In hazardous environments where flammable gases, vapors, or dust are present, ordinary electrical equipment can pose significant safety risks. That’s why explosion-proof electric actuators are critical for industrial facilities. These actuators are specifically designed to prevent the ignition of explosive atmospheres, ensuring safe and reliable operation for valve control in industries such as petrochemical, natural gas, power generation, and chemical processing.

However, not all explosion-proof actuators are built the same. Selecting the right one requires careful consideration of multiple technical and safety factors. Beyond torque and mounting size, you need to ensure the actuator's certification, construction, and control system align with your operational environment. To help guide your selection, here are the five key factors to consider when choosing an explosion-proof electric actuator.

Verify Explosion-Proof Certifications and Standards

The first and most important step is to confirm that the actuator meets the required explosion-proof classification for your operating zone. Globally, the two primary certification systems are ATEX (Europe) and IECEx (International), both defining strict criteria for electrical equipment used in hazardous areas.

Each classification includes several key parameters:

• Zone – Indicates how frequently an explosive atmosphere is present (Zone 1 or Zone 2 for gas; Zone 21 or Zone 22 for dust).
• Gas or Dust Group – Specifies the type of hazardous substance (e.g., IIA, IIB, IIC for gases; IIIC for dust).
• Temperature Class – Determines the maximum surface temperature the equipment can reach (T1–T6).

For example, Sun Yeh’s explosion-proof actuators comply with II 2 GD Ex db IIB T4 Gb / Ex tb IIIC T130°C Db, meaning they are flame-proof and dust-tight, suitable for environments containing Group IIA and IIB gases or combustible dust. Always verify that your actuator’s certification matches the specific zone, gas group, and temperature class of your facility.

Select the Proper Torque or Thrust Rating

Torque and thrust are fundamental performance criteria for any actuator. The actuator must generate sufficient force to operate the valve under all conditions — including pressure fluctuations, temperature changes, or long-term wear.

Undersized actuators can fail to close or open the valve completely, leading to potential leaks or process disruptions, while oversized units may damage the valve or increase costs unnecessarily.

When determining torque or thrust requirements, consider:

• Valve type – Ball, butterfly, plug, or globe valves each require different torque profiles.
• Operating conditions – Fluid pressure, viscosity, and flow rate all affect torque demand.
• Safety margin – Always add an additional 25–30% torque margin for reliable performance.

Sun Yeh’s OME Series explosion-proof electric actuators offer torque ranges from 35 Nm to 4500 Nm, covering everything from small control valves to large industrial pipelines, ensuring precise and safe valve movement in hazardous areas.

Evaluate Environmental Protection and Material Durability

An actuator’s explosion-proof certification doesn’t necessarily mean it’s suitable for outdoor or wet environments. You should also verify its IP rating (Ingress Protection), which defines the actuator’s resistance to dust and water.

For most industrial applications, IP67 or higher is recommended, providing protection against water immersion and airborne dust particles. In addition, consider the following aspects:

• Corrosion resistance: Look for anodized aluminum or epoxy-coated housings for chemical plants or coastal facilities.
• Ambient temperature range: Ensure the actuator can operate in extreme heat or cold; internal heaters may be required in low temperatures.
• Vibration and impact resistance: Necessary for offshore, mining, or heavy machinery applications.

Sun Yeh explosion-proof actuators are built with robust aluminum alloy housings and NEMA 4X/IP67 protection, providing outstanding resistance against moisture, corrosion, and mechanical impact.

Determine Control Type and Fail-Safe Functionality

Explosion-proof actuators can operate in two primary control modes — On/Off or Modulating.

• On/Off Control: Designed for fully open or fully closed valve positions, ideal for isolation or emergency shut-off operations.
• Modulating Control: Allows proportional movement according to input signals such as 4–20 mA or 0–10 V, suitable for precise flow or pressure regulation.

For applications requiring enhanced safety, a fail-safe mechanism is strongly recommended. This feature ensures the actuator automatically returns to a predefined safe position during a power failure.

Sun Yeh’s SE Series integrates a spring-return fail-safe system, which mechanically returns the valve to its safe position without relying on external power. This is especially critical in hazardous operations like refineries, gas treatment plants, or chemical reactors, where even a brief power interruption can pose risks.

Check Installation Compatibility and Maintenance Accessibility

Lastly, ensure that the actuator is compatible with your valve and easy to install and maintain. Look for compliance with the ISO 5211 mounting standard, which ensures seamless compatibility with most industrial valves. This standard also makes actuator replacement or upgrade easier without additional adapters.

Other practical design features to consider include:

• Manual override for manual operation during emergencies.
• Mechanical position indicator for quick valve position verification.
• Clear terminal layout for safe and efficient wiring.
• Modular design for simplified servicing and part replacement.

Sun Yeh actuators are designed with the user in mind — featuring wide terminal compartments, easy-access covers, and handwheel overrides for quick and safe operation even under field conditions.

Conclusion: Prioritizing Safety, Reliability, and Compliance

Selecting the right explosion-proof electric actuator is not just about technical specifications — it's about ensuring safety, efficiency, and long-term reliability in hazardous environments. By paying close attention to certification, torque, protection level, control type, and installation features, you can significantly reduce operational risks and downtime.

With over three decades of experience, Sun Yeh Electrical Ind. Co., Ltd. provides a comprehensive range of explosion-proof electric actuators — including the OME, SE, and LE Series — all certified to international standards and engineered for maximum safety and durability.

Whether you need compact models for space-limited applications or high-torque solutions for heavy industrial use, Sun Yeh delivers performance and reliability you can trust.

👉 Learn more about our explosion-proof actuator lineup at Sun Yeh Official Website.