Comparison Stal KSR-04/50 50 L vs Minsk PT-0020 24 L

The method of transferring rotation from the motor shaft to the working mechanism of the compressor.

— Straight. In direct drive compressors, the operating mechanism shaft is aligned directly with the motor shaft — therefore, such models are also called coaxial. Their main advantage is the low cost due to the simplicity of the design, as well as the small dimensions of the compressor unit. However, this simplicity does not extend to repairs: it is likely that even with a small malfunction, you will have to disassemble most of the device. In addition, this option is characterized by a high level of noise, and the speed of rotation of the shaft is quite high, which greatly wears out the working mechanism. It is very difficult to create a high-performance compressor based on a direct drive, because design features adversely affect cooling efficiency. Therefore, such models usually belong to entry-level devices with low performance.

— Belt. The operation of this drive is based on the use of two pulleys (one on the motor shaft, the other on the shaft of the working mechanism) connected by a drive belt. It is more bulky, somewhat more complex in design and more expensive than a straight line, but outperforms it in a number of other indicators. First of all, this is performance: separately located engine and working mechanism is much easier to cool, which allows you to create compressors of almost...any capacity without the risk of overheating. In addition, due to the difference in the diameter of the pulleys, the speed of rotation of the shaft of the working mechanism is lower than that of the engine, which further reduces heating and has a positive effect on the resource. Belt-driven compressors are easy to repair and maintain (due to the ability to access the engine and mechanism separately), and their noise level is low.

The amount of air that the compressor is able to process per unit of time; usually stated in liters per minute. Performance, along with pressure (see below), is one of the most important parameters: it is it that primarily determines how compatible the compressor will be with one or another pneumatic tool.

It is worth choosing a model according to this indicator in such a way that it can be guaranteed to “pull out” all the tools that can be connected at the same time. Air consumption is usually directly indicated in the characteristics of each tool, and it is quite simple to calculate the total requirement. However, due to the design features, the compressor must have a certain performance margin; the specific value of this stock depends on a number of nuances.

The main point is that some companies indicate for their units the performance at the outlet (how much air is supplied to the tool), while others indicate at the inlet (how much air the compressor sucks in). Since no compressor is perfect, part of the air is inevitably lost during the compression process, so the amount of air at the outlet will always be less than at the inlet. Accordingly, if the output performance is indicated in the characteristics, a margin of 10-20% is recommended, and if the input is 35-40%.

There are also more complex techniques that allow you to more accurately derive the required performance depending on the characteristics of specific tools; they can be found in...special sources.

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.

The number of cylinders provided for in the design of the compressor; by definition only indicated for reciprocating models (see "Compressor type"). This characteristic is primarily associated with performance indicators (see above). For example, values above 400 L / min among single-cylinder units are rather rare exceptions; therefore, if you need a high performance reciprocating compressor, you should look into multi-cylinder models. The second application for multiple cylinders is a multi-stage operation scheme (see "Number of stages").

The receiver is a tank (cylinder) into which compressed air is pumped during operation of the compressor; it is from this cylinder (and not directly from the working mechanism) that it is fed to the connected instrument. The main meaning of such a scheme is that the receiver compensates for pressure unevenness that occurs during the operation of the main mechanism; it does not guarantee absolute constancy, however, all changes occur very smoothly. In addition, energy savings are ensured in this way: part of the time the compressor runs on the stored air from the receiver, and the engine turns on only when the pressure in the tank is significantly reduced to replenish supplies. Therefore, this piece of equipment is practically mandatory, models without a receiver are extremely rare today.

In general, the larger the volume of the receiver, the less often it will have to be pumped up after the initial filling with compressed air. It is also believed that a volumetric receiver can partly compensate for the lack of compressor performance; however, this moment does not ensure the constant stable operation of the “gluttonous” tool and serves only as a fallback in case of a short-term increase in air consumption. On the other hand, large volumes mean the corresponding dimensions of the tank (and it is already the largest part in most compressors), and the cost of the device increases accordingly. Therefore, when choosing, it is worth observi...ng a certain balance and choosing a receiver depending on the specifics of the work. For various types of activities there are recommendations, they can be found in special sources. Here we note that for relatively uniform work in time with a small air flow, a small receiver is usually enough, and if peak loads can occur frequently, it is better to choose a larger cylinder.

Some compressors may provide the expansion of the receiver with additional tanks.