June 17, 2020
Oil-free, oil-less, oil-injected with filters or Technically oil-free, these are the common terms used in the industries where compressed air is a vital utility. But did you know, what is the difference between these terminologies, significance of quality class and how it may impact your production process?
There are various applications especially in food, dairy and pharmaceuticals industries wherein compressed air directly come in contact of product. Some critical applications are instrument air, operating control valves, actuators for filling, packaging & bottling, transport of food such as powdered milk, sugar,etc in food industry; mixing of binder in active ingredients in tablets, coating & sorting of tablet and capsules in pharmaceuticals, supply of oxygen to bacteria during fermentation, separation of nitrogen used to preserve foods in cans, cleaning of bottle, package & mold etc.
Hence the risk of contamination and possibility of severe consequences for the business are very high.
Following the first-time-right policy, It is always recommended avoiding system contamination initially rather than dealing with the potential losses at a later stage. Remember, the scrap and rework costs are a manufacturing reality that is affecting the profitability of companies across all industries.
Few examples of potential costs & losses due to contaminated compressed air:
Hence, the right selection of compressed air equipment with control on the compressed air quality may help you to reduce these costs and thus, improves efficiency and profitability.
In compressed air, the main contaminants are dust particles, water, and oil. These contaminants should properly be treated before using the compressed air for end products. There are various technologies and methods are available to treat the compressed air. However, it is recommended to know the pros and cons of each available technology.
Can your oil injected air compressor with line filters (Technically oil-free) deliver 100% oil-free compressed air?
Oil-injected air compressors, describe compressor in which the oil is present in the compression chamber, used to lubricate the moving parts further treated with downstream filtration systems are often referred as 'Technically oil-free air' compressors. Under optimum conditions and with several stages of oil removal, the air quality with respect to oil will always in suspect.
So, the answer of above question is No. Oil-injected screws does not provide 100% oil-free compressed air.
'Technically Oil Free' compressed air system was used often till the time oil vapor was given negligible importance in ISO Quality class.
On the other hand, oil-less or oil-free air compressors do not use any oil for the lubrication in the compression chamber, hence, it ensures 100% oil-free air at the outlet. This 100% oil-free compressed air will not only reduce the cost of ownership but also prevent the risk of severe consequences for the business and safeguard the environment by eliminating the need of condensate treatment.
The original version of ISO compressed air purity standards was first published in 1991. The standard defined five classes of oil concentration, the best of which was class 1.
Class 1 specifies an oil concentration of 0.01 mg/m3 at 1 bar(a) 14.5 psia and 20 degree C (68 degree F), confirming to these criteria was sometimes called a 'Technically' oil-free solution.
Due to low initial cost solution, it was a natural choice over oil-free compressed air solutions. However, at high temperature there is more oil vapor in the air which reduces the efficiency and life of the filters, especially the life of activated carbon filter. This leads to increased contamination in compressed air. When these facts were found correlated with the increased number of user complaints, a need for modification in the quality standard has arisen.
Accordingly ISO class was modified first time in 2001 and further updated in 2010.
The current standard sets limits on total oil content (aerosol, liquid, and vapor), and a specific standard was introduced for the measurement of oil vapor. A new class - Class 0 was also added to cover more stringent quality requirements.
As per the latest addition of quality class ISO 8573-1:2010, this is now ranked between 0-6 ISO class.
Class 0 category is the most stringent category in all defined categories.
Class 0 air with respect to the oil contamination (including aerosol, liquid, vapor) in the compressed air is specified by the equipment user or supplier but always more stringent than Class 1.
When selecting an oil-free air compressor, make sure you’re choosing a Class 0 oil-free air compressor and not a 'technically' oil-free air compressor. With Class 0 oil-free air compressor, your end products are contamination free and thus help you to high profitability and earnings from your plant.
CLASS 0 air means 'Zero Risk, “Zero Oil'
If you need help in selecting a right class 0 compressor, or you have a question about your existing compressor...