ISO 8573-1: The Standard for Compressed Air Quality
Defining Air Purity Classes for Reliable and Safe Industrial Compressed Air
Compressed air is an essential utility in almost every industrial process. However, without proper monitoring, contaminants such as particles, oil vapor, and moisture can affect product quality, damage equipment, and create safety risks.
The ISO 8573-1 standard defines purity classes for compressed air and provides the foundation for evaluating and maintaining air quality according to global standards.
By implementing ISO 8573-1, operators ensure reliability, efficiency, and safety in all compressed air applications.
Page Overview
- What is ISO 8573-1
- ISO 8573-1 Purity Classes
- Why the Standard Matters
- Main Contaminants and Test Methods
- SUTO iTEC Measurement Solutions
- Applications and Industries
- From Audits to Continuous Monitoring
What is the ISO 8573-1 Standard?
The ISO 8573-1 standard defines purity classifications for compressed air, focusing on the presence of particles, water, and oil. This framework is essential to ensure that compressed air used in various applications meets the required quality standards.
Key features of ISO 8573-1:
- Purity classes: It categorizes compressed air into different purity classes based on permissible contamination limits, enabling standardized measurement across different air systems.
- Overview of Contaminants: The standard provides a detailed insight into the types of contaminants commonly found in compressed air systems, enabling companies to identify potential performance or safety issues.
- Measurement Flexibility: Importantly, ISO 8573-1 defines these purity classes independently of where measurements are taken within the compressed air system, ensuring consistent quality control regardless of the air’s point of use.
- Reference to Other Parts: The standard also refers to other parts of ISO 8573 that address the measurement of air purity and the specification of purity requirements, providing comprehensive guidance for maintaining air quality.
This classification helps operators determine the appropriate air quality level for their specific processes, ensuring safety and regulatory compliance.
Why ISO 8573-1 Matters
Implementing ISO 8573-1 helps companies to:
- Protect equipment from premature wear and contamination.
- Avoid product defects caused by contaminants in compressed air.
- Ensure compliance with customer and industry quality requirements.
- Reduce maintenance costs and prevent unplanned downtime.
- Create transparency through documented measurements and reports.
Complying with ISO 8573-1 is not only about meeting regulations, but also about achieving operational excellence and long-term reliability.
The Three Main Contaminants Defined by ISO 8573-1
1. Particles
Particles originate from ambient air, corrosion, or wear within the compressed air network.
If not removed, they can block valves, damage pneumatic tools, or contaminate end products.
ISO 8573-1 defines particle size ranges and maximum concentrations per cubic meter for each purity class.
2. Water
Moisture in compressed air causes corrosion, bacterial growth, and freezing in pipelines or valves.
The standard defines limits for water content by specifying the dew point temperature.
A lower dew point indicates drier and safer compressed air.
3. Oil
Oil can be present in compressed air as aerosol, liquid, or vapor. It mainly originates from lubricated compressors or from contaminants in the surrounding environment.
ISO 8573-1 defines the permissible total oil content to ensure the required air purity in critical applications.
ISO 8573-1 Purity Classes
The table below defines the purity classes for particles, water, and oil content according to ISO 8573-1.
Each class corresponds to a maximum contamination level for the respective parameter.
| Class | Particle Concentration | Pressure Dew Point | Oil Concentration | ||
|---|---|---|---|---|---|
| cn/m3 | ºC (ºF) | mg/m3 | |||
| 0.1 < d ≤ 0.5 µm | 0.5 < d ≤ 1.0 µm | 1.0 < d ≤ 5.0 µm | |||
| 0 | As specified by the equipment user or supplier and more stringent than class 1 | ||||
| 1 | ≤ 20,000 | ≤ 400 | ≤ 10 | ≤ -70 (94.0) | ≤ 0.01 |
| 2 | ≤ 400,000 | ≤ 6,000 | ≤ 100 | ≤ -40 (-40.0) | ≤ 0.1 |
| 3 | undetermined | ≤ 90,000 | ≤ 1,000 | ≤ -20 (-4.0) | ≤ 1 |
| 4 | undetermined | undetermined | ≤ 10,000 | ≤ +3 (+37.4) | ≤ 5 |
| 5 | undetermined | undetermined | ≤ 100,000 | ≤ +7 (+45.6) | > 5 |
| 6 | x | x | x | ≤ +10 (+50.0) | x |
This table provides a visual overview of how the individual purity classes are defined and helps users match measurement results with their specific process requirements.
