Frequently Asked Questions

A: Generally this unit can be calibrated on instrument-grade air or ambient air, which contains 20.9% (by volume) oxygen. This is providing the sensor is operated seeing atmospheric pressure (e.g. venting to an atmospheric vent).​

A: The pressure dependence of the sensor signal is in the range of 150 mbar ... 800 mbar 2.0 % of measuring signal / 100 mbar in the range of 800 mbar ... 5.0 bar 0.5 % of measuring signal / 1 bar​

A: There are several possibilities.

How are you calibrating the sensor? Are you calibrating it in open air or against a standard cylinder of gas? If somehow the cylinder or calibration method is flawed, theses are the results you might get

the other possibility is a damaged sensor (you mentioned earlier it might have frozen?). That might have damaged it somehow, although I would not say it is likely.

It could however, be a generically just bad sensor.

the other possibility is somehow the electronics are damaged or defective.

One other thing to look at is the interconnect wiring. There are four wires from the sensor (two for the sensor itself, and two for the thermistor). If the thermistor wiring is intermittent, it can do exactly what you say happens. This should be checked carefully.

Another possibility is RFI. If there is a strong RFI surge, it can couple into the wiring and cause a spike lasting a second or two. ​

A: The unit has a low low O2 alarm fixed in the sw that detects the condition when the sensor anode is completely dead. As this is a percent O2 unit the expectation of the designers was that in application there would be enough O2 in the stream so that the low low o2 condition would not occur. 

I suspect you are sampling unusually pure gas that is causing this alarm to flash. You are correct, in this case the sensor is indeed okay.​

A: Please refer to the following document: impact_of_atmospheric_conditions_on_O2_readings.pdf​

A: Maximum resistive load is 500 ohms.​

A: Streams containing H2S or Sox, organic vapors or halogens (e.g. F, Cl, Br) should be avoided, as well as water or condensed humidity.​