Unlike piston compressors, in screw compressors there are no valves or other mechanical forces that can cause unbalance. This allows a screw compressor to operate at high speeds, while combining a large flow rate with small exterior dimensions. The ideal application of rotary screw compressors are continuous, workplace and industrial applications. There are two primary versions, oil-free and oil-injected, with options of fixed speed or variable speed drive operation.
The main benefit of rotary screw compressors is the energy efficiency. But this type of compressor has many other benefits. These include:
- low noise output
- small footprint for point-of-use installations
- no duty cycle
- continuous operation at temperatures of up to 46 degrees C
- low oil-carryover (as little as 3 ppm) in oil lubricated machines
- zero loss of capacity over time
There are a wide variety of options available in the 2.2-500 kW range of workplace and industrial rotary screw compressors. Recent introductions offer advanced designs such as a vertical, close-coupled configuration. Another distinguishing feature are interior permanent magnet motor drive and inverter systems. Such systems are capable of achieving energy savings of up to 50 per cent over conventional fixed speed designs.
- In oil injected screw compressor technology, the male rotor drives the female rotor
- In oil free compressor technology, a timing gear drives both rotors for harmonic running, with minimum calculated clearance between both elements
Discover our oil-injected screw air compressors for sale:
Much like the oil-lubricated variant, oil-free screw compressors also have other names. Users will often refer to them as oilless compressors or no oil compressors. The names, however, can be somewhat misleading. The naming convention for these compressors comes from the presence (or absence, in our case) of oil in the compression process. An oil-free compressor will still use lubricant for its other processes, such as motor cooling or removing heat from the rotors. Some variants will use water as an alternative lubricant. Our AQ water-injected compressors are such an example. Other variants rely on a special coating applied to the rotor elements, which eliminates the need for lubricants. That is the concept behind our popular ZR oil-free rotary screw compressors. The oilless compressor is generally used by sensitive industry applications. This is because they adhere to the rigorous standards expected in food and beverage or pharmaceuticals. They are also better suited to the stringent requirements in the oil and gas industry.