Focus on safety -
With ATEX-compliant systems and test cabinets

Depending on the environment and application in which explosive atmospheres may occur, safety is of paramount importance. The ATEX directive provides a binding framework for the design, construction, testing, and operation of systems and test chambers that are used in potentially explosive environments or in which an explosive atmosphere may occur.

Users: Responsibility and caution
ATEX Workplace Directive 1999/92/EC (ATEX 137)
Applies to the operator and stipulates that a risk assessment must be carried out in potentially explosive areas and a comprehensive explosion protection concept must be drawn up. This includes identifying potential ignition sources, assessing explosion risks, and implementing appropriate protective measures. Regular training of personnel and review of safety protocols are essential components of ensuring safe operation.

Manufacturers: Safety and conformity of ATEX equipment
ATEX Product Directive 2014/34/EU (ATEX 114)
Applies to equipment manufacturers. The directive regulates the design, manufacture, and conformity assessment of equipment and protective systems used in potentially explosive atmospheres. Suitable materials and technical solutions must be selected as early as the design phase in order to rule out ignition sources under all operating conditions. Customer risk assessments and explosion protection concepts form an essential basis for evaluation.

Each system undergoes a conformity assessment procedure to verify its safety. After completion, the systems undergo official testing by a certified testing service provider (e.g., TÜV, DEKRA, IBExU).

Once this testing has been completed and the reports evaluated, the systems may be placed on the market and operated in ATEX zones. Compliance with this directive is not only a matter of safety, but also a sign of quality and reliability.

National regulations are crucial for the successful implementation of and compliance with ATEX guidelines. In Germany, these include DGUV Information 213-850 “Safe Working in Laboratories,” the Industrial Safety Regulation (BetrSichV), the Hazardous Substances Regulation (GefStoffV), and the Technical Rule for Industrial Safety (TRBS) 1201 Part 1. These regulations provide a detailed framework for the installation and operation of equipment, taking into account the risk of explosion.

Risk assessment is an essential part of explosion protection and must be carried out by a competent plant operator. The aim is to systematically identify and assess all potential explosion hazards. This also includes dividing the work area into zones based on the frequency and duration of an explosive atmosphere.

Technical, organizational, and personnel protective measures are defined on the basis of this analysis. These are incorporated into the explosion protection concept, which pursues three central objectives:

• To prevent or significantly reduce the formation of explosive atmospheres
• To reliably prevent ignition sources
• To effectively limit the effects of an explosion

A clearly structured and practical explosion protection concept ensures that plants and work processes can be operated safely even in potentially explosive areas.

A key legal and technical document is the explosion protection document, which must be prepared by the operator in accordance with Section 6 (9) of the Hazardous Substances Ordinance (GefStoffV). It provides comprehensive documentation that all hazards have been identified, assessed, and secured with effective measures.

It contains:

• Results of the risk assessment
• Zone classification
• Defined protective measures
• Inspection and maintenance intervals
• Documentation of effectiveness checks

The document must be created before the system is put into operation and updated whenever there is a relevant change to the system, the process, or the substances used. This is the only way to ensure that explosion protection remains permanently effective, traceable, and legally compliant.

Compliance with the ATEX directives is not only a legal obligation, but also a clear promise of quality. It stands for precise design, standard-compliant manufacturing, consistent testing, and complete documentation – the cornerstones of maximum operational safety.

Our common goal is clear: to protect people and equipment in potentially explosive areas. Those who consistently implement these standards not only protect lives, but also ensure the longevity, operational safety, and efficiency of the technology used.

For series-produced systems, a certificate of conformity and the corresponding certificates from the manufacturer are usually available. This means that no additional external testing is necessary as long as no changes are made to the device.

In the case of custom-developed systems or test cabinets, however, acceptance and certification by an approved testing agency (e.g., TÜV, DEKRA, IBExU) is required after completion. Only with this confirmation may the devices be placed on the market and used in ATEX zones.

What is a flash point?

The flash point (according to DIN-ISO 2592) is the lowest temperature, measured at a normal pressure of 1013 hPa, at which sufficient vapors develop from a liquid to form a mixture with the surrounding air that can be ignited by an external source. However, combustion stops again if not enough combustible gases are released to allow the fire to continue burning.

If the combustible liquid has a temperature lower than the flash point, the liquid cannot be ignited with an external ignition source. Only when the flash point temperature is reached does the liquid form a sufficient amount of combustible vapors that can then be ignited. However, if the amount of vapor flowing in is not large enough to enable sustained combustion, combustion will cease even if the ignition source is not removed.

This is clearly illustrated by the example of diesel fuel, which has a flash point of around +55 °C and cannot be ignited with a match at room temperature. However, holding a match to the liquid can raise its temperature to such an extent that the flash point is reached and ignition occurs.

