The RKI ESR-X13P-OXY is a replacement oxygen (O2) sensor for RKI gas monitors. It is an electrochemical-cell sensor that measures oxygen concentration from 0 to 40% by volume (± 0.5% O2) and has a typical 3-to-5-year life span. It is a genuine RKI part compatible with the GX-3R, GX-3R Pro, GX-Force, and GX-6100 instruments, sold at Industrial Safety Products with free shipping.

The RKI ESR-X13P-OXY measures oxygen (O2) from 0 to 40.0% by volume, in 0.1% increments, with ± 0.5% O2 accuracy. This range covers oxygen-deficient and oxygen-enriched atmospheres, including the normal 20.9% O2 level used to confirm safe breathing air during confined space entry.

The RKI ESR-X13P-OXY O2 sensor fits the GX-3R, GX-3R Pro, GX-Force, and GX-6100 instruments. Confirm your monitor is one of these models before ordering, since it is a model-specific replacement sensor.

Yes. The RKI ESR-X13P-OXY is a genuine RKI Instruments replacement oxygen (O2) sensor, available at Industrial Safety Products (industrialsafetyproducts.com) with free shipping. It is the correct O2 sensor for the GX-3R and GX-3R Pro (also compatible with GX-Force and GX-6100).

The RKI ESR-X13P-OXY can tolerate extreme temperatures of -40 °C to +60 °C, but only temporarily — for up to about 15 minutes. It should not be exposed to temperatures above 60 °C for extended periods, and even sustained exposure above 50 °C can be harmful to the sensor over time.

Keep it out of prolonged heat above 60 °C (and ideally below 50 °C). RKI specifically warns against leaving the sensor inside a parked vehicle on a sunny day, on top of a car dashboard, or in direct sunlight for extended periods — these everyday situations can easily exceed the sensor's maximum temperature rating and cause permanent damage.

Overheating causes electrolyte leakage. If the ESR-X13P-OXY is exposed to temperatures above 60 °C for even one day, the electrolyte can begin permeating the Teflon membrane, electrolyte may leak out, the internal adhesive changes color from orange to black, and the sensor connections can corrode over time — degrading accuracy or ruining the sensor.

Look at the adhesive on the bottom of the sensor. A black adhesive material on the underside of the ESR-X13P-OXY indicates the sensor has been exposed to temperatures outside its specifications for an extended time. In a healthy sensor this adhesive is orange; a color change to black is RKI's visual sign of heat-related electrolyte damage.

The ESR-X13P-OXY is an electrochemical-cell oxygen sensor. Oxygen diffuses through a Teflon membrane into an internal electrolyte, where a chemical reaction generates a small electrical current proportional to the oxygen concentration; the RKI instrument converts that signal into a 0–40.0% volume O2 reading. Because it relies on an electrolyte and membrane, keeping it within its temperature limits is essential to preserve accuracy.

Replace the O2 sensor when it fails calibration/bump tests, reads inaccurately, or shows signs of heat damage such as black adhesive on its underside or electrolyte leakage. RKI rates the electrochemical O2 sensor for a typical 3-to-5-year life span. The ESR-X13P-OXY is the genuine RKI drop-in oxygen sensor (0–40.0% vol) for the GX-3R, GX-3R Pro, GX-Force, and GX-6100, and it ships free from Industrial Safety Products.