Why ISO 8573-1 Matters
Implementing ISO 8573-1 helps companies to:
- Protect equipment from premature wear and contamination.
- Avoid product defects caused by contaminants in compressed air.
- Ensure compliance with customer and industry quality requirements.
- Reduce maintenance costs and prevent unplanned downtime.
- Create transparency through documented measurements and reports.
Complying with ISO 8573-1 is not only about meeting regulatory requirements, but also about achieving operational excellence and long-term reliability.
How ISO 8573-1 is Tested
Testing according to ISO 8573-1 is divided into specific sub-standards:
- ISO 8573-2: Measurement of oil aerosols
- ISO 8573-3: Measurement of humidity
- ISO 8573-4: Particle measurement
- ISO 8573-5: Measurement of oil vapor
- ISO 8573-6 to 8573-9: Additional analysis methods
These standards describe the procedures, instruments, and reporting requirements necessary to determine the purity class of compressed air.
Traditional Testing Methods
Conventional tests are often carried out through manual sampling and laboratory analysis.
Air samples are collected at specific points and then analyzed for oil, water, and particles.
While this method provides accurate results for certifications or audits, it only represents the air quality at a specific point in time.
Contamination events or system failures may remain unnoticed between testing intervals.
|
Measurement Frequency |
Regular sampling |
|
Response Time |
Delayed (after laboratory results) |
|
Data Transparency |
Limited to specific tests |
|
Accuracy |
High laboratory conditions |
|
Use Case |
Certification, audits |
Real-Time Monitoring
Modern monitoring systems, such as those offered by SUTO iTEC, continuously measure air quality directly within the compressed air network.
Sensors for dew point, oil vapor, and particles provide instant readings and alarm signals when purity limits are exceeded.
Real-time data logging and wireless connectivity enable performance trend tracking, early detection of deviations, and consistent compliance with ISO 8573-1 classes.
|
Measurement Frequency |
Continuous measurement |
|
Response Time |
Immediate alerts |
|
Data Transparency |
Complete long-term visibility |
|
Accuracy |
High under real operating conditions |
|
Use Case |
Continuous compliance and system control |
Industries Benefiting from ISO 8573-1 Compliance
Food and Beverage Packaging
Compressed air in food production often comes into contact with products and packaging.
Monitoring according to ISO 8573-1 prevents contamination, ensures hygienic processes, and supports compliance with food safety requirements.
Pharmaceutical and Medical
Clean, dry air is essential for sterile production environments.
Compliance with ISO 8573-1 helps meet GMP standards, while SUTO iTEC instruments enable reliable documentation and validation.
Automotive and Metal Processing
The quality of compressed air directly affects the performance of painting, coating, and tools.
Continuous monitoring improves surface quality, process reliability, and reduces maintenance effort.
Electronics and Semiconductor
Even minimal contamination from oil or particles can damage sensitive components.
SUTO iTEC sensors ensure stable, particle-free air quality for precise and defect-free manufacturing.
Packaging and Industrial Manufacturing
Clean air is essential for automation, handling, and packaging systems.
Monitoring according to ISO 8573-1 minimizes failures, increases efficiency, and ensures consistent production quality.
From Auditing to Continuous Monitoring
While periodic testing provides a snapshot of system performance, continuous monitoring enables ongoing control and early detection of problems.
SUTO iTEC combines both approaches: portable instruments for audits and stationary solutions for continuous compliance.
With advanced data management, wireless connectivity, and modular design, users can scale their monitoring systems as their requirements evolve.
SUTO iTEC Solution for ISO 8573-1 Compliance
To comply with ISO 8573-1, all three parameters must be measured accurately: particles, oil content, and moisture.
