Divesoft 22S Oxygen Sensor
Divesoft 22S Oxygen Sensor
- OEM Replacement oxygen sensor for the Divesoft gas analyzers
- NOT suitable for use in rebreathers
- Divesoft warranty of sensor life is 12 months
The Divesoft 22S Oxygen Sensor is a Divesoft branded replacement for the oxygen sensor with a three pin Molex connector in the Divesoft gas analyzers. The sensor is also a plug compatible replacement for R-22S type sensors found in other gas analyzers such as Cochran Lifeguard, DiveTek Oz, DiveNav cootwo, Mares EANx, and OxySpy analyzers. Lacking a hydrophobic membrane, this sensor is NOT suitable for use in any rebreather.
The sensor’s accuracy is ± 1% full scale. Typical life of this type sensor is 36 to 48 months depending on usage and amount of oxygen being analyzed, but can be as little as 12 months in frequent shop use. Divesoft warranty of sensor life is 12 months.
We are occasionally asked about availability of the helium sensors for the Divesoft Trimix analyzers. They are available by special order, but Divesoft tells us that the helium sensors are not consumable, and expected to last the life of the analyzer.
The R-22 type oxygen sensor in diving
Teledyne Analytical, a early pioneer in the development of galvanic oxygen sensors, manufactures a variety of sensors for different applications. The R-22 models are all characterized by the same physical dimensions and 3-pin Molex connector. However the various models differ internally in order to support specific applications such as automotive (R-22A), medical (R-22MED), and gas analyzers (R-22S). Very early rebreathers used the R-22S model (because it was what was available), but the sensor was found to be too sensitive to the high levels of humidity found in rebreather loops. Teledyne eventually offered a version for the diving market (R-22D) that improved it's resistance to moisture. We originally sold the Teledyne diving grade sensor as an OEM private label under the part number R-22DR.
In the late 2000's, Teledyne Analytical had to defend the sensors in several (frivolous?) lawsuits associated with rebreather fatalities. Although the sensors were never found to be at fault, Teledyne ceased manufacture of the R-22D diving model because the litigation costs to defend the sensor exceeded the value of the very small rebreather sensor market at the time. Several other competing manufacturers began to offer plug-compatible replacements for the now discontinued R-22D model. Over time those other manufacturers have made significant improvements to the original design, although the physical and connector specifications have remained the same. They are often still generically referred to as "R-22 type compatible" after the original Teledyne model number.
The primary difference between the "S" type sensor and the "D" type sensor is the presence of a hydrophobic membrane on the face of the diving grade sensor. The membrane improves resistance to moisture, but slows the response of the sensor to changes in oxygen partial pressures by several seconds. In practice, for use in diving gas analyzer applications the slightly slower response time of diving grade sensors is little consequence with the benefit being the design is more resistant to moisture found on the face of tank valves. If the diver or fill station operator fails to wipe or blow away any moisture present on the valve outlet, that moisture can enter the stream of gas being analysed and affect the accuracy of the analysis. Some prefer to use the D type sensors even in analyzers because of their resistance to moisture, others prefer the S type sensors for their slightly faster response time in analyzers - especially in frequent use applications. Both types will work in gas analyzers but the S type must never be used in rebreathers.