Cematic Explosion-Proof Electric Actuators — ATEX, IECEx, and CSA Certification for Hazardous Locations

When a process valve needs to be automated in a classified area—a petrochemical plant, a refinery, an offshore platform, a solvent storage facility, an LPG plant, an industrial paint booth, or any facility with potentially explosive atmospheres—a standard electric actuator is not an option. Any spark generated by an internal electrical arc can initiate an explosion if the actuator does not have a certified housing and design to contain that event without ignition propagating to the external environment. Cematic explosion-proof electric actuators are specifically designed and certified for this condition: aluminum housing with a flameproof structure compliant with international hazardous area standards, with ATEX II 2 GD, IECEx, and CSA certifications that Cematic maintains active and up-to-date.

The Cematic Ex-proof actuator range covers three families with distinct functions: the SE series for quarter-turn with mechanical spring fail-safe (ball and butterfly valves in a predefined fail position upon power loss), the LE series for linear motion (globe and gate valves), and the OME series for standard quarter-turn with a self-locking worm gear system for higher torque. All three series share the same housing, certification, and operating temperature standards.

Why is a standard actuator NOT sufficient in classified areas?

Hazardous area (zone) classification determines the likelihood of an explosive atmosphere being present in the installation environment:

• Zone 0 / Zone 20: Explosive atmosphere continuously present. Requires Category 1 equipment—the highest protection. Very rare in process valve automation.
• Zone 1 / Zone 21: Explosive atmosphere likely during normal operation. Requires Category 2G (gases) or 2D (dusts) equipment. Cematic Ex-proof actuators are Category 2G—suitable for Zone 1 and Zone 2.
• Zone 2 / Zone 22: Explosive atmosphere unlikely—only under abnormal conditions. Requires Category 3G or 3D equipment minimum. Cematic actuators, being Category 2G, also cover Zone 2.

A standard electric actuator (without Ex certification) in Zone 1 not only represents a safety risk—it is a regulatory violation that can result in fines, facility shutdown, and legal liability in the event of an accident. The correct solution in Zone 1 is always an Ex-certified actuator of the correct category.

Hazardous area certifications available for Cematic actuators

ATEX — European Union (and international reference)

The ATEX directive (94/9/EC, updated to 2014/34/EU) is the European regulatory framework for equipment in potentially explosive atmospheres. The ATEX marking for Cematic actuators is:

• II 2 GD — Group II (surface, not mining), Category 2 (Zone 1/2 for gases, Zone 21/22 for dusts), G (gas) and D (dust)
• Ex db IIB T4 Gb — Explosion-proof enclosure (db), Gas Group IIB (includes propane, ethylene—covers most industrial gases), Temperature Class T4 (max surface 135 °C), protection level Gb (Zone 1)
• Ex tb IIIC T130°C Db — Protection by enclosure for dusts (tb), Group IIIC (conductive dusts—the most restrictive group), max surface temperature 130°C, protection level Db (Zone 21)
• Applied standards: EN IEC 60079-0 (general requirements), EN 60079-1 (flameproof enclosures), EN 60079-31 (protection by enclosure for dusts)

IECEx — International Recognition

The IECEx scheme is the international equivalent of ATEX, recognized in over 50 countries outside the European Union. The IECEx marking for Cematic actuators is technically identical to ATEX: Ex db IIB T4 Gb / Ex tb IIIC T130°C Db, under standards IEC 60079-0, IEC 60079-1, and IEC 60079-31. This certification facilitates the acceptance of actuators in multinational projects and in Mexican facilities operated under international standards by major oil companies or global engineering firms.

