For a metal fabrication shop with 3 workstations, covering grinding, manual plasma cutting and painting, the requirement is around 1,400 l/min including margins. A 11 kW 4-in-1 screw compressor such as the K 110, which delivers 1.7 m³/min at 8 bar with a built-in dryer and filtration, serves all three stations. A locksmith or gate shop with no painting can stay on the K 75.
This article details a typical three-station shop. The uses of air in metalwork are on our page on compressors for metal fabrication.
What runs at each station
A three-station shop is often:
- a preparation station: grinder or cut-off tool, 450 l/min as a guide according to our configurator;
- a cutting station: manual plasma cutter, around 150 l/min for a common unit;
- a finishing and assembly station: paint spray gun, 350 l/min as a guide, and a 1/2" impact wrench, 300 l/min in bursts.
Add a blow gun per station. Take the real figures from each tool's manual: those are what count.
The calculation, step by step
Add up what runs at the same time, one tool per person present.
- Grinder: 450 l/min. In metalwork you often grind for long minutes, so count it at 100 %.
- Plasma: 150 l/min, counted at 100 % while cutting.
- Paint spray gun: 350 l/min, counted at 100 % during the pass.
- Subtotal: 950 l/min.
- 25 % safety margin: 950 × 1.25 = 1,188 l/min.
- 20 % margin for growth, for a fourth station: 1,188 × 1.2 = about 1,430 l/min.
The K 75, which delivers 1,100 l/min at 8 bar, is not enough. The K 110 delivers 1,700 l/min at 8 bar and keeps a reserve.
Three variants of the same shop
| Shop | Calculation | Recommended model |
|---|---|---|
| Locksmith or gate shop, no painting: grinder, plasma, impact wrench in bursts | (450 + 150 + 150) × 1.25 = 940 l/min | K 75, 1.1 m³/min at 8 bar |
| Metalwork with painting, the example above | about 1,430 l/min | K 110, 1.7 m³/min at 8 bar |
| Two grinders, plasma and painting at once | (900 + 150 + 350) × 1.25 = 1,750 l/min | K 150, 2.2 m³/min at 8 bar |
If the shop already has a dryer and receiver, the S 110 or the S 150 give the same flows without the built-in equipment.
What about the air receiver?
The K 110 and K 150 have a built-in 340 L receiver, the K 75 a 420 L receiver. Our configurator recommends about one litre of receiver for every 3 l/min of demand. For 1,430 l/min that is about 480 litres: a 500 litre receiver, or the built-in one plus a buffer receiver near the paint station. Our air receiver size calculator refines this figure.
Pitfalls in a three-station shop
- One line for everything. Plasma and the spray gun need dry, clean air, while the grinder often wants a little oil. Put the lubricator at the grinding station only, never at the head of the network. Our article what compressor for a 45 A plasma cutter details the air the torch expects.
- Drops without drains. Take air off the top of the main pipe and fit a drain point at the bottom of each drop. See our guide to connecting to the air network.
- Sparks and dust. Install the compressor out of reach of the grinding station, with a clean air intake.
- Sandblasting. A small blast cabinet is sized separately: our article on the blast cabinet gives the method. High-volume sandblasting, for structures or large parts, is quoted on request: the S series goes up to 132 kW, and our page on compressors for sandblasting starts from the nozzle diameter.
For your own shop, enter your tools in the configurator, then send us the list of your stations with a quote request.
For your trade: Compressor for metalwork and fabrication shops.