Additional nozzle
The width of the additional nozzle provided with the device.
Additional attachments are mainly supplied with window models (see "Type"). Such a nozzle is usually made narrower than the main one — it makes it easier to work on small glasses and in hard-to-reach places. However, there is also the opposite option: a small capture width in the device itself, increased by using an additional nozzle.
Voltage
The voltage of the battery used in the machine with the corresponding type of power supply. This parameter is not key when choosing; it may only be needed when looking for a third-party charger or a replacement/spare battery, as well as for specific calculations related to capacity (see below).
Autonomy time
Operating time of a battery-powered cleaning machine on one charge of a standard battery.
This parameter itself is quite approximate: it is most often indicated for standard operating modes and simple conditions. However, the actual autonomy is usually not very different from the stated one; so, based on the stated operating time, it is quite possible to both evaluate the capabilities of different models and compare them with each other.
Charging time
The time required to fully charge the battery of cleaning machine (see "Power supply").
The larger the battery, the longer it may take to charge it. On the other hand, this moment also depends on the type of battery. In addition, special technologies are being used to speed up the process. So two machines with a similar battery capacity can differ in charging times.
Noise level
The noise level created by the harvesting machine during operation.
Low noise levels are important for the comfort of both the operator and others; the latter is especially true in some specific places such as hospitals or kindergartens. On the other hand, the higher the power, the louder, as a rule, the unit operates and the more difficult it is to reduce this noise to a certain level; despite the fact that in many cases high volume operation is not a particular problem. So you should specifically look for a “quiet” cleaning machine only if a low noise level is more critical for you than high cost and/or reduced power.
When assessing specific loudness values, it is worth considering that the decibel used to indicate the noise level is a non-linear quantity. Therefore, the easiest way is to evaluate specific values using comparative tables. Here's a simplified table for the range that most modern harvesting machines fit into:
55 dB - background noise in an office without special noise sources;
60 dB - loud conversation;
65 dB - city street with average traffic intensity;
70 dB - a conversation between several people in a raised voice.
75 dB – high power vacuum cleaner.
80 dB - traffic noise on a busy street.
