The term ATEX zone designates areas where, under certain conditions, an explosive atmosphere may form. For work with hydraulic demolition and splitting tools, as used by Darda GmbH in the fields of concrete demolition and special deconstruction, building gutting and cutting, rock excavation and tunnel construction, natural stone extraction as well as in special operations, understanding the zoning scheme and the resulting safety measures is crucial. Especially when working at a tank farm, in process plants, in silos with combustible dusts, or in poorly ventilated cavities, explosion protection can decisively determine the workflow. The correct equipment selection and clean work organization reduce ignition sources without putting work output first.
Definition: What is meant by ATEX zone
An ATEX zone is a spatially defined area in which the occurrence of an explosive atmosphere consisting of air and flammable gases, vapors, mists, or dusts is temporally and locally predictable. The zoning describes the probability and duration of occurrence:
- Gases/vapors: Zone 0 (continuous or long-lasting), Zone 1 (occasional), Zone 2 (only short-term, infrequent)
- Dusts: Zone 20 (continuous or long-lasting), Zone 21 (occasional), Zone 22 (only short-term, infrequent)
The zoning results in requirements for equipment and protective systems (equipment groups, categories, and types of ignition protection). For above-ground industrial and construction areas, equipment group II (gases) and III (dusts) are typically relevant. In addition, temperature classes or maximum surface temperatures indicate the temperature up to which a device may be operated without igniting the surrounding atmosphere. The classification is based on a hazard analysis that considers substance data, ventilation conditions, operating states, and potential ignition sources.
Zoning and hazard analysis in practice
In practice, zones are defined based on the substances (e.g., hydrocarbons, solvents, alcohol vapors, sugar or flour dust), the emission sources (e.g., vents, flanges, tank manholes), ventilation, and the residence time of the atmosphere. A hazard analysis determines:
- Which flammable substances may be released (gas, vapor, mist, dust)?
- How much can occur and how often?
- How is the atmosphere diluted or removed (ventilation, inerting)?
- Which ignition sources are likely (hot surfaces, sparks, static electricity, electrical equipment, mechanical friction)?
- Which operating states are critical (start-up and shutdown, malfunction, cleaning, maintenance)?
The classification is documented and serves as the basis for selecting suitable work equipment and planning the work method. It is dynamic: if the plant condition or process changes, the zone extent may change.
Relevance for hydraulic demolition and splitting technology
Hydraulic tools operate without an open flame. Nevertheless, ignition sources can arise, for example from hot surfaces of drives, mechanical sparks from metal contact, static electricity, or aerosols from hydraulic fluids. For tools and units from Darda GmbH in ATEX zones, the following applies:
- Limit surface temperatures: The maximum temperature of power units and tool surfaces should be lower than the permissible temperature class or the minimum ignition temperature of the substance.
- Avoid sparks: When cutting or separating with steel shears, combi shears, or multi cutters, consider mechanical spark formation from metal-on-metal contact. Low-spark methods are preferred in explosive atmospheres; use hydraulic demolition shear accordingly.
- Observe hydraulics: Leaks can create mist. Plan tightness, hose routing, couplings, and pressure ranges carefully, including each hydraulic hose line.
- Minimize electrostatics: Potential equalization and grounded components reduce static charges, especially on non-conductive substrates or in dry air.
Cold-working methods
When working near ATEX zones, cold-working methods are advantageous. Hydraulic splitter for stone and concrete, such as rock splitters, as well as a concrete pulverizer typically do not create open flames; processing is via hydraulic pressure and mechanical fracture. This often reduces ignition sources. This does not release one from considering surface temperatures, friction-induced sparks, and electrical grounding.
Equipment characteristics and marking in ATEX zones
Equipment operated in classified zones requires an appropriate category and marking depending on the zoning. Common elements of the marking include equipment group (e.g., II or III), category (1/2/3), type of explosive atmosphere (Gas G, Dust D), gas or dust group, and the permissible surface temperature or temperature class. A marking may, for example, indicate suitability in gas or dust zones with a specific level of protection. For selection in each case, substance data (e.g., group IIA/IIB/IIC, dust particle classes), temperature limits, and the required protection type are decisive.
Hydraulic power pack, controls, and auxiliary equipment (e.g., radio remote controls) must be considered separately in ATEX zones. Depending on whether the power pack is located outside or inside the zone, different requirements may apply. This also applies to hose penetrations through zoned areas and every hydraulic hose line.
Application areas: ATEX overview
Concrete demolition and special demolition
In industrial plants or former production buildings, residues of solvents, paints, oils, or process chemicals are possible. When opening pipelines, removing tanks, and deconstructing production areas, Zones 1/2 or 21/22 may be present. A concrete pulverizer and hydraulic splitter allow openings in slabs, walls, or foundations without thermal input; nevertheless, grounding, dust suppression, and temperature control are important.
Building gutting and cutting
When cutting steel beams, piping, or vessels, consider mechanical sparks and hot chip formation. Steel tank cutting and hydraulic demolition shear may come into contact with hazardous substances if vessels are not completely cleaned or degassed. Prior to starting, gas tests, suitable work permits, and, if necessary, inerting are standard.
Rock excavation and tunnel construction
Gases can occur in cavities within geological formations. Diesel exhaust in poorly ventilated areas also plays a role. Hydraulic splitter and a concrete pulverizer operate without flame; still, avoid sparks from metal contact at embedded components or rails. Good ventilation and continuous atmosphere monitoring are central in tunnels.
