Allow around 350 L/min per orbital sander, as a rough guide, and add a 25 % margin. A 1.1 m³/min screw compressor such as the K 75 runs 2 sanders plus a blow gun, the K 110 runs 3 and the K 150 runs 4. If the booth is spraying at the same time, add the spray gun to the calculation.
Why a sander counts at 100 %
An impact wrench blows for a few seconds, then stops. An orbital sander runs as long as the prepper sands, often several minutes in a row, panel after panel. Our configurator therefore classes it as a continuous-use tool: it counts for its full consumption.
The receiver does not change this calculation. It absorbs start-ups and short peaks, but it cannot make up for a compressor that produces less than the sanders use. When flow runs short, pressure falls, the sander loses speed and sanding takes longer.
Our page on compressors for body shops covers the workshop as a whole. Here we count the sanders.
Step by step calculation
The rule fits on one line:
flow needed = (number of sanders × 350 L/min + blow gun) × 1.25
The blow gun, around 150 L/min, is used in bursts: it counts at 50 %, so 75 L/min. The 1.25 factor is the safety margin our configurator applies.
Example with 3 sanders running at the same time:
- Sanders: 3 × 350 = 1,050 L/min.
- Blow gun: 75 L/min.
- Total: 1,125 L/min.
- With the margin: 1,125 × 1.25 = about 1,410 L/min.
The K 110 delivers 1.7 m³/min at 8 bar, or 1,700 L/min: it covers this need with headroom. The K 75, at 1,100 L/min, would be too tight.
Check your sanders' consumption in their manual: it varies with the model and pad diameter. If it is given in cfm, our flow and pressure converter turns it into L/min.
The table, from 1 to 5 sanders
| Sanders at the same time | Need with blow gun | With margin | Model |
|---|---|---|---|
| 1 | 425 L/min | about 530 L/min | S 55, 600 L/min, or K 75 |
| 2 | 775 L/min | about 970 L/min | K 75, 1,100 L/min |
| 3 | 1,125 L/min | about 1,410 L/min | K 110, 1,700 L/min |
| 4 | 1,475 L/min | about 1,840 L/min | K 150, 2,200 L/min |
| 5 | 1,825 L/min | about 2,280 L/min | S 220 PM, 3.6 m³/min at 8 bar, with receiver and dryer |
Flows are those of our data sheets, at 8 bar. If a painter is spraying at the same time, add the gun's consumption, around 350 L/min, before applying the margin. With 2 sanders and a spray gun, you reach about 1,410 L/min: that is already the K 110.
Do you need more pressure for sanding?
No. An orbital sander typically works at around 6 bar, as a rough guide. An 8 bar version is enough and gives the best flow. On the K 75, flow goes from 1.1 m³/min at 8 bar to 0.95 m³/min at 10 bar and 0.8 m³/min at 13 bar: choosing a high pressure version for sanding just means losing air.
Pitfalls specific to sanding
- Hose and fittings. At 350 L/min per tool, a hose that is too thin or narrow quick couplers drop the pressure at the sander. Measure the pressure with the tool running, not at rest.
- Lubrication. Some sanders need a few drops of oil, others do not: follow the manual. A lubricator goes on a dedicated line, never upstream of the paint station.
- Dust. Install the compressor away from the sanding area. Dust clogs the intake filter and the cooler, and the compressor runs hot. Our article on the compressor room gives the installation rules.
- The piston compressor. It is designed for intermittent use. Run continuously by several sanders, it overheats and wears quickly. See our article on compressor overheating.
- Demand that varies. The number of sanders running changes through the day. Our screw compressors are variable speed: they follow demand. Our article on variable speed explains the benefit.
For your workshop, enter your sanders, spray guns and number of people in the configurator, or describe your stations in a quote request.
For your trade: Compressor for body shops.