The flash point is usually only a few degrees below the combustion point, at which point sustained combustion is possible even without an ignition source. If further heating occurs, the liquid ignites spontaneously when it reaches its ignition temperature, without an external ignition source.

The flash point is an important safety parameter for assessing and classifying hazardous goods and substances.

What is an ignition temperature?

The ignition temperature (also known as the flash point or ignition point) describes the temperature at which a substance spontaneously ignites in the presence of oxygen without external influence. At this point, a liquid reaches a vapor pressure high enough that the resulting gas-air mixture ignites spontaneously.

Unlike the flash point, where the gas mixture only ignites through an external ignition source, the ignitability of a mixture also depends on its mixing ratio with oxygen. This ratio determines the explosion range of the mixture.

What is an explosion limit?

Explosion limits mark the boundaries of the explosion range. The lower explosion limit (LEL) and the upper explosion limit (UEL) define the minimum and maximum concentrations of a combustible substance in a mixture of gases, vapors, mists, or dusts at which a self-sustaining flame can just form or can no longer form. A mixture within these limits is flammable.

Each gas-air mixture has a specific explosion limit (ignition limit) that depends on temperature and pressure. Below the LEL, the mixture is referred to as lean, and above the UEL, it is referred to as rich. A rich mixture can ignite and burn with additional air supply, but without exploding. A lean mixture, on the other hand, is not flammable.

The concentration of the combustible gas or vapor is given in volume percent (vol.%) or grams per cubic centimeter (g/cm³). These safety-related key figures can be found in the safety data sheets for the respective substances, researched in specialized databases such as the GESTIS substance database (GESTIS substance database), or analyzed and determined by specialized institutions.

What are potentially explosive atmospheres?

Potentially explosive atmospheres (Ex areas) can occur in potentially explosive areas. A potentially explosive atmosphere is a mixture of air and combustible gases, vapors, mists, or dusts that can ignite in the presence of an ignition source.

The ATEX directive classifies these areas into three ATEX zones or Ex protection zones depending on the explosion hazard. The aim of this classification is to ensure that only suitable, ATEX-certified devices and equipment are used in order to minimize the

explosion risk. Zone classification is an essential part of the risk assessment and is decisive for the selection of suitable technology.

Markings are usually made with yellow, triangular warning signs bearing the inscription “EX”.

The zones are divided according to the degree of risk and the frequency and duration of the occurrence of explosive atmospheres:

Zone 0/20: Constant or frequent presence of an explosive atmosphere.
Zone 1/21: Occasional occurrence of an explosive atmosphere during normal operation.
Zone 2/22: Rare and only short-term occurrence of an explosive atmosphere during normal operation.

Explosion protection comprises a graduated system of measures aimed at preventing the formation of explosive atmospheres, avoiding the ignition of an existing explosive atmosphere, and eliminating the effects of a possible explosion. This concept follows the principle of “preventive before protective” and is divided into three levels:

Primary explosion protection - Preventing the formation of explosive atmospheres

The aim of primary explosion protection is to prevent or limit the formation of an explosive atmosphere.

This can be achieved by the following measures:

• Replacing combustible materials with less combustible or non-combustible alternatives
• Limiting the concentration of combustible gases, vapors, or dusts released inside
• Monitoring concentrations so that further protective measures are automatically triggered in the event of an incident
• Ventilation measures: Controlling the concentration of combustible substances in the air through adequate ventilation
• Inerting
• Use of closed systems

Secondary explosion protection – avoiding ignition sources

If the formation of an explosive atmosphere cannot be completely ruled out, the focus is on preventing ignition.

This includes:

• Use of equipment and operating materials that are designed in such a way that they do not constitute effective ignition sources in potentially explosive areas (e.g., ATEX-certified equipment)
• Avoiding ignition sources such as sparks, hot surfaces, or electrostatic discharges at the installation site
• Adapting work procedures to avoid mechanical sparking and frictional heat

Tertiary explosion protection – limiting the effects of an explosion

If an explosion occurs despite primary and secondary measures, the aim of tertiary explosion protection is to minimize the consequences for people, equipment, and the environment.

Possible measures include:

• Pressure relief devices to reduce the explosion pressure in the plant
• Implementation of explosion protection systems that prevent the spread of an explosion within a plant
• Pressure-resistant and fire-safe workplace or installation site

These levels of explosion protection follow the principle of risk minimization and are an important part of safety concepts in areas where explosive atmospheres can occur. The selection and implementation of suitable explosion protection measures requires a comprehensive risk assessment and a deep understanding of the specific conditions and hazards at the respective location.

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