The spray nozzle is an inconspicuous yet central component when it comes to dust suppression, cooling, wetting, and cleaning in demolition, deconstruction, and natural stone extraction. Whether separating and crushing concrete with concrete demolition shears, controlled splitting with hydraulic wedge splitters, or rock excavation in tunnel construction: the right spray pattern, the appropriate droplet size, and a robust nozzle determine efficiency, occupational safety, and the quality of the work result. This article combines the technical classification of the spray nozzle with practice-oriented notes from the application areas of Darda GmbH, without being promotional.
Definition: What Is a Spray Nozzle
A spray nozzle is an assembly that converts an applied pressurized volumetric flow into a defined liquid jet or mist. Depending on the nozzle geometry, this produces flat sprays, full or hollow cones, and fine or coarse mists. The goal is the targeted distribution of water or media with additives to wet surfaces, bind dust, cool tools, or clean material. In demolition and special deconstruction, the spray nozzle is often used as a water-mist or atomizing nozzle to capture fine dust fractions at the point of origin—such as at the crushing and cutting edges of concrete demolition shears or directly at the splitting zone of hydraulic wedge splitters.
Design and Operating Principle of Spray Nozzles
Typical spray nozzles consist of a nozzle body with inlet thread, a filter seat (optional), a flow chamber, and the actual orifice or outlet opening. In swirl-chamber nozzles, the liquid is imparted with a swirl; it leaves the nozzle as a hollow- or full-cone spray. Flat-spray nozzles shape the stream over an edge into a fan-shaped spray pattern. Atomization—i.e., the breakup into droplets—depends primarily on pressure, nozzle geometry, medium viscosity, and temperature. Higher pressure and smaller orifices generally produce finer droplets; larger openings deliver coarser drops with higher momentum density and throw distance.
Nozzle Geometries and Spray Patterns
The choice of geometry depends on the task, distance, and desired droplet size. In dust-intensive applications around concrete demolition and special deconstruction, building gutting, and tunnel heading, the following types are primarily used:
Flat-Spray Nozzle
A uniformly distributed fan for linear wetting, e.g., along the jaw and cutting edges of concrete demolition shears. Suitable when a targeted, slender spray zone is needed without soaking adjacent areas.
Full-Cone and Hollow-Cone Nozzle
Full cones distribute water homogeneously over a circular cross-section and are versatile for dust binding over a work area. Hollow cones are efficient when a ring-shaped droplet cloud should enclose the dust, for example around the breakout point of a hydraulic wedge splitter.
Mist Nozzle for Fine Aerosols
Fine-atomizing nozzles—single- or two-fluid—produce very small droplets for binding respirable fine dusts at the point of origin. They should be positioned close to the dust source, as fine mist is wind-sensitive and easily drifts.
Relevance in Concrete Demolition and Special Deconstruction
Breaking, splitting, crushing, and cutting concrete generate mineral dusts with variable grain sizes. Here, the spray nozzle is a central means of dust reduction directly at the source. Specific tasks include:
- Dust binding in the jaw and cutting area of concrete demolition shears using directed flat sprays.
- Wetting the splitting zone on hydraulic wedge splitters to effectively bind released fine dust.
- Cooling of tool cutting edges and bearing areas, if this is intended for the work process.
- Securing the operator’s field of view through a stable, tuned spray cloud with sufficient momentum.
Use in Rock Excavation and Tunnel Construction
In rock demolition and tunnel construction, spray nozzles are exposed to high loads: abrasive particles, fluctuating water quality, limited accessibility, and drafts. Robustly designed full- or hollow-cone nozzles with wear-resistant inserts (ceramic, carbide) have proven themselves. They are positioned in the immediate vicinity of the attack point so that the droplets envelop the dust before it enters the air. Short distances, sufficient pressure, and a spray angle aligned with the work geometry are crucial.
Natural Stone Extraction as Well as Gutting and Cutting
In natural stone extraction, spray nozzles are used for dust binding during loosening, separating, and sorting. Indoors—such as during gutting works—finely metered wetting is required to bind dust without soaking components. Flat sprays with lower flow and limited angle provide precise control, while finer mists work optimally only at very low air movement.
