 ppm
reporting are suspended in Gas Test Mode to prevent false
alarms.
3
Expose the gas detector to gas from the cylinder. Monitor
the 4 digit LED display reading.
4
Wait for the ppm reading to stabilize. This should take
approximately 4-6 minutes. Minor changes (less than 5 ppm
in 10 seconds) are considered stable readings. Compare the
response value with the calibration gas concentration.
5
Adjust the gas detector displayed value by using the UP or
DOWN buttons to increase or decrease the value shown.
Adjust until the reading is within
r
2% of the calibration gas.
For example, if the calibration gas is 1000 ppm, the gas
detector is adjusted properly when the displayed reading is
between 980 and 1020 ppm.
6
Press the Enter button to store the new adjustment. Turn off
the calibration gas and remove the tubing from the calibration
port.
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