Ventilation

Ventilation is a central topic in demolition and extraction technology because air and gases in hydraulic systems, cavities, or work areas can reduce performance and increase risks. Whether with concrete pulverizers, stone and concrete splitters, hydraulic power packs, or tank cutting: proper ventilation supports operational safety, process stability, and occupational safety in concrete demolition and special demolition, building gutting and cutting, rock excavation and tunnel construction, natural stone extraction, as well as in special operations. Consistent de-aeration and controlled air exchange also reduce downtime and support compliance with applicable health and safety requirements.

Definition: What is meant by ventilation?

Ventilation is the targeted removal of air or gases from systems, components, or ambient air to ensure proper function. In hydraulics, ventilating means expelling trapped air from oil circuits, cylinders, and lines. In the work environment, ventilation describes the air exchange to reduce dusts, exhaust gases, or vapors. For vessels and tanks, the term also includes degassing and the controlled removal of flammable atmospheres. In technical usage, related terms include bleeding, de-aeration, and purging, depending on context. The goal is always: greater operational safety, reliable performance, and reduced wear.

Ventilation in hydraulic systems of demolition and cutting technology

Hydraulically driven tools such as concrete pulverizers as well as stone and concrete splitters react sensitively to air ingress. Air bubbles make oil compressible, reduce transmitted force, promote cavitation, and can cause pressure spikes and temperature rises. Systematic ventilation – especially after assembly work, hose changes, or initial commissioning – ensures full working force, precise response, and long service life of cylinders, valves, and seals. Typical bleed points include pump housings, cylinder heads, valve blocks, and high points of the return line, supported by slow, low-load cycling to move microbubbles toward the tank.

Causes and effects of air ingress in hydraulics

Air can enter the system via connections, porous suction sections, or when the oil level is too low. Turbulent returns, foaming due to incorrect viscosity, or temperature changes also promote microbubbles. Suction-side leaks and worn shaft seals are frequent root causes under high duty cycles. The effects are noticeable: delayed closing of concrete pulverizers, fluctuating splitting force with stone and concrete splitters, jerky movements, increased noise levels, and increased wear on pumps and valves. In the medium term, the likelihood of leakage and the need for maintenance increase, and microcavitation can damage surfaces and shorten component life.

Practical notes for ventilating hydraulic power packs

Hydraulic power units provide pressure and flow for combination shears, Multi Cutters, steel shears, or stone-splitting cylinders. Clean, depressurized ventilation after interventions in the oil circuit, working with the ventilation points at the system’s high points, and running in the cylinders at low speed help dissolve air from the oil and guide it to the return side. Suitable temperature and viscosity ranges, a correct oil level, and intact suction seals reduce foaming and renewed air ingress. Transparent sections or sight glasses can help verify bubble-free return flow during the bleeding phase, while adherence to cleanliness classes and approved oil specifications stabilizes de-aeration behavior.

Inspection and indication checks

• Milky or foaming hydraulic oil in the tank
• Unsteady pressure profile, conspicuous noises (cavitation)
• Jerking, spongy cylinder response
• Elevated oil temperature at comparable load
• Run-on or yielding under load
• Visible bubbles in the sight glass or return line during operation
• Relief valve chatter or pressure oscillation at constant load

Ventilation during tank cutting: safe preparation of vessels

Tank cutting is often used in special operations and in building gutting and cutting when vessels, pipelines, or apparatus are segmented. Tools such as the Tank Cutter may be used depending on the method. Prior to thermal or mechanical separation, safe ventilation and – if required – degassing of vessels is essential to avoid explosive atmospheres. Measures for airflow management, controlled opening of ventilation points, diverting vapors, and competent clearance measurement for residual gases are established elements of a safe approach. Even during cold cutting, good ventilation and gas-free conditions remain decisive. Inerting can reduce ignition risk but is no substitute for verified ventilation and reliable gas detection.

Hazards during vessel separation

• Residues of flammable liquids, solvent vapors, or gases
• Ignition sources from sparks, hot surfaces, or static charging
• Uncontrolled atmosphere changes in convoluted vessel sections
• Stratified atmospheres and oxygen displacement in low areas

Air exchange and dust management: concrete demolition, tunnel construction and building gutting

In concrete demolition and special demolition as well as in tunnel construction, effective ventilation of the work environment is crucial. It lowers fine dust and particle exposure, removes engine exhaust gases, and keeps visibility and temperature conditions stable. Concrete pulverizers generate lower secondary emissions compared to impact tools; nevertheless, a combination of air exchange, local dust extraction, and – depending on the situation – dust suppression is advisable. Indoors during building gutting, maintaining negative pressure can help prevent spread into clean areas. Airflow rates should be dimensioned to machine fleet, heat release, and cross-sections, with periodic verification using suitable indicators.

