SU1599716A1 - Method of determining counter concentration of aerosols - Google Patents

Abstract

The invention relates to the development of methods for determining the countable concentration of particles in aero dispersion systems and can be used to control the level of dispersed soils in radio electronics, biotechnology, pharmacology and ecology. The aim of the invention is to increase the sensitivity of determining the concentration of aerosols. The method is based on mixing the analyzed aerosol stream and a carrier gas containing the gaseous product of a natural radioactive series, for example, ²² ° RN in the volume of the settling chamber. The nonvolatile daughter products of radioactive transformations — ²¹⁶ PO, ²¹⁶ PB, and ²¹² BI, used as a tracer, are sorbed on the surface of aerosols, which are collected on the surface of the collector. The product of the tracer concentration, the diffusion deposition time of the radioatom should be constant. The desired aerosol concentration is determined from the α-activity of the sediment collected on the collector using a linear calibration graph linking the sediment activity with the concentration of aerosols obtained using standard aerosol systems. 2 Il.

Description

The invention relates to the measurement of parameters of dispersed systems, in particular, to methods for determining the countable concentration of particles in aerodisperse systems, and can be used in aerosol technology, for example, to monitor performance, aerosol generators, industry, biotechnology and pharmacology to determine aerosol particles, as well as in environmental management to control

the level of dispersed man-made pollution.

The aim of the invention is to increase the sensitivity of determining the concentration of aerosols.

Figure 1 is a schematic diagram of the installation for the implementation of the proposed method; figure 2 - calibration dependence of the number of aerosol particles Cj, selected at the collector, on alpha activity

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afroMOB daughter radioisotopes of radio-N (ci6) deposited on aerosol particles. The installation includes a TLig.1 point-Hfri K 5 and 1 „2 with compressed gas, air vents 2.1 –2-2, and flow meters 3.1–3.3 ; 4 aerosol generator; 5 sodium chloride crystals; upper and lower furnaces 6 and 7; contour 8 dilution of aerosols; filter 9 E | shingles; teflon capillary p 10; There is a P emanator; ampoule 12 with emanat torus; fiber filter 13; Troy Yik 14; chamber 15 - sump; collector 16 radioactive aerosols.

The method is carried out as follows.

. Through-heated ampoule 12 with an emanator containing the radioactive element of the natural radioactive 7 7 A

for example, Th (T, 1.9 years) is a member of the tori family.

or

 227

Ac (T, / 2. 22 years) - member

216

Ro

156

2a

Pb

T, 1 g 0.15 s

After deceleration in the chamber volume, radioactive atoms Po, Pb and