EX Zones: Classification, Description & Key Characteristics with Application of HX5.EX Scales

Introduction

Hazardous areas, where flammable substances are handled or processed, pose a constant risk of explosion or fire. Industrial safety depends on clearly classifying these explosive zones (EX zones) and ensuring only certified, intrinsically safe equipment operates within them.

The HX5.EX series of intrinsically safe weighing systems exemplifies modern engineering that meets these rigorous standards. This article outlines the classification, description, and key characteristics of EX zones and shows how devices like HX5.EX scales can be used safely within them.

Understanding Explosive Atmospheres

An explosive atmosphere forms when a mix of air and flammable substances—gas, vapour, mist, or dust—reaches an ignitable concentration. When exposed to a source of ignition, such as a spark or hot surface, these mixtures can trigger devastating explosions.

In such environments, only ATEX- or IECEx-certified devices, such as the HX5.EX weighing terminals, can be used to prevent ignition. These systems are designed to operate safely even when surrounded by explosive atmospheres.

EX Zone Classification: Gases, Vapours, and Dusts

Gas/Vapour Zones

Zone	Definition	Typical Use of HX5.EX
Zone 0	Explosive atmosphere present continuously or for long periods	Not typical for weighing, but if required, HX5.EX’s Ex ia protection is suitable
Zone 1	Explosive atmosphere likely during normal operations	HX5.EX scales are widely used in Zone 1 for processes involving regular handling of flammable vapours
Zone 2	Explosive atmosphere unlikely under normal conditions, may exist briefly	HX5.EX provides reliable and compliant operation here with less stringent requirements

Dust Zones

Zone	Definition	Typical Use of HX5.EX
Zone 20	Explosive dust atmosphere present continuously	HX5.EX scales are compliant but rarely used directly in Zone 20
Zone 21	Dust atmosphere likely during regular operation	Common application area for HX5.EX, e.g., in bulk powder handling
Zone 22	Dust clouds occur only briefly and infrequently	HX5.EX terminals meet the safety standards and are suitable for Zone 22 deployments

Equipment Groups and Categories

According to ATEX Directive 2014/34/EU:

Group I: Equipment used in mines with methane or coal dust risk
Group II: Equipment used in other explosive areas (like manufacturing plants)

HX5.EX scales fall under Group II, and are available in:

Category 2G / 2D – for use in Zone 1 (gases) and Zone 21 (dusts)
Category 3G / 3D – for Zone 2 and 22, ensuring flexibility across environments

Their design ensures intrinsically safe operation, meaning they are incapable of releasing enough energy to ignite explosive mixtures, even in the event of a fault.

Temperature Classes and Surface Protection

Temperature classification defines the maximum surface temperature equipment can reach, ensuring it does not ignite the surrounding atmosphere. HX5.EX scales comply with stringent T4 (135 °C) or T6 (85 °C) temperature limits, depending on the configuration.

Additionally, the stainless-steel housing of the HX5.EX terminal is IP66/IP68 rated, offering exceptional resistance to dust ingress and moisture—critical in dust-prone Zone 21/22 environments.

Real-World Application of HX5.EX Scales in EX Zones

The HX5.EX series, including platform scales and weighing terminals, is tailored for safe use in:

Petrochemical refineries — for monitoring fluid batches
Chemical mixing facilities — managing precise quantities of reactive substances
Pharmaceutical cleanrooms — in powder filling and formulation
Food processing plants — involving dust from grains or dry ingredients

Functionality includes:

Checkweighing and dosing for hazardous material handling
Parts counting under safe conditions
ALIBI memory for audit-compliant traceability
Modular communication with IM01.EX (Ethernet, Profibus, Analog outputs)

These features ensure that weighing accuracy is not compromised by safety restrictions.

Installation & Maintenance Considerations in EX Zones

When deploying HX5.EX equipment, consider:

Proper zoning: Ensure installation aligns with the designated zone (1/2/21/22)
Cable routing: Follow intrinsic safety wiring practices and use approved conduit systems
Power supply: Use PM01.EX modules outside of hazardous zones to safely power terminals
Routine inspections: Confirm sealing, grounding, and connection integrity regularly
Calibration: Use certified personnel and explosion-safe test weights

HX5.EX systems are designed to minimise maintenance intervention, extending the lifespan of safe operation in critical areas.

Why HX5.EX is the Right Fit for EX Zones

HX5.EX scales are engineered to meet the highest standards for weighing equipment in hazardous zones:

Compliance: Fully ATEX/IECEx certified
Protection: Intrinsically safe circuits (Ex ia), flameproof designs
Durability: Resistant to dust, moisture, and corrosion
Connectivity: Integration into industrial control systems
Flexibility: Multiple models for single-load cell or multi-platform applications

By matching zone classification, category, and temperature class, HX5.EX ensures reliable weighing without compromising safety.

Conclusion

Correctly identifying EX zones and using certified equipment like the HX5.EX series is critical to industrial safety. With precise classification—Zones 0/1/2 for gases and 20/21/22 for dust—engineers and safety managers can confidently select suitable devices that protect people, assets, and productivity.

The HX5.EX series not only complies with regulations but also provides robust performance, data accuracy, and long-term reliability in explosive environments. For any operation in hazardous areas, it stands out as a trusted solution in safe and smart industrial weighing.

September 25, 2025 | View: 82 | Categories: Industrial Safety