Adjustment Using Calibration Gas - Emerson MRLDS-250 Installation And Operation Manual

Figure 6-1 Using Calibration Gas
6.4. Adjustment Using
Calibration Gas
Adjustment Using Calibration Gas requires a gas
cylinder with the appropriate gas and concentration.
Note that a calibration kit if offered that consists of a
calibration gas cylinder and a flow regulation valve
with flexible non-absorbent tubing.
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 a lower than expected
response.
Bump Testing Using Calibration Gas
Step
1 Connect the regulator to the test gas port using 3 mm
or 1/8" inside diameter tubing.
2
Activate parameter P.-17 Gas Test Mode (Section 5,
Configure the Gas Detector). The gas detector will
report 0 PPM if the calibration gas is off; otherwise,
it will report the real time gas concentration in PPM.
NOTE: The analog outputs, relay activity, and 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.
Table 6-2 Adjustment Using Calibration Gas Cylinders
18 • MRLDS-250 Gas Detector Manual
Cylinders
Bump Testing Using Calibration Gas
Step
4 Wait for the PPM reading to stabilize. This should
take approximately four (4) to six (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 ± 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. If no further changes to the
other Parameters are required, press and hold the
information button for five (5) seconds to exit the
Parameter list.
Table 6-2 Adjustment Using Calibration Gas Cylinders
NOTE: When Gas Test Mode is activated, the
gas detector disables the relay and analog
output signals for 30 minutes. This allows time
for the calibration gas to dissipate after testing
to help avoid false alarms. Remove the calibration gas
as soon as possible after completing the test to allow the
gas detector to clear.
NOTE: All calibration gas mixtures have a
blend tolerance. The tolerance will limit the
actual adjustment accuracy that is achievable.
Cylinders
026-1315 Rev 2 11-APR-2017