Sizing: Pressure, Flow Rate, Droplet Size
The sizing of a spray nozzle results from the interplay of pump performance, desired droplet size, and spray range. In principle: coarser droplets (e.g., 200–400 µm) have more momentum, penetrate turbulent zones, and are well suited for dust binding in moving air. Finer droplets (e.g., 20–100 µm) wet sensitive areas more uniformly but are more wind-sensitive and require a very close position to the emission source.
- Flow rate: size to match the available water delivery and the desired degree of wetting.
- Pressure: choose so that the nozzle operates in its optimal range; too low a pressure leads to coarse jets, too high a pressure to unwanted fogging.
- Spray angle: adapt to working distance and tool width; angles that are too large reduce surface intensity.
- Medium properties: temperature and viscosity influence droplet formation; clean, filtered water reduces wear.
Materials, Resistance, and Service Life
Nozzle bodies are manufactured from brass, stainless steel, or high-grade plastics; with abrasive media, ceramic or carbide inserts offer a significantly increased service life. Corrosion and chemical resistance are relevant with varying water qualities. A regular visual inspection of the outlet is sensible: even slight edge erosion changes the spray pattern and thus the dust-binding performance.
Positioning on Concrete Demolition Shears and Splitters
For effective dust binding, the spray nozzle must operate close to the emission source without disturbing the workflow. Mounting positions that follow the material flow and account for the opening and closing movements of the tools have proven effective. Hose routing must be protected against crushing and abrasion.
- Align the discharge direction with the process (near the breakout, opposite to the dust plume).
- Select the spray angle based on the working distance; check and document a test spray pattern in advance.
- Ensure uniform wetting; stagger multiple nozzles on wide tools.
- Observe splash-back and misting; if necessary, adjust droplet size by changing the nozzle.
Maintenance, Cleaning, and Operation
Simple measures are sufficient to keep spray nozzles reliably operating over time when implemented consistently.
- Filtration: use upstream filters to keep particles out of the supply; flush filters regularly.
- Descaling: in regions with hard water, remove deposits early using suitable, material-compatible methods.
- Flushing cycles: after dust-intensive use and before downtime, flush the lines with clear water.
- Winter operation: drain water from exposed lines or use frost-protected media.
- Hygiene: avoid stagnation; regularly flush systems completely to reduce microbial growth.
Occupational Safety and Environmental Aspects
A well-designed spray nozzle reduces airborne fine dusts and supports health protection. At the same time, sparing use of water is important: it is advisable to match water delivery to dust generation and to drain collected water in a controlled manner. Slip hazards due to puddles should be minimized through targeted spray directions and drainage. The applicable local regulations and organizational protective measures are always decisive.
Quality Control and Documentation
The performance of a spray nozzle can be checked with simple means. A practical approach is to determine flow rate over time in a measuring container and visually check the spray pattern for homogeneity and reach. Deviations indicate wear, blockages, or unsuitable operating pressures. A brief record with date, nozzle code, pressure, flow rate, and observed spray pattern facilitates repeatability.
Typical Failure Patterns and Countermeasures
- Mist too fine and drifting: choose a nozzle with a larger orifice or reduce pressure, decrease distance.
- Insufficient dust binding: increase droplet size, place the nozzle closer to the source, correct the spray angle.
- Unstable spray pattern: check filters, remove deposits, replace worn nozzle.
- Over-wetting of surroundings: focus the spray pattern, use a flat spray instead of a full cone, consider interval operation.
- Unsuitable pump sizing: match delivery flow and pressure range to the nozzle data.
Relation to Other Tools and Processes
The spray nozzle can also contribute to dust reduction, cooling, and spark reduction on multi cutters, steel shears, and combi shears, provided the process allows it. With a tank cutter, nozzle selection and arrangement must be planned with particular care; water-carrying systems should be operated so that they support the intended safe sequence. Hydraulic power packs provide the drive power for tools, while the supply and control of spray nozzles in practice often run via separate pumps or supply lines. Decisive is an overall design tuned to the process: suitable nozzle, adequate filtration, correct pressure, and proper positioning on the tool.