Honeywell 2106B1201 Sensepoint LEL Combustible Gas Sensor M25

Honeywell 2106B1201 Sensepoint LEL Combustible Gas Sensor (M25 Entry)

The Honeywell 2106B1201 is a sealed catalytic pellistor gas sensor engineered for continuous atmospheric monitoring of combustible gases and vapors in 0 to 100% Lower Explosive Limit (LEL) ranges. Designed for harsh industrial and marine environments, this fixed-point sensing element features an M25 metric mechanical mounting thread and integrates into certified Ex d (flameproof) or Ex e (increased safety) junction boxes.

Operating on a standard 3-wire catalytic mV bridge circuit powered by a 200 mA constant-current loop, the 2106B1201 provides reliable flammable gas monitoring with built-in poison resistance against silicones, sulfur compounds, and halogenated hydrocarbons. The sensor body is injection-molded from PPS (Polyphenylene Sulphide / Fortron®), delivering exceptional mechanical rigidity and chemical resistance against corrosive marine salt mist and offshore hydrocarbon exposure.

Model Details:

• Model Details: Sensepoint Combustible 0–100% LEL Sensor
• Manufacturer Part Number (MPN): 2106B1201
• Mounting Thread: M25 × 1.5 metric
• Sensing Technology: Poison-resistant matched-pair catalytic bead (Pellistor)

Technical Specifications

Key Features

1. Poison-Resistant Catalytic Bead Technology: High operational stability with resistance to catalytic deactivation from siloxanes, lead, and airborne sulfur compounds.
2. Standard 3-Wire mV Bridge Output: Direct linear mV bridge compatible with all industry-standard gas detection controllers, transmitter heads, and analog PLC/DCS input modules.
3. Robust Fortron® PPS Construction: High-integrity polyphenylene sulphide body eliminates corrosion, galvanic degradation, and harsh environmental wear.
4. Hazardous Area Certified: Fully certified for Zone 1 and Zone 2 explosive gas atmospheres (ATEX / IECEx II 2GD Ex d IIC T6 Gb).
5. IP65/IP67 Ingress Protection: Retains IP65 dust and water ingress sealing natively, upgradeable to IP67 when deployed with dedicated external weather housing.

Frequently Asked Questions

What is the difference between the Honeywell 2106B1201 and the 2106B1200?

The difference lies entirely in the mechanical junction box entry thread. The 2106B1201 features an M25 × 1.5 metric thread, whereas the 2106B1200 utilizes an M20 × 1.5 metric thread. Both units use the identical catalytic pellistor sensing element and 3-wire bridge electronics.

Can the 2106B1201 be directly connected to a 4-20mA PLC input?

No. The 2106B1201 provides a raw 3-wire catalytic bridge mV output and requires a 200 mA constant current supply. To connect to a standard 4-20mA analog PLC or DCS loop, you must route the sensor through a catalytic-to-4-20mA bridge converter card (such as Honeywell module 2106B1110) or a dedicated gas controller.

What gases will this sensor detect?

The catalytic pellistor detects virtually all combustible gases and hydrocarbon vapors, including methane, propane, butane, hydrogen, hexane, ethanol, and diesel/petroleum fuel vapors. The sensor is typically factory-referenced to methane (CH4) or pentane.

How often does the 2106B1201 require calibration?

In marine and industrial installations, safety regulations mandate a routine bump test every 3 to 6 months and a full span calibration every 6 to 12 months. Environments with high humidity, airborne particulates, or trace silicone/sulfur exposure require more frequent calibration checks.

What causes catalytic sensor poisoning?

Catalytic bead degradation occurs when active catalytic sites on the detector bead are contaminated by silicones (greases, sealants), lead additives, phosphate esters, or high concentrations of hydrogen sulfide and halogenated hydrocarbons. The 2106B1201 features a poison-resistant pellistor formula to mitigate standard operational degradation, but direct contact with silicone vapors must be prevented.