Power
The power of the engine installed in the compressor. It is not the main parameter in evaluating the efficiency of the device — here the performance and nominal pressure play a decisive role (see above), and the engine is selected in such a way that its power is sufficient to ensure the claimed characteristics. However, this indicator still has practical significance: in compressors with an electric motor (and there are now most of them; see “Engine type”), the engine power determines the total energy consumption of the device, as well as the requirements for the network where it is planned to connect it (for more details, see “Voltage networks"). In addition, the power of the engine (regardless of its type) must be known in order to calculate the optimal performance value using some special formulas.
For internal combustion engines, power is traditionally expressed in horsepower (hp); you can convert it to watts in this way: 1 hp. = 735 W.
Rotation speed
The speed of rotation of the compressor motor shaft in normal operation. This parameter, usually, does not affect the efficiency of the unit — the main indicators are still the performance and nominal pressure (see above). At the same time, it allows you to evaluate the design features of the compressor and its durability. The fact is that a higher rotation speed allows the use of fairly simple and inexpensive working mechanisms, but it increases the wear of moving parts and reduces the motor resource. Therefore, a model with a lower number of revolutions is likely to cost more than the "high-speed" version, but it will also last longer (ceteris paribus characteristics — performance, pressure, drive type, design; see all above).
Noise level
The maximum noise level produced by the compressor during operation. When evaluating it, it must be taken into account that the decibel used to evaluate noise is not an absolute value. In fact, this means that noises, for example, 20 dB and 40 dB differ in level not by a factor of 2, but by 100 — it is this multiplicity that corresponds to a difference of 20 dB; a twofold increase corresponds to a 3 dB increase. Therefore, to assess noise levels, it is worth referring primarily to comparative tables. For values found in modern compressors, this table would look something like this:
70 dB — loud conversations at a distance of about 1 m;
75 dB — scream;
80 dB — motorcycle engine with silencer;
85 dB — loud scream;
90 dB — freight train car at a distance of 5-7 m;
95 dB — noise inside the subway car.
Anyway, the lower the level of noise produced by the unit, the more comfortable its use, the less it will “hit on the ears” and increase the volume of the entire set of working instruments.
Noise level (LPA)
The sound pressure level in decibels at a certain distance between the noise source and the ear of the compressor equipment operator. Since people do not work in the immediate vicinity of the compressor, the parameter will be useful for estimating the noise level at a distance. It is most often measured at a distance of 7 m from a working installation, less often at a distance of 1 m.
