DESC:FIELD
The present disclosure relates to air purification systems, particularly indoor air purification systems and filter system thereof.
DEFINITIONS
As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicates otherwise.
The term “Scaffold” for the purpose of the present disclosure refers to a stationary solid structure, in part and as a whole, that is used to hold up or support another material with functional groups.
The term “PCO filters” for the purpose of the present disclosure refers to photocatalytic oxidation filters.
The term “HEPA filter” for the purpose of the present disclosure refers to high efficiency particulate arrester filters.
The term “MERV filter” for the purpose of the present disclosure refers to minimum efficiency reporting value of the filter. The term “VOCs” for the purpose of the present disclosure refers to volatile organic compounds.
The term “Multichem filter” for the purpose of the present disclosure refers to filter capable of removal of one or more inorganic gaseous contaminants along with VOCs.
The term “PPI” for the purpose of the present disclosure refers to Pores Per Inch designates the number of pores in one linear inch, used in the measurement of porosity.
The term “sponge” or “foam” or “ spongiferous matrix” for the purpose of the present disclosure refers to the macroporous and microporous polymer.
BACKGROUND
Air contamination and pollution is a long-standing problem. The air pollution levels continue to rise, with the contaminants like dust, mold, allergens, pollen and bacteria being prevalent. Other major contaminants are gaseous chemical contaminants, including volatile organic compounds (VOC's), such as formaldehyde, ammonia, and other common contaminants, which are released from indoor sources like building materials, adhesives, pesticides, cleaning agents, etc. Further, carbon monoxide is released from fireplaces, gas stoves and smoking. Apart from the indoor sources, gaseous chemicals from the outdoors such as vehicular emissions, smog, etc., can affect the indoor air quality. This problem is aggravated by inadequate ventilation in the newer "tight" construction buildings.
The inhalation of such contaminated air can cause serious health risks, mostly for people suffering from dust/pollen allergies, asthma, emphysema and other respiratory illnesses. Filters have long been used to remove contaminants like particulate, mold, pollen and dust/smoke. The filters, however, are designed only to remove contaminants up to a specific size.
Many devices use activated charcoal filters and high efficiency particulate arrester (HEPA) filters to remove the air contaminants.
A plethora of indoor air purification devices that are currently available use mechanical filters in conjunction with electronic air cleaners or ion generators. The negatively charged ions have the effect of purifying the atmosphere. A typical indoor area has an increased ratio of positive ions to negative ions, due to household activities like smoking, cooking or dusting or even due to the static electricity generated by synthetic fibers, which is not conducive to preservation of negative ions. However, these devices are not able to completely remove contaminants like gaseous chemicals and bacteria/viruses.
Purification of polluted air by removing gaseous chemicals has also been accomplished through the use of adsorbents or catalysts. Effective clean-up of air requires a combination of different types of adsorbents. In many applications, ozone is used to destroy viruses, bacteria, mold spores, pathogens and also remove odors and harmful gases. Ozone itself is toxic beyond a certain threshold level. It has been proved that long exposure to ozone might influence a critical step in the development of lung cancer by increasing the frequency of early, precancerous changes in cells.
There have also been attempts to use ultra-violet or UV lamps to destroy bacteria on a variety of surfaces, including filter surfaces. It is known that UV-C light is an effective germicidal, capable of destroying microorganisms in the air. As contaminated air passes through intense UV-C light, bacteria, viruses and other organic compounds get destroyed.
Photo-catalytic Oxidation (PCO) is the current state of the art technology used for air purification for removal of various contaminants mainly molds, pollen, bacteria/micro-organisms and to some extent odors. PCO requires a combination of UV light rays with a titanium oxide (TiO2) coated filter. The process creates hydroxyl radicals and super-oxide ions, which are highly reactive electrons. These highly reactive electrons aggressively combine with other elements in the air, such as bacteria and VOC’s. Once bound together, a chemical reaction takes place between the super-charged ion and the pollutant, effectively oxidizing (or burning) the pollutant and breaking it down into harmless carbon dioxide and water molecules, thereby purifying the air. Single or multiple PCO filters coated with titanium dioxide (with and without dopant) coated on different supports, including woven/ non-woven fabric, have been used. A number of different air purification devices using the photo-catalytic oxidation technology for providing purified indoor air have been developed in the past.