Natural stone extraction
In open quarries, the ATEX risk from gases is usually low; however, closed crushing and screening plants can generate dust clouds. Mineral dusts are often non-combustible, but mixed dusts (e.g., with organic components) must be evaluated. Dust suppression with water and dust extraction are common methods.
Special operations
Work at tank farms, in storage areas for solvents, or in the process industry is frequently accompanied by zoning. Cold-cutting methods and alternative work procedures are often required. Depending on the concept, tank cutting can greatly limit spark ejection; the specific suitability is determined by the prepared hazard analysis.
Typical ignition sources with hydraulic tools and power units
- Hot surfaces: Engines, gearboxes, and hydraulic power units can reach temperatures that must be checked against the minimum ignition temperature of the medium.
- Mechanical sparks: Metallic contact (e.g., a steel shear on structural steel), falling parts, or impact on oxide-free metals.
- Electrostatic charging: Non-conductive hose jackets, dry environments, insulating tires, or pads.
- Electrical equipment: Switches, plug connections, controls. Use only suitable equipment in zones.
- Mist/aerosols: Escaping hydraulic fluid may, under certain conditions, form an ignitable atmosphere.
Work organization and safety measures
Reducing explosion risk begins before work starts. Typical building blocks are:
- Gas testing and, if necessary, cleaning, emptying, and inerting affected plant sections
- Defining zone boundaries and the protection concept (ventilation, extraction, work distances)
- Grounding and potential equalization of power units, tools, and components
- Dust suppression via adapted water application; avoid dust layers on hot surfaces
- Select cold-working methods where possible; ensure low-spark work practices
- Suitable safety equipment and work permit processes
- Keeping means for hazard mitigation ready and defined escape routes
These measures are usually part of a corporate explosion protection document or a project-specific work permit. The exact design is based on the on-site assessment.
Concrete pulverizer and hydraulic splitter in the ATEX context
A concrete pulverizer crushes components in a controlled manner via mechanical pressure. Ignition sources here arise mainly from friction at reinforcement or from contact of the pulverizer blades with metallic embedded parts. Gentle machine handling, clean cut guidance, and avoiding unnecessary metal contact can limit sparks. The temperature of the pulverizer head and attachments should be monitored.
A hydraulic splitter creates controlled separation joints without thermal energy input. In ATEX zones, selecting the drive unit (hydraulic power pack), routing the hoses, and avoiding leaks are essential. Potential equalization between power unit, tool, and component is recommended to minimize static charging.
Hydraulic power units, hoses, and peripherals
Hydraulic power units supply energy to the tools. For operation in or near zoned areas, the following generally applies:
- Position the power unit outside the zone if possible; plan hose lengths and routes accordingly
- Keep the power unit’s surface temperature within the permissible range; ensure ventilation
- Lay hose lines to avoid chafing, kinking, and heating
- Regularly check for tightness; rectify drip leaks immediately
- Verify the suitability of electrical components (start/stop, control) for the intended area
Practical application examples
Tanks and vessels
When opening or dismantling tanks, internal areas are often classified as Zone 0/20, the immediate surroundings as Zone 1/21 or 2/22. Tank cutting and a concrete pulverizer are used when opening foundations or separating pipe runs. Emptying, cleaning, gas testing, and, if necessary, inerting are standard before starting. Cold-working methods reduce the likelihood of ignition.
Pipeline deconstruction in production plants
When dismantling pipe racks and lines, hydraulic demolition shear are used. Valves and flanges are potential emission points. Close coordination with plant owners, defining work distances, and preventing spark ejection are key measures.
Concrete foundations near ATEX zones
When deconstructing foundations beneath tanks or near ATEX zones, a hydraulic splitter and a concrete pulverizer are suitable cold-working solutions. Positioning the hydraulic power pack outside the zone and monitored hose routing further reduce risk.
Maintenance and servicing in ATEX environments
Regular inspections and documented maintenance operations support operational safety. Relevant are:
- Checking wear parts (cutting blades, jaws, splitting wedges) for burr formation and unintended spark sources
- Inspection of the hydraulics for tightness and temperature, condition of hoses and couplings
- Cleanliness: remove combustible deposits, dust layers, and oil films
- Verification of electrical components and potential equalization
In zoned areas, maintenance work should be adapted to the zoning and coordinated via a work permit.
Estimating the zone and limits of explosion protection
Not every construction or deconstruction site is an ATEX zone. Mineral dusts are often non-combustible; however, mixed dusts or residues from processes can be explosive. Even the best equipment selection does not replace a systematic hazard analysis. Where in doubt, the atmosphere should be measured and conservatively classified. If the process changes (e.g., from crushing to cutting), the zoning must be reviewed.
Planning, roles, and documentation
For Darda GmbH’s work in potential ATEX zones, a structured approach has proven itself:
- Early involvement of occupational safety and plant owners
- Clear assignment of responsibilities for gas testing, work permits, and supervision
- Documentation of zone boundaries, safety measures, and operating parameters
- Team communication, on-site briefing, and continuous observation of the atmosphere
These points support the safe execution of work with a concrete pulverizer, hydraulic splitter, and other hydraulic tools near explosive atmospheres.