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 resource in almost every industrial process. However, without proper monitoring, contaminants such as particles, oil vapor, and moisture can compromise product quality, damage equipment, and create safety risks.
The ISO 8573-1 standard defines purity classes for compressed air and provides the foundation for assessing and maintaining air quality according to global standards.
By implementing ISO 8573-1, operators ensure reliability, efficiency, and safety across all compressed air applications.
Page Overview
- What is ISO 8573-1
- ISO 8573-1 purity classes
- Why the standard matters
- Main contaminants and testing 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, with a specific focus on the presence of particles, water and oil. This framework is essential for ensuring that compressed air used in various applications meets the required quality standards.
Key features of ISO 8573-1:
- Purity classes: It categorises compressed air into different purity classes based on allowable contaminant limits, enabling standardised measurements across various air systems.
- Contaminant Overview: The standard provides detailed insights into the types of contaminants commonly found in compressed air systems, enabling businesses to identify potential performance or safety issues.
- Flexibility in measurement: Importantly, ISO 8573-1 specifies these purity classes independently of where measurements are taken within the compressed air system, ensuring consistent quality control regardless of air usage points.
- Reference to Other Parts: The standard also refers to other sections of ISO 8573 that focus on measuring air purity and specifying purity requirements, providing comprehensive guidance on maintaining air quality.
This classification helps operators determine the correct air quality level for their specific processes, ensuring system safety and compliance.
Why ISO 8573-1 Matters
The implementation of ISO 8573-1 helps companies to:
- Protect equipment from premature wear and contamination
- Avoid product defects caused by impurities in compressed air
- Ensure compliance with customer and industry quality requirements
- Reduce maintenance costs and prevent unplanned downtime
- Create transparency through documented measurement and reporting
Meeting ISO 8573-1 is not only about compliance but about 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 in the compressed air network.
If not removed, they can block valves, damage pneumatic tools, or contaminate final 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 lines or valves.
The standard defines limits for water content by specifying dew point temperature.
A lower dew point means drier and safer compressed air.
3. Oil
Oil can appear in compressed air as aerosol, liquid, or vapor. It originates mainly from lubricated compressors or ambient contamination.
ISO 8573-1 defines the total permissible oil content to ensure the required air purity in critical applications.
ISO 8573-1 Purity Classes
Below table 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 each purity level is defined and helps users match measurement results with their specific process requirements.
Why ISO 8573-1 Matters
The implementation of ISO 8573-1 helps companies to:
- Protect equipment from premature wear and contamination
- Avoid product defects caused by impurities in compressed air
- Ensure compliance with customer and industry quality requirements
- Reduce maintenance costs and prevent unplanned downtime
- Create transparency through documented measurement and reporting
Meeting ISO 8573-1 is not only about compliance but about 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: Oil aerosol measurement
- ISO 8573-3: Humidity measurement
- ISO 8573-4: Particle measurement
- ISO 8573-5: Oil vapor measurement
- ISO 8573-6 to 8573-9: Additional analytical methods
These standards describe the procedures, instruments, and reporting requirements needed to determine the purity class of compressed air.
Traditional Testing Methods
Conventional testing is often performed through manual sampling and laboratory analysis.
Air samples are collected at specific points and then analyzed for oil, water, and particles.
While this method delivers accurate results for certification or audits, it only represents the air quality at one point in time.
Between test intervals, contamination events or system failures may remain unnoticed.
|
Measurement frequency |
Periodic sampling |
|
Reaction time |
Delayed (after lab results) |
|
Data transparency |
Limited to specific tests |
|
Accuracy |
High under lab conditions |
|
Use case |
Certification, audits |
Real-Time Monitoring
Modern monitoring systems, such as those offered by SUTO iTEC, measure air quality continuously and 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 make it possible to track performance trends, detect early deviations, and maintain consistent compliance with ISO 8573-1 classes.
|
Measurement frequency |
Continuous measurement |
|
Reaction time |
Immediate alerts |
|
Data transparency |
Complete long-term overview |
|
Accuracy |
High under real 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 contacts products and packaging.
