ATEX Weighing Equipment Explained, A Complete Guide to Safe Weighing in Hazardous Areas

When weighing operations take place in environments containing flammable gases, vapours or combustible dusts, safety becomes just as important as accuracy. Standard industrial weighing equipment can introduce ignition risks that make it unsuitable for hazardous locations, which is why ATEX certified weighing equipment exists.

Whether you are installing a simple bench scale in a solvent dispensing room or integrating load cells into a large chemical process vessel, selecting the correct ATEX equipment is a legal and operational requirement.

At WOMAG, we supply a comprehensive range of ATEX weighing equipment including:

Our solutions are designed for industries including pharmaceutical manufacturing, chemical processing, food production, grain handling, paint manufacture, oil and gas, and any environment classified under DSEAR regulations.

How Hazardous Area Weighing Has Changed

Many years ago, hazardous area weighing installations were often large, expensive and complicated.

Traditional systems commonly relied on:

  • Explosion-proof (Ex d) enclosures
  • Heavy flameproof junction boxes
  • Dedicated hazardous area indicators
  • Complex cabling installations
  • Specialist maintenance whenever equipment required servicing

Although these systems were safe, they were often difficult to maintain and expensive to install.

Modern intrinsically safe technology has transformed hazardous area weighing.

Today's systems limit electrical energy so that sparks or excessive heat cannot ignite an explosive atmosphere. This approach allows much simpler installations while maintaining the highest levels of safety.

Benefits include:

  • Smaller and lighter equipment
  • Lower installation costs
  • Easier maintenance
  • Improved reliability
  • Greater flexibility for future expansion

Understanding ATEX Zones

One of the most common mistakes is assuming all hazardous areas require the same equipment.

In reality, hazardous environments are classified into different zones depending on how frequently an explosive atmosphere is likely to occur.

Gas and Vapour Zones

Zone 0

An explosive atmosphere is present continuously or for long periods.

Typical examples:

  • Inside storage tanks
  • Solvent vessels
  • Process reactors

Equipment requirements are extremely stringent.

Zone 1

An explosive atmosphere is likely during normal operation.

Examples include:

  • Chemical dosing rooms
  • Solvent filling stations
  • Paint mixing areas

Many intrinsically safe weighing systems are designed specifically for Zone 1.

Zone 2

An explosive atmosphere is not normally present but may occur occasionally under fault conditions.

Typical locations include:

  • Packaging areas
  • Storage rooms
  • Transfer stations

Zone 2 generally offers greater flexibility when selecting equipment.

Dust Hazard Zones

Dust explosions are often overlooked, yet they can be equally dangerous.

Zone 20

Combustible dust is continuously present.

Zone 21

Combustible dust is likely during normal operation.

Common industries include:

  • Flour milling
  • Animal feed production
  • Pharmaceutical powder handling
  • Wood processing

Zone 22

Dust is only present occasionally.

Examples include:

  • Warehouses
  • Packaging areas
  • Bulk ingredient stores

WOMAG supplies weighing equipment certified for Zone 1, Zone 2, Zone 21 and Zone 22 installations.

 

An infographic titled 'WOMAG Understanding ATEX Zones' with color-coded panels for gas and vapour zones (red, orange, green) and dust zones (black, gray) showing zone numbers, risk levels, and industrial illustrations.

Intrinsically Safe vs Explosion Proof

These two terms are often confused.

Intrinsically Safe (Ex i)

Intrinsic safety works by limiting voltage and current so that electrical energy is never high enough to ignite an explosive atmosphere.

Advantages include:

  • Lower installation costs
  • Easier servicing
  • Reduced maintenance
  • Compact equipment
  • Ideal for weighing systems

Explosion Proof (Ex d)

Explosion-proof equipment assumes an ignition may occur inside the enclosure.

Instead of preventing ignition, the enclosure contains the explosion so it cannot escape into the surrounding atmosphere.

These systems are generally:

  • Larger
  • Heavier
  • More expensive
  • More difficult to maintain

For many weighing applications, intrinsically safe systems provide the most practical solution.

What Is a Zener Barrier?

One of the most important components of an intrinsically safe weighing system is the Zener Barrier.

A Zener Barrier is installed between the safe area and the hazardous area.

