GF-201-O2 Oxygen Gas Sensor

Overview

The GF-201-O2 is a fixed-point oxygen (O2) gas sensor for continuous monitoring of oxygen deficiency and enrichment in agricultural and industrial environments. A sensing cell with automatic temperature compensation holds readings stable over long deployments, while a flameproof aluminium alloy enclosure (Ex d IIC T6) suits hazardous areas.

The sensor shows live concentration and alarm status on its LCD and drives three independent output paths at once: a 4-20 mA analog loop, an RS485 Modbus-RTU bus, and two normally-open alarm relays. That lets a single unit report to an Omni Genesis controller while its relays directly drive a door interlock, ventilation fan, or local horn.

Why Monitor Oxygen

Controlled-atmosphere fruit and produce storage runs at deliberately low oxygen levels to slow ripening. Those rooms are lethal to enter until the atmosphere is restored, so every entry must be verified against a live oxygen reading, not a schedule or an assumption.

Confined spaces around silos, manure pits, and fermentation cellars go oxygen-deficient without warning: microbial activity, fermentation, and stored grain all consume oxygen or displace it with other gases. A fixed sensor at the entry point gives a continuous, visible reading and an alarm before anyone steps in.

The two-stage relay alarm supports entry interlocks: one set point can hold a door lock or warning beacon while the second drives ventilation or a horn, with both thresholds freely configurable.

Key Features

• Dedicated O2 range: 0-30 %VOL with 0.01 %VOL resolution (0-100 %VOL available on request)
• Fast response: ≤15 s (T90), with automatic temperature compensation
• Two-stage alarm: independent relays for deficiency and enrichment set points, freely configurable
• Three outputs in parallel: 4-20 mA, RS485 Modbus-RTU, and two dry-contact relays
• Hazardous-area rated: flameproof Ex d IIC T6 aluminium enclosure, IP65
• Wide supply: 12-30 VDC, ≤2 W
• Field serviceable: LCD menu for calibration, alarm set points, and bus address

How It Works

The sensing cell produces a signal proportional to the oxygen concentration at the sensor inlet. On-board electronics linearise and temperature-compensate that signal, display it in %VOL, and publish it on the analog and digital outputs. Normal atmosphere reads 20.9 %VOL; when the concentration crosses a configured set point in either direction, the matching relay changes state to drive an alarm or interlock.

Installation

Mount the sensor at breathing height, approximately 1.5 m above floor level, near the entry points of spaces that can go oxygen-deficient: storage room doors, cellar stairs, and silo access hatches. Keep the sensor inlet clear of splashing water, oil, and dust, and leave service access around the housing. Calibrate with certified gas at commissioning and at least every six months thereafter.

One Detector, Replaceable Sensing Cell

The GF-201 family shares one platform: the same flameproof housing, display, relays, and outputs, with a replaceable sensing cell that sets the target gas. The family: H2S, NH3, CO2, O2, and CH4.

Additional sensing cells are available for the same platform by quote:

Gas	Formula	Selectable ranges
Carbon monoxide	CO	0-500 to 0-10000 ppm
Ozone	O3	0-10 to 0-1000 ppm
Chlorine dioxide	ClO2	0-20 to 0-1000 ppm
Chlorine	Cl2	0-10 to 0-200 ppm
Sulfur dioxide	SO2	0-100 to 0-1000 ppm
Nitrogen dioxide	NO2	0-100 to 0-1000 ppm
Formaldehyde	CH2O	0-5 to 0-200 ppm
Ethylene	C2H4	0-50 to 0-1000 ppm

Contact us with your target gas and range for a tailored quote.

Connectivity and Integration

The RS485 Modbus-RTU output (9600 bps, 8-N-1) connects directly to the Omni Genesis and Genesis Lite controllers and to any PLC or DCS that speaks Modbus. The parallel 4-20 mA loop covers legacy analog inputs, and the two relay contacts provide a wiring-free local trip for a door interlock or horn. This is the same modular approach as the rest of the Agrinovo range: one controller, any mix of sensors.