For pneumatic formwork vibrators, size the compressor on the total of the vibrators running together during the pour, plus a 25% margin. Four 300 L/min vibrators need about 1,500 L/min, which means an 11 kW screw compressor. Eight vibrators of the same size need about 3,000 L/min, which means a 22 kW screw compressor.
Why vibrators count at 100%
In a workshop, tools do not all run at the same time, so you apply a simultaneity factor. Vibrators are different. While a mould or vibrating table is being filled, every vibrator clamped to the formwork runs at once, sometimes for several minutes. A receiver cannot cover that long: the compressor's flow is what counts.
Our page on the compressor for construction and precast concrete gives a guide range of 200 to 800 L/min per vibrator, depending on the model. Take the exact figure from your vibrators' data sheet, at their working pressure.
The calculation, step by step
Take a vibrating table fitted with eight vibrators of 300 L/min each.
- Total of the vibrators: 8 × 300 = 2,400 L/min.
- Other users during the pour: if a blow gun (≈ 150 L/min) runs at the same time, add it. Here we do: 2,550 L/min.
- Margin: 2,550 × 1.25 ≈ 3,190 L/min.
- Choice: you need at least 3.2 m³/min at working pressure.
If two moulds are poured at the same time, add their vibrators together. If pours follow one another without overlapping, size on the largest mould.
Which compressor for your set-up?
| Set-up | Demand with margin | Suggested model |
|---|---|---|
| 4 vibrators at 300 L/min | ≈ 1,500 L/min | K 110, 1.7 m³/min at 8 bar |
| 5 to 6 vibrators at 300 L/min | ≈ 1,900 to 2,250 L/min | K 150, 2.2 m³/min at 8 bar |
| 8 vibrators + blow gun | ≈ 3,190 L/min | S 220 PM, 3.6 m³/min at 8 bar |
For six vibrators, the calculation gives 6 × 300 × 1.25 = 2,250 L/min, right at the K 150's limit. If you plan to add vibrators, go straight to the S 220 PM. Beyond that, or for a plant with several lines, a compressed air audit measures real consumption before you choose.
Keeping the pressure steady
A pneumatic vibrator's frequency and force change with pressure. If pressure drops mid-pour, vibration weakens and the concrete consolidates less well. The K and S series are variable speed: the compressor speeds up when all the vibrators start and holds the pressure. We explain how in variable speed vs fixed speed.
A receiver helps too. It covers the surge when the vibrators start together, while the compressor ramps up. Our air receiver calculator gives a starting size.
Traps specific to vibrators
Icing at the exhaust. Air expands in the vibrator and cools sharply. If the air is damp, the exhaust can ice up and the vibrator slows, especially in winter. Dry air solves it: the dryer is built into the K series and added on the S series. See water in compressed air.
Lubrication. Some vibrators need lubricated air, others do not. Follow the manufacturer's manual. If a lubricator is needed, fit it on the vibrator line only, so no oil reaches the mould blowing.
Pipe size. Eight vibrators on a pipe that is too small means a pressure drop at the far end of the table. Size the pipe on the total flow.
To price your line, use the configurator or send your vibrators' data sheet with a quote request.
For your trade: Compressor for construction and precast concrete.