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If the zero drift of the sensor is larger, user can do the zero calibration,
this will make the default of target gas concentration as “0”.
Attention: zero calibration must be in the clean air.
6.2.5 Target Calibrate
（
Only professional engineer operation allowed
）
OC-903 portable gas detector can make the six level target
concentration calibration for the detecting gas, as the picture shows, this
must with the standard concentration gas, pressure
relief valve, flow meter, calibration cap, and good
connection of gas, or will be prohibited.
Operation details: Connecting the device as the
picture, enter into the target gas calibration interface,
slowly turn on the calibrate gas and control the flow
rate within 500ml/min, observing the detector gas
concentration(now should be rising), when the value
up to the peak value and keep stable, then choose a
non-calibrated option(“√” means been calibrated,
“×” means non-calibrated): firstly input the calibrate
gas concentration, then press the “calibrate”. After completing the target
point calibration, the target gas concentration of detector will be the
calibrate gas concentration.
6.2.6 Alarming setting
OC-903 with two adjustable alarm threshold values, high alarming
value and low alarming value. When set the low alarming, gas
concentration lower than the set value will alarm; when set the high
alarming , gas concentration higher than the set value will alarm.
