KIEKENS AIR CLEANER TYPE AIRMASTER

       ODOUR CONTROL BY THE KIEKENS AIRMASTER                                                                                      

A brief survey with regard to the properties and applications when using (active) carbon for the filtration of health hazardous and/or irritating odours.

There are two methods to filter odour molecules from the air with the help of carbon.

       Physisorption

This is also called adsorption. Odour molecules adhere to the side in the pores of the carbon. Because of the so-called "Van de Waals-forces" (weak electric forces) the molecules stay adhered to the side.

We speak of adsorption when these forces take care of adhering. When for instance a drop is sticking to a glass, we speak of absorption. It is a matter of absorption when substances adhere to one another by cohesion, hygroscopic or for instance capillary working.

The pore dimension is put in Angstrom (1 Å = 0.000001 mm). This way of attachment can only be for substances which have an organic origin (hydrocarbon compounds). For a proper adhering a contact time of  0.1 seconds is necessary. In general the particle size lies between 15 - 30 Å. One gram carbon can have an area of 800-1500 m².

      Chemisorption

In this case chemicals are added to the carbon. Generally the anorganic vapours are handled, such as:

*              Acids

*              Ammonia / Amino

*              Formaldehyde

*              Hydrogen sulphide

*              mercury

*              Sulfur dioxide

In order to give the chemical reaction time, a longer contact time is necessary.         Usually this time is set on 0. 2 seconds. However, for mercury vapours a contact time of 5 - 6 seconds is recommended.

In case of physisorption adherence is obtained by the Van der Waals-forces. These forces are normally sufficiently strong to hold on to multiple layers of molecules (so-called multi-layer). In case of chemisorption the adherence is acquired by the chemical reaction with the chemical impregnation. Once the chemical layer is used, no further reaction can take place. This is called one layer adsorption.

         General remarks

         Dust and liquid clog the pore, structure of the carbon causing the area to become smaller which lessens the filtration. Also condensation has to be avoided at all times. The use of a dust pre-filter and a mist expulser in the form of a streched metal filter increase the life span of the carbon filter.

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KIEKENS AIR CLEANER TYPE AIR MASTER

Certain kinds of lacquer which contain a plastic element or softener have very long odour molecules which can block the pores. The softening agent most used is Di-Octyl-Phtalate (DOP). To this end a high-quality HEPA-filter as pre-filter is an excellent solution.

Usually the carbon is applied in granulated form with diameters of 150 µm -25 mm. In the Airmaster the carbon is applied as loose filling (also cartridges with a fixed filling exist, the so-called 'bound carbon block^’).

          Airmaster

This machine is furnished with a carbon cartridge E 450 x 500 mm. By that the flow area is 0.7068 m². The Airmaster has a capacity of 1.200 m³/h. The concerning air flow velocity will become 0.47 m/s. The carbon layer has a thickness of 130 mm by which the contact time is 0.27 seconds. This makes the Airmaster extremely suitable for physisorption as well as chemisorption. A very broad spectrum of odours can be filtered. Based on this analysis one can quickly and easily determine to what extent competitive air cleaners can function properly at all.

Because of the relatively long contact time, which is often < 0.1 m/s in case of competitive machines, the Airmaster is also suitable for low concentrations. As the odour concentration is lower, a longer contact time is necessary.

Owing to its round form an optimal air division and air flow velocity of the carbon is realized. With this a constant filter load over the carbon is obtained which prolongs the life considerably. Dependent on the use, a life span of 0.5 -1 year may be taken for granted.

The carbon cartridge is fitted with a Viledon filter mat. With this the necessary dust filtration is brought about. Dust regardless of the particle size, clogs the pores which reduces the filter area drasticly.

The carbon cartridge is standard filled with 35 kg granulated material. In the optimal case this can adsorb 1/3 of its weight. With this the end weight is becoming ± 47 kg. Based on this Kiekens chose a robust design, by which it concerns primarily the construction and the frame.

The air flow is consciously directed downwards. Because of this a pre-separating working is developing where it concerns larger dust particles. Nevertheless a dust-free application is recommended.

     The influence of atmospheric humidity

The humidity level determines the adsorption ability of the carbon. Carbon also takes up water vapour. The adsorption ability decreases when the relative humidity increases. Up to a r.h. of 50% the decrease is limited, from 50% -100% the adsorption ability is slowly decreasing till ± 50% with regard to dry air. Generally it prevails that up to 40°C and 70% r.h. a good cleaning is guaranteed. Water molecules are usually very small with respect to the odour molecules and are therefore easy pushed away by the odour molecules.

