HEPA filter systems are designed to filter harmful chemicals, micro-organisms and microbiological airborne contaminants from the air.
These high efficiency particulate air filters can be installed in bio-safety cabinets or mounted on the wall or ceilings as well as in air discharge systems connected to hazardous industries.
Due to the nature of the contaminants filtered through these systems, a safe change housing is used to provide the technician with maximum protection against all harmful pathogens.
Additionally, the purpose of the housing is to ensure that all trapped pathogens, chemicals or micro-organisms remain contained within the housing.
The concept of safe change methods was initially applied within the nuclear industry in order for operators to safely handle radio-active airflow.
It has since evolved and is now applied in the biochemistry and pharmaceutical industry where exposure to harmful pathogens and chemicals is possible.
The changing procedure for a safe housing is relatively complex, therefore, it should only be carried out by a qualified technician.
The first and most important step is for the technician to dress in personal protective clothing which includes a respirator mask, isolation suit and gloves.
The reason this protective gear is necessary is because it provides the necessary protection in the event of an accident during the safe change procedure.
The following are 4 steps which need to be followed in order to successfully change and replace the filter within the housing:
Before proceeding, the filtration system must either be turned off entirely, or the airflow must be temporarily diverted by means of airtight bubble dampers for the duration of the change-out.
Then, the external and internal pressures must equalise. Isolation shutoff dampers must be closed before opening the housings. In the case of the filter installed in a bio-safety environment, then decontamination of the area should first be performed.
The lid of the filter housing is removed and the filter bag is visible. Careful inspection of both the old and the new filter bag must be carried out to ensure there is no damage to either bag. If everything is in order, the old filter can be removed while keeping it in the bag. Then, the bag can be tied, welded or heat-sealed-taped shut. The technician can now cut the bag between the seals and the bag can be removed and the older filter can now be disposed.
While keeping the new filter inside of the safety bag, it can now be installed by placing it over the remains of the previous bag and secured in place. It’s extremely important that the bags are properly rolled up or pinched in the cover of the housing. Should there be an error like this, it will greatly compromise the procedure.
Once the housing has been properly closed and sealed, the air which flows through the filter needs to be assessed. Additionally, a DOP leak test must be done to measure the integrity of the filter. This leak test is done by introducing known mass and size particles into the filter.
HEPA filters should be handled with utmost care as they are extremely fragile. Filters should be checked on a regular basis to ensure they are still filtering air efficiently.
Should the filter become damaged or if the airflow suddenly drops, it is necessary for the filter to be replaced again and the same procedure must be followed each time.
High quality HEPA filter systems are crucial in any clean room environment and safe change filter housings ensure maximum protection against harmful micro-organisms and chemicals.
For more information about our clean air equipment, contact us.
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