Air-line apparatus works on a different principle from a filtering device: it does not clean the air, it delivers clean air from an external source — a compressor or a cylinder — through a hose. That makes it usable where a filter cannot work.
Where it is indispensable
- Oxygen-deficient atmospheres (<17%) — a filter cannot create oxygen.
- Unknown or fluctuating concentrations.
- Substances with no warning properties, where a filter would exhaust unnoticed.
- Very long tasks — furnace cleaning, paint booths, abrasive blasting.
Classes
- LDH1
- Protection factor 5×
- LDH2
- Protection factor 20×
- LDH3
- Protection factor 100×
The supplied air must meet the purity requirements of EN 12021 — the compressor intake has to be sited away from contaminant sources and the line must carry filtration and oil removal.