The main challenge in PCO is selection of the right kind of base matrix on which TiO2 coating is to be done and the right coating methodology to ensure uniformity and rigidity of TiO2 particles onto the substrate. The other major aspects one need to consider when PCO is employed in air purification devices is filter cost, filter life, ease of manufacturing and pressure drop.
PCO filters especially made from fabric when not safeguarded with tighter pre-filters may lead to dust deposition which will reduce light impedance on catalytic surface hence efficiency. Another common limitation would be life of these filters. Fabric based PCO filters generally has low life, mainly due to mechanical abrasion and catalyst site deactivation. These filters are of the use and throw type and cannot be reused. Frequent replacement of these filters calls for the high operating cost of air purification device. The discarded filters also cause their own waste disposal issues.
In the Indian patent application No. 1723/MM/2013, there is disclosed an air filter system which includes a module for destroying/killing organisms in the air using the photocatalytic oxidation (PCO), along with other modules. Said application requires the other modules such as a primary purification unit which include a prefilter and an MERV (minimum efficiency reporting value) filter, a secondary purification unit which includes the PCO filter with UVA light source and a tertiary purification unit which includes a HEPA and /or an activated carbon filter to be placed in a particular sequence. The PCO filter disclosed in the Indian patent application no. 1723/MUM/2013 has a fabric based element. The requirement of a sequence of filters and use of UVA light as described in 1723/MUM/2013, results in high pressure drops, high element replacement costs due to lower PCO filter life and not so efficient use of the UVA light and overall purification system.
Therefore, there is felt a need to provide an air purification system having enhanced efficacy.

OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.
An object of present disclosure is to provide an air purification system that requires less production costs as compared to fabric based PCO filters.
Another object of the present disclosure is to provide an air purification system that has long life.
Still another object of the present disclosure is to provide an air purification system that can be washed and reused.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure envisages an air purification system. The air purification system comprises a housing. The housing includes an inlet, an outlet, and a set of components. The inlet receives air, which is to be purified and an outlet for discharging air after purification. The set of components is disposed in the housing. The set of components is arranged sequentially between the inlet and the outlet in a sequential order. The set of components comprises at least one filter, a purifier block, and a fan.
The at least one filter is selected from a group consisting of at least one mesh type pre-filter and at least one minimum efficiency reporting value (MERV) filter.
The purifier block comprises at least one photo-catalytic oxidation (PCO), at least one UV-lamp, at least one high efficiency particulate air (HEPA) filter and at least one granular/multichem filter. In an embodiment, the multichem filter is selected from the group including an activated carbon, an alumina or special zeolites based adsorbent medias with a chemical impregnation of KMnO4, H3PO4, copper, silver and any combination thereof.
In another embodiment, the components of the purifier block are arranged in a sequential order. The sequential order comprises the HEPA Filter, the PCO filter, the UV-lamp and the multichem filter. In another embodiment, the components of the purifier block are arranged in sequential order including the HEPA Filter, the UV-lamp, the PCO filter and the multichem filter.
In another embodiment, the components of the purifier block are arranged in a sequential order comprising the multichem filter, the HEPA filter, the PCO filter and the UV-lamp.
In still another embodiment, the components of the purifier block are arranged in a sequential order comprising the HEPA filter, the multichem filter, the PCO filter and the UV-lamp.
In an embodiment, the components of the purifier block are arranged in a sequential order comprising the multichem filter, the PCO filter, the UV-lamp and the HEPA filter.
In an embodiment, the at least one photo-catalytic oxidation (PCO) filter includes at least one scaffold. The scaffold comprises of an alumina zirconia matrix which is coated with TiO2. The alumina zirconia matrix has a pore size in the range of 0.1 mm to 3 mm and a pore density in the range of 20 PPI to 60 PPI. In an embodiment, the coating composition comprises a TiO2 precursor sol, a binder and a solvent mix.
