Selecting a Fixed Multi-Gas Transmitter: Channel Count, Outputs, and Accessories Checklist

Understanding Channel Count Requirements

When selecting a fixed multi-gas transmitter, the first technical consideration is channel count—how many distinct gases the device can simultaneously monitor. Industrial environments vary in hazard complexity: a chemical processing plant may require monitoring of H₂S, CO, CH₄, and O₂, while a confined space in a wastewater facility may only need H₂S and O₂. Choosing a transmitter with the correct number of channels ensures comprehensive coverage without overpaying for unused functionality.

At 上海格为电子安全设备有限公司, our GDE and GDC series transmitters support up to four independent sensor channels, enabling simultaneous detection of combustible gases, toxic gases, and oxygen deficiency. The modular architecture allows users to mix sensor types—such as electrochemical for CO and infrared for CH₄—on the same unit, providing flexibility across diverse applications.

Over-specifying channel count increases cost, calibration burden, and failure risk. Under-specifying compromises safety. Always match the transmitter’s channel count to the site’s actual gas hazards, as defined by risk assessment and regulatory requirements.

Output Signal Types and System Integration

Transmitters must communicate with control systems, alarms, and monitoring platforms. The choice of output signal directly impacts integration complexity and scalability.

Analog Output (4–20mA)

The 4–20mA current loop is the industry standard for fixed gas detection due to its immunity to voltage drop over long distances. Our GDE820 and GDC811 models provide programmable 4–20mA outputs per channel, with defined fault states: 0–2mA for power failure, 2–2.5mA for sensor fault, 3mA during calibration, and >22mA for over-range. This enables remote diagnostics and reduces false alarm rates.

Digital Communication (RS485, Modbus)

For larger installations, RS485 with Modbus RTU protocol allows daisy-chaining of up to 32 devices on a single bus, reducing wiring costs. The GM820 controller supports automatic addressing, simplifying commissioning. This topology is ideal for facilities using centralized monitoring via SCADA or our proprietary 物联网云平台, which enables real-time data logging, remote alerts, and predictive maintenance analytics.

Relay Outputs for Local Action

Each channel in the GDA100VIR includes dual relay outputs—low alarm and high alarm—rated at 2A@120VAC/30VDC. These can trigger local 声光报警器, exhaust fans, or emergency shutdown systems without requiring external controllers. For critical processes, relay redundancy ensures fail-safe operation.

Sensor Technology Selection by Gas Type

The accuracy and longevity of a gas detection system depend on matching the sensor technology to the target gas and environment.

Infrared (IR) Sensors

Our GDE series uses infrared sensors for CH₄, C₃H₈, and other hydrocarbons. IR sensors are immune to poisoning, have a lifespan exceeding five years, and maintain ±3% accuracy even in high-humidity or high-temperature environments. They are ideal for oil refineries, LNG terminals, and chemical plants where catalytic sensors degrade rapidly.

Electrochemical and Catalytic Sensors

For toxic gases like H₂S and CO, electrochemical sensors offer high specificity and low detection limits. The GDC810 uses anti-poison catalytic sensors with a 3-year lifespan for combustible gas detection in environments with silicone vapors or high CO concentrations. These are paired with automatic zero and span calibration to minimize drift.

Smart Sensor Modules

All 格为 transmitters support pre-calibrated smart sensors that can be swapped in the field without tools. The GM810 controller automatically recognizes sensor type, range, and calibration history, reducing downtime and human error.

Essential Accessories for Reliable Operation

Even the most advanced transmitter requires proper accessories to function reliably in harsh environments.

Environmental Protection

Transmitters installed outdoors or in washdown areas require IP66-rated enclosures. Our stainless steel housing option for the GDC series resists corrosion from salt spray, acids, and cleaning agents. For explosive atmospheres, all models carry Ex d IIC T6 Gb certification for Zone 1 and 2 installation.

Power and Redundancy

Industrial systems demand uninterrupted operation. We recommend integrating backup power supplies and redundant signal paths for critical applications. The GM8 series supports hot-swappable modules, ensuring maintenance without system shutdown.

Remote Display and Control

For hard-to-reach locations, the color LED display on the GDE820 remains visible from 25 meters. Combined with infrared remote control, it allows calibration and configuration without opening the enclosure—critical in explosive atmospheres.

For large-scale deployments, our 4G and Wi-Fi modules enable cloud connectivity. Data from transmitters is streamed to the 云平台软件, where AI algorithms analyze trends, detect sensor aging, and generate predictive maintenance alerts via mobile client.

Final Checklist Before Purchase

• Confirm channel count matches the number of target gases
• Verify output types (4–20mA, RS485, relay) align with control system requirements
• Select sensor technology based on gas type, environment, and maintenance cycle
• Include accessories: weather shields, calibration kits, backup power, and communication modules
• Ensure compatibility with existing fire detection systems and 物联网平台 for unified monitoring

At 格为, we integrate AI-powered flame detection, multi-gas monitoring, and cloud intelligence into a single safety ecosystem. Our transmitters are not standalone devices—they are nodes in a proactive risk management network designed for modern industry.