Overview
ISO 8573-1:2010 - "Compressed air - Part 1: Contaminants and purity classes" defines a classification system for compressed air purity with respect to the main contaminants: particles, water and oil. It specifies reference conditions (20 °C, 100 kPa, zero relative water vapour pressure) and provides the designation format used to state compressed air quality at any sampling point. The document also identifies gaseous and microbiological contaminants and gives guidance (Annex A) on applying the purity classes in practice.
Key topics and requirements
- Purity classes: Numeric classes for
- Particles (delineated by size ranges and maximum particle counts per m3; classes 0–7)
- Humidity / liquid water (pressure dewpoint classes and liquid water concentration classes 0–9)
- Total oil (liquid/aerosol/vapour concentration classes 0–4 and X)
- Designation principle: Air quality is expressed as ISO 8573-1:2010 [A:B:C] where A = particle class, B = humidity class, C = oil class. Unspecified classes use “–”. Class X values include the measured concentration in brackets.
- Reference conditions: Gas volume reference (20 °C, 100 kPa, zero relative water vapour pressure) for reporting.
- Contaminant identification: Gaseous and microbiological contaminants are reported separately using related parts (see Related Standards).
- Measurement linkage: ISO 8573-1:2010 is the classification core - measurement methods are given in other parts of ISO 8573 (e.g., parts 2–9).
- Guidance (Annex A): Emphasizes that achieving a purity class depends on system design, lubricants/coolants, temperature control and maintenance - not on a single component.
Applications and users
ISO 8573-1:2010 is used to:
- Specify compressed air quality for pneumatic systems, instrumentation and production lines.
- Communicate requirements between equipment buyers, system designers and compressed-air suppliers.
- Define acceptance criteria for air treatment equipment (filters, dryers, separators) and maintenance programs.
Typical users:
- Facility engineers, maintenance teams and compressed air system designers
- OEMs of pneumatic equipment and process machinery
- Quality managers in manufacturing, food & beverage, pharmaceuticals and electronics
- Suppliers of filters, dryers and air quality monitoring equipment
Related standards
ISO 8573-1:2010 is the core of the ISO 8573 series. Relevant parts include:
- ISO 8573-2 (oil aerosol test methods)
- ISO 8573-3 (humidity measurement)
- ISO 8573-4 and -8 (particle measurement)
- ISO 8573-5, -6, -7, -9 (oil vapour, gaseous contaminants, microbiological, liquid water)
Using ISO 8573-1:2010 with the corresponding test-method parts ensures consistent, auditable reporting of compressed air purity and supports compliance with industry quality and safety requirements.
