Ensuring oil-free air for controlled manufacturing environments

IN SENSITIVE manufacturing process environments maintaining the highest levels of air purity is a critical consideration, any traces of oil in the air can lead to costly production downtime, product spoilage, and reputational damage.
 
For example, in the crucial semiconductor manufacturing industry, oil contamination resulting in the spoilage of high-value computer chips being processed would represent a 'game over' scenario.

So how do plant managers avoid the risks and guarantee 100% oil-free air in their operations? The answer for manufacturers in these sectors is to eliminate contamination risk by installing an oil-free air compressor system. 

Oil-free compressor categories

Today's state-of-the-art, oil-free compressors not only produce the highest quality Class Zero air, but they also deliver significant savings in lifecycle costs. Oil-free air technology helps to avoid expensive filter replacements, cuts the cost of oil condensate treatment and disposal, and reduces energy loss from pressure drops. 

However, in selecting the most suitable oil-free compressor; there is an important distinction between ‘Class 0’ oil-free compressors, which guarantee absolutely no contamination of air, and what is known as ‘technically oil-free’ category where oil as a contaminant is introduced to the compressed air system and needs to be filtered out and removed downstream of the compressor.

How oil-free compressors work

Oil-free compressors operate without oil in the compression chamber, which eliminates the chance of downstream contamination with oil in the compressed air supply. Rather than using oil for lubrication, sealing and cooling, these types of compressors utilise other technologies, such as water jackets and advanced, coated compression elements, engineered with microscopic tolerances to deliver oil-free compressed air.

In oil-free screw compressors, which make up the bulk of the market for this type of product, external gears synchronise the position of the counter-rotating screw elements. As the rotors do not come in contact, nor create friction between each other, no oil is required for lubrication within the compression chamber. 

Precision engineering of the housing and screw elements minimises air leakage and pressure drops from the pressure side to the inlet. As the internal pressure ratio is limited by differences in air temperature between the inlet and discharge ports, oil-free screw compressors are frequently built with several stages and inter-stage cooling to maximise the pressure reach. 

Saving on energy costs with VSD and heat recovery

In addition to saving on through-life costs, using modern oil-free compressor technologies can also deliver significant energy savings. For large-scale, high-energy applications, like glass processing, food production, steel manufacturing, automotive, and petro-chemicals, centrifugal compressors offer significant energy efficiency in process air or bulk air applications presenting a flat load, or when providing a baseline flow in mixed installations with VSD screw compressors

A VSD compressor, which matches output to load, saves on average 35% of energy consumption, while advanced models can save as much as 50% compared to fixed speed units even at full load. It is also possible to equip oil-free compressors with an energy recovery unit, where up to 94% of the compressor’s input power is converted into usable energy. 

Finally, oil-free compressors can also take advantage of advanced central controllers and remote monitoring tools to further boost energy efficiency. A master controller will optimise the operation of a compressed air system with multiple compressors. 

From the foregoing information it is clear that it pays plant management to seek the knowledge, experience, and expert advice of leading compressor technology manufacturers to ensure the most suitable oil-free compressor is selected for the task at hand

Mark Ranger is business line manager, oil-free air at Atlas Copco UK and Ireland

For more information: 

www.atlascopco.com

Tel: 0845 601 0001