Compressed Air ISO Quality Standards
compressed air ISO Quality Standards
Compressed Air ISO Quality Standards
A Guide to Benchmarking Performance with ISO 8573, ISO 12500,
and ISO 7183
Introduction
Often
referred to as the 4th utility after electricity, water, and gas, compressed
air is the only major industrial power source generated on site by users
bearing full financial and legal liability for its quality.
A
thorough understanding of compressed air quality and testing standards is therefore
indispensable when designing your system to achieve the purity levels your
application on requires. The International Organization on for Standardization
(ISO) sets three such standards, ISO
8573, ISO 12500, and ISO 7183. Which standards you should apply will depend on the specific
contaminants you aim to remove and the purification equipment you will rely on
to do so.
This white paper outlines:
- The most commonly encountered compressed air system contaminants.
- The types of equipment you can use to remove these contaminants.
- The applicable ISO standards you may use to benchmark your equipment’s capabilities and results.
- Several examples of op mised compressed air network con gura ons on which to model your own system.
- A set of simple guidelines to use when selecting your purification equipment.
- A quick reference guide to products used to deliver various compressed air purity levels for different applications.
Compressed
air contaminants and their sources
The
four main sources of contaminants in a compressed air system are the
atmospheric air surrounding the compressor intake, the air compressor itself,
the air storage device (the air receiver), and the system’s distribution
piping. The main types of contaminants are particulates, water, oil, and
micro-organisms, with their specific forms and corresponding sources are listed
below.
1.
Particulates Atmospheric
air
Atmospheric
Dirt. Atmospheric air in an industrial
environment typically contains 140 million dirt particles for every cubic meter
of air. 80% of these particles are less than 2 microns in size and are too
small to be captured by the compressor intake filter, therefore passing
directly into the compressed air system.
2.
Water Atmospheric
air
Water vapor. The ability of compressed
air to hold water vapor depends on its temperature. Higher temperatures allow
the air to hold more vapor. During compression, air temperature and pressure
increases significantly and can subsequently retain more moisture.
Water liquids and aerosols. When cooled after compression,
water vapor condenses into liquid water. Condensation occurs at various stages
throughout the system as the air is cooled further by the air receiver, the
distribution piping and the expansion of air in valves, cylinders, tools, and machinery.
3.
Oil Atmospheric
air
Oil vapor. Atmospheric air contains
oil in the form of un-burned hydrocarbons which are drawn into the compressor
intake. Typical concentrations can vary between 0.05 and 0.5mg per cubic meter of ambient air.
4.
Oil Compressor
Oil liquids and aerosols. Most air compressors use
oil in the compression stage for sealing, lubrication and cooling. During
operation, lubricating oil is carried over into the compressed air system as
liquid oil and aerosols. This oil mixes with water in the air and is often very
acidic. Additionally, once inside the compressed air system, oil vapor will
cool and condense, effectively causing liquid oil contamination.
Particulates Air
receiver and distribution piping
Rust and pipe scale. Rust and pipe scale occur
in air receivers and the piping of “wet systems” (systems without adequate
purification equipment) or systems which were operated “wet” prior to
purification equipment being installed. Over time, this contamination breaks
away to cause damage or blockage in production equipment, which can also
contaminate final product and processes.
Micro-organisms Atmospheric
air
Micro-organisms. Bacteria and viruses may be drawn into the compressed air
system through the compressor intake. A cubic meter of ambient air typically
contains around 100,000,000 (100 million) micro-organisms per cubic meter, only
a few of which can diminish product quality or even render a product entirely
unfit for use and subject to recall.
ISO
Compressed Air Quality and Testing Standards
ISO
8573 is a nine-part group of international standards relating to compressed air
quality and testing. The first part, ISO 8573-1, specifies compressed air
quality classes with regard to each contaminant type. The remaining eight
parts, ISO 8573-2 to ISO 8573-9, specify methods to test and verify that a
given air sample falls into one of these air quality classes. The most recent
revision of ISO 8573-1 took place in 2010, with the current editions of ISO
8573-2 to 8573-9 having come into effect over several years dating back to
1999.
To
specify air purity from each type of contaminant, ISO 8573-1 employs 10 classes
numbered from 0 – 9. Each class indicates the levels of the specific
contaminant allowable in a cubic meter of compressed air. Classes 1 – 9 specify
pre-established contaminant levels universally recognized by compressed air
equipment manufacturers, suppliers, and users. The use of Class 0 however,
allows interested parties to agree their own acceptable contaminant levels for
a given compressed air application, provided that the agreed levels surpass
Class 1 standards, are measurable according to ISO 8573-2 to 8573-9 testing
standards, and are formally documented.
When specifying air purity in accordance with ISO 8573-1 standards, it is necessary to identify:
- The standard itself
- The edition of the standard
- The classes of purity from particulates, water, and oil, respectively, according to the standard
For
example, ISO 8573-1:2010 Class 1.2.1 refers to compressed air with Class 1
levels of particulate contamination, Class 2 levels of water contamination, and
Class 1 levels of oil contamination as per the 2010 edition of the ISO 8573-1
quality standards. Please see the opposite table for full details on allowable
contaminant levels for each ISO 8573-1 class. specified only at the point of use for the most critical
applications to achieve cost-effectiveness
ISO
12500 and ISO 7183 compressed air purification testing standards
ISO
12500 is the group of international standards designed to assess the
operational performance of compressed air filter and water separator products.
ISO 12500 consists of four parts, ISO 12500-1 to ISO 12500- 4, each covering the
performance of a different variety of filter or water separator. Similarly, the
ISO 7183 standard serves to assess the operational performance of compressed
air dryers.
