FI114044B - Method of sampling air - Google Patents

Description

114044

Method of sampling of air Förfarande för tagning av prov ur luft

The present invention relates to a method for sampling and measuring 5 particles in the air, such as microbes and other nanoparticle particles of a size or greater.

In many places it is necessary to find out the amount of these particles in the air. These include hospitals, the pharmaceutical industry, the food industry, reception and intervention rooms, and other biotechnology working environments. It is often necessary to know whether the room air contains bacteria, viruses, spores, toxic particles, etc.

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If the number of particles to be detected is high and the particle size is> 0,01 μτη, for example, an electric filter may be used for sampling. Most viruses and DNA molecules are then completely excluded from collection because they have a particle size of <0.01 µm. Fiber filters are not suitable for the collection of nanoparticle particles with a level of reliability that is relevant to the conclusions;

, 25 The biggest disadvantage at the moment is, for example, that no infectious hospital bacteria can be detected! .. * in the hospital world, especially if they are very small in number and low in incidence.

It is an object of the present invention to eliminate these problems, V, by a method known in the art of passing a volumetric sample of air through an insulating tube having a removable conductive film on its inner surface and with an axis in the center • ·. 35 tubes with high voltage, radially extending

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• t ..: tiny emitting tips which, under the effect of the corona phenomenon, generate ion jets, which cause the particles in the air to adhere to an electrically conductive film, from which they can be detected and quantified in a manner known per se after 2 114044 sampling. The method is capable of collecting and determining the number of particles in the range of about 0,001 μπ - to about 100 μιη, regardless of their density. If only small amounts of particulate matter are present in the air, the volume of the air sample must be increased, which is easily accomplished by extending the sampling time in accordance with the invention since all particles in the air flowing through the duct are adhered to the electrically conductive membrane. Thus, the air leaving the ductwork is clean, so that the process does not spread contaminants or germs into the environment.

Other features of the invention will be apparent from the appended claims.

The invention will now be described in more detail with reference to the accompanying drawing, in which Fig. 1 shows, by way of example, a longitudinal section of the device used in the method according to the invention. Fig. 2 is a cross-sectional view of the apparatus of Fig. 1. . 25, Fig. 3 shows a perspective view of an embodiment of a device for use in the method according to the invention.

According to the invention, it is possible to detect various particles of air in a room or outdoor space, such as microbes and other nanoparticles or more, and measure their amounts per specific volume of the test. This will be done '. such that a predetermined volume of air is flown through an insulating tube 1 in the sampler, the inner surface of which has a removable conductive membrane 2. The insulating tube 1 has a tube 5 extending along its central axis and connected to a high voltage source 14. radial emitting tips 6 which, by the effect of a corona effect, generate ion jets 7 between these emitting tips 6 and the conductive film 2 on the inner wall of the insulating tube 1. Under the action of ion jets 7, any particles in the air are adhered to the electrically conductive film 2 if, after sampling, they are detectable and quantifiable in a manner known per se.

According to one embodiment, the electrically conductive film 2 is grounded and a negative high voltage 10 is applied to the emitting tips 6.

According to another, more preferred embodiment, a positive voltage is applied to the electrically conductive membrane 2 which forms a positive electric field in front of the membrane. At high voltages above 5 kV, the emitting tips 6 15 form negative electrons under the effect of the corona phenomenon, thereby generating ion jets towards the opposing collector film 2. The emitting tips 6 are directed towards said collecting film 2. Thus, a significantly lower voltage is required for the emitting tips 6 and the collecting diaphragm 2 to achieve the desired power than the grounded diaphragm 2.

According to an exemplary embodiment, the vertical insulating tube 1 has a diameter of 300 mm and a length of 900 mm. The electrically conductive film 2, removably attached to the inner surface of the insulating tube 1: 25, may be about 600 mm high, leaving a height of about 200 mm in the upper part of the insulating tube 1 'and a height of about 100 mm in the lower part. \; ·. dry insulating surface. The insulating tube 1 of the sampler is covered by electrically conductive, earthed side walls 4, and an air gap 3 remains between the insulating tube 1 and the side walls 4.