Its purpose is to limit:

  • Voltage
  • Current
  • Electrical energy

If a fault occurs on the safe side, the barrier prevents excessive electrical energy from entering the hazardous zone.

Think of it as an electrical safety gate.

Without the barrier, a fault could potentially provide enough energy to ignite gas or dust.

Typical applications include connecting:

  • Load cells
  • Junction boxes
  • Weight transmitters
  • Remote displays
  • Sensors

to equipment located outside the hazardous area.

Galvanic Isolators vs Zener Barriers

Modern installations increasingly use galvanic isolators rather than traditional Zener barriers.

Galvanic isolators provide the same protection while offering additional advantages:

  • No dedicated earth connection required
  • Improved noise immunity
  • Easier installation
  • Better signal integrity over long cable runs

The correct choice depends on the application, cable lengths and system design.

Intrinsically Safe Power Supplies

Power supplies play a critical role in hazardous area installations.

An intrinsically safe power supply limits the maximum electrical energy delivered into the hazardous area while maintaining stable operation of the weighing system.

These certified power supplies are designed to work alongside:

  • Weight indicators
  • Load cells
  • Junction boxes
  • Transmitters
  • Process control equipment

Using an incorrect power supply can invalidate the ATEX certification of the entire installation.

For this reason, hazardous area systems should always be designed as a complete certified solution rather than assembled from incompatible components.

Choosing the Right ATEX Weighing Equipment

Every application is different.

Questions worth considering include:

  • Which ATEX zone is the equipment installed in?
  • Is the hazard gas or combustible dust?
  • What weighing capacity is required?
  • Is high precision needed?
  • Does the equipment integrate with PLCs or SCADA?
  • Is stainless steel construction required?
  • Will the equipment require washdown?
  • Is trade approval required?

Selecting equipment based solely on capacity or price can lead to costly mistakes if certification requirements are overlooked.

Typical Applications

ATEX weighing equipment is commonly used for:

  • Chemical processing
  • Pharmaceutical production
  • Paint manufacture
  • Solvent dispensing
  • Oil and gas
  • Grain storage
  • Flour mills
  • Food ingredient handling
  • Battery manufacturing
  • Recycling plants
  • Bulk storage vessels
  • Process dosing systems

Why Choose WOMAG?

WOMAG supplies complete hazardous area weighing solutions, not simply individual scales.

Our engineers can assist with:

  • Equipment selection
  • System design
  • Load cell integration
  • Process weighing
  • Commissioning
  • Calibration
  • Ongoing servicing

Whether you require a single ATEX bench scale or a fully integrated vessel weighing system, our team can help specify equipment that complies with both ATEX requirements and your operational needs.

Frequently Asked Questions

What does ATEX stand for?

ATEX comes from the French term ATmosphères EXplosibles and refers to equipment designed for use in potentially explosive atmospheres under the ATEX Directive 2014/34/EU.

What is DSEAR?

DSEAR stands for the Dangerous Substances and Explosive Atmospheres Regulations. It requires UK employers to identify hazardous areas, carry out risk assessments and ensure suitable certified equipment is installed.

Can standard weighing scales be used in hazardous areas?

No. Standard electrical equipment may create sparks or heat capable of igniting explosive gases or combustible dust.

What is the purpose of a Zener Barrier?

A Zener Barrier limits electrical energy entering the hazardous area, ensuring faults on the safe side cannot create an ignition source.

Is a galvanic isolator better than a Zener Barrier?

Neither is universally better. Galvanic isolators are often easier to install and provide improved electrical isolation, while Zener Barriers remain widely used in many certified installations.

Can the weight indicator remain outside the hazardous area?

Yes. Many intrinsically safe systems locate the indicator in a safe area while connecting to certified load cells through approved barriers or isolators.

Can ATEX weighing systems integrate with PLCs?

Yes. Modern hazardous area weighing systems can communicate with PLCs, SCADA systems, batching software and process control equipment using certified interfaces.

Can ATEX equipment be calibrated?

Yes. ATEX weighing equipment can be calibrated and serviced using approved safe working procedures by suitably qualified engineers.

Do I need to know my ATEX zone before purchasing equipment?

Absolutely. The hazardous area classification determines which equipment can legally and safely be installed. If you are unsure, your DSEAR assessment or hazardous area survey should identify the correct zone before equipment is specified.