RKI Replacement LEL Sensor NCR-6309

The NCR-6309 is compatible with specific RKI multi-gas instruments that use the catalytic bead LEL sensor configuration. Compatible models may include instruments in the GX-3R/GX-3R Pro family. Confirm compatibility with your specific instrument model by contacting PK Safety at 1-800-829-9580 or reviewing your instrument's sensor specification sheet.

An LEL (Lower Explosive Limit) catalytic bead sensor responds to most combustible gases and vapors, including methane (CH4), propane, hydrogen, and general hydrocarbon vapors. The sensor measures the concentration of combustible gas as a percentage of the gas's lower explosive limit — the minimum concentration required to sustain combustion. Alarms typically trigger at 10% LEL and 20% LEL to warn workers before concentrations approach explosive ranges.

Catalytic bead sensors can be poisoned by exposure to silicones, lead compounds, and chlorinated solvents, which coat the catalytic surface and reduce sensitivity. Sensors can also fail through normal end-of-life degradation. Regular bump testing detects sensor poisoning early. If the sensor does not respond correctly to bump test gas, replace it immediately before returning the instrument to service.

OSHA 29 CFR 1910.146 requires that the atmosphere of a permit-required confined space contain less than 10% of the LEL of any flammable gas or vapor before entry is permitted. Many safety programs set monitor alarms at 10% LEL for the first alarm and 20% LEL for a second alarm, allowing workers time to evacuate before reaching dangerous concentrations. The NCR-6309 supports continuous monitoring of these levels.

Handle replacement sensors with care to avoid physical shock and exposure to contaminating chemicals prior to installation. Follow the installation procedure in your instrument's service manual exactly, complete the required warm-up and stabilization period, then perform a full calibration using RKI-approved calibration gas before placing the instrument back in service.