Airflow management in tunnel construction

• Separate supply and exhaust airflows so that low-contamination areas are preserved
• Source-capture of exhaust gases and dusts at workstations
• Adjust air change to the number of machines, load, and tunnel length
• Continuous monitoring of CO, NOx, and diesel particulates where combustion engines are used

Dust reduction during demolition

• Near-source capture at processing points on concrete structures
• Combination of extraction and adjusted air change rate
• Avoid unnecessary recirculation with re-entrainment of fine particles
• When permitted by the method and materials, combine water mist or wet cutting with local extraction

Cylinder ventilation in combination shears, Multi Cutters and steel shears

Hydraulic cylinders in cutting and shearing tools only work powerfully and precisely when no air cushions remain in the pressure chamber. After service work, cylinders should be actuated open and the end positions approached slowly several times so that trapped air can escape toward the return line. Where provided, careful opening of bleed screws at cylinder ports or on manifolds can support this. This protects seals, reduces pressure spikes, and improves the cutting edge and repeatability.

Special importance for concrete pulverizers as well as stone and concrete splitters

In concrete pulverizers, air ingress affects fracture control and clean cracking of concrete structures. Delayed response or yielding under load can shift cut lines and release components unexpectedly. Stone and concrete splitters require stable hydraulics to load split wedges uniformly with force. Ventilated systems deliver reproducible splitting results and reduce mechanical loading on tool mounts and attachments. In practice, this improves cycle times, cut quality, and the predictability of separation sequences.

Planning and execution: general guidelines

1. Deliberately ventilate hydraulic systems after assembly or oil changes and check for foaming
2. Identify ventilation points and work safely, depressurized, and clean
3. Keep oil level, viscosity, and temperature within the approved range
4. Operate work areas with sufficient air exchange, especially indoors and underground
5. For tank cutting, anchor ventilation/degassing and clearance measurements organizationally
6. Validate effectiveness with functional tests and trend data rather than single observations
7. Define responsibilities, checklists, and lockout-tagout for ventilation-related tasks
8. Document oil type, fill quantity, filter status, and the last successful bleeding date

Materials, media and component compatibility

Ventilation also affects material compatibility: air and moisture promote oil aging, oxidation, and micro-sludge. Seals and hoses benefit from homogeneous oil without air pockets. Selecting suitable sealing qualities and filter ratings supports low foaming. Smooth return paths, adequately sized tanks with calming zones, and ventilation valves at high points facilitate stable fluid routing. Anti-foam additives, low-turbulence return inlets, and effective tank breathers (for example with desiccant) further reduce re-aeration and moisture ingress.

Quality assurance and documentation

The effect of ventilation measures can be better assessed through documented visual inspections, noise and function observations, as well as temperature and pressure trends. Recurring checks – such as after transports, longer downtimes, or component changes – ensure consistent behavior of concrete pulverizers, stone and concrete splitters, and other hydraulic tools from Darda GmbH. Define acceptance criteria for maximum start-up time, allowable temperature rise, and pressure stability, and compare new measurements to established baselines.

Occupational safety and environmental aspects

Ventilation reduces hazards from vapors, exhaust gases, and dusts. At the same time, the protection of environmental media is important: hydraulic fluid must neither leak nor be aerosolized. Care when opening ventilation points, suitable collection means, and clean work help avoid emissions. In tank cutting, minimizing explosive atmospheres is paramount; organizational, technical, and personal protective measures must be considered together. Capture hoods and local extraction reduce worker exposure, while appropriate zoning and selection of protective equipment support safe execution.

Avoid common misconceptions about ventilation

• “Air disappears by itself”: Without targeted ventilation, air pockets often remain in the system for a long time.
• “A bit of foam doesn’t matter”: Foam indicates air ingress, reduced lubrication, and possible cavitation.
• “Only the high-pressure side matters”: The suction and return sides also influence air dissolution in the oil.
• “Outside air is always sufficient”: In tunnel construction and indoor areas, calculated air exchange is crucial.
• “Cold cutting is automatically safe”: In tank cutting, ventilation/degassing and clearance measurement remain fundamental.
• “One-time bleeding is enough”: Load changes and temperature cycles can reintroduce air, so periodic checks remain useful.

Fields of application and typical scenarios

• Concrete demolition and special demolition: ventilated hydraulics for controlled separation and cracking with concrete pulverizers
• Building gutting and cutting: air exchange indoors, safe ventilation during tank cutting work
• Rock excavation and tunnel construction: flow-guided ventilation, exhaust gas and dust removal at the tunnel face
• Natural stone extraction: stable splitting force in stone and concrete splitters through air-free hydraulics
• Special operations: degassing/ventilation in complex plant areas prior to separation work
• Maintenance and commissioning: controlled bleeding after repairs, retrofits, and long downtimes