In an embodiment, the binder is a colloidal silica.
In an embodiment, the solvent mix comprises at least one reactive solvent and optionally germicidal inorganic particles. The reactive solvent is selected from the group consisting of isopropanol, acetic acid, nitric acid, hydrogen peroxide or combinations thereof. In an embodiment, the germicidal inorganic particles are selected from the group consisting of nanoparticles of silver, copper, gold or combinations thereof.
The TiO2 precursor sol comprises titanium tetra isopropoxide or titanium tetrabutoxide, or a combination thereof. In another embodiment, the alumina zirconia matrix comprises an alumina content is in the range of 80% to 99.5%. The alumina zirconia matrix is a coated matrix obtained by dipping the alumina zirconia matrix in a coating composition having viscosity in the range of 10-5000 centipoise (cps), at a predetermined speed and at a controlled temperature for a predetermined hold time, which is followed by drying and cooling at room temperature to obtain a dipped matrix. The obtained dipped matrix is calcined in a furnace with a calcining temperature control followed by cooling the dipped matrix to obtain a coated matrix. In an embodiment, the calcining temperature control is in a range of 450oC to 700oC.
The alumina zirconia matrix is cleaned prior to dipping it in an ultra-sonication bath with at least one cleaning agent comprising at least one diluted organic solvent.
In an embodiment, the at least one UV-lamp is configured to emit UV-light.
In an embodiment, the fan is disposed proximal to the outlet for inducing a draft for directing purified air outside the housing and sucking in air to be purified through the inlet.
The present disclosure also envisages a method for purifying air. The method purifies air through a housing having an inlet and an outlet. The method comprising following steps:
• arranging in series from the inlet and the outlet a pre-filter, a purifying block and a fan;
• sucking air by means of the fan through the inlet and forming a draft of air from the inlet through the outlet;
• extracting coarse solid particles via the pre-filter;
• photo-catalytically oxidizing chemical compounds in in photo-catalytic oxidation (PCO) filter, chemical compounds, contained in the draft of air and destroying microorganisms through strong oxidative radicals by emitting UV light on the photo-catalytic oxidation (PCO) filter;
• extracting fine particles in the draft of air by a high efficiency particulate air (HEPA) filter; and
• extracting inorganic gaseous contaminants by at least one granular/multichem filter.
BRIEF DEESCRPTION OF DRAWING
A system and method for air purification of the present disclosure will now be described with the help of the accompanying drawing, in which:
FIG. 1 illustrates a block diagram of the air purification system, in accordance with an embodiment of the present disclosure; and
FIG 2A and 2B illustrate a flow diagram of a method for purifying air, in accordance with an embodiment of the present disclosure.
LIST OF REFERENCE NUMERALS USED IN DETAILED DESCRIPTION AND DRAWING
100 – System
102 – Housing
104 – An Inlet
106 – An Outlet
108 – A Set of Components
110 – At least One Filter
112 – A Purifier Block
112A – At Least One Photo-Catalytic Oxidation (PCO) Filter
112B – At Least One UV-Lamp
112C – At Least One High Efficiency Particulate Air (HEPA) Filter
112D – At Least One Multichem Filter
114 – A Fan
DETAILED DESCRIPTION
The present disclosure envisages an air purification system. The air purification system 100 of the present disclosure is now explained with reference to Figure 1.
The air purification system 100 comprises a housing 102. The housing 102 includes an inlet 104, an outlet 106 and a set of components 108 disposed in the housing 102. The set of components 108 are arranged sequentially between the inlet 104 and the outlet 106 in a sequential order.
The set of components 108 includes at least one filter 110, a purifier block 112, and a fan 114. The at least one filter 110 is selected from the group consisting of at least one mesh type pre-filter and at least one minimum efficiency reporting value (MERV) filter.
