A screw compressor makes a steady sound, without jolts: it is one of its advantages over a piston compressor. Those who work next to it know it by heart. When that sound changes (hissing, knocking, rumbling, vibration), look for the cause early: a little wear spotted in time costs far less than a damaged screw element.
Stop immediately if
- the noise is metallic (scraping, grinding, regular knocking);
- you smell burning or see smoke;
- the noise comes with a rise in temperature or an alarm.
In these cases, switch off, lock out and make a request from the warranty and service page.
The frequent causes, from the simplest to the most serious
A loose fixing or panel
A badly fixed cover panel, a loose screw or a part touching the casing vibrates and resonates. With the machine locked out, check that everything is in place.
The machine is not installed correctly
An uneven floor, a machine touching a wall, rigid pipework connected directly: the vibrations travel into the building. The compressor must stand level, with a flexible connection. See compressor room installation.
The fan or cooler is dirty
Dust building up on the blades unbalances the fan, and a blocked cooler makes the machine overheat. Regular cleaning solves both problems.
Hissing: a leak
A high-pitched hiss often comes from an air leak at a fitting, hose or seal, in the machine or in the network. See detect and repair leaks.
A rumble that grows over time: the bearings
A dull noise that gets louder week after week can come from the bearings of the motor or the screw element. Old oil or a low level speeds up this wear. This is a diagnosis for a technician, to be made without delay.
A compressor that starts and stops constantly
Repeated starts can be heard and tire the machine. See compressor runs constantly or restarts too often.
The normal noise level
A screw compressor is generally quieter than a piston compressor, but it remains an industrial machine. To compare noise levels in decibels and decide where to install it, see compressor noise in dB(A).
Prevention
Maintenance by running hours (oil, filters, separator), a clean and ventilated room and regular visual checks prevent most unusual noises. See when to service a screw compressor.
Other symptoms are covered in our compressor troubleshooting guide.