Air injection systems are indispensable in many construction and deconstruction processes when safe breathing air, controlled airflow, and targeted displacement of dust or gases are required. In combination with hydraulic tools from Darda GmbH—such as concrete pulverizers or rock and concrete splitters—they create reliable working conditions in confined spaces, shafts, tunnels, or tanks. When properly planned and operated, they support dust suppression, degassing, cooling, and drying without becoming a risk themselves.
Definition: What is meant by air injection system
An air injection system is a technical installation that blows ambient or conditioned air in a targeted manner into work areas, cavities, tanks, or pipelines. Objectives can include ventilation (fresh air supply), dilution of contaminants, creation of slight positive pressure, drying, mixing, or process assistance. An air injection system typically consists of a drive unit (blower or compressor), intake and filtration stage, air ducting, distributors or nozzles, and a control for setting flow rate and pressure. In deconstruction, a basic distinction is made between mobile, quickly deployable units and fixed, ducted systems that transport larger air volumes over longer distances.
Design and operating principle of an air injection system
The operating principle is simple: A blower generates a volumetric airflow that is routed via hoses or ducts to the point where air is needed. Filtration stages prevent particles from being drawn in or distributed. Using distributor heads, perforated pipes, or nozzles, the airflow can be adapted—broadly for room air supply, or as directed jets for blowing out boreholes or cavities. Control valves and variable-speed drives allow adaptation to changing conditions. Important parameters are volume flow (m³/h), static pressure (Pa), flow velocity (m/s), and sound power. With long duct runs, pressure drops must be considered, as well as temperature, condensate formation, and material compatibility with the environment.
Use in concrete demolition and special demolition
Demolition work generates dust, aerosols, and—depending on the method—gases. Air injection systems provide fresh air and, through slight positive pressure, can reduce dust ingress into adjacent areas. In conjunction with concrete pulverizers and hydraulic attachments, a targeted airflow stabilizes visibility, supports the removal of fine particles, and facilitates accompanying air quality measurements.
Borehole cleaning for rock and concrete splitters
For rock and concrete splitters, boreholes must be dust-free and dry so wedges engage evenly. Air is often blown in here to expel drill dust. A suitable nozzle, a short, pulsed volume flow, and assured dust extraction (e.g., a downstream dust extraction plant in the work area) improve process reliability and reduce exposure. Cleanly blown-out boreholes help ensure that splitting forces are transmitted as intended.
Ventilation when using concrete pulverizers
When crushing concrete with concrete pulverizers, finely distributed particles are produced. An air injection system can push air into the work area from the rear and simultaneously guide the airflow so that dust clouds do not return to the operator. In enclosed spaces, a combination of supply (injection) and extracted air (separate flow paths) is recommended to achieve traceable airflow management.
Rock excavation and tunnel construction: fresh air, pressure control, and emergency ventilation
In tunnel construction and rock excavation, airflow management and fresh air supply are particularly important. Air injection systems with longer duct runs supply the tunnel face with sufficient oxygen, dilute exhaust gases from other equipment on site, and stabilize temperature. For changing tunnel face positions, modular hoses and quick coupling distributors are practical. Redundant power supply and clearly marked air routes increase operational safety.
Gutting works and cutting: work area ventilation
During gutting works, dust sources change within rooms that have limited ventilation options. An air injection system can create slight positive pressure in the work area while using defined discharge openings to steer particle flows. In combination with cutting and breaking tools from Darda GmbH, this improves visibility and cleanliness without interfering with hydraulic operations. A steady, laminar supply airflow is important so that dust is not unnecessarily stirred up.
Cutting torches and work in tanks
When opening or separating containers, silos, or tanks with cutting torches, interior spaces must be ventilated and degassed before work begins. Air injection systems support the dilution of potentially critical atmospheres and direct residual gases outward. Work should only begin after adequate ventilation and proper atmospheric measurements by competent personnel. Continuous, controlled supply air during cutting stabilizes conditions in the tank and reduces backflow toward the operator.
Interfaces with hydraulic power packs and tools
Hydraulic Power Units require unobstructed airflow for cooling. An air injection system must not blow directly across the intake openings or direct waste heat back toward the power pack. Hose routing must be arranged so that hoses are not pinched by concrete pulverizers or hydraulic demolition shears. Principle: Plan the airflow so that tools maintain clear visibility, power packs are adequately cooled, and airflow does not strike loose particles or debris surfaces in a way that causes uncontrolled agitation.
Planning, design, and sizing
Sizing is based on room volume, required air changes, duct routes, and the desired operating pressure. For small rooms, a moderate volume flow with well-guided supply air is often sufficient. Long tunnel sections or branched ducting require higher pressures and coordinated distributors. Silencers and flexible couplings reduce vibration and noise. Filter classes are selected to suit the environment without unnecessarily increasing flow resistance.
Example procedure for sizing
- Survey the work area: dimensions, leak paths, potential dust and gas sources.
- Define the objective: fresh air supply, positive pressure, drying, or borehole cleaning.
- Derive the volume flow: set air changes based on task, calculate duct losses.
- Plan duct routing: short paths, large radii, tight-sealing transitions.
- Provide filters, silencers, measuring points: pressure, volume flow, temperature, and optionally particles.
- Conduct trial operation and validate readings; adjust nozzles or distributors if necessary.
Commissioning, operation, and maintenance
Before commissioning, check mechanical connections, electrical connections, and blower rotation direction. During operation, regularly monitor flow direction and air velocity. Replace filters as needed and remove condensate from ducts. In the event of dust exposure, gentle cleaning of equipment is advisable to prevent deposits from entering bearings or motors.
Typical faults and remedies
- Insufficient volume flow: check filters, seal leaks, adjust duct cross-sections.
- Undesired dust backflow: clearly separate air routes, change discharge position, increase positive pressure.
- Overheating near power packs: reroute supply air, prevent heat build-up with spacers.
- High noise levels: use silencers, improve vibration isolation.
Occupational safety and regulatory framework
Ventilation concepts should follow recognized rules of technology. These include adequate fresh air supply, avoidance of backflow into occupied areas, and documentation of operating parameters. When working in confined spaces or tanks, special precautions must be taken, including permit-to-work processes and appropriate measurements. Explosive atmospheres must be avoided; equipment selection and procedures should be suitable for this. The notes are general in nature and do not replace a case-by-case assessment.
Sustainability and environmental aspects
Efficient air injection systems save energy and reduce emissions. Variable-speed blowers, demand-based air changes, and well-calibrated nozzles lower consumption. Clean filters not only protect the equipment but also contribute to ambient air quality. Appropriate silencing reduces noise emission.
Practical guidance for coordination with demolition tools
Airflow should enter from the rear of the work location and be discharged laterally so that concrete pulverizers do not pull the fracture zone into a dust cloud. When blowing out boreholes for rock and concrete splitters, position the nozzle so that ejected material is directed in a controlled way into a safe area. Lightweight, abrasion-resistant hoses make routing between power pack, tool, and work surface easier. Markings on hose couplings reduce the risk of mix-ups—especially where hydraulic lines and power cables are routed in addition.