Introduction to Air Quality standards for the classification of Compressed air quality

  1. Introduction

ISO (International Standards Organisation) is the world’s largest developer and publisher of international standards. An intermediary between the public and private sectors, ISO is a non-governmental organization. It has developed international standards to test the quality of compressed air. There are now three standards in use that are specifically related that directly relate to compressed air quality (purity) and testing:

  1. ISO8573 Series
  2. ISO12500 Series
  3. ISO7183

The most used standard is the ISO8573 Series and in particular ISO8573-1:2010. The ISO air quality standard measures three types of contaminants present in compressed air: water, oil content, and solid particles. It does not consider microorganisms and gases.

2.     What is compressed air quality & why it is needed?

When air is gathered to be compressed, more particles are also gathered, resulting in contaminated air. When air is compressed, the number of impurities present exponentially rises. Additionally, when compressing air, other pollutants could be included. To clean up the compressed air system’s pollutants, air treatment is required. The types of contaminants found in a compressed air system include:

  1. Solid particles / Dust
  2. Water (in liquid or vapor form)
  3. Oil content (in vapor or aerosol form)

Schematic presentation of contaminants present in compressed air

When air is adequately treated, it is considered clean and safe. However, the quality of compressed air is determined not just by how clean it is, but also by how dry it is. The number of particles of a specified size present in one cubic meter of air, the dew point, and the number of oil aerosols and vapor must all be counted to assess how clean and dry the compressed air is.

Compressed air is utilized in a variety of industries, including mining, manufacturing, textile manufacturing, and food processing. The air quality utilized in industrial applications has a direct impact on the work process, installed machines, and product quality. As a result, it is critical that the compressed air be clean and devoid of pollutants.

The smaller the chance of contamination, breakdowns, and product rejection, the cleaner the air. This is especially important in businesses like food and beverage and pharmaceuticals. There is a possibility that the air will come into direct touch with the product or will come into indirect contact with the packaging.

  1. Classification of Compressed air quality

Compressed air is the only utility created by the end user of all the key utilities used in the food manufacturing setting. This means that the end-user has a direct impact on the quality of this energy source.

High-quality compressed air is essential for producing food that is not only cost-effective to process but also safe to consume. Therefore, choosing the appropriate compressed air equipment for food processors is in the best interests of everyone. The basis for choosing air treatment products is made much easier by the ISO 8573 air quality standards and ISO 12500 compressed air filter standards.


      Standards used for air quality measurement

  1. What is ISO 8573 & how it defines different air purity classes?

ISO 8573 is the compressed air quality standard. ISO8573 is a series of international standards that address compressed air quality (or purity). Part 1 of the standard describes the compressed air quality requirements, and parts 2 through 9 detail the testing techniques for various pollutants.

  • ISO 8573-1: Contaminants & purity classes
  • ISO 8573-2: Oil aerosol test methods
  • ISO 8573-3: Humidity test methods
  • ISO 8573-4: Solid particle test methods
  • ISO 8573-5: Oil vapor test methods
  • ISO 8573-6: Gas test methods
  • ISO 8573-7: Viable microbiological content tests
  • ISO 8573-8: Solid particle test methods by mass concentration
  • ISO 8573-9 Liquid water test method


       Various air quality classes


This above standard also determines air quality, which is designated by the following nomenclature: Compressed Air Purity Classes A, B, C:
A= Solid particle class designation
B= Humidity and liquid water class designation
C= Oil class designation

Air quality designation

5.     Why is it important to consider the air quality?

Compressed air can contain unwanted substances, such as water in drop or vapor form, oil in drop or aerosol form, and dust. Depending on the compressed air’s application area, these substances can impair production results and even increase costs. Air treatment aims to produce the compressed air quality specified by the consumer. When the role of compressed air in a process is clearly defined, finding the system that will be the most profitable and efficient in that specific situation is simple. This will be determined by your finished product and the working environment of your application.

6.     What does Class 0 mean for air quality?

It is recommended that only compressed air classified as Class 0 be used in critical processes to eliminate the risk of air contamination. This level of classification does not mean zero contamination. Class 0 refers to the highest air quality possible with minimum contamination present in the air and must be lower in contamination than Class 1.

A combination of compressed air equipment can be installed to produce clean air. This may include various air filters and dryers. Identifying which contaminants need to be removed will help you to determine which equipment you need.

  1. Conclusion:

A specific compressed air class is assigned depending on the number of contaminants found. The air quality class is set according to ISO 8573-1. This standardized system defines parameters from the least to most contaminated sources of compressed air. These standards are very much useful when it comes to selecting air compressors/ compressed air systems for industrial purposes. As Compressed air is a vital energy source and is utilized in multiple operations in a food processing facility.

When properly treated, compressed air is regarded as a safe, clean utility, as compared to other energy sources. It is ultimately used to package, wrap, seal, palletize and label food products prior to storage or shipment. ISO 8573 is a European Standard that describes contaminants in compressed air and defines purity classes for them. This multi-part standard also defines approved measurement methods for testing contamination levels.

  1. Reference


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