Air Filtration

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A decision was made to follow suit with most other global filter manufacturers in moving towards in-house validation rather than continue with third-party NATA accreditation. Covid has however placed renewed awareness on air filtration and filter testing efficiency, with a focus on independent N.A.T.A. accredited certification. AES Environmental have successfully incorporated into its AS1324 test rig facility an ability to test products to meet other standards for industrial enclosure applications and other requirements.
One such test was a request from a global consortium to conduct filter and pressure containment testing in extreme and normal operational circumstances. An actual assimilation of the workspace environment which the new product would encounter had to be created. This workspace had to replicate the operational environment. Following completion of testing, the product had to be “fit for purpose” and demonstrate use over many years. A filter breakthrough contamination factor was established when dust commenced shedding particles from the filter.

The multi-billion dollar contract included a high percentage of Australian manufacturing content. To proceed the product and its filtration devices needed to meet a high Mil-STD specification. The test plan took over six months to prepare including actual testing and report detailing. This included compiling the test data from various dust sampling and temperature ports, which took a further four weeks to compile.

This test had only been completed in two overseas countries and due to international travel restrictions. The global consortium contacted AES Environmental at our South Western Sydney filter manufacturing facility, to review our capability in AS1324 air filter test methodology and if this could be applied to manage and complete the project within Australia.

To meet the stricter Australian workplace guidelines AES Environmental recommended changes to some of the test materials and installation set ups. These changes improved the products “test to real-life assimilation” as well as provide a safe work place environment. The test included laboratory screened dust samples sourced within Australia. Clarity on particle size range and critical gravimetric contamination could be controlled better between PM1, to PM10 and included heavier dust contamination up to 130 micron. This is essentially assimilated bush fire, wind and dust storm conditions. The material was dispensed into the test chamber at controlled intervals during the testing period. In between inspections, cataloguing and weighing would commence. Some testing was conducted at extreme temperatures, applying variable air volumes to better reflect real life human occupancy load situations. Almost all energy efficient air conditioning system managed through a BMS system apply a similar approach to variable air conditioned environments.

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Analysis of dust test results

Following test completion, analysis was conducted on equipment wear and filter performance durability, and efficiency capability.
The Filter ( image 4) was carefully removed and weighed following the test. A replacement set of filters were installed for each test criteria. The filter arrangement consisted of two efficiency stages F5 and F8 performance.

Assessment of the coil condition (Image 5) following the sequence of test cycles, revealed slight dust residue which defined dirt breakthrough from the filter discharging into the clean air chamber. This defines a filters anticipated life cycle period and determines the filter replacement maintenance frequency. Obtaining this critical information will enable users to manage energy consumption, and short/long term wear and tear on the air conditioning associated plant and equipment. There was no component failure during any of the test cycles or on completion of all testing. Some test procedures ran for periods of eight hours in high/low dust loads in both temperature and volume fluctuations.

Inside the clean air compartment (Image 6) following removal of the dirty filters. There was no visible wear or dust build up from the larger range of coarse particles 80-130 micron. The faint speckles of what was considered suspended impurities could be viewed settling as light dust on the floor of one compartment.

Data recording stations were established to monitor various areas of the product for sampling dust and measuring for contamination breakthrough.

Laboratory testing for filters remains an effective proposition for research purposes, however Covid has increased the awareness on the air within occupied building space. Laboratory tested filters won’t meet the expectations due to uncertainty. Some filters will discharge more fibres than they will stop, and if the filter sealing integrity is flawed then the filter efficiency remains irrelevant because air will always find the least point of resistance. AES Environmental can be contacted to discuss your air filter testing requirements for air and water applications. AES Environmental is N.A.T.A accredited in a number of testing professions and offers national and international certification including laboratory equipment, HEPA filtration, clean room to both Australian Standards and ISO requirements.

Contact AES Environmental on 1300 550 116 or visit the AES website to discuss you air filter testing requirements for air and water applications!

Background:

The new AS1807 series was developed from a requirement to consolidate TWENTY-SIX individual standards in to ONE comprehensible test method that could be applied to a range of products. As a result there have been some notable improvements in transparency, test methodology and a reduction in the barriers of entry.

In this context the AS 1807 series of test methods is utilised by registered service organisations, Australian laboratories and associated safety cabinet users. Those groups have regularly completed an annual certification process under the guidance of National Australian Testing Accreditation “NATA”. This is due to the practical ease and transparency for delivering a rapid “pass or fail result” to end users at their work place environment which has resulted in high user uptake of more than 85% within the work place, significantly higher than any other regions of the world.

Consolidation of the various test methods would seem like an obvious solution however in the past this has not been the case. The driving force behind change came from an unlikely source; the adaptation of an ASNZ/ISO Clean Room Test Method that would likely cause conflict in the market.

So, what’s new?

AS1807, was given a new title “Separative Devices” with a clear definition for use “Biological and Cytotoxic Drug Safety Cabinets, Clean Workstations, and Pharmaceutical Isolators – Methods of Test”.  With a defined focus it is now clear where these standards should be applied. Test methods that are not applicable to the definition have been removed and about half have been revised and updated.

A critical aspect of the new standard was the requirement to independently validate the competency of service providers in the delivery of on-site technical services, safety cabinets and other separative devices to ensure that those devices are safe and fit for purpose at the users place of work.  The test validation process needed to be relevant, simple to apply, cost effective, provide a ready pass/fail outcome and reproduceable within any work place environment. A high level of importance was provided to the types of equipment to be used, and the effect of aerosol test challenge and pressures.

Driving this development was the increase in the range of deemed diseases, from what had been traditionally asbestos related diseases to include numerous additional types now included many found within the laboratory work place. AS1807:2021 appendix B table B1 references the higher risk posed to laboratory personnel for brucellosis, Q fever and Typhoid due to their low infectious doses and increased infection caused through aerosol inhalation.

In addition to the actual test methods, technical aspects of test equipment have been reviewed and updated. This includes anemometers, lighting, and the effect building vibration can place on the placement of bio safety cabinets in high rise buildings.

It is considered critical for effective measurement of HEPA sealing integrity to ensure an upstream concentration of aerosol. An effective range was considered to be 1mg /m3 to 100mg/m3.  Given the complexity within the test methods and how one test adjustment can impact another.

The new standard provides useful information for users and the industry by providing a guide of estimated times, one should consider when conducting tests in accordance to AS1807:2021. This guide is shown in Table 2.1 and offers users an indicative time frame for when their annual services are required. Procedure 4.4.5.2 refers to the travers rate for effectively scan testing HEPA filters and references to the time using varying size tips and speeds between 0.3 to 0.6m/s are shown in Appendix D. Speeds outside the recommended test velocity are shown with a traverse rate of “0” and highlighted in blue.

Conclusion

The new AS1807 Standard combines all of the relevant individual standards in one convenient location. This has significantly reduced the cost of owning this standard and provides clarity to all user groups. Furthermore, the test methods have been refined and modernised based on research and to suit the latest equipment. This is more than comprehensive update of AS 1807; this new Standard sets out a clear test methodology with performance targets for Biosafety Cabinets and other Separative Devices that no other global standard clearly defines.

AS 1807:2021 is a focussed, locally developed standard that takes in to account the unique challenges that face stakeholders within Australia. This is unlike modern adaptations of global standards that take a broader approach to accommodate a wider user-group