No home workshop is truly compete without an air compressor. But spend any time working around one and you may soon find yourself wishing you didn’t rely on air to run so much of your shop. To put it mildly, conventional reciprocating-piston air compressors tend to be loud. Not a good kind of loud, either. Just loud. They drown out your music, your thoughts, and any chance of a normal conversation while they’re running.
An alternative to the conventional noisemaker is a scroll-type compressor, like Eastwood’s QST 30/60 compressor. The basic design has been around for decades, using a rotating spiral scroll that rotates eccentrically around a fixed spiral scroll of the same geometry. The quiet, smooth operation makes them popular for use in air conditioning and other mechanical applications. Volkswagen even developed a variation in the late ‘80s known as the “G-lader” or G-charger that served as supercharger.
When applied to air compressors, the scroll design is more efficient and much quieter than the traditional reciprocating compressors most of us know. While there are numerous advantages to a scroll compressor versus a reciprocating design, the primary advantage for most buyers, especially those working in a home garage, is noise reduction.
A typical air compressor generates as much as 86 dB of sound from 10 feet away, more than 20 dB higher than a normal conversation. A scroll compressor, by comparison, can come in quieter than that conversation. That makes a huge difference in comfort and fatigue when working.
Why so quiet?
But what makes the scroll compressor so quiet? There are two major factors. First, the synchronized scrolls are generating continuous pressure throughout each revolution instead of pulses of pressure. There’s simply less acoustic signature from the uneven inlet and outlet of air.
The second factor is fewer moving parts. There is only one major component that moves in a scroll compressor. There are no valves clicking open and closed, no piston ring slap, no violent vibration from as crankshaft reaches its extremes.
The concept of a scroll compressor can be difficult to visualize, but the advantages become immediately obvious once you’ve experience one in action.