The UK’s manufacturing sector requires ever-growing quantities of high-quality compressed air to power plant and factory applications. With such stringent processes in place to monitor potential product and process contamination, Richard Hilton, Product Director at Gardner Denver, outlines the oil-free technologies available to plant owners and operators, and the efficiencies oil-free compressors can help realise.
Compressed air is often referred to as the ‘fourth utility’, and is used in a wide variety of applications across the manufacturing sector. For production sites where compressed air comes into direct contact with the goods – such as the food and beverage, pharmaceuticals and electronics industries – this resource needs to not only be constant, but also of very high quality.
In some cases, the demand for high-quality air has been achieved by using oil-lubricated compressors relying on filtration to protect products and equipment from contamination. However, this can be very risky as any contamination can have a huge impact on manufacturing processes and requiring significant expense to resolve, many organisations are switching to oil-free compressors. Combined with the continued tightening of hygiene regulations governing sensitive production environments, this trend looks set to only increase.
Stringent hygiene regulations
While there are currently no regulations specific to oil-free compressors, compressed air provision is subject to extremely stringent standards regulating quality and performance. For example, the required standard of compressed air quality is set out in the group of international standards known as ISO8573.
ISO8573 consists of nine separate parts, with part one highlighting the amount of contamination allowed in each cubic metre of compressed air, and the remaining eight specifying the testing methods for an array of contaminants. These methods range from measuring oil aerosol content and humidity, to monitoring solid particle and oil vapour content.
With less contaminants present to compromise compressed air, it is clear that oil-free compressors are better equipped to meet these standards than their oil-lubricated counterparts. Therefore, they are therefore a more logical choice in sectors where air quality cannot be compromised.
Further benefits
As well as producing a better quality of compressed air, oil-free systems can also be more efficient and cost-effective than their oil-lubricated counterparts. For example, investors in oil-free systems do not need to purchase an oil separator element or replacement downstream filters. This is not possible with an oil-lubricated system, which will require oil change intervals through its lifetime.
Owners of oil-lubricated systems may also encounter problems when disposing of their oil or oil-contaminated condensate, both of which can impact the environment.
Additionally, oil-free units do not experience the downstream pressure drop that can occur in oil-lubricated units. Further energy is not required to increase force and compensate, leading to a reduction in overall energy costs.
Different oil-free designs
There are multiple types of oil-free compressor technologies available to owners and operators. For example, some units utilise scroll technology. This design consists of an orbiting, rotating scroll and fixed scroll housing connected together to create compression chambers. The orbiting scroll’s continual movement transfers atmospheric air from the intake to the centre, compressing the air in progressively smaller areas.
The compressed air is directed to the compressor’s centre discharge point, and discharge pressure is accomplished during these multiple stages of compression. The end result is a constant supply of oil-free air at the required pressure.
Alternatively, owners and operators may opt for water-injected rotary screw technology when specifying an oil-free compressor. Through the use of reverse osmosis filtration, models utilising this technology lubricate, seal and cool the compression process by providing high-quality water throughout.
A key advantage of this type of compressor is that it is 100 per cent oil free. thanks to its low running temperature, it does not require an internal aftercooler. Consequently, the unit can achieve near-isothermal compression, resulting in minimised pressure drop and reduced power consumption.
Gardner Denver can also offer its own revolutionary oil-free system with the Ultima drive design. Ultima differs from other oil-free compressors in that it does not use a single motor and mechanical gearbox design to drive the low and high-pressure air-ends. Instead, it adheres the U-Drive concept, replacing the gearbox and single motor with two high-efficiency, permanent magnetic motors.
This set-up allows for performance optimisation throughout the complete volume range. This is because the airends are powered by two separate inverters, so they can be individually driven at different speeds dependent on demand. An intelligent digital gearbox design then monitors and continuously adjusts the speeds of each aired, ensuring maximum efficiency and pressure ratios at all times.
Opting for oil-free
In conclusion, manufacturers are increasingly selecting oil-free compressors for guaranteed air purity. Though it is possible to opt for oil-lubricated models to preserve air quality, products and equipment, the efficiencies and air quality from the latest oil-free technology is encouraging many compressed air users to choose an oil-free system.
For more information about Gardner Denver’s oil-free compressor technology, please visit www.gardnerdenver.com.
