A Guide To Oxygen Sensor Calibration


Published on December 1st, 2021

Sensors are not only used in the medical sector alone, they are used in many other sectors as well. Whether for cars, workers safety, or medical purposes, each applies different kinds of sensors according to its purpose. That said, if you need to calibrate your oxygen sensor, you’ve come to the right place.

When calibrating, the first thing to do is to choose the right sensor for your device. Installation should be according to the original equipment manufacturer.

A brand new oxygen sensor does not necessarily need calibration. But over time, the sensor will drift and there will be a need for calibration.

Before you attempt calibration, however, you should allow the sensor to adjust to the environment’s temperature. This is because environmental conditions like temperature, humidity, and atmospheric pressure can affect the output of the sensor.

It is therefore important to know or control the values of these three variables during calibration to have a good calibration standard.

Oxygen sensors can come in two ways: internally or externally.

Internal Sensors

These generally have a barb protruding from the case where a known oxygen concentration can be applied via oxygen tubing. Through the tubing, the instrument can be calibrated at 100% oxygen.

External Sensors

This sensor comes at the end of a coiled wire. It can be connected to an oxygen T-piece in an oxygen circuit. It can as well be calibrated at 100% oxygen. You can get more information here.

For calibration, you can use either a one-point or two-point calibration procedure. Thd procedure you use will be dependent on the sensor model’s number.

In the case of a one-point calibration system, the correct barometric pressure data must be fed into the sensor’s meter. The basic requirement is just to provide a 100% oxygen saturated environment.

There are many methods to acquire a 100% oxygen saturated environment for calibration. Placing deionized water until its temperature reaches equilibrium with the calibration environment is one of them.

Also, bubbling air through a reservoir or water can create 100% air-saturated water. Another method is filling a poked plastic bag with oxygen.

For a two-point system that runs in a zero-oxygen solution, you can employ the following procedure.

  • For the initial step, the calibration input of the board is to be short-circuited to zero volts for a second or more.
  • Push and hold the calibrate button on the sensor using a paper clip. Enter a value of 0 for the initial reading.
  • Release the button and take the second reading in the air. The oxygen reading should drop to 20. 9% in the room atmosphere.

Note that oxygen sensors should never be stored for longer than 6 months because it could cause problems when unboxed and activated.

Oxygen sensors that have been left sitting on the shelf for over six months may not calibrate correctly as a result of the sensor potentially drying out or other unknown factors.

Keep in mind that instructions for calibrating dissolved oxygen sensors are unique for every manufacturer. So be sure to go through your manual to see the appropriate one for your device.