Camfil Clean Air Solutions: Filter selection for hospital

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Optimizing the operational cost for clean air handling system
Higher costs of energy together with the increased focus on global climate has raised the demands on lower energy consumption worldwide. Sustainability has increased the focus on energy saving, so every new system needs to be optimised.

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Air handling units (AHU) supplying clean air to buildings in the industry, offices and dwellings are important to  create a good indoor air quality for both humans and production processes. An air handling system normally consists of many subsystems or components like: fans, heat exchangers, sound reduction, air filters etc.
HEPA Filters for Critical Areas
HEPA filters are specified for air supplies serving operating theatres, protective environment rooms for treatment of patients with high susceptibility to infection and exhaust systems from isolation rooms.
HEPA filters are also specified for discharge air from fume hoods or safety cabinets in which infectious or radioactive materials are processed. The filter system should be designed to permit safe removal, disposal, and replacement of contaminated filters.
A HEPA filter, by definition, has an efficiency of at least 99.97% when tested on particles 0.3 micron in size. The key word is “tested”. A HEPA filter must be tested and certified by the manufacturer as to efficiency, rated  airflow and resistance to airflow.
A Certificate of Conformance should be included with each HEPA before it is installed in your facility. This certificate includes complete testing data and ensures that the manufacturer has built the product to the required specifications and tested each individual filter before leaving the manufacturing facility. Some vendors  do not test or may “batch test”, rather than individually testing each filter. Camfil test each unit and ensure conformance prior to packing.
Certificates of Conformance for each filter should be filed with the onsite scanning report for evidence should problems arise and as support documentation for facility audits.
Sealing of HEPA Filters
Gasketing of the HEPA filter should be aligned properly, assuring that the gasketing, when compressed, will seal  all surfaces from air bypass. The filter sealing mechanism should compress the gasketing material to 50% of its original depth. HEPA filters should include the latest poured-in-place seamless gasket that prevents leaks  through gasketing junctures found in traditional HEPA filters.
Where a fluid sealing method is used, the knife edge should uniformly penetrate the sealant but not fully to the base of the channel.
HEPA Filter Service Life
Initial considerations concerning the service of HEPA filtration relate to minimising pressure drop within the HVAC system for energy conservation, and extending the life of the HEPA filters. The chart here shows the typical  life extensions of HEPA filtration when various levels of pre-filtration are used.
When the Life Cycle Cost of the HEPA cost is considered, F7 (MERV 13) or F8 (MERV 14) pre-filtration is the norm.  A 5-micron size particle looks like a boulder to HEPA filtration media. The microfine glass fibres that make up  the media of the HEPA filter have an operating fibre diameter of 0.67 micron. Large particles can block a  relatively expansive area of the filter, increasing pressure drop prematurely and reducing the effectiveness and  life of the filter.
The CamHosp 2 System offers the following advantages;

1. Unidirectional flow, according to EN ISO 14644.


2. H14 standard gasket or gel seal terminal HEPA filters.


3. Guaranteed airtight plenum which is assembled using a system of flanges and bolts and complies with class B of  the EN1886 standard (completely airtight casing). The plenum area and the structural elements are made of electro-galvanised steel with an oven-baked epoxy coating, which is highly abrasion resistant, perfectly smooth  and can easily be decontaminated. The materials are also resistant to the standard disinfectants used in  hospitals.


4. The clamping system, which has a compression limiter with captive stops ensures excessive compression of the  gasket is prevented. This allows for an easy, safe and quick filter assembly.


5. Protective Screentek screen to ensure maximum usage of the theatre by providing individual protection for the  HEPA filters. These are protective screens made of monofilament polyester fabric on a clip-on frame a few centimetres away from the HEPA filter. If a Screentek screen becomes contaminated during the course of an operation, the individual screen can easily be replaced by a clean one in only a few minutes. This ensures that the ceiling is hygienic and that the next operation can take place. The major benefit of this protective system is that the HEPA filters do not need to be replaced, which would require the operating theatre to be closed down for maintenance, cleaning and re-testing.

For information visit www.camfil.com.au