Preferably, the entire sampler is wheel-displaceable. The upper end of the device is preferably covered by a protective screen 10, through which particulate matter leaving the duct 1 is: ··· air returned to the surrounding room or outdoor air.

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A fan 9 is mounted at the upper end of the insulating tube 1, which allows ♦ · the air sample to be sucked into the sampler, either of its>> ·! through the sampling opening 16 at the bottom of the side wall 4, or through the flexible sampling line 17 if an air sample is to be taken from a higher level.

The high voltage is applied from the high voltage source 14 through the cables 5 to the electrically conductive membrane 2 as a plus sign and through the electrical insulator 11 surrounding the upper end of the center tube 5 to the emitter tip 6 as the minus sign.

For example, an electric current of 5 to 14 kV and 0.1 to 2.0 mA may be applied to the electrodes 10, 2 of the sampler of the size described above for sampling. The power consumption of the sampler is approximately 100 W for the fan and about 20 W for the particle collection energy. The sampler has a mains connection of 110-240 V 50-60 Hz.

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With a device of the size described above, sampling of, for example, 100 cubic meters of air takes about 20 minutes.

Because the sampler is small and relatively light, weighs about 25 kg, and is easily movable on wheels, the sampling frequency can be arranged even for a large hospital, for example, by using one sampler.

For example, the particles collected on the electrically conductive membrane 2 can be microscopically detected and measured after removal of said membrane from the insulating tube 1 via a door 13 on the side 4 of the sampler (Fig. 2). A gel may also be applied to the collection surface of the conductive membrane 2, where the collected microbes may be maintained for visual or • 30 other examination. For a new sampling, a new electrically conductive membrane 2 is mounted inside the insulating tube 1 through the same '·' * door 13. For safety reasons, the door opening handles 15 »· ♦ * are preferably fitted with microswitches that break the voltage ··· on the device when the door 13 is opened. .

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It is clear that the structure of the sampler is not limited to the structure example shown in the drawing, but may vary: within the scope of the claims.

Claims (9)

114044 A method for sampling and measuring airborne particles, such as microbes and other particles of order 5 nanoparticles, characterized in that a volumetric sample of air is conducted through an insulating tube (1) having a removable conductive film on its inner surface. (2) having in its center an axial tube (5) 10 having radially extending discharge tips (6) coupled to a high voltage source (14) which, under the effect of a corona phenomenon, emit ion jets (7) which cause airborne particles to , from which they can be detected and quantified after sampling. Method according to Claim 1, characterized in that the electrically conductive film (2) is grounded and a negative high voltage is applied to the emitting tips (6). 20 _ Method according to patent application 1, characterized in that the electrically conductive film (2) forms an electric field (8) in front of the collecting surface and the emitting tips (6) form ionic jets (7) opposite to the electric field; 25: 4. The method of claim 1, characterized. ·: The presence of a conductive film (2) on the collection surface; a gel applied to collect the microbes collected for visual or other examination. 30 Method according to one of Claims 1 to 4, characterized in that a voltage of about 5 to 14 kV is applied to the electrodes (2, 6), whereby the particles are removed from the air leaving the insulating tube (1). ·: ··: 35 Method according to Claim 5, characterized in that the air sample is drawn into the insulating tube (1) by means of a blower (9) 6 114044, the volume of the air sample being determined by the sampling time. Method according to Claim 6, characterized in that the air sample is drawn into the insulating tube (1) through the sampling opening (16) on the side (4) of the wheeled sampling device. A method according to claim 6, characterized in that the air sample is taken from the desired height through the sampling line (17). Method according to one of the preceding claims, characterized in that the amount of the various particles in the air sample is determined microscopically. * I • · * · • * · I · · 114044