Both are lubricated machines that deliver a continuous flow. The screw is the machine of industry: from 3.7 to 250 kW, it reaches large flows and comes in variable speed and two-stage versions. The vane turns slowly on a single rotor, in direct drive: from 4 to 110 kW, it accepts repeated starts, keeps its efficiency over the hours and runs quietly in its hood.
For a plant that uses a lot of air for long hours, the screw. For a workshop that runs intermittently, or a machine that lives close to people, the vane. In both cases, if demand varies during the day, the variable speed version.
Wherever the air never touches the product: workshops, mechanical engineering, construction sites, energy, plastics, most assembly lines. The oil injected into the airend seals it, carries the heat away and lubricates the bearings; that is what makes the machine cheaper to buy, robust, and familiar to every maintenance team.
As soon as the air touches a food, a drug or an electronic component, the question changes. The trade has settled it: class 0 means an oil-free machine. Read the oil-free compressors page before sizing anything.
Two figures open the catalogue: the flow to deliver in m³/min and the working pressure in bar. Flow is measured at the point of use, leaks included; according to the US Department of Energy, a network without a leak programme often loses 20 to 30% of its flow to leaks. Pressure is set as low as the process allows: every bar too many costs about 7% of the energy.
The third figure is the load profile. A flat demand all day calls for fixed speed; a demand that rises and falls calls for a drive. In the catalogue: fixed-speed screws from 7.5 to 250 kW, permanent-magnet VSD screws from 7.5 to 250 kW, two-stage screws from 22 to 250 kW, low-pressure 3 to 5 bar units from 22 to 250 kW, single-phase units from 3.7 to 9 kW, rotary vane from 4 to 110 kW, all-in-one units with dryer and receiver from 7.5 to 22 kW, diesel site compressors from 37 to 447 kW.
An unloaded screw still draws 15 to 35% of its full-load power while producing nothing, according to the US Department of Energy's Sourcebook. On a fluctuating load, a permanent-magnet drive removes those idle hours. On a flat load, fixed speed remains the simplest and the cheapest to buy.
Two-stage is the high-efficiency version, built for energy savings: about 10% less energy than a standard screw, 6 to 11% according to the same source, with the largest gain on large machines running continuously. On a 75 kW machine at 8,000 hours a year, the gap runs to tens of thousands of kilowatt-hours.
According to the US Department of Energy, electricity is about three quarters of what a compressor costs over ten years; purchase and maintenance share the rest. That is why flow, pressure and noise are measured machine by machine and published as they are: specific power is compared on those figures, not on a brochure.
Heat is the second lever: 80 to 93% of the electricity drawn leaves as heat, and 50 to 90% of it can be recovered to heat a workshop or process water. A lubricated screw lends itself well to it, its heat being carried by the oil at a usable temperature.
A receiver sized on the flow, a refrigerated dryer for a +3 °C dew point, filtration matched to the target air class, a drain at every low point and an oil-water separator for the condensate. Every model page computes these on the machine's flow; the quote covers them together.
The catalogue answers in flow, not in power: add up the consumption of your tools, add a margin for leaks, set the pressure as low as possible, then read the range table at that pressure. The diagnostic on the home page does this in three questions.
Yes if demand varies through the day, whatever the power; no if the machine runs at full load most of the time. The gain comes from the idle hours the drive removes: it is real on a varying load and melts away on a flat one.
Three years of machine warranty, extended to five years as long as the installation stays supervised by SEENTINEL; if supervision stops, the warranty returns to three years. Parts available for ten years after delivery, shipped within 24 to 48 hours in mainland France.
