A compressor produces hot, wet, laden air. What makes it usable comes afterwards: drying, filtering, draining. It is also what determines the air class at the point of use.
Positive dew point, around +3 °C. The workshop standard: economical, simple, enough anywhere the air never drops below zero.
Dew point of -40 °C and below. Required wherever condensation is unacceptable: pharmaceuticals, electronics, instrument air, outdoor branches.
Particles, oil aerosols, vapours, micro-organisms. Stages are fitted in order, and it is their sequence that sets the air class obtained.
Condensate must leave the network, and it does not go down the drain as it is. Electronic drains with no air loss, oil/water separation before discharge.
No electricity, no moving parts. For small flows and isolated points of use, where installing a machine makes no sense.
Compressing air concentrates its water vapour; as it cools in the network, it condenses. Water corrodes pipes, freezes outdoor outlets, damages tools and product. The dryer removes that water before the network; filters remove particles and oil; drains evacuate the condensate at low points; the oil-water separator treats it before discharge.
Air quality is decided here, not in the compressor: an oil-free machine produces air as wet as a lubricated one.
ISO 8573-1 grades water by pressure dew point classes: class 4 at +3 °C, class 2 at -40 °C, class 1 at -70 °C. An indoor network, in a heated building, is content with +3 °C: that is the refrigerated dryer, from 0.7 to 400 m³/min in the catalogue, air- or water-cooled, with versions for hot inlet air.
A network that runs outdoors, a moisture-sensitive process, a class 2 or class 1 requirement call for adsorption: heatless for -40 °C, heated down to -70 °C, from 0.5 to 83 m³/min. The membrane dryer, from 0.05 to 3 m³/min, treats an isolated point of use without electricity.
A dryer is sized on the flow to treat, at the real inlet pressure and temperature: hotter inlet air or lower pressure reduce its capacity. Every compressor page computes the dryer, the filtration and the receiver on its own flow, in the “What goes with it” block.
Filtration is chosen by the target class: particles, then coalescing for oil aerosols, then activated carbon for oil vapour, then sterile for food and pharma. Each stage exists for one contaminant only.
Every filter is crossed at the cost of a pressure drop, and a saturated element makes it climb. The compressor compensates by raising its pressure, and every bar costs about 7% of the energy. According to the US Department of Energy, a separator is replaced when its pressure drop reaches 10 to 12 psi, that is 0.7 to 0.8 bar; the same logic applies to filter elements.
A heatless adsorption dryer consumes part of the dried air to regenerate; the heated version consumes less, at the cost of a heater. The refrigerated dryer only consumes its refrigeration compressor.
Refrigerated for an indoor network and a +3 °C dew point, which covers most uses. Adsorption as soon as the network runs outdoors, the process fears moisture, or the specification writes class 2 or class 1 for water.
Yes. Water does not depend on oil: compressed air carries vapour whatever the machine, and condensation comes as soon as the network cools.
As many as there are contaminants to remove: particles, oil aerosols, oil vapour, germs. Workshop air is content with two stages; air in contact with a food needs four, sterile filter included.
The full table for each range as a PDF: flow, pressure, dimensions, weight. Enough to quote at your customer's site without calling us.
Your flow or your power, then your pressure. No sign-up, and the answer names machines.
