What is Hepa and Ulpa Filter?
Hepa stands for High Efficiency Particulate Arresting. It stands for high efficiency particle catcher. Hepa filters are filters that can purify particles up to 0.3 microns from the air at a rate of 85% and above. Filters that are more sensitive than HEPA filters and have a rate of 99.999% are called ulpa filters. Hepa and ulpa filters are maintenance-free, consist of special fibers and have a paper-like structure. These filters must be replaced with a new one within a certain period of time. It is recommended to replace HEPA and ulpa filters every 6-12 months depending on the ambient air pollution, frequency of use and pressure loss. Today, hepa and ulpa filters are used in operating rooms, hospitals and clean room applications due to their filtering performance, reliability and maintenance-free structure. Hepa and ulpa filters are available in MDF, plastic or metal framed models.
What is Bag Filter?
Bag filters made of synthetic fiber material show superior performance with their high dust holding capacity. Bag filters, which are manufactured at 500 mm and 600 mm depths, are also produced in special sizes. Synthetic fiber bag filters are used in ventilation systems. In the hygienic air conditioning system, they are mounted inside the air handling unit in order to retain large particles and protect the hepa filter. Synthetic fiber bag filters filter in the G3 (EU4) – G4 (EU4) – F5 (EU5) – F6 (EU6) – F7(EU7) – F8 (EU8)- F9(EU9) class.
What is a Cassette Filter?
Cassette panel filters are made of a controlled and renewable special raw fiber blend and have an extremely durable structure. The protection cage around it has been placed in order to protect the filtering feature from impacts. Cassette panel filters are G2 (EU2) – G3 (EU3) – G4(EU4) – F5 (EU5) class filters. Cassette filters are produced on the basis of cellulosic and fiber glass.
What is Activated Carbon Filter?
The activated carbon filter has the ability to capture and hold gas molecules. The surface of the activated carbon filter consists of millions of tiny pores. Thanks to these pores, toxic gases that emit many odors are caught. Activated carbon filters should be changed depending on the ambient air pollution and frequency of use. For example, activated carbon filters need to be changed every 3 to 6 months in a smoking environment. Activated granular carbon filters are used as odor-retaining filters in places where heavy odors occur. In activated granular carbon filters, only granular carbons are replaced when the filter becomes dirty. There is no need to change the cells of the filter.
What is Electrostatic Filter?
Electrostatic filters work with the principle of capturing the charged particles in the air passing between them by the plates with the electrostatic attraction force, taking advantage of the high voltage field created between the plates. Particle holding capacity is quite high.
The dirty air drawn by the fan passes through the washable metal pre-filter. This filter traps coarse dust and oil particles. Then, the oil, smoke and soot in the air coming to the electrostatic filter, which operates according to the principle of ionizing the particles, are negatively charged by high voltage charge. As the negatively charged polluted air passes through the positively charged area in the second stage, the oil, smoke and soot particles in the air are strongly attracted by the collector plates and adhered to the filter surface.
The air cleaned by 95% here is cleaned by 99% by passing through the active granular carbon filter and ozone filter.
What is Ozone Filter?
Ozone is a chemical compound consisting of three oxygen atoms. Ozone is a colorless gas with a pungent odor.
Ozone is formed as a result of the combination of oxygen atoms with other oxygen molecules, which are formed by the collision of high-energy sun rays with normal oxygen molecules.
Ozone is a colorless, pungent odor gas at room temperature. It is easily felt in high places or by the sea after rainy, lightning or stormy weather. You can smell the sharp smell of ozone in high-voltage transformers, high-voltage lines, behind televisions, and in copiers.
Ozone gas in the upper layer of the atmosphere acts as a shield that protects living things against the deadly ultraviolet rays of the sun. If there were no ozone layer, the sun’s radiation would reach the earth and cause genetic damage on living things. The blue color of the sky is also due to ozone gas.
Ozone disinfection destroys odor molecules, microorganisms and microbes by breaking down the cell membrane.
Ozone has a disinfection effect 3.100 times stronger than chlorine under the same conditions. As a result of the ozone gas disinfection process, it transforms into oxygen, which is its raw material, within 30 minutes in an open environment, within 8-12 hours in a closed package, without leaving any residual residue.
When should filters be changed? The resistance that the filter creates against the air flow when it is clean is called the initial resistance or pressure drop. This value is measured in Pa (pascal). This value increases as the filters get dirty. The filter whose resistance value reaches the recommended final resistance should be replaced. The recommended final resistance values for pre-filters and bag filters are determined according to ISO 16890 European standards.
There are 4 ISO groups in the ISO 16890 standard, namely ISO ePM1, ISO ePM2,5, ISO ePM10 and ISOCoarse. Evaluation is made at particle size between 0.3 μm and 10 μm.
How long do the filters last? The life of the air filters depends on the pollution rate of the air where the filters are installed and the performance of the system. Factors such as the increase or decrease of pollutants in the air and the seasons also affect the life of the filter. Based on our experience, we can say that cassette filters last 2-3 months, bag filters 4-6 months, and hepa filters 6-12 months.
Which filters are washable? Pre-filters and electrostatic filters with an internal structure of polyurethane or metal are washable. Bag, hepa and ulpa filters filter invisible particles by attracting and sticking them to the filter fibers on the basis of molecular attraction. This type of filters cannot be cleaned, they must be replaced with a new one.
Which filter should be used? The importance of filtering the air is increasing rapidly with the increase of industrialization and population. In addition to the appropriate filter types that should be used to purify the air from pollutants such as dust, particles, soot, smoke, oil or odor, filter cross-section, filter sequence, air flow, air velocity, pressure loss, working conditions, temperature, ease of maintenance, sealing, service life, Efficiency criteria should also be taken into account. Air filtration systems should be designed according to the needs, taking into account the criteria. Filter systems to be applied without considering expert opinion may expose the user to undesirable results and high costs.
İlker KURAN
Alperen Ltd Sti.