In an embodiment, the purifier block 112 includes at least one photo-catalytic oxidation (PCO) filter 112A, at least one UV-lamp 112B, at least one high efficiency particulate (HEPA) filter 112C, and at least one granular/multichem filter 112D. The photo- catalytic oxidation (PCO) filter 112A further consists of at least one scaffold, and the scaffold comprises an alumina zirconia matrix. In an embodiment, the alumina zirconia matrix is coated with TiO2.
In an embodiment, the air is received at the inlet 104 via suction force generated by the fan 114 disposed at the outlet 106. The air is directed to the at least one filter 110. The air traverses through the meshes of the at least one filter 110 and reaches the purifier block 112. The purifier block 112 has the PCO filter 112A, the UV lamp 112B, the HEVA filter 112C, and the multichem filter 112D arranged in one of the combination as shown below:
• HEPA Filter – PCO Filter – UV Light – Multichem Filter
• HEPA Filter – UV Light – PCO Filter – Multichem Filter
• Multichem Filter – HEPA Filter – PCO Filter – UV Light
• HEPA Filter – Multichem Filter – PCO Filter – UV Light
• Multichem Filter – PCO Filter – UV Light – HEPA Filter
In an embodiment, the PCO filter 112A and other filter elements (112B to 112D) are disposed in a relation to enable the irradiation of UV light onto two or more filters, preferably UV light on PCO filter 112A and either of or both HEPA filter 112C, Multichem filter 112D. In an embodiment, the at least one UV-lamp 112B is configured to emit UV-light. The UV light emitting from the UV lamp 112B passes through porous structure of the PCO filter 112A to impinge light on HEPA filter 112C and/or Multichem filter 112D. Effective use of germicidal UV-light emitting from the UV-lamp 112B is such that it prevents the growth of micro-organisms on filtration surfaces. Any kind of exposure to the UV light is safeguarded by use of mechanical shielding means. The fan 114 is disposed proximal to the outlet 106. The fan 114 sucks the air and induces a draft for directing the purified air outside the housing 102.
In an embodiment, the method 200 for purifying air through a housing 102 having an inlet 104 and an outlet 106, as depicted in Figure 2A and 2B. The method 200 comprises the following steps:
• at 202, arranging in series from the inlet 104 to the outlet 106 the pre-filter 110, the purifying block 112 and the fan 114;
• at 204, sucking air by means of the fan 114 through the inlet 104, thereby forming a draft of air from the inlet 104 through the outlet 106;
• at 206, extracting coarse solid particles via the pre-filter 110;
• at 208, photo-catalytically oxidizing in a photo-catalytic oxidation (PCO) filter 112A, chemical compounds contained in the draft of air and destroying microorganisms through strong oxidative radicals by emitting UV light on the photo-catalytic oxidation (PCO) filter;
• at 210, extracting fine particles from the draft of air by the high efficiency particulate air (HEPA) filter 112C; and
• at 212, extracting inorganic gaseous contaminants by at least one granular/multichem filter 112D.
In accordance with one aspect of the present disclosure, there is provided a scaffold comprising alumina zirconia matrix having controlled pore size, controlled pore density, controlled shape and controlled size. The controlled pore size ranges from 0.1 mm to 3 mm. The controlled pore density ranges from 20 PPI to 60 PPI (pores per linear inch). The controlled pore shape can be cuboid, cylindrical, disc shaped having a rectangular, circular, oval or any other geometric and non-geometric cross section as per requirement. In an embodiment, the alumina content in the matrix ranges from 80% to 99.5%.
In an embodiment, the multichem filter 112D is selected from the group consisting of activated carbon, alumina or special zeolites based absorbent medias with chemical impregnation of KMnO4, H3PO4, copper, silver and any combination thereof.