CSA — North American Certification

CSA (Canadian Standards Association) certification is the recognized hazardous area standard in Canada and the United States, applied in two systems:

• Zone System:
  • Class I Zone 1, Groups IIA and IIB — for gases (SE and OME series at -30°C to +70°C; LE series at -30°C to +65°C)
  • Class II Zone 21, Groups IIIA, IIIB, and IIIC — for dusts
  • Standards: CAN/CSA-C22.2 No. 60079-0, 60079-1, 60079-31 / UL 60079-0, 60079-1, 60079-31
• Division System:
  • Class I Division 1, Groups C and D, T4 — for flammable gases (SE and OME series)
  • Class II Division 1, Groups E, F, and G, T130°C — for dusts (SE and OME series)
  • Standards: CAN/CSA-C22.2 No. 30-M1986, CSA C22.2 No. 25-17, FM 3600, FM 3615, FM 3616

CSA certification is crucial for projects involving US or Canadian companies, contracts with international majors in Mexico, and export projects for facilities to North America.

SE Series — Quarter-Turn Actuator with Fail-Safe Spring Return

The SE series is the Ex-proof solution for ball and butterfly valves where a fail-safe position upon electrical power loss is a process safety requirement. Unlike actuators with battery or capacitor fail-safe—which rely on a stored energy source that can degrade over time—the mechanical spring of the SE series stores kinetic energy during normal operation and releases it instantly and reliably upon any loss of power, without relying on any active electronic component at the moment of emergency.

SE Technical Specifications

• Mechanism: Rack and pinion with spring return. The spring compresses during motor operation and releases upon power loss, moving the valve to the predefined fail position.
• Standard fail position: Fail Clockwise (FC). Option available: Fail Counter-Clockwise (FCC). Important: the fail direction must be specified at the time of order—it is not field adjustable.
• Mechanical buffer: For ON/OFF models, a mechanical buffer at the end of the spring stroke reduces the water hammer effect in piping—protects the installation from the impact of rapid spring closure.
• Standard ON/OFF control. Options: floating control and modulating control 4–20 mA / 1–5 V / 2–10 V (with potentiometer included)
• Clutchless manual override (optional): Allows manual operation of the valve during power loss. The handwheel does not rotate during motor operation—operator safety guaranteed.
• Protection: IP68 — 7 meters for 72 hours. The highest protection available in industrial actuators.
• Duty cycle: 50%
• Motor insulation: Class F
• Operating temperature: -30 °C to +70 °C
• Relative humidity: 30 to 95%

Available SE Models

Operating times based on 110 VAC / 60 Hz / 50% duty cycle / ON/OFF control.

Available SE Voltages

24 VAC, 24 VDC, 110–120 VAC, 220–240 VAC, 380 VAC, 440 VAC.

Typical SE Applications

• Ball and butterfly isolation and shut-off valves in hydrocarbon lines in petrochemical, refinery, and fuel storage facilities
• Emergency Shut-Down (ESD) valves in natural gas and LPG plants where power loss must result in automatic valve closure
• Vent and purge systems in facilities with flammable gases where fail-safe is closure
• Solvent and industrial paint plants in Zone 1
• Offshore platforms and onshore production facilities with Zone 1 classification

LE Series — Explosion-Proof Linear Actuator for Globe and Gate Valves

The LE series converts the motor's rotational motion into linear motion (axial stem displacement), enabling the automation of globe valves, non-rising stem gate valves, and any other linear motion control device in classified areas. All LE models include modulating control as standard—it is not an option, it is standard—making them the direct solution for PID control loops of temperature, pressure, and flow with globe valves in Zone 1.

LE Technical Specifications

• Motion type: Linear—axial displacement of the valve stem
• Maximum stroke: 50 mm (2 inches) for LE-250 and LE-500; 100 mm (4 inches) for LE-1000 and LE-2000. Adjustable stroke to adapt to the specific travel of the valve stem.
• Standard modulating control: Included in all models—2 force switches for overload protection and modulating control integrated from the factory.
• DC Motor: 75% duty cycle—the highest cycle of the three series, suitable for control loops with frequent positioning.
• Linear speed: 0.46 mm/sec (0.018 in/sec) in all models.
• Thrust overload protection: Force switches cut off the motor when the output force exceeds the rated value—protects both the actuator and the valve stem and seat from mechanical obstructions.
• Interface: ISO 5210 (interface standard for linear valve actuators—linear equivalent of rotary ISO 5211)
• Protection: IP68 — 7 meters for 72 hours
• Duty cycle: 75% (DC motor)
• Operating temperature: -30 °C to +70 °C (ATEX/IECEx); -30 °C to +65 °C (CSA)

Available LE Models

Speed based on 110 VAC / 60 Hz / 75% duty cycle.

