The location of your compressor installation is critical! For example, if your equipment is installed outside and near a main road, hydrocarbons from the vehicles will be ingested by the compressor and sent downstream. The main 3 contaminates to worry about entering your system from the atmosphere are Water vapour, Hydrocarbons and particulates like pollen.
The compression process
In modern compressors, none of the compression components physically touch and are separated by the oil within the equipment. However, as a result of the compression process, compressor oil, oil vapour and tiny particles of worn materials can pass through into your air system.
The distribution system
Once the compression process is complete, this is where your distribution system comes into effect. Pipes and air receivers can contribute to all manner of contaminates; from rust to pipe scale, mineral deposits to bacteria, even grease and condensate.
How to prepare a compressor to be used for breathable air?
There really is only one way to minimise the potential hazards form the contaminants mentioned above – to design a compressed air system to your specific industry requirements, and that is exactly where Air Energy Limited can help.
One of the first questions we ask our customers when they ask for a new system is what class of air they require, (we will get to this later), if they don’t know, we ask questions to make sure we can help our customers make an informed and suitable decision for them.
There are a few industries where the quality of air is incredibly important, these are food and beverage, pharmaceutical and spray shops to name just a few. Even though these 3 have a more stringent set of requirements, the requirements between all 3 are drastically different. In food and beverage industries, there are separate requirements for air quality depending on if the compressed air comes into contact with the product or packing directly, or indirectly. In pharmaceuticals, the requirements will differ depending on the product being made and the location of the product compared to the compressor system.
So how do we make sure the air is of the highest standard for these industries?
A standard compressor will often have no dryer and no additional filtration installed alongside it, this means an Air Purity class of X:X:X, a normal set up will include a refrigerant dryer and 1 micron filtration, this provides an Air Purity class of 2:4:2. A breathing air set up will include 4 types of filtration and a desiccant dryer reducing the pressure dewpoint down to -40c, this will provide an Air Purity class of 1:2:1, please see the below image for more information on this. The 4 types of filter used are a water separator inline filter, a 0.01 micron inline filter, a dust filter and an activated carbon filter. Each of these filters has a specific job to do.
1. The water separator removes 85% of the bulk moisture before it hits the desiccant dryer.
2. The 0.01 micron removes particles before they reach the dryer (including oil mist)
3. The dust filter protects the downstream process from particles that have made it through filters one and two or come from the dryer.
4. Finally, the activated carbon filter removes unsatisfactory odours and taste from the air.
Below is a sample of Walker Filtration (W.F) systems for breathing air set-ups. Air Energy are partnered with W.F and we frequently supply their products to our customers.
Pressure Dewpoint is the temperature at which moisture will turn to condensate. To prevent condensation, the dryer installed should be matched to the process accordingly. This means if you have a compressed air requirement in a freezer that has a lowest temperature of -20c, the pressure dewpoint needs to be below -20c, because at this temperature condensate will form in the pipework.
ISO Compressed Air Purity Class
Normally, compressed air treatment is carried out in the plant room straight after the compressor to prevent any contamination entering the pipes and the rest of the system to ensure it does not then find its way through to your process e.g. breathing air. However, sometimes this is not enough, and sometimes it is highly recommended to install point of use treatment as well. This will very much depend on your industry and the process you are using air for.
Air Energy Limited have extensive knowledge around Air Quality and testing procedures, we are fortunate enough to work with hospitals, laboratories, food processing plants, drinks manufacturers, emergency services and many other companies who need to control and measure the quality of air they are using.
There are 3 ISO standards that are set out to advise on the requirements your specific process may require; ISO 8573, ISO 12500 and ISO 7183.
ISO 8573 is the main standard for air purity classes, it is made up of 9 parts and provides information on accurate testing of the major contaminants inside compressed air, moisture, particulates and microorganisms. ISO 8573 is used by many within the compressed air industry, from manufacturers, suppliers, and testing laboratories.
ISO 12500 is the standard for air filtration and water separators, it is made up of 4 parts. These outline the efficiency and operational performance of all filtration utilised in your compressed air system.
ISO 7183 is the standard for compressed air dryers. ISO 7183:2007 specifies the standard criteria required to test compressed air dryers, namely: pressure dew point, flow rate, pressure drop, compressed air loss, power consumption (including partial-load tests) and noise emission (operating and loading conditions)
ISO 8573 Testing
At Air Energy all of our engineers complete training to ensure they can carry out an air quality test effectively, enabling us to visit your site with our calibrated ISO 8573 air quality testing equipment and assist accordingly. We can complete periodic compressed air purity testing at point of use with certified results that can be measured against ISO: 8573-1 standards, testing for CO2 levels, pressure dewpoint and temperature.
What is 0 class air?
This is a question we are frequently asked. Class 0 does not mean zero contamination, what it means is it has purity levels that have been agreed by the user and manufacturer of the equipment in writing. It also doesn’t account for purity levels greater than those measurable in ISO 8573-2 to 8573-9. Class 0 should only be specified at point of use for the most critical applications to achieve cost effectiveness.
Breathing Air Testing
The required quality of breathing air is stated in BS EN12021 to provide information on the safe limits of potential contaminant gases within breathing air and to ensure that the life supporting gas (oxygen) is of an adequate level.
BS EN 12021 advises that samples should be taken and analysed at least every three months or more frequently if there has been a change in, or concerns relating to, the production process. The final decision on frequency of test is the responsibility of the Employer and needs to not only reflect local legislation but also the task and frequency of use. It should be incorporated into your risk assessment and updated regularly to reflect results from ongoing breathing air tests to maintain a robust control system.
During a breathing air test, the tester will test the air for Carbon Dioxide, Carbon Monoxide, Pressure dewpoint, Pressure, Temperature, Water content, Oxygen level and Oil content to verify the breathing air quality is as required.
All employers have a duty of care to their employees to ensure that the breathing air supplied to users is adequate for the respiratory protective equipment (RPE) they are using and safe to breathe, whether this is supplied via a fresh hose or a source of compressed air.
Compressed gas for breathing should not contain contaminants at a concentration which cause harmful effects. All contaminants should be kept to as low a level as possible and shall be less than 1/10 of a national 8-hour exposure limit.
Finally, records of completed breathing air checks must be retained in either physical or electronic form for a minimum of 5 years.
For support on your Air Quality Testing, please contact a member of our service team on +44 1992 586 666