Monitoring according to ISO 8573-1 prevents contamination, ensures hygienic processes, and supports food safety compliance.
Pharmaceutical and Medical
Clean, dry air is essential for sterile production environments.
ISO 8573-1 compliance helps meet GMP standards, while SUTO iTEC instruments provide reliable documentation and validation.
Automotive and Metal Processing
Compressed air quality directly affects painting, coating, and tool performance.
Continuous monitoring improves surface quality, process reliability, and reduces maintenance.
Electronics and Semiconductor
Even minimal oil or particle contamination 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 vital for automation, handling, and packaging systems.
ISO 8573-1 monitoring 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 offers ongoing control and early detection of issues.
SUTO iTEC combines both worlds: portable instruments for auditing and stationary solutions for permanent compliance.
With advanced data management, wireless connectivity, and modular design, users can scale their monitoring systems as their requirements evolve.
SUTO iTEC Solutions for ISO 8573-1 Compliance
Ensuring compliance with ISO 8573-1 requires precise measurement of all three parameters: particles, oil content, and humidity.
SUTO iTEC offers a complete portfolio of portable and stationary instruments designed to help industries achieve and maintain the desired air purity class through accurate, traceable measurements.
All-in-One Compressed Air Monitoring – S600 Portable and S601 Stationary Air Purity Analyzers
For complete air quality analysis according to ISO 8573-1, SUTO iTEC offers both portable and stationary solutions.
The S600 Portable Compressed Air Quality Analyzer enables fast, guided on-site testing of particles, dew point, and oil vapor in one instrument. It is ideal for audits, service work, and field verification of compressed air purity.
The S601 Stationary Compressed Air Purity Analyzer provides continuous 24/7 monitoring of the same parameters, combining high-resolution measurement, data logging, and alarm functions.
Together, the S600 and S601 deliver full coverage — from mobile testing to permanent air quality assurance in production and clean room environments.
Oil Vapor Measurement
S120 Oil Vapor Sensor
Oil contamination poses a major risk to product quality and process safety.
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.
Designed for continuous or portable use, it connects easily to SUTO data loggers or control systems, ensuring reliable monitoring and compliance with the oil purity requirements of ISO 8573-1.
Particle Measurement
S130 / S132 Laser Particle Counters
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, providing real-time measurement and long-term data logging.
Compact and robust, they integrate easily into both portable and stationary monitoring setups, ensuring compliance and early detection of contamination.
Dew Point Measurement
S220 and S520 Dew Point Meters
Moisture in compressed air can cause 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
Audit and Baseline Measurement
Begin with a comprehensive system audit using the S120 Oil Vapor Sensor, S130/S132 Laser Particle Counters, and the S520 Portable Dew Point Meter to establish the current air purity levels across all critical points in the compressed air network. Or use the all-in-one S600 Portable Compressed Air Quality Analyzer.Define Target Purity Classes
Determine the required ISO 8573-1 purity classes for each process zone. This ensures that particle, oil vapor, and humidity requirements are aligned with the quality thresholds necessary for safe and efficient operations.Install Continuous Monitoring
Implement permanent monitoring using the S601 Stationary Compressed Air Quality Analyzer for real-time verification of particles, oil vapor, dew point, pressure, and temperature. The system provides continuous oversight to ensure compliance under all operating conditions.Data Logging and Reporting
Integrate SUTO iTEC data loggers such as the S331 Display & Data Logger or the S551 Portable Data Logger, together with SUTO S4M Montioring Software, to automate data collection, reporting, and long-term documentation of air quality performance.Maintain Calibration and Verification
Ensure long-term measurement stability through regular calibration and service of sensors and analyzers, using SUTO iTEC’s accredited calibration services to maintain accuracy and compliance over the lifetime of the installation.
This structured approach helps maintain consistent air quality and reliable ISO 8573-1 compliance across production environments.
SUTO iTEC – Your Partner for Reliable Air Quality
For over 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 for certification, energy optimization, or process safety, 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.