Available LE Voltages

24 VAC, 24 VDC, 110–120 VAC, 220–240 VAC.

Typical LE Applications

• Globe control valves in PID temperature loops for heat exchangers in refineries and petrochemical plants
• Globe valves for process steam flow regulation in Zone 1 plants
• Non-rising stem gate valves in hydrocarbon process lines where modulating control is required
• HVAC systems in industrial buildings with the presence of flammable gases (paint, solvents)

OME Series — Ex-proof Quarter-Turn Actuator with Self-Locking Worm Gear

The OME series is the explosion-proof version of the standard quarter-turn actuator in the Cematic range, with a key constructive difference from the SE series: instead of the rack and pinion mechanism, it uses a self-locking worm drive system that provides quieter operation, higher positioning accuracy, and higher available torque in larger models. It does not incorporate a fail-safe spring—in case of power loss, the valve remains in its last position (fail-last). This is the option when the correct fail position is to maintain the last position, or when higher operating torque is required for large diameter or high differential pressure valves.

OME Technical Specifications

• Mechanism: Self-locking worm drive—prevents position rollback due to vibration or differential pressure without additional braking
• Adjustable mechanical stops: Available on all models except OME-1, OME-A, and OME-AM—allow limiting the actual open and close travel in the field
• Standard control: ON/OFF and floating (2 SPDT limit switches + torque switches, except OME-1, OME-A, and OME-AM). Modulating optional.
• Clutchless manual override: Standard on all models except OME-A. The handwheel does not rotate during motor operation.
• Protection: IP66 and IP68 (7 meters / 72 hours)
• Duty cycle: 30%
• Motor insulation: Class F
• Operating temperature: -30 °C to +70 °C
• Available voltages: 12 VDC, 24 VAC, 24 VDC, 110–120 VAC, 220–240 VAC

Available OME Models

Operating times based on 110 VAC / 60 Hz / 30% duty cycle / ON/OFF or floating control.

Typical OME Applications

• Ball and butterfly valves in refinery and petrochemical process areas where the fail-last position is the correct safety mode
• Large diameter valves in oil and gas production manifolds where higher torque is required than available in the SE series
• Industrial paint booths and solvent plants in Zone 2
• Chemical industry with zone classification due to the presence of solvent vapors, acids, or hydrocarbons

Options and accessories common to all three series

Anti-condensation — Heater Resistor

Available in all three series (SE, LE, and OME). Raises the internal temperature of the actuator to prevent lubricant freezing and keep the interior dry in environments with high temperature variations. Not recommended if the ambient temperature continuously exceeds 35 °C. It is recommended to combine with a heater thermostat to avoid unnecessary overheating.

Heater Thermostat

Available in all three series. Disconnects the heater resistor when the internal temperature exceeds 25 ±5 °C, optimizing heating power consumption.

Auxiliary Limit Switches (LS3 and LS4)

Available in SE and OME. Actuators come from the factory with two limit switches (LS1 for fully open position, LS2 for fully closed position). Optional auxiliary LS3 and LS4 provide additional feedback signals for intermediate positions or for multiple signaling systems.

Modulating Control with Potentiometer

Available in SE and OME (standard in LE). Converts the actuator into a proportional positioning device with analog signal. Accepted inputs: 4–20 mA, 1–5 V, 2–10 V. Feedback output: 4–20 mA and 2–10 V.

