GF-201-NH3 Ammonia Gas Sensor

Overview

The GF-201-NH3 is a fixed-point ammonia gas detector for continuous air-quality monitoring in livestock housing and agricultural facilities. A sensing cell with automatic temperature compensation and zero/span drift correction holds readings stable through long deployments in dusty, humid barn air, while the flameproof aluminium enclosure (Ex d IIC T6) and IP65 sealing survive washdown environments.

The detector 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. In a poultry house that means one unit can report to an Omni Genesis controller while its relays directly stage the ventilation fans.

Why Monitor Ammonia

Ammonia is the defining air-quality problem of poultry and livestock housing. It builds up from litter and manure, irritates eyes and respiratory tracts, suppresses growth rates and feed conversion, and rises fastest exactly when ventilation is turned down to save heat in winter. Because NH3 levels swing with litter moisture, stocking density, and ventilation cycles, spot checks with hand meters miss the buildup; a fixed detector with continuous logging and alerts shows the pattern and catches the drift before the flock pays for it.

Key Features

• Livestock-grade range: 0-100 ppm at 0.1 ppm resolution, covering the full span from target levels to acute buildup
• Continuous compensation: temperature-compensated cell with zero and span drift correction
• Two-stage alarm: independent low and high relays with freely configurable set points, wired straight to fans or sirens
• Three outputs in parallel: 4-20 mA, RS485 Modbus-RTU, and two dry-contact relays
• Built for barns: flameproof Ex d IIC T6 aluminium enclosure, IP65, wide -20 to 50°C operating range
• Field serviceable: LCD menu for calibration, alarm set points, and bus address

How It Works

The sensing cell produces a signal proportional to the NH3 concentration at the detector inlet. On-board electronics linearise and temperature-compensate that signal, display it in ppm, and publish it on the analog and digital outputs. When concentration crosses a configured set point, the matching relay changes state to drive ventilation, an alarm, or an interlock.

Installation

Ammonia is lighter than air, so mount the detector high: 0.3-0.6 m below the ceiling, above animal reach, near ventilation dead spots and litter areas where gas accumulates. Keep the sensor inlet clear of direct water spray, dust jets, and mechanical impact, 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, putting continuous NH3 curves, thresholds, and alerts on the same dashboard as temperature and humidity from the rest of the house. The parallel 4-20 mA loop covers legacy climate computers, and the two relay contacts provide a wiring-free local trip for ventilation staging. This is the same modular approach as the rest of the Agrinovo range: one controller, any mix of sensors.