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KIEKENS AIR CLEANER TYPE AIRMASTER

        Odour specifications

In order to determine the admission ability of the carbon one has to know:

*   Which gas has to be separated;

*   The concentration of this gas;

*   The temperature during the admission;

*   The relative humidity.

The strength of the Van de Waalskrachten is dependent on the the environmental conditions as air structure, concentration aromatic substances, temperature, atmospheric pressure and air humidity. Every gas has its own attraction with carbon. So is a one gas better adsorbed than an other. In the undermentiond survey the gasses are classified as follows:

*   Very low adsorption qualities with carbon,

*   Weak adsorption qualities with carbon, further study necessary.

*   Acceptable adsorption qualities with carbon, with generally good results.

*   Excellent adsorption where 1/3 of more of the carbon weight can be adsorbed.

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b Acetaldehyde

d Acetic acid

d Acetic anhydride

c Acetone

d Acetylene

c Acrolein

d Acrylic acid

d Acrylonrtnie

h Amines

b Ammonia

d Amyl acetate

d Amyl alcohol

d Amyl ether

d Aniline

d Benzene

b Brornhydric acid

d Bromine

c Butadiene

b Butane

b Butana

d Butyl acetate

d Butyl alcohol

d Butyl callosolve

d Butyl chloride

d Butyl after

b Butyne

c Butyric acid

d Camphor

c Carbon bisulphide

a Carbonic acid

d Carbon tetrachloride

d Cellosoive

d Cellosolva acetate

c Chlorine

d Chlorobenzene

d Chlorobutadiene

d Chloroform

d Chloronitropropane

d Chloropicrin

d Creosote

d Cresol

d Crotonaldehyde

d Cyclohexanol

d Cyclohexanone

d Cyctohexane

d Decane

d Dibromoethane

d Dichlorobenzene

d Dichloro-difluro methane

d Dichloroathane

d Dichloroethylene

d Dichloroethylether

c Dichloromonofluoromethane

d Dichloronitroethane

d Dichloropropane

c Dichlorotetrafluoroethane

c Diethylacetone

c Diethylamine

c Dimethylsulphate

d Dioxane

d Dipropy ketone

a Ethane

d Ethyl acetate

d Ethyl acrylate

d Ethyl alcohol

c Ethyl amine

d Ethyl benzene

c Ethyl bromide

c Ethyl chloride

a Ethylene

c Ethylene oxide

c Ethyl ather

c Ethyl formate

d Elhylmercaptan

d Ethyl silicate

c Fluorotriehlormethane

b Formaldehyde

c Formic acid

c Freon

d Gasoline

d Glycol chlorhydrine

d Heptane

d Heptylene

c Hexane

c Hexene   

c Hexyne

b Hydrochloric add

c Hydrocyanic acid

b Hydrofluoric acid

a Hydrogen

c Hydrogen sufphid

d lndole

d Iodine

 r lodhydrlc acid

d lodoform

c Isoprene

d Isopropyl acetate

d Isopropyl alcohol

d Isopropyl ether

d Kerosene

d Lactic acid

d Menthol

d Mercaptans

d Mesityl oxide

a Methane

c Methyl acetate

d Methyl acrylate

 r Methyfal

c hflethyl alcohol

c Methyl bromide

c Methyl butylketone

c Methyl chloride

d Methyl chloroform

d Methylcyclohexane

d Methylcyclohexanol

d Methylcyclohexanone

d Methylene chloride

c Methyl ether

d Methyl ethyl ketone

d Methyl cellosolve acetate

c Methyl formate

d Methyl isobutyl ketone

d Methyl mercaptan

d Monochlorbenzene

c Monofluorotrichlormethane

d Naphthalene

d Nicotine

c Nitric acid

d Nitrobenzene

d Nitroethane

b Nitrogen dioxide

d Nitnomethane

d Nitropropane

d Nitritoluene

d Nonane

d Octane

d Ozone

c Pentane

d Pentanone

e Pentene

c Pentyne

d perchlorethylene

d Phenol

c Phosgen

b Propane

b Propene

d Propionic acid

c Propionic aidehyde

d Propyl acetate

d Propyl alcohol

d Propyl chloride

d Prapyl ether

d Propyl mercaptan

b Selenhydride

c Solvents (various)

d Styrene monomer

b Sulphur gas

d Sulphuric acid

c Sulphuric anhydride

d Sulphurous compounds

d Terpentine

d Tetrachloroethane

d Tetrachloroethyene

d Toluene

d Toluidine

c Toxic gases

d Trichloroethylene

c Vinyl chloride

d Xylene