In one aspect of the present disclosure, the arrangement of filters are defined in order including the pre-filter, the minimum efficiency reporting value (MERV) filter and typically followed by one of the below combination:
• HEPA Filter – PCO Filter – UV Light – Multichem Filter
• HEPA Filter – UV Light – PCO Filter – Multichem Filter
• Multichem Filter – HEPA Filter – PCO Filter – UV Light
• HEPA Filter – Multichem Filter – PCO Filter – UV Light
• Multichem Filter – PCO Filter – UV Light – HEPA Filter
To obtain the desired matrix, an experiment was performed using a coating composition. The alumina zirconia matrix was dipped in the coating composition with a viscosity in the range of 10-5000 centipoise (cps). The alumina zirconia matrix was dipped at a predetermined speed and at a controlled temperature for a predetermined hold time which is followed by drying and cooling at room temperature to obtain a coated matrix. The obtained dipped matrix was calcined in a furnace with a controlled calcining temperature followed by cooling the dipped matrix to obtain a coated matrix.
In an embodiment, the calcining temperature ranges from 450oC to 700oC. The alumina zirconia matrix was cleaned prior to dipping in an ultra-sonication bath with at least one cleaning agent. In an embodiment, the cleaning agent comprises at least one diluted organic solvent.
In another aspect of the present disclosure, there is provided a coating composition comprising, TiO2 precursor sol, a binder and a solvent mix.
Typically, TiO2 precursor sol comprises a titanium tetra isopropoxide or titanium tetrabutoxide or a combination thereof. However, the solvent system can be a combination of isopropanol, acetic acid, nitric acid, hydrogen peroxide and the like. Typically, the solvent mix comprises at least one reactive solvent and optionally germicidal inorganic particles. Typically, the germicidal inorganic particles are selected from a group consisting of nanoparticles of silver, copper, gold or combination thereof.
Typically, in the present disclosure, the binder may be colloidal silica, however, other suitable organic or inorganic binders may also be used in the preparation of the coating composition.
Typically, the surfactant may vary between 80 or any other suitable anionic, cationic, non-ionic surfactant.
The coating of the scaffold may be repeated multiple times typically twice or thrice to ensure uniform desired coating thickness.
Actual combination of filter elements used for the selected application depends on target air contaminant and typically at least two or more filter elements in any specified order can be arranged in the air purification system 100.
TECHNICAL ADVANCES AND ECONOMICAL SIGNIFICANCE
The air purifier and filter system thereof in accordance with the present disclosure described herein above has several technical advantages including but not limited to the realization of an air purification system that:
• is less expensive;
• can be washed and reused; and
• has long life.
The foregoing description of the specific embodiments fully reveals the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein has been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired object or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values ten percent higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.
,CLAIMS:WE CLAIM:
1. An air purification system (100), said system (100) comprising:
a housing (102) having:
an inlet (104) for receiving air to be purified;
an outlet (106) for discharging air after purification; and
a set of components (108) disposed in said housing, said set of components (108) arranged sequentially between said inlet and said outlet in a sequential order, comprising:
(a) at least one filter (110) selected from a group consisting of at least one mesh type pre-filter and at least one minimum efficiency reporting value (MERV) filter;
(b) a purifier block (112) comprising:
i. at least one photo-catalytic oxidation (PCO) filter (112A) comprising at least one scaffold, said scaffold comprising an alumina zirconia matrix, coated with TiO2,
ii. at least one UV-lamp (112B) configured to emit UV-light,

iii. at least one high efficiency particulate air (HEPA) filter (112C), and
iv. at least one granular/multichem filter (112D); and
(c) a fan (114) disposed proximal to said outlet for inducing a draft for directing purified air outside said housing (102) and sucking in air to be purified through said inlet (104).
2. The air purification system (100) as claimed in claim 1, wherein said alumina zirconia matrix has a pore size in a range of 0.1 mm to 3 mm and a pore density in a range of 20 PPI to 60 PPI.
3. The air purification system (100) as claimed in claim 1, wherein the components of said purifier block (112) are arranged in a sequential order comprising said at least one HEPA Filter (112C), said at least one PCO filter (112A), said at least one UV-lamp (112B) and said multichem filter (112D).
4. The air purification system (100) as claimed in claim 1, wherein the components of said purifier block (112) are arranged in a sequential order comprising said at least one HEPA Filter (112C), said at least one UV-lamp (112B), said at least one PCO filter (112A) and said multichem filter (112D).
