COMPRESSED AIR ISO8573 – WHEN QUALITY MATTERS
Roy Brooks, Technical Development Officer at the British Compressed Air Society (BCAS) discusses the basics of ISO 8573, the international standard for air purity (quality) and why operators should con- sider all parts of a compressed air system during the specification process.
A
ir quality is not just a requirement of hygiene- critical manufacturing environments, such as food and beverage production or pharmaceutical processing, but a factor that should inform the equipment selection and testing methods for any compressed air installation.
As many as 90 per cent of all industrial manufacturing sites rely on compressed air for some aspect of their operations, so ensuring a high-quality source of air always is vital for uptime and productivity.
CONTAMINANT TYPES Compressed air is not clean. In fact, it typically contains up to ten different contaminants, which need to be treated correctly.
These tend to be combined into three distinct categories: particles (including viable and non-viable microbiological organisms), water and oil. ISO 8573-1 refers to the main contaminants in this format. When selecting purification equipment, do not forget that contaminants will be in one of three different phases (states of matter). For example, water and oil in a compressed air system will be found in liquid form, as an aerosol (fine mist) and in a vapour (gaseous) phase and a different purification technology will be required depending upon the phase of the contaminant.
SELECTING THE CORRECT STANDARD
Depending on the application, there are a number of different compressed air standards and best practice guidelines that can assist you.
ISO8573 series is the most commonly used standard for compressed air (excluding breathing air or medical air). It is made up of nine separate parts. Part 1 refers to air purity (quality), while parts two to nine provide details on the equipment and methodology to be used to measure for different contaminants in a compressed air system (and meet the air purity (quality) classifications shown in part one). ISO8573-1 – International Standard Relating to Compressed Air Purity (Quality) ISO8573-1 provides guidance on specifying the air purity (quality)
required for the entire compressed air system and/or for individual usage points, based upon application requirements.
The BCAS BPG 102 Food and Beverage Compressed Air guide details the specific requirements for compressed air that comes into direct or indirect contact with food or beverage products, while HTM02-1 will provide recommendations for medical and surgical air and HTM2022 for dental air. Finally, BS EN 12021:2014 is the specified standard for breathable air, indicating maximum permitted contaminant levels both in the UK and the EU.
SPECIFYING CORRECTLY Whether designing new systems or reviewing existing systems, your first step should be to define the precise compressed air purity (quality) requirements your application requires.
To achieve the degree of air purity (quality) specified by ISO8573-1, a careful approach to system design, commissioning and operation must be adopted. Best practice is to treat compressed air prior to entry into the distribution system and at critical usage points and application, to ensure that contamination already in the distribution system is removed. Purification equipment should ideally be installed where the air is at the lowest possible temperature, i.e., downstream of air receivers, but also protected from freezing. Point-of-use purification equipment should be installed as close as possible to the application. To allow correct sizing and selection of purification equipment, make sure you have the following operating parameters to hand: * The maximum compressed air flow rate into the filters/dryer * The maximum operating temperature into the filters/dryer * The maximum ambient air temperature where the equipment is to be installed (required for some dryer technologies) * The required dewpoint (dryers) Individually, each of the primary operating parameters can influence product sizing, however, collectively they can have a major
impact on product sizing and performance. Many manufacturing plants only need a proportion of the compressed air to be treated to very high purity (quality). In these cases, excellent savings are achievable by treating all the generated air to the minimum acceptable level and improving the purity (quality) to the desired level at the usage point. If most of the compressed air is needed at high purity (quality), it can make sense to treat all the compressed air to the level required by the highest purity (quality) application.
FURTHER TRAINING A full understanding of ISO 8573 is vital before any decisions on equipment selection and testing methods are undertaken. This course, therefore, explains the importance of considering all parts of a compressed air system, whether you are a supplier, consultant, service provider, or user of compressed air. Learners complete a self-study e-learning module followed by a virtual classroom with a BCAS tutor to help cement learning and understand the most frequently asked questions. The course is completed with an online examination leading to the BCAS certificate in ‘Understanding ISO 8573 – The Compressed Air Quality Standard.’ The course is aimed at typical industrial compressed air applications operating at low pressure, with a range between 7 bar g to 20 bar g and provides guidance on the differences between indicative testing and air quality verification, which is a key component of compliance with the ISO 8573 standard.
BCAS offers a blended learning workshop for ISO 8573, available to view at https://elearning.bcas.
org.uk/our-courses/blended-learning-courses/ understanding-iso-8573-the-air-quality-standard/ In addition, detailed guidance can be found in the ‘Filtration and Drying of Compressed Air - Best Practice Guide 104 at
www.bcas.org.uk/ airtreatment.
British Compressed Air Society
https://www.bcas.org.uk
30 APRIL 2022 | FACTORY&HANDLINGSOLUTIONS
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