Guidance on the calibration interval of the O2NE+ and Safe-Ox+ devices can be found in the O2NE+ & Safe-Ox+ User Manual which is available on both the O2NE+ and Safe-Ox+ product pages in the Analox Sensor Technology website.


As a rule, Analox recommends the Safe-Ox+ and O2NE+ devices are proof tested once per year (flow a challenge gas across the sensor to confirm it reads correctly). Calibration adjustment is unnecessary if your O2NE+ / Safe-Ox+ reads correctly on the proof test gas.


For best performance the monitor should be powered and allowed to warm-up for approximately 2 hours before calibration is performed. This will allow the whole instrument to stabilise at operating temperature.


In order to perform a calibration check, you will need the following equipment:

Calibration gas: with 20.9% oxygen in nitrogen for devices manufactured after 04/03/2014 older models use 24% oxygen in nitrogen.

0.5 lpm regulator: To suit the calibration gas bottle.

Flow adaptor kit: Part No: P0120-651K for devices manufactured between 09/08/2012 and 01/11/2016.


Then follow this procedure:

  1. Remove the flow adaptor and gasket from its protective backing (if using the P0120-651K).
  2. Fit the flow adaptor including its gasket (if using the P0120-651K) to the O2 sensor and connect, with tubing, to the cylinder.
  3. Open the regulator to allow for the flow of gas over the sensor.
  4. Enter 'Technician Mode' by pressing the mode switch 3 times. If entered successfully the green LED will flash off for 1.5 seconds and on for 0.5 of a second.
  5. Select auto calibration by pressing the mode switch 4 times. The 2 Red Alarm LED's will light up to show you are now in this mode.
  6. Press the mode switch 2 times to start the Auto Calibration, the Red Alarm LED's will turn off and the Green LED will continue to flash.
  7. Wait one minute for the instrument to adjust. When the instrument has a new calibration value, the buzzer will sound one bleep and all the LED's will be off.
  8. Accept this new calibration value by pressing the mode switch 2 times. The green LED will flash to show the instrument has accepted the new oxygen value.
  9. To return to normal operation, press the mode switch once. The LED's and buzzer will illuminate/ sound 4 times before returning to normal operation.


If during the one minute wait period, the red or yellow LED's are illuminated consult the table below:

ALARM 1 LAMP (RED)ALARM 2 LAMP (RED)FAULT LAMP (YELLOW)MEANINGACTION
ONOFFOFFCalibration gas is above allowable rangeEnsure the calibration gas is 20.9% oxygen in nitrogen with ±2% tolerance.
OFFONOFFCalibration gas is below allowable range

Ensure the calibration gas is 20.9% oxygen in nitrogen with ±2% tolerance

OFFOFFONInternal faultContact Analox


For a brief demonstration of the calibration process, please watch the video below:

O2NE - 4. Calibration from Analox.