As we all know, the pharmaceutical clean room has extremely high requirements for hygiene and safety. If there is dust in pharmaceutical clean room, it will cause pollution, health damage and explosion risks. Therefore, the use of hepa filters is indispensable. What are the standards for the use of hepa filters, replacement time, replacement parameters and indications? How should pharmaceutical clean room with high cleanliness requirements choose hepa filters?
In pharmaceutical clean room, hepa filters are used as terminal filters for the treatment and filtration of air in production spaces. Aseptic production requires the mandatory use of hepa filters, and the production of solid and semi-solid dosage forms is sometimes also used. Pharmaceutical clean rooms are different from other industrial clean rooms. The difference is that when aseptically producing preparations and raw materials, not only the suspended particles in the air must be controlled, but also the number of microorganisms must be controlled. Therefore, the air conditioning system in the pharmaceutical plant also has sterilization, sterilization, disinfection and other methods to control microorganisms within the scope of relevant regulations. The air filter uses porous filter materials to capture dust from the airflow, purify the air, and purify the dusty air and send it into the room to ensure the air cleanliness in clean room. For pharmaceutical clean rooms with higher requirements, gel seal hepa filters are usually used for filtration. The gel seal hepa filter is mainly used to capture particles below 0.3μm. It has better sealing, high filtration efficiency, low flow resistance, and can be used for a long time to reduce the cost of later consumables, providing clean air for the clean workshop of pharmaceutical companies. Hepa filters are generally leak tested before leaving the factory, but non-professionals need to pay more attention during handling and installation. It sometimes happens that pollutants leak from the frame into the clean room due to improper installation, so leak detection is usually performed after installation to confirm whether the filter material is damaged; whether the box is leaking; whether the filter is installed correctly. Regular inspections should also be carried out in later use to ensure that the filtration efficiency of the filter meets production requirements. Commonly used processes include mini pleat hepa filters, deep pleat hepa filters, gel seal hepa filters, etc., which achieve the purpose of cleanliness through air filtration and flow to filter out dust particles in the air. The load of the filter (layer) and the upstream and downstream pressure difference are also important. If the upstream and downstream pressure difference of the filter increases, the energy demand of the supply and exhaust air system will increase, so as to maintain the necessary number of air changes. Such a pressure difference between the upstream and downstream of the filter may increase the performance limit of the ventilation system. During use, in order to protect the hepa filter, a front-end filter must be used - usually a fine filter such as F5, F7 and F9 filters (EN779). The hepa filter must also be replaced regularly to protect the hepa filter from clogging.
Whether it is a hepa filter installed at the end of the purification air conditioning unit or a hepa air filter installed at the hepa box, these must have accurate operating time records and cleanliness and air volume as the basis for replacement. For example, under normal use, the service life of the hepa filter can be more than one year. If the front-end protection is good, the service life of the hepa filter can be more than two years without any problem. Of course, this also depends on the quality of the hepa air filter, or even longer. The hepa filters installed in clean room equipment, such as the hepa filters in the air shower room, can have a service life of more than two years if the front-end primary filter is well protected; for example, the hepa filters on the purification workbench can be replaced by the prompt of the pressure difference gauge on the purification workbench. The hepa filters on the clean shed can determine the best time to replace the air filters by detecting the wind speed of the hepa air filters. For example, the hepa air filters on the FFU fan filter unit can be replaced by the prompts in PLC control system or the pressure difference gauge. The replacement conditions for hepa filters in pharmaceutical factories stipulated in clean room design specifications are: the air flow velocity is reduced to the minimum limit, generally less than 0.35m/s; the resistance reaches 2 times the initial resistance value, and is generally set at 1.5 times by enterprises; if there is an unrepairable leakage, the repair points shall not exceed 3 points, and the total repair area shall not exceed 3%. For a single point repair area, it should not be larger than 2*2cm. Some of our experienced air filter installers have summarized valuable experience. Here we would like to introduce the hepa filters for pharmaceutical factories. We hope that this will help you grasp the best time to replace air filters more accurately. In the air conditioning unit, when the pressure differential gauge shows that the resistance of the air filter reaches 2 to 3 times the initial resistance, the air filter should be maintained or replaced. In the absence of a pressure differential gauge, you can use the following simple two-body format to determine whether it needs to be replaced: observe the color of the filter material on the upper and lower wind sides of the air filter. If the color of the filter material on the air outlet starts to turn black, you should prepare to replace it; touch the filter material on the air outlet side of the air filter with your hand. If there is a lot of dust on your hand, you should prepare to replace it; record the replacement status of the air filter many times and summarize the best replacement cycle; if the pressure difference between the clean room and the adjacent room drops significantly before the hepa air filter reaches the final resistance, it may be that the resistance of the primary and secondary efficiency filters is too large, and you should prepare to replace it; if the cleanliness in clean room does not meet the design requirements, or there is negative pressure, and the primary and secondary efficiency air filters have not reached the replacement time, it may be that the resistance of the hepa air filter is too large, and you should prepare to replace it.
Under normal use, the hepa filter is replaced once every 1 to 2 years (depending on the air quality in different regions), and this data varies greatly. The empirical data can only be found in a specific project after the operation verification of the clean room, and the empirical data suitable for the clean room can only be provided for the clean room air shower room. Factors affecting the service life of the hepa filter:
1. External factors:
1. External environment. If there is a big road or roadside outside the clean room, there is a lot of dust, which will directly affect the use of the hepa filter and the life will be greatly reduced. (Therefore, site selection is very important)
2. The front and middle ends of the ventilation duct are usually equipped with primary and medium efficiency filters at the front and middle ends of the ventilation duct. The purpose is to better protect and utilize the hepa filter, reduce the number of replacements, and reduce expenditure costs. If the front-end filtration is not handled properly, the service life of the hepa filter will also be shortened. If the primary and medium efficiency filters are directly removed, the use time of the hepa filter will be greatly shortened.
2. Internal factors: As we all know, the effective filtration area of the hepa filter, that is, its dust holding capacity, directly affects the use of the hepa filter. Its use is inversely proportional to the effective filtration area. The larger the effective area, the smaller its resistance and the longer its use time. It is recommended to pay more attention to its effective filtration area and resistance when selecting a hepa air filter. Hepa filter deviation is inevitable. Whether it needs to be replaced is subject to on-site sampling and testing. Once the replacement standard is reached, it needs to be checked and replaced. Therefore, the empirical value of the filter life cannot be arbitrarily expanded. If the system design is unreasonable, the fresh air treatment is not in place, and the clean room air shower dust control plan is unscientific, the service life of hepa filter will definitely be short, and some will even have to be replaced in less than a year. Related tests:
1. Pressure difference monitoring: When the pressure difference before and after the filter reaches the set value, it usually indicates that it needs to be replaced;
2. Service life: Refer to the rated service life of the filter, but also judge in combination with the actual situation;
3. Cleanliness change: If the air cleanliness in clean room drops significantly, it may be that the filter performance has dropped and it is necessary to consider replacement;
4. Experience judgment: Make a comprehensive judgment based on previous usage experience and observation of the filter condition;
5. Check the physical damage of the media, discoloration spots or stains, gasket gaps and discoloration or corrosion of the frame and screen;
6. Filter integrity test, leak test with a dust particle counter, and record the results as required.
Post time: Feb-26-2025