ISO
12500 and ISO 7183 both complement the ISO 8573-2 to 8573-9 testing standards, which
notably fail to account for challenge concentrations. A challenge concentration
is an initial level of compressed air contamination against which
post-purification contamination levels can be compared. Standardization of
these critical performance variables allows consumers to compare the relative
Performance
of compressed air purification equipment from different suppliers.
For
a detailed description of each ISO testing standard and the type of
purification equipment to which it applies, please see the next section.
The below table summarizes:
- The most common forms of compressed air purification technologies
- The contaminants they remove
- Their applicable ISO testing standards
- The ISO 8573-1:2010 purity classes used to specify their operational results
Types
and examples of purification technology with their respective ISO testing
standards
Cost-effective
compressed air system design
To
achieve the stringent air quality levels required for today’s modern production
facilities, a careful approach to system design, commissioning and operation
must be employed. Treatment at one point alone is not enough and it is highly
recommended that the compressed air be treated prior to entry into the
distribution system to a quality level suitable for protecting air receivers
and distribution piping. Point of use purification should also be employed,
with specific attention being focused on the application and the level of air
quality required. This approach to system design ensures that air is not “over
treated” and provides the most cost effective solution for high quality
compressed air.
The
following are examples of cost-effective compressed air system configurations:
Example configurations: Compressor room
 |
| Example configurations: Compressor room |
 |
| Example configurations: Point of use application protection |
Example configurations: Point of use application protection.
 |
| Example configuration: Critical applications A+C, D or E, B+F or G |
Example configuration: Critical applications A
+ C, D or E
B +
F or G
Typical
Applications:
- Pharmaceutical products
- Silicon water manufacturing
- TFT / LCD screen manufacturing
- Optical storage devices (CD, CD/RW, DVD, DVD/RW)
- Optical disk manufacturing (CDs/DVDs)
- Hard disk manufacturing
- Foodstuffs
- Dairies
- Breweries
- CDA systems for electronics manufacturing
- Blow moulding of plastics g. P.E.T. bottles
- Film processing
- Critical instrumentation
- Advanced pneumatics
- Air blast circuit breakers
- Decompression chambers
- Cosmetic production
- Medical air
- Dental air
- Lasers and optics
- Robotics
- Spray painting
- Air bearings
- Pipeline purging
- Measuring equipment
- Blanketing
- Modified atmosphere packaging
- Pre-treatment for on-site gas generation
Example configuration: General Usage B + C, D
or E
Typical Applications:
- General ring main protection
- Pre-filtration to point of use adsorption air dryers
- Plant automation
- Air logistics
- Pneumatic tools
- General instrumentation
- Metal stamping
- Forging
- General industrial assembly (no external pipework)
- Air conveying
- Air motors
- Workshop (tools)
- Garage (tyre filling)
- Temperature control systems
- Blow guns
- Gauging equipment
- Raw material mixing
Simple guidelines for the selection of purification equipment
When evaluating compressed air filters or dryers, you can best serve your operational and financial interests by emphasizing the following two criteria:
- The quality of the compressed air reliably delivered over the equipment’s life the purpose of compressed air purification equipment is to eliminate the problems and costs associated with contamination by delivering high-quality, clean, and dry air. When selecting this type of equipment, the delivered air quality and the verification of performance must always be the primary decision drivers.
- The equipment’s
total cost of ownership. Equipment
with a low purchase cost may turn out to be a very costly investment over the
longer term. Always consider the initial purchase cost, plus the cost of
operating and maintaining the purification In addition, consider the cost to
your business of poor air quality.
Note that while the equipment’s purchase price may be an important and easy-to-understand criterion, it should not be the primary factor affecting your decisions. Instead, to select air purification equipment optimised for your application, you should undertake a broad review of your system requirements that includes the following ten considerations:
- As the purpose of purification equipment is to ensure air quality, you must first identify the quality of compressed air required for your Depending on your application, each usage point in the system may require a different quality of compressed air. Using the ISO 8573-1:2010 quality classifications will allow your equipment supplier to identify the correct purification equipment quickly and easily for each part of your system.
- ISO 8573-1:2010 is the latest edition of the standard. Ensure it is written in full when contacting Specifications of air quality as “ISO 8573-1” or “ISO 8573-1:1991” likely refer to a previous edition of the standard and may result in a lower quality of compressed air delivered.
- Ensure that the equipment under consideration will in fact deliver air quality in accordance with the quality classifications you have selected from ISO 8573-1:2010.
- When comparing coalescing filters, ensure that they have been tested in accordance with ISO 8573-2:2007, ISO 8573-4:2001 and ISO 12500-1:2007.
- Ask for independent, 3rd party validation of product
- For peace of mind, ensure that the manufacturer provides a written guarantee of delivered air
- Oil-free compressor installations require the same filtration considerations as oil- lubricated compressor
- When comparing the operational costs of coalescing filters, consider only the initial saturated pressure Dry pressure loss is not representative of performance in a normally wet compressed air system. ISO 12500-1:2007 requires pressure losses for coalescing filters to be recorded when the element is saturated.
- Look at the blockage characteristics of the Just because it has a low starting differential pressure, doesn’t mean it will remain low throughout the filter element’s lifetime. Energy costs should always be calculated based upon the blockage characteristics of the filter, not just initial saturated differential pressure.
- Look at the total cost of ownership for purification equipment, including the costs of purchase, operation, and maintenance A low initial purchase price may look inviting but may result in high operational costs and other complications due to poor air quality.
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