Analog Position Output

Available in OME (OME-2 to OME-8 models). For use with ON/OFF or floating control actuators that require continuous position signal without needing to switch to modulating mode. Selectable outputs: 0–20 mA, 4–20 mA, 0–5 V, 0–10 V, 1–5 V, 2–10 V.

Modbus RTU RS-485 Communication

Available in the LE series. Allows direct integration with PLCs and SCADA systems via Modbus RTU protocol over RS-485, without the need for additional analog signals. Up to 32 actuators in a daisy chain over a single pair of wires.

Conduit Entries

Standard: 2 × ½" NPT on all series. Available options: 2 × ¾" NPT (SE and LE, and OME-2 to OME-8); 2 × M20 (all series); 2 × M25 (SE and LE, and OME-2 to OME-8). For OME versions with JPEx (Japan) certification, it is mandatory to use the A2F series cable gland from CMP Products Ltd. to comply with Japanese hazardous area standards.

Fail-Safe Direction — SE Series

Applies only to the SE series. Standard: fail clockwise (closes the valve upon power loss in the standard configuration). Option: fail counter-clockwise. Fail direction is NOT field-adjustable — it must be specified at the time of order.

Ex-proof series selection guide by application

Main Industries and Applications in Mexico

• Oil and Gas (PEMEX, IPPs, private companies): Field production facilities (wellheads, manifolds, separators), natural gas compression stations, hydrocarbon storage terminals, and offshore platforms. The SE series with spring fail-safe is the standard for ESD valves in this sector. ATEX and IECEx certification for projects with international standards.
• Refining and Petrochemical: Process valves in distillation, cracking, reforming units, and petrochemical production. The LE series for precise control of globe valves in temperature loops; the OME series for large diameter isolation valves in manifolds classified as Zone 1.
• LPG and Natural Gas Distribution: Regulation and metering stations, LPG distribution plants, and distribution pipelines with Zone 1 in the vicinity of metering and regulation equipment.
• Chemical Industry with Solvents: Plants producing paints, lacquers, adhesives, solvents, and resins where the presence of organic solvent vapors classifies production areas as Zone 1 or Zone 2.
• Industrial Paint Booths: Electrostatic and conventional application paint booths in automotive plants, metal furniture manufacturing, and industrial equipment, where paint vapors generate Zone 1 classification indoors and Zone 2 in the immediate vicinity.
• Fuel Storage and Terminals: Gasoline, diesel, jet fuel, and fuel oil tanks, loading and unloading arms in liquid fuel storage and distribution terminals.
• Natural Gas Power Generation: Combined cycle plants, cogeneration plants, and thermal power plants with natural gas supply, where areas around the fuel system are classified as Zone 1 or Zone 2.
• Mining with Flammable Reagents: Processing plants using organic solvents in the solvent extraction (SX) process for copper recovery, and any mining process with flammable fluids in the plant.

The Cematic Advantage in Ex-proof Actuators

Having active ATEX certification is not merely having a stamp on the product — it implies maintaining up-to-date technical documentation, traceability of certification records, and the ability to provide the certification documents required by safety engineers, industrial insurers, and ASEA (Agency for Safety, Energy and Environment) inspectors in regulated projects. Cematic provides with each Ex-proof actuator:

• ✅ ATEX / IECEx Declaration of Conformity with certificate number
• ✅ Datasheet with full Ex marking (II 2 GD Ex db IIB T4 Gb / Ex tb IIIC T130°C Db)
• ✅ Installation and Operation Manual in hazardous areas (IOM Ex)
• ✅ CSA Certificate for projects with North American requirements
• ✅ Advice on selecting the correct series (SE / LE / OME) according to the zone, valve type, and required fail-safe mode
• ✅ Formal technical quotation with complete specification on the same business day

Stock available in Mexico City for the most demanded models. Shipments throughout the Mexican Republic including industrial areas of Tabasco, Veracruz, Tamaulipas, Nuevo León, and Coahuila. Contact us via WhatsApp or at ventas@cematic.com.