5. The air purification system (100) as claimed in claim 1, wherein the components of said purifier block (112) are arranged in a sequential order comprising said multichem filter (112D), said at least one HEPA filter (112C), said PCO filter (112A) and said at least one UV-lamp (112B).
6. The air purification system (100) as claimed in claim 1, wherein the components of said purifier block (112) are arranged in a sequential order comprising said at least one HEPA filter (112C), said multichem filter (112D), said at least one PCO filter (112A) and said at least one UV-lamp (112B).
7. The air purification system (100) as claimed in claim 1, wherein the components of said purifier block (112) are arranged in a sequential order comprising said multichem filter (112D), said at least one PCO filter (112A), said at least one UV-lamp (112B) and said at least one HEPA filter (112C).
8. The air purification system (100) as claimed in claims 1-7, wherein said multichem filter is selected from a group comprising activated carbon, alumina or special zeolites based adsorbent medias with chemical impregnation of KMnO4, H3PO4, copper, silver and any combination thereof.
9. The air purification system (100) as claimed in claim 1, wherein said alumina zirconia matrix comprises an alumina content in a range of 80 to 99.5%.
10. The air purification system (100) as claimed in claim 1, wherein said alumina zirconia matrix is a coated matrix obtained by dipping said alumina zirconia matrix in a coating composition having viscosity in a range of 10-5000 cps, at a predetermined speed and at a controlled temperature for a predetermined hold time followed by drying and cooling at room temperature to obtain a dipped matrix, and calcining said dipped matrix in a furnace with a calcining temperature control followed by cooling to obtain said coated matrix, wherein said alumina zirconia matrix is cleaned prior to said dipping in an ultra-sonication bath with at least one cleaning agent comprising at least one diluted organic solvent.
11. The air purification system (100) as claimed in claim 10, wherein said calcining temperature control is in a range of 450 oC to 700 oC.
12. The air purification system (100) as claimed in claim 10, wherein said coating composition comprises a TiO2 precursor sol, a binder and a solvent mix.
13. The air purification system (100) as claimed in claim 12, wherein said TiO2 precursor sol comprises titanium tetra isopropoxide or titanium tetrabutoxide, or a combination thereof.
14. The air purification system (100) as claimed in claim 12, wherein said binder is colloidal silica.
15. The air purification system (100) as claimed in claim 12, wherein said solvent mix comprises at least one reactive solvent and optionally germicidal inorganic particles, wherein said at least one reactive solvent is selected from a group consisting of isopropanol, acetic acid, nitric acid, hydrogen peroxide or combinations thereof and said germicidal inorganic particles are selected from a group consisting of nanoparticles of silver, copper, gold or combinations thereof.
16. A method (200) for purifying air through a housing (102) having an inlet (104) and an outlet (106), said method (200) comprising following steps:
i. arranging in series from said inlet (104) and said outlet (106) a pre-filter (110), a purifying block (112) and a fan (114) (202);
ii. sucking air by means of said fan (114) through said inlet (104) and forming a draft of air from said inlet (104) through said outlet (106) (204);
iii. extracting coarse solid particles via said pre-filter (110) (206);
iv. photo-catalytically oxidizing in a photo-catalytic oxidation (PCO) filter (112A), chemical compounds contained in said draft of air and destroying microorganisms through strong oxidative radicals by emitting UV light on said photo-catalytic oxidation (PCO) filter (208);
v. extracting fine particles in said draft of air by a high efficiency particulate air (HEPA) filter (112C) (210); and
vi. extracting inorganic gaseous contaminants by at least one granular/multichem filter (112D) (212).
17. The method (200) for purifying air as claimed in claim 16, wherein said purifier block (112) has method steps (iv), (v), and (vi), said method steps are carried out in the following chronological order:
• iv – v – vi
• vi – iv – v
• iv – vi – v
• v – vi – iv
• vi – v – iv
• v– iv – vi