Selection Guide for Explosion-Proof IoT Gateways in the Chemical Industry: A Comparison of Ex d and Ex i Certified Devices
In the chemical industry, explosion-proof IoT gateways serve as the core equipment for ensuring production safety and stable data transmission. Faced with flammable and explosive gas environments (such as ethylene, hydrogen, methanol vapor, etc.), the explosion-proof performance of gateways directly determines the reliability of equipment operation and personnel safety. However, there are significant differences between the two mainstream explosion-proof certified devices, Ex d (flameproof type) and Ex i (intrinsic safety type), in terms of principles, applicable scenarios, costs, and maintenance. This article provides a selection guide for chemical enterprises through in-depth comparisons and case analyses, along with a convenient channel to obtain quotations via a form.
- Core Logic of Explosion-Proof Certification: From Principles to Classification
1.1 Ex d (Flameproof Type): The "Steel Tough Guy" with Physical Defense
Ex d certified devices construct a physical barrier through a thick-walled casing (≥3mm steel plate), with the core principle of "pressure relief and temperature reduction." When an electrical spark or high temperature inside the circuit triggers an explosion, precisely designed gaps (≤0.2mm) can contain the explosion energy within the casing and reduce the temperature through pressure relief channels, preventing the ignition of external gases.
Applicable Scenarios: Suitable for Class ⅡC hydrogen environments (the most severe operating conditions), such as hydrogen storage tank areas and ammonia synthesis workshops. Its advantage lies in its ability to withstand extreme explosion pressures, but its drawbacks are evident: the casing is bulky (40% heavier than ordinary equipment), and it is strictly prohibited to open the cover for inspection while powered on. It requires professional tools for disassembly and assembly, leading to high maintenance costs.
1.2 Ex i (Intrinsic Safety Type): The "Soft Overcomes Hard" Approach with Energy Limitation
Ex i certified devices eliminate the possibility of electrical sparks igniting gases at the source by limiting circuit energy (voltage ≤ 30V, current ≤ 100mA). The core logic is "energy threshold control," ensuring that even if a spark occurs due to equipment failure, the energy is insufficient to ignite explosive mixtures.
Applicable Scenarios: Suitable for Zone 0 (continuous presence of explosive gases), Zone 1 (possible presence), and Zone 2 (only present during abnormalities) environments, especially for intelligent instruments and sensors that require frequent debugging. Its advantage lies in supporting inspection with the cover open while powered on (in a safe area), but it requires the use of safety barriers and has limited transmission distances (usually ≤ 500m).
1.3 Explosion-Proof Classification and Gas Groups: The "Golden Rule" for Selection
According to the national standard GB/T 3836-2021, explosion-proof equipment must be clearly labeled with gas groups and temperature groups:
Gas Groups: ⅡA (propane, universal for three types) → ⅡB (ethylene, excluding Ex e) → ⅡC (hydrogen, only Ex d/i applicable).
Temperature Groups: T1 (450℃, suitable for ammonia gas) → T4 (135℃, mandatory for methanol facilities) → T6 (85℃, for highly sensitive gases like ether).
Case Warnings: A petrochemical enterprise mistakenly used an Ex e motor in a Zone 1 ethylene environment, where operating sparks ignited leaking gas, resulting in direct losses of 8 million yuan. Another enterprise ignored T4 requirements during selection, and an overheated junction box ignited methanol vapor, triggering a plant-wide shutdown. - In-Depth Comparison of Ex d vs. Ex i: Four Key Dimensions
2.1 Cost and Maintenance: The "Invisible Ledger" of Long-Term Investment
Ex d Devices: The initial procurement cost is relatively high (due to thick-walled casings and precision machining), but a single device can have a lifespan of over 10 years. Maintenance requires a professional team, and each inspection requires power-off operations, leading to high downtime costs.
Ex i Devices: The initial cost is lower (without thick-walled casings), but safety barriers are required (increasing costs by 10%-15%). Online maintenance is supported, reducing downtime and resulting in lower long-term operation and maintenance costs.
