Understanding Compressed Air Quality Requirements

Class 1

Class 1 compressed air quality represents a slightly less stringent level than Class 0 but still ensures high levels of purity, suitable for many critical applications where contamination risks must be minimised.

An example of Class 1 compressed air would be found in electronics manufacturing or laboratories, where even low levels of oil, particulates, or water vapor can affect production quality or testing accuracy, but slightly higher contamination levels are permissible compared to Class 0.

For instance:

• Application: In an electronics assembly line, Class 1 compressed air may be used for cleaning circuit boards, operating pneumatic tools, or powering equipment without risking the integrity of sensitive components.
• Contaminant Levels:
  • Oil (aerosol, liquid, and vapor): < 0.01 mg/m³
  • Particulate matter: Maximum of 100 particles per cubic meter for particles larger than 0.1 microns
  • Water vapor: Dew point of -40°C or below
• Equipment Used: Typically involves oil-lubricated compressors with enhanced filtration systems, such as coalescing filters, particulate filters, and desiccant dryers, to remove contaminants to the required standards.

Class 1 compressed air is ideal for most applications in industries where the impact of air quality on final product performance is significant but not as critical as in pharmaceutical or food production. It offers a balance between air purity and cost-efficiency

Class 2

Class 2 compressed air offers a moderate level of purity suitable for industrial applications where the risk of contamination is less critical but still needs to be controlled. This level is often used in industries where compressed air is utilised for non-critical tasks, such as general manufacturing or cleaning, where product quality may not be as directly impacted by minor levels of contamination.

An example of Class 2 compressed air would be used in automotive manufacturing for tasks like powering pneumatic tools, operating machinery, or providing compressed air for general purposes in an environment where the risk of contamination to the product is low.

For instance:

• Application: In an automotive assembly plant, Class 2 compressed air might be used for powering pneumatic equipment or for cleaning parts and surfaces before assembly, without the risk of affecting the product quality.
• Contaminant Levels:
  • Oil (aerosol, liquid, and vapor): < 0.1 mg/m³
  • Particulate matter: Maximum of 200 particles per cubic meter for particles larger than 1 micron
  • Water vapor: Dew point of +3°C or below
• Equipment Used: Typically includes standard oil-lubricated compressors with basic filtration, such as particulate filters and moisture separators & refrigerated compressed air dryers to meet the Class 2 requirements. Desiccant dryers or advanced filtration may not always be required for this level of air quality.

Class 3

Class 3 compressed air is suitable for applications where air quality is important, but the risks of contamination do not significantly affect product quality or machinery performance. This level is often used in less critical industrial applications or environments where higher levels of contamination are tolerable without significant operational consequences.

An example of Class 3 compressed air would be in construction or mining operations, where compressed air is used for tasks like powering pneumatic tools, clearing debris, or operating large equipment, and minor contamination is unlikely to interfere with the task at hand.

For instance:

• Application: In a mining operation, Class 3 compressed air might be used to power pneumatic drills, air hammers, or other equipment that does not directly impact the quality of the extracted materials.
• Contaminant Levels:
  • Oil (aerosol, liquid, and vapor): < 1.0 mg/m³
  • Particulate matter: Maximum of 1,000 particles per cubic meter for particles larger than 5 microns
  • Water vapor: Dew point of 3-7°C
• Equipment Used: Basic oil-lubricated compressors with standard filtration, such as moisture separators and coalescing filters, to remove larger particles and reduce the amount of water vapor in the air.

Class 3 compressed air is typically used in environments where air quality is secondary to the operational needs of the equipment. These applications are usually rugged and do not require the utmost purity, making it a cost-effective solution for non-critical tasks.

Class 4

Class 4 compressed air quality is often used in environments where contamination can be tolerated to a greater degree, such as in certain non-food manufacturing or maintenance applications. The air may still be suitable for general machinery use but is not recommended for sensitive or high-precision operations.

An example of Class 4 compressed air would be in pneumatic conveying systems for transporting bulk materials, such as in cement manufacturing or textile production, where the air is used to push materials through pipes or hoppers but where even noticeable levels of contaminants have minimal impact on the process.

For instance:

• Application: In a cement manufacturing plant, Class 4 compressed air may be used in pneumatic conveying systems to transport raw materials like sand or cement powder, where the air quality does not impact the material integrity or production process.
• Contaminant Levels:
  • Oil (aerosol, liquid, and vapor): < 5.0 mg/m³
  • Particulate matter: Maximum of 5,000 particles per cubic meter for particles larger than 10 microns
  • Water vapor: Dew point of 3-10°C
• Equipment Used: Basic industrial compressors with minimal filtration, primarily designed to remove larger particulate matter and some water vapor. Additional filtration and drying may be optional depending on the specific system.

Class 4 compressed air is widely used in low-cost, high-volume applications where purity is not a priority. It is typically sufficient for tasks where the air does not come into direct contact with the end product or affect the performance of heavy-duty equipment.

Class 5

Class 5 compressed air represents the lowest standard of air quality, typically used in basic industrial applications or for tasks where contamination has no impact on the performance or safety of equipment. This level is often found in applications where the air is primarily used for non-critical tasks such as powering large machinery or general cleaning.

An example of Class 5 compressed air might be used in construction or agricultural equipment maintenance, where the air is used to clean out systems, clear large surfaces, or blow debris from tools, without the need for high-quality air.

For instance:

• Application: In an agricultural equipment repair workshop, Class 5 compressed air may be used for cleaning and blowing off dirt and debris from large machinery, where oil or particulates in the air won’t affect the operation or safety of the equipment.
• Contaminant Levels:
  • Oil (aerosol, liquid, and vapor): < 10.0 mg/m³
  • Particulate matter: 50 microns or larger at less than 50 mg/m³
  • Water vapor: Dew point of +10°C or above
• Equipment Used: Basic compressors without significant filtration. Only moisture separators and large mesh particulate filters may be used to capture larger debris.

To meet specific air quality requirements, selecting the right products is essential:

1. Compressed Air Dryers
   • Refrigerated Dryers: Ideal for Class 4-5 air, removing moisture to a dew point of around 3°C. Suitable for general-purpose use.
   • Desiccant Dryers: Achieve dew points as low as -70°C, ideal for Class 1-2 air, and critical in applications requiring ultra-dry air like pharmaceuticals.
   • Membrane Dryers: Compact and efficient, often used for localized drying where portability is required.
2. Inline Filters
   • Particulate Filters: Essential for capturing dust and dirt particles, ensuring compliance with Class 5 or higher.
   • Coalescing Filters: Remove oil aerosols and fine particulates, critical for Class 1-2 air quality.
   • Activated Carbon Filters: Eliminate oil vapors and odors, ensuring Class 0 air purity for sensitive applications.
3. Condensate Management Systems
   • Oil-Water Separators: Essential for environmental compliance, ensuring proper disposal of condensate.
   • Automatic Drains: Prevent moisture buildup, reducing system inefficiencies.