Oxygen Sensors for Diving

Most rebreathers require one or three oxygen sensors to measure the real-time PO2 in the breathing loop, and a few optionally use a fourth sensor. We offer a variety of oxygen sensors manufactured by Analytical Industries for use in diving rebreathers.

Most models of AI diving sensors from Dive Gear Express now ship with the documentation of a final pressure test for each sensor. The sensor is tested at approximately one ATA in air and 100% oxygen, then tested again at 1.6 ATA of oxygen. The millivolt readings are recorded and the results document the cell is within specifications for current and linearity up to a PO2 exceeding 1.6 ATA. The dated individual test results are included in the package with each sensor.

Our R-22DR with the standard 3-pin Molex connector is equivalent to the Teledyne R-22D and is actually our part number for the Analytical Industries PSR-11-39-MD. This sensor is used in the Dive Rite O2ptima, Jetsam KISS Classic, Innerspace Megalodon, Hammerhead, rEvo, and CCR-2000 rebreathers. It's also used in some third party controllers and dive computers such as the Juergensen Marine Hammerhead, HydroSpace Explorer, Shearwater Research, and early Delta P VR2 and VR3 monitoring cables.

Our R-17DR with the 3.5mm mini-jack is equivalent the Teledyne R-17D and is actually our part number for the Analytical Industries PSR-11-39-JD. This sensor is used in the, CIS-Lunar, VR Technology Ouroboros and Sentinel rebreathers. In early 2007, VR began switching their monitoring cables for the VR2 and VR3 to use this mono-plug version. It's also widely used in handheld oxygen analyzers, but many handheld oxygen analyzers for verifying cylinder contents use a medical grade oxygen sensor. The oxygen sensors for diving have a 'hydrophobic membrane', which is a necessity for rebreather applications, but will slightly slow (by two or three seconds) the response time of handheld O2 analyzers. This is true for any diving sensor, not just ours and to be clear does not affect the accuracy of the analysis, just the response time of the sensor. However, the medical versions are often more difficult to find and much more expensive. If you have been using an R-17D type diving sensor in your handheld unit, such as the Dive Rite VTI, Mini-Ox brand, Spectrum brand, Vandagraph VN202, El Cheapo/Expedition, or Teledyne AD300/MD300 and have been satisfied with it, by all means order the R-17DR from us.

The PSR-11-39-MHD with the molex connector is a special version of the PSR-11-39-MD. Some users of prefer this version which provides a slightly higher signal output. The lower end of the signal output of range of the cell has been shifted from 8.5mv to 10mv. We do not recommend using the MHD version and offer it only because it has been specifically requested by some customers.

The APD10 (also known as the R-22APD) oxygen sensor with the coaxial connector is used exclusively on the Ambient Pressure Diving Inspiration and Evolution rebreather. While Dive Gear Express sells other types of diving sensors, the purchase of APD10 sensors with coaxial connector requires you to contact APD or the appropriate international distributor. The sensors are not available for order from their on-line store, you must contact APD directly to purchase the APD10 sensors.

Oxygen Sensor Life in Rebreathers

When any new oxygen sensor is removed from the sealed bag, it can take a few minutes to a few hours for it to acclimate and the millivolt output to stabilize. We recommend waiting 12 hours before calibrating your rebreather with a freshly opened sensor. Once acclimated, a new sensor should output approximately 10 to 15 millivolts in air and 50 to 60 millivolts in pure oxygen. In actual use in rebreather applications, all brands of oxygen sensors seem to last between one and two years. In rebreather applications, we recommend discarding any sensor acclimated at 1 ATA with less than 40 mv output in pure oxygen or less than 9 mv in air. As oxygen sensors reach end-of-life they can become unpredictable, causing problems that are sometimes difficult to diagnose. Because oxygen sensors are critical to operational safety of the rebreather, some divers annually replace all oxygen sensors rather than wait for one to reach end-of-life at a most inconvenient time.

to read Oxygen Sensor Handling - Best Practices

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