SU1033540A1 - Apparatus for microbiological analysis of air - Google Patents

Description

The invention relates to microbiology, medicine, and other areas of technology that require information on the characterization of microbiological aerosols. .

A device for microbiological analysis of air is known, consisting of detachable cylindrical cascades, each of which includes a nozzle array consisting of identical apertures, and a substrate covered under it. solid nutrient medium. The diameter of the holes decreases from cascade to cascade so that microbial particles with a size smaller than in the previous cascade l are deposited on the surface of the nutrient medium when air is passed through the device with a certain flow rate.

However, in this device, it is very often observed that some stages of the device are overloaded, with the number of colonies growing at a hill, the colonies on the bottom (Petri dishes) are equal to the number of nozzles in the corresponding multi-nozzle grid. When overloading at least one cascade, the entire sample is considered lost. One of the main causes of overloads is due to the fact that the volume of air passed through all the steps is the same, and it is not possible to dose different volumes of air through each stage.

The more cascades, the more accurate information about the dispersed composition of suspended microbial particles can be obtained with its help. However, an increase in the number of cascades leads to a complication of the structure and its cost, to an increase in the internal volume, which reduces the upper limit of the change in the concentration of microbial particles.

In addition, when disassembling a used known device, an unanalyzed volume of air with microbial particles gets into the room of the microbiological box and contaminates it.

The closest technical solution to the invention is a device for microbiological analysis of air, comprising a housing with an opening for evacuating the analyzed air, a grating with nozzles placed in the housing, and a substrate with a nutrient medium located under it (2

The disadvantages of the known device are that it cannot measure the dispersed composition of microbial particles, as well as in the substrate overload with microbial particles, on which all particles with a diameter greater than, for example, 2 microns are deposited. Moreover, the higher the concentration of the analyzed particles, the greater the likelihood of the imposition of individual particles

each other, the lower the accuracy of the analysis.

The purpose of the invention is to make it possible to measure the size of microbial particles and to eliminate overload or substrate.

This goal is achieved by the fact that a device for microbiological analysis of air, including a housing with an opening for exhausting the analyzed air, a grating with nozzles placed in the housing, and a substrate with a nutrient medium located beneath it, is provided with an additional nozzle mounted below the grating with nozzles preliminary capture of the analyzed fraction of microbial particles, located in the housing with a disk for substrates installed with the possibility of its rotation for changing the last x, k air flow control mechanism, made in the form of a horizontally movable plate with critical nozzles, located under the hole for exhausting the analyzed air.

FIG. 1 schematically shows a device for microbiological analysis of air, a longitudinal section in FIG. 2 is a section A-A in FIG. 1 (substrate, mounted on the disk).

The device for microbiological analysis of air includes a housing 1, with an opening 2 for exhausting the test air,. placed in the lattice 3 with nozzles, mounted above the latter an additional nozzle 4 with the substrate 5 placed under it to preliminarily trap the analyzed fraction of microbial particles, a disk 6 for substrates 7 with a positive medium, mounted in the housing, mounted for rotation of the latter, and air flow control mechanism, made in the form of a movable, horizontally plate 8 with critical nozzles 9 of different diameters, located under the hole for removal of the analyzed air ear.

The disk b is mounted on the shaft 10, which is hermetically connected to the handle 11. The said disk has holes (12) for the passage of the analyzed air. Gaskets 13 are installed on the plate 8 around the critical nozzles 9. The plate 8 is provided with a handle for moving in a horizontal plane.

The proposed device works as follows.

Before the beginning of the air analysis, the grid 3 with nozzles is folded back and the prepared substrate 7 is placed on the disk b. Next,

using hands (7 webs 11, the disk b is turned to 72 and the next substrate 7 is installed, etc., until all the substrates are installed on the disk 6. Then the cradle 3 with the nozzles is lowered to its original position and secured.

To analyze large microbial particles (larger than 8 microns), the nozzle 4 with the substrate 5 is removed, and the movable plate 8 is installed (for example, in the first position, the critical nozzle 9 of which in this position provides a certain air flow (for example, 0.5 l / min) and hole 2 through a hose connects with a discharge source at a rate of, for example, 32 l / min.

Microbial particles weighed in the analyzed air, larger than 8 microns having passed through the grid 3 with nozzles, are deposited on the surface of the nutrient medium of the substrate 7. The analyzed air, free from microbial particles less than 8 microns, is removed through the critical nozzle 9. The sampling time (for each size fraction) is chosen so that the number of grown colonies of microbial particles on the surface of the nutrient medium of the substrate 7 is less than the number of nozzles in the grid 3. After the selection of large microbial particles, the plate 8 is transferred to the intermediate a position in which the opening 2 is completely closed and the air is stopped. When analyzing the size fraction, less than 8 µm, install the nozzle 4c with the substrate 5 and, rotating the handle 11, replace the spent substrate 7 with a New one. The movable plate 8 is installed in the second position, in which the air flow through the device is, for example, 2 l / min. With this air flow rate, particles larger than 8 microns, i.e., are deposited on the substrate 7. particles that are already. analyzed. Analyzed air.

free from particles less than 8 microns, passes through a grid 3 with nozzles, bends around the substrate 7 on which particles larger than 4 microns are deposited.

After selection of the dimensional (} from 8 to 4 µm subspecies plate 8 is transferred again to an intermediate position at which the opening 2 is completely blocked, the spent substrate 7 is replaced with a new one, and then the movable plate 8 is transferred

0 to the third position at which the air flow rate through the device is set to 8 l / min. At this flow rate, particles larger than 4 µm are deposited on the substrate 7, i.e.

5, the particles that have already been analyzed, and the particles from 4 µm to 2 µm, passed through the grate 3 with nozzles, are deposited on the substrate 7. To analyze the smallest particles, the sequence of operations is repeated.

After the completion of the sampling of the analyzed air, the spent substrate 7 is removed from the device and installed in a thermostat to form visible microbial colonies at the sites of microbial particle deposition. Know the size sampling time: particle fractions and air flow; through the device, the concentration of particles of each fraction is determined.

The presence in the proposed device of a single grating with 400 nozzles and 5 substrates, as well as an additional nozzle with a substrate that delays the analyzed fraction of microbial Chartz at each disk position, makes it possible to measure concentrations up to 10 ° part / m, while using the known devices to measure such high concentrations are not possible.

The choice of the minimum exposure (for example, 2 with the separation of one or another size fraction eliminates the substrate overload by microbial particles and improves the accuracy of the analysis.

FIG. 2

Claims (1)

DEVICE FOR MICROBIOLOGICAL ANALYSIS OF AIR, including a housing with an aperture for removal of the analyzed air, placed in the housing. A grid with nozzles and a substrate with a nutrient medium located under it. characterized in that, in order to ensure the possibility of measuring the size of microbial particles and to eliminate the overload of the substrate, it is equipped with an additional nozzle mounted above the grating with nozzles with a substrate placed under it for preliminary collection of the analyzed fraction of microbial particles located in the housing of the substrate disk, established with the possibility of its rotation to change the latter, and the control mechanism in the form of a hoist, a plate located water of the analyzed air flow rate, ypolpodvizhnoy on Horizons has critical nozzle hole under The relative S · 3S 'l > t. & £ ζΓμ ¹ GO GO ,. JV>