 | | Efficient and reliable production of premium quality compressed air | |
Compressed Air Treatment is Essential |  |
A dependable source of premium quality compressed air is essential for the brewing, beverage and food industries. However, as different applications have different compressed air quality requirements, ISO standard 8573-1 was introduced in 1991 to stipulate the various quality classes. Nevertheless, some operators wanted to go one stage further by having defined residual oil content thresholds. Therefore, under their initiative, the so-called "Class 0" was introduced in 2001. But what does it mean? What’s the best way to achieve and reliably maintain compressed air quality in accordance with such a classification? The stipulations for ISO standard 8573-1 from 1991 were an important step, as they provided clear definitions with regards to air quality and did away with vague terms such as “technically oil-free” or “pure”. Accordingly, for compressed air to comply with quality Class 1 it should have a total remaining oil content of ≤ 0.01 mg/m³, contain solid particles no larger than 0.1 µm in diameter at a concentration of no more than 0.1 mg/m³. Residual moisture levels should correspond to a pressure dew point of ≤ -70 °C. Introduced in 2001, the newly created "Class 0” was intended to provide compressed air system providers and users with a specified defined value or specification for air quality better than Class 1. However, Class 1 already covered values of 0.01 mg/m³ or less with regards to residual oil content, which of course includes the value “0”. The same also applied to residual moisture and remaining particle content. In practice therefore, “Class 0” can be viewed as being somewhat misleading rather than helpful. Quality compressed air: Impossible without treatment
In spite of all the advances in air pollution control, it is an undeniable fact that air contamination levels in many regions continues to increase. Much of this contamination takes the form of mineral oil aerosols and other gaseous hydrocarbons. Even systems used for production and packaging etc. of products that require high levels of hygiene, such as beverages, foodstuffs or medicines, also lead to increased hydrocarbon levels in the ambient air. Compressor systems often suck in significant levels of contaminants along with the ambient air. This is why it is impossible to ensure precisely defined compressed air quality without using appropriate air treatment measures, especially when it’s not known which contaminants are in the intake air. This is the case irrespective of the method used for air compression and still applies even if individual compressed air system components, such as the compressor, are certified as being quality “Class 0” compliant under certain intake conditions. In addition, certifying a hydrocarbon and residual oil content of 0.0000 mg/m³ is much easier said than done. In fact, it is widely accepted amongst experts that detection of hydrocarbons and residual oil below a concentration of 0.003 mg/m³ is very difficult and is consequently hard to prove in a compressed air network. Certified treatment systems
As users have to be able to count on a specific compressed air quality under all operating conditions there is only one option: to have the treatment system designed and certified as a whole in accordance with the ISO standards. Having said that, however, systems can also be certified with multiple treatment classes (Fig. 1) as per customer requirement, as not every area of each system requires compressed air of the highest quality. Systems with so-called oil-free screw compressors have to use a corresponding treatment system to meet the same stringent quality requirements (Fig. 2). Even 10 years ago, compressors from Kaeser were already achieving residual oil content values that were far superior to those required by quality Class 1 and were consequently awarded the TÜV (German Technical Inspection Authority) quality certificate. After the introduction of "Class 0", the following question arose: What should be written into the measurement protocol? In order to document the most accurate values, it was decided to include the exact figures of 0.00233 and 0.00238 mg/Nm³ instead of the also mathematically correct and more promotionally favourable alternative: To round the figure down to “0” due to negligible measurement values.
Users are also able to trust these measurement results, as they were carried out under normal operating conditions. Furthermore, Kaeser Kompressoren does not rely on the (fluctuating) quality of the intake air, but installs application-specific treatment systems that feature optimised monitoring and control to ensure unrivalled reliability. ‘Normal operating conditions’ means that the compressor takes in air of a quality that would normally be found in an Industrial setting. No reliability without treatment
Those who believe that untreated compressed air can be brought into contact with sensitive products, such as beverages, foodstuffs or pharmaceuticals, will almost certainly encounter serious production and/or product quality problems within a very short time. The reasons for this are as follows: firstly, the uncertain quality of the intake air and secondly, it is only the compression chamber in so-called “oil-free” compressors that is in fact oil-free. Even in these systems, moving parts such as bearings and shafts have to be lubricated and are only separated from the compression chamber via seals. Summary
As compressed air treatment is essential for the production of high- and premium-quality (ISO Class 1) compressed air, it is best to choose the most cost-effective and energy-efficient systems. These comprise a compressor, air treatment and a master control/monitoring system. With a quality certificate in all of these areas since 1997, Kaeser has a perfectly tailored solution for every compressed air application.
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