A noisy piston compressor is first quietened by how it is installed: a floor that does not resonate, a flexible connection to the network, a place away from workstations. Next come servicing (belt, filter, valves) and cutting its running time (leaks, pressure). If the compressor runs almost non-stop, the noise is mainly a sign that it is overworked: a screw compressor is then the real answer.
To understand why a screw compressor is quieter, see our page on the quiet workshop compressor.
Where does the noise come from?
Listen to the machine running and locate the source:
- the hammering of the pistons and the clatter of the valves, inherent to the piston principle;
- a whistle at the intake, often a dirty air filter;
- slapping or squealing from the belt, when it is worn or badly tensioned;
- a hum carried into the floor by the receiver, the wheels or rigid pipes;
- a hiss at each stop, as the head unloads, and from the drain.
The last three can be reduced a lot. The first comes with the technology.
Lever 1, installation
- A stable floor. Avoid wooden floors and mezzanines, which amplify vibration.
- Locked wheels, or anti-vibration mounts rated for the weight if the manual allows. An E 75 weighs 190 kg and an E 110 430 kg according to their data sheets.
- No corner, not right against a wall. Let air circulate around the head.
- A flexible hose between the receiver and the network, so the pipes do not act as a sounding board.
Lever 2, servicing
- The belt: tension and condition, every month.
- The air filter: a clogged filter whistles and makes the head run hot.
- The oil: a low level wears the mechanism and makes it noisier.
- The valves: if they clatter louder and the receiver takes longer to fill, have them checked.
- Bolts and the belt guard, which rattle as they work loose.
The intervals are covered in our article when to service a piston compressor.
Lever 3, run it for less time
A compressor that runs less makes less noise. Work out its duty cycle: average consumption ÷ compressor flow.
Example with an E 75, 0.9 m³/min according to its data sheet, or 900 L/min:
- Two orbital sanders at 350 L/min each, the indicative value in our configurator, in continuous use: 700 L/min.
- Duty cycle: 700 ÷ 900 = 78%.
- With 100 L/min of leaks: 800 ÷ 900 = 89%.
A piston compressor is designed for intermittent use, with rest periods. At this rate it runs almost continuously, gets hot and makes noise all day.
To cut that running time:
- Fix the leaks, which restart the compressor even when nobody is working: see detecting and repairing leaks.
- Set the pressure to what you actually need, within the limits in the manual: every extra bar means more work for the machine. Our article on calculating compressor pressure explains the method.
Lever 4, move it away or isolate it
In open space, the noise level drops by about 6 dB each time the distance doubles. In a workshop, walls reflect sound and the gain is smaller, but a few extra metres still count. A separate, ventilated room remains the most effective solution: see where to install your compressor. Never shut the compressor in a box without ventilation.
When to switch to a screw compressor
If the duty cycle is well over half the time, or if air is used all day, a screw compressor is the right choice. It compresses air by continuous rotation and sits inside a soundproofed enclosure.
For the example above, 800 L/min with a 25% margin gives 1,000 L/min: the S 75 (1.1 m³/min at 8 bar, 65 to 68 ± 2 dB(A)) or the K 75 (66 ± 2 dB(A), with receiver and dryer) will do. For a small workshop, the S 55 delivers 0.6 m³/min at 8 bar, at 65 to 68 ± 2 dB(A). Compare these values with the data sheet of your current compressor, at the same measuring distance.
Our guide screw or piston compressor helps you decide. Enter your tools in the configurator, or send us your case with a quote request.
For your trade: Quiet compressor for workshops.