Air Quality in Dense Phase Pneumatic Conveying
A fundamental element
Dense phase pneumatic conveying systems require compressed air to move powdery or granular products. Since these materials come into direct contact with the air, it is essential that the air is dry and free of contaminants, especially when dealing with food or pharmaceutical products, where air quality can directly affect the safety and integrity of the product.
Air Tec does not manufacture compressors nor install compressor rooms but provides customers with data regarding the required air quantity for the proper operation of its machines. It is the customer’s responsibility to work with companies specialized in compressed air supply to ensure the availability of a system suited to their needs.
Compressed Air Quality According to ISO 8573-1
Compressed air is an essential resource in many industries, from automation to pharmaceuticals, food processing to electronics manufacturing. However, to ensure efficient and safe processes, it is crucial that compressed air is free from contaminants. The ISO 8573-1 standard defines the quality requirements for compressed air, classifying purity levels based on particulate matter, water, and oil contamination.
ISO 8573-1: Air Quality Classification
The ISO 8573-1 standard categorizes compressed air quality into three main types of contaminants:
- Solid Particles: Includes dust, particulates, and other impurities present in the air.
- Water Contamination: Present in the form of vapor or condensate.
- Oil Contamination: Includes both aerosols and oil vapors.
The standard assigns a numerical class to each contaminant: the lower the number, the higher the air purity. For example, air classified as 1.1.1 is extremely pure, whereas 5.4.3 indicates higher levels of contamination.
Example: Class 1.1.1
- Solid Particles: Maximum particle diameter of 0.1 microns
- Water Contamination: Maximum pressure dew point of -70°C
- Oil Contamination: Maximum concentration of 0.01 mg/mc
Example: Class 5.4.3
- Solid Particles: Maximum particle diameter of 40 microns
- Water Contamination: Maximum pressure dew point of +3°C
- Oil Contamination: Maximum concentration of 1 mg/mc
Types of Filters for Compressed Air Treatment
To achieve the different purity classes specified by ISO 8573-1, various types of filters are used, including:
- Mechanical Filters (Pre-Filters): Remove larger dust particles and debris.
- Coalescing Filters: Eliminate oil aerosols and moisture present in compressed air.
- Activated Carbon Filters: Absorb oil vapors and unwanted odors, improving air quality.
- Adsorption Dryers: Reduce compressed air humidity, which is essential for achieving high purity classes.
- Sterilizing Filters: Used in pharmaceutical and food applications to remove bacteria and microorganisms.
How to Choose the Right Filtration System
Selecting the appropriate filtration system depends on the level of purity required for the industrial process. Here are some key factors to consider:
- General Applications: For pneumatic tools and standard industrial applications, a system with a coalescing filter to remove oil and a dryer to reduce humidity is often sufficient.
- Food and Pharmaceutical Industry: Air with minimal contamination levels is required. Adsorption filters are used to eliminate oil vapors, while sterilizing filters remove microorganisms.
- Electronics and Painting: The air must be extremely dry and free of particles to prevent defects in finished products. Membrane dryers and high-efficiency filters are commonly used.
The Importance of Relying on Specialized Suppliers
Choosing the right filtration system is not just about regulatory compliance but also about efficiency and reducing operational costs. For this reason, it is always advisable to rely on specialized compressed air suppliers who can provide personalized consultations and optimized solutions tailored to the specific needs of each facility.
Conclusion
In dense phase pneumatic conveying, the quality of compressed air is a critical factor in ensuring the safety and integrity of the materials being transported. The ISO 8573-1 standard provides an essential framework to define the required purity levels and identify the most suitable filtration solutions. Relying on specialized suppliers ensures high-quality compressed air, optimizing production processes and ensuring compliance with industry standards.
