R-22MED Sensor FAQ
Q: According to the R-17/R-22 specification sheet, the output voltage is stated as follows;
[Output Voltage: 7-13mV in air, 25 degrees, sea level (standard)]
We are trying to include the voltage testing for the sensors and prospect that the actual voltage of the sensors are within 7-13 mV, and if not within that range, we determine those sensors to be defect sensors. When we perform the trial voltage testing to your sensors, we found quite a few sensors exceed the range.
Would it be sufficient to judge the sensors to be a defect if measured voltage exceeds the voltage stated in the specification? Or should we set the tolerance level to this testing? Please advise.
A: Our sensors are partial pressure O2 sensors. The output of the sensors varies as a function of the partial pressure of O2, which is affected by O2 percentage level in the gas it sees, the barometric pressure, or sample pressure, and the humidity in the air, and the temperature.
We test our sensors by exposing them to atmosphere in our facility and then seeing if they are within these limits.
When we ship the sensors to you, it is possible that your atmospheric pressure when you test is slightly higher than our test conditions, so that the voltage output correspondingly is higher.
Our sensors work according to Dalton's Law of partial pressures.
To accommodate this effect, I would suggest you build in a tolerance in your acceptance criteria of approximately 5%., so instead of 7-13mv you check 6.5mv to 13.7mv or something like that.
It is important that you test the sensors in open air, and not pressurize the sample in any way. also you need to test the sensors at about 22c to avoid any errors associated with the temperature compensation network.
For additional questions, please contact Technical Support.