SUTO iTEC offers a complete portfolio of portable and stationary measuring instruments that help industries achieve and maintain the required air purity class through accurate, traceable measurements.
All-in-One Monitoring with the S600 Portable and S601 Stationary Air Purity Analyzers
For a complete air quality analysis according to ISO 8573-1, SUTO iTEC offers both portable and stationary solutions.
The S600 Portable Compressed Air Purity Analyzer enables fast, guided on-site testing of particles, dew point, and oil vapor in a single device. It is ideal for audits, service work, and on-site verification of compressed air purity.
The S601 Stationary Compressed Air Purity Monitor provides continuous 24/7 monitoring of the same parameters, combining high-resolution measurements, data logging, and alarm functions.
Together, the S600 and S601 provide complete coverage—from mobile testing to permanent assurance of air quality in production and cleanroom environments.
Oil Vapor Measurement
S120 Oil Vapor Sensor
Oil contamination poses a significant risk to product quality and process reliability.
The SUTO iTEC S120 Oil Vapor Monitor uses advanced PID technology to measure oil vapor concentrations from 0.001 to 5.000 mg/m³ in real time.
It is designed for continuous or portable use and can be easily connected to SUTO iTEC data loggers or control systems to ensure reliable monitoring and compliance with ISO 8573-1 oil purity requirements.
Particle Measurement
S130 / S132 Laser Particle Counter
Solid particles are one of the most critical contaminants in compressed air.
The SUTO iTEC S130 and S132 Laser Particle Counters measure particle sizes from 0.1 to 5 µm according to ISO 8573-4 and provide real-time measurements and long-term data logging.
Compact and robust, they can be easily integrated into portable and stationary monitoring systems to ensure compliance and early detection of contamination.
Dew Point Measurement
S220 and S520 Dew Point Measurement
Moisture in compressed air can lead to corrosion, bacterial growth, or system failures.
The S220 Dew Point Sensor provides precise, continuous dew point and temperature monitoring for process and dryer control.
For service and field testing, the S520 Portable Dew Point Meter offers fast and accurate spot checks.
Both comply with ISO 8573-3 and feature digital outputs, data logging, and optional wireless communication for flexible operation.
Implementation Strategy
1. Audit and Baseline Measurement
Start with a comprehensive system audit using the S120 Oil Vapor Sensor, the S130/S132 Laser Particle Counters, and the S520 Portable Dew Point Meter to determine the current air purity levels at all critical points in the compressed air network. Alternatively, use the S600 Portable Compressed Air Purity Analyzer, which combines all measurements in one device.
2. Define Target Purity Classes
Determine the required ISO 8573-1 purity classes for each process zone. This ensures that particle, oil vapor, and moisture requirements align with the quality thresholds necessary for safe and efficient operation.
3. Install Continuous Monitoring
Implement permanent monitoring with the S601 Stationary Compressed Air Purity Analyzer for real-time verification of particles, oil vapor, dew point, pressure, and temperature. The system provides continuous monitoring to ensure compliance under all operating conditions.
4. Data Logging and Reporting
Integrate SUTO iTEC Data Loggers such as the S331 Display & Data Logger or the S551 Portable Data Logger together with the SUTO iTEC S4M Monitoring Software to automate data collection, reporting, and long-term documentation of air quality.
5. Maintain Calibration and Verification
Ensure long-term measurement stability through regular calibration and maintenance of sensors and analyzers. Use SUTO iTEC accredited calibration services to maintain accuracy and compliance throughout the lifetime of the installation.
This structured approach helps ensure consistent air quality and reliable compliance with ISO 8573-1 across all production environments.
SUTO iTEC – Your Partner for Reliable Air Quality
For more than two decades, SUTO iTEC has been developing innovative measurement solutions for compressed air and gases.
Our instruments combine precision, reliability, and ease of use under real industrial conditions.
Whether it is certification, energy optimization, or process reliability, SUTO iTEC provides the expertise and technology to help you achieve and maintain ISO 8573-1 compliance.
Contact our experts to discuss your air quality requirements or to find the ideal monitoring system for your application.
