DC compressors are devices most commonly used for the provision of compressed air from a direct current (DC) power source, and are most useful away from sources of mains electricity, which is usually alternating current (AC). These compressors are most useful for those working outdoors, where only DC power source are available, for instance, automotive batteries.
Uses of compressors
Compressors have a variety of uses, the most obvious being the inflation of tyres. In addition to this, the high pressure air that these devices provide is useful in mechanical applications for running tools that require high power, for instance, pneumatic drills for drilling concrete, nail guns or air ratchets used to tighten wheel nuts to high-torque factory specifications. Compressed air hoses can be used for cleaning, especially in precision engineering.
Compressed air cylinders, as used in aviation or the diving industry, require a compressor to fill the cylinder to the required pressure, and they are also used in the diving industry where a re-compression chamber is needed to treat victims of decompression sickness, or the bends. DC compressors
are used for portable re-compression chambers, where victims of decompression sickness can be treated quickly in the field, with the power supplied by automotive batteries.
How they work
Positive displacement DC compressors use a DC electric motor to force air into a chamber of decreasing size, through a one-way valve, thereby compressing the air. This may be by the use of a screw, vane or piston. Negative displacement compressors work by using the centrifugal force of an impeller to accelerate air, which then compresses on contact with the edge of a chamber.
Compressors can be used with or without a tank, which will even out the supply and demand of compressed air by providing a reservoir of pre-compressed reserve air. There may also be additional stages of compression, where air is required to be supplied at higher pressures.