Data Support: A comparative test in a chemical park showed that the total cost of ownership (TCO) of Ex d devices over 5 years was 23% higher than that of Ex i devices, with the main differences lying in maintenance labor and downtime losses.
2.2 Applicable Scenarios: From "Extreme Environments" to "Smart Upgrades"
Ex d Devices: Suitable for scenarios with high explosion risks, fixed equipment, and no need for frequent debugging, such as hydrogen compressor rooms and storage tank areas.
Ex i Devices: Suitable for scenarios requiring digital signal transmission, remote monitoring, or intelligent control, such as DCS control systems and wireless sensor networks.
Trend Insights: With the popularization of the Industrial Internet of Things (IIoT), Ex i devices are gradually replacing some Ex d devices due to their support for digital protocols (such as MQTT, OPC UA) and edge computing. - Scalability and Compatibility: The "Elastic Space" for Future Upgrades
Ex d Devices: Hardware scalability is limited, and adding IO interfaces requires replacing the entire unit. Protocol compatibility relies on custom development by manufacturers.
Ex i Devices: Support modular expansion (e.g., the USR-M300 can be externally connected to 6 expansion units, each supporting 8 IO channels), and have stronger protocol compatibility (supporting over 200 protocols such as Modbus, Profinet, and EtherCAT).
Case Application: A large refinery adopted the USR-M300 intrinsic safety gateway, achieving multi-protocol conversion through graphical programming and uploading data from 12 brands of inverters to Alibaba Cloud, reducing deployment time by 60%. - IoT Gateway USR-M300: The "All-Rounder" for Explosion-Proof Gateways in the Chemical Industry
In the intelligent transformation of the chemical industry, the USR-M300, with its core advantages of "intrinsic safety design + edge computing + flexible expansion," has become the preferred solution for explosion-proof gateways:
Explosion-Proof Certification: Passed Ex i IIC T4 Gb certification, supporting deployment in Zones 0 to 2, and can be directly connected to equipment in high-risk areas such as hydrogen and ethylene.
Edge Computing: Built-in 1.2GHz dual-core CPU, supporting 2000 real-point acquisitions and logical operations. It can locally process analog data such as temperature and pressure, uploading only abnormal values and reducing bandwidth usage by 30%.
Protocol Compatibility: Supports protocols such as Modbus RTU/TCP, OPC UA, and Profinet, enabling seamless connection to PLCs, sensors, instruments, and other equipment, solving the problem of digital transformation of legacy systems.
Flexible Expansion: The main unit integrates 2DI/2DO/2AI interfaces and supports the external connection of 6 expansion units (8 IO channels per unit), meeting the complex control needs of chemical workshops.
Security Protection: Supports SSL encryption, VPN tunnels, and firewall functions, complying with the requirements of Class III of the Cybersecurity Classification Protection 2.0, ensuring secure data transmission.
Typical Scenarios:
Hydrogen Storage Tank Area: The Ex i certified USR-M300 collects pressure and temperature data in real-time. When parameters exceed thresholds, it triggers local alarms and activates shut-off valves while uploading data to the cloud, achieving three-level protection of "local-edge-cloud."
Ethylene Cracking Workshop: The gateway is compatible with the Profinet protocol, connecting to Siemens S7-1500 PLCs. Through edge computing, it optimizes the temperature control of cracking furnaces, reducing coking phenomena and saving over 500,000 yuan in annual energy consumption costs. - Selection Decision Tool: Three Steps to Obtain a Customized Solution
To help chemical enterprises make precise selections, we offer the following services:
Submit a Requirement Form: Visit our official website and fill in key information such as plant size, equipment type, communication protocol, and explosion-proof area.
Free Solution Evaluation: Our expert team matches Ex d/Ex i devices based on requirements, providing protocol compatibility, cost calculations, and deployment topology diagrams.
Faced with the dual challenges of safety and efficiency in the chemical industry, selecting an appropriate explosion-proof IoT gateway is not only a technical decision but also a commitment to life and assets. The USR-M300, with its "intrinsic safety as the foundation and intelligence as the wings," helps chemical enterprises move towards a safe, efficient, and sustainable future.
