HEPA filter general knowledge introduction

Brief description of high efficiency filter

1、Mainly used for end filtration of purification air conditioning system to filter 0.1-0.5 µm dust particles.

2、The selection of brand-name quality filter media, strict quality management, clean production environment, rich manufacturing experience, and the test method of unit-by-unit testing, can meet the high-level requirements of clean engineering.

3、Frame material is generally aluminum alloy, galvanized plate, stainless steel, PVC, wood

The importance of air filter

According to our understanding of the use of air filters and their related knowledge for many years, considering that the majority of customers still generally lack understanding of the selection, replacement and maintenance of air filters, we will now make some brief explanations about the general customer concerns such as maintenance and replacement cycles during the use of air filters, hoping that it will help you in the scientific selection of air filters.

As we all know, air filter is the core component of clean room air treatment system, clean room is fundamentally rely on its filtration of atmospheric dust and achieve "clean". For the general ventilation and air conditioning environment, it is also relied on to filter dust to achieve the clean air requirements we need. Improper use of the filter will not only cause damage to the air handling system itself, but may also cause deterioration of the workshop environment, affecting normal production and damaging products.

Matching selection of air filter

General ventilation with central air conditioning selection of primary and intermediate efficiency two-stage filter, select F7 efficiency air filter "air conditioning duct system can be 10 years without cleaning", so in order not to time-consuming and laborious shutdown for air duct cleaning, smart business owners or businesses choose F7 air filter to avoid annual air duct cleaning.

Filter selection generally has the following principles: the performance of the final high-efficiency filter should be reliable; the efficiency of the protective intermediate filter should be reasonable; the primary filter should be easy to maintain; in addition, the universal size air filter should be used.

Resistance of the filter

The use of the filter forms a resistance to the airflow that penetrates its filter media organization. When the resistance increases to a certain specified value, the filter will be scrapped. Sometimes the excessive resistance will cause the dust captured on the filter to fly away, so the filter should be scrapped and replaced with a new filter in time. The resistance of the new filter (under the lowest wind speed) is called "initial resistance", and the resistance when the corresponding filter is scrapped is called "final resistance", in most cases the final resistance is 2-4 times of its initial resistance, and the resistance value under the rated air volume and its air volume is generally its average value. In most cases, the final resistance is 2-4 times its initial resistance.

The service life of high efficiency filter

For the running clean room, the value of the end high efficiency filter is not high, all together may be less than the output value of the user for a few hours, but the risk and overhead cost of replacing the end high efficiency filter will be very high. When replacing filters, production has to be stopped, and the loss of production stoppage can only be calculated by the owner himself, and this loss is definitely higher than the cost of filter spare parts. 

Replacing a high efficiency filter is a very careful operation, and anything in the clean room can be expensive, and the damage to one part can be higher than the cost of all the filters. After replacing the filter to be tested by professionals, and sometimes the air conditioning system has to be debugged, but also after a period of trial operation. The cost of testing, commissioning, and commissioning can add up to a price comparable to that of the filter. Smart homeowners always want to extend the life of the high-efficiency filter as much as possible, not to save the filter that a few dollars, they want to avoid a bunch of trouble due to the replacement of the filter. The most fundamental way to extend the life of a high-efficiency filter is to keep dust out of the pre-filter. 

Replace the pre-filter generally without stopping production, without commissioning, so experienced owners will spend their attention and money on the pre-filter and protection level intermediate filter. For class 10K and 100K clean plant, pre-filter choose G4, intermediate can choose F8 filter (colorimetric method 95%), so that the life of the end high efficiency filter is generally up to 5 years. In the project, F8 filter is the most common pre-filter for non-uniform flow clean room.

In some occasions, the service life of high efficiency filter is not specified for resistance consideration, but other factors. If there is hydrofluoric acid in the plant, and the workshop air conditioning is not a full fresh air system, the glass fiber filter paper in the HEPA filter will be corroded by the return air, and the HEPA filter must be replaced regularly for safety. Some large pharmaceutical plants, every year after the rainy season to replace the high-efficiency filter, in order to prevent any possible mold contamination on the filter. Some biological laboratories and laboratories dealing with hazardous materials will require new HEPA filters for reliability before carrying out a new and important subject.