The RKI NCR-6309 is a genuine replacement combustible gas (LEL) sensor for RKI gas monitors. It is a catalytic-type sensor that detects flammable gases across the 0–100% LEL range and is factory-standard calibrated to methane, though it also responds to a wide variety of combustible gases. It is compatible with the GX-3R, GX-3R Pro, GX-Force, and GX-6100 instruments, carries a 3-year warranty, and ships free from Industrial Safety Products.

The RKI NCR-6309 detects combustible (flammable) gas over a 0–100% LEL (Lower Explosive Limit) range. It is standard-calibrated to methane but will detect and respond to many other combustible gases, making it the LEL channel for RKI's GX-3R and GX-3R Pro multi-gas monitors.

The NCR-6309 is a catalytic combustion (thermo-catalytic) sensor with two catalytic elements: a standard element and a poison-resistant element. When combustible gas reacts with oxygen at the element, the element's resistance changes; the GX-3R's circuitry amplifies that change, converts it to a gas concentration, and displays the reading in % LEL on the monitor.

Yes. The NCR-6309 uses a poison-resistant catalytic element alongside its standard element, specifically to resist common sensor poisons such as silicone. This helps extend usable life and reliability in environments where silicones and other contaminants can degrade ordinary catalytic LEL sensors.

Yes. With the NCR-6309 installed, the GX-3R is rated Ex da ia IIC T4 Ga and carries ATEX (DEKRA 17ATEX0103 X), IECEx (IECEx DEK 17.0050 X), and CSA "C/US" Intrinsically Safe approvals — Class I, Division 1, Groups A, B, C, D, T4. The NCR-6309 itself is a flameproof (Ex da) component, and its ambient temperature range for the safety rating is -40 °C to +60 °C.

Because the NCR-6309 is the only flameproof (flame-proof) part of the GX-3R gas monitor system. RKI warns that if assembly is not performed as specified, explosion-protection performance can be compromised — so only a genuine NCR-6309 installed with the specified genuine parts and torque preserves the instrument's intrinsic-safety and flameproof approvals. It is a sealed flameproof product that must not be disassembled or modified.

Handle it carefully to protect its flameproof construction. RKI specifies: do not subject the NCR-6309 to strong force or shock (breakage can damage flameproof performance); never expose it to ultraviolet light or use it unless fully enclosed; do not expose it to oil or hydraulic fluid; do not disassemble or modify it; and keep it within its -40 °C to +60 °C ambient range. If the enclosure is damaged, take the unit out of service and have it repaired before further use.

The RKI NCR-6309 LEL sensor is designed for the GX-3R, GX-3R Pro, GX-Force, and GX-6100 gas monitors. Confirm your instrument is one of these models before ordering, since it is a model-specific replacement combustible-gas sensor.

Yes. The NCR-6309 is a genuine RKI Instruments replacement LEL (combustible gas) sensor, available at Industrial Safety Products (industrialsafetyproducts.com) with free shipping and a 3-year warranty. It is the correct LEL sensor for the GX-3R and GX-3R Pro (also compatible with GX-Force and GX-6100).

Replace the combustible-gas sensor when it fails calibration or bump tests, reads inaccurately, responds sluggishly, or has been exposed to high concentrations, poisons, or physical shock. The NCR-6309 is the genuine RKI drop-in LEL sensor (0–100% LEL, catalytic, poison-resistant) for the GX-3R, GX-3R Pro, GX-Force, and GX-6100. Because it is the instrument's only flameproof part, always fit a genuine unit and follow RKI's installation/torque instructions to keep the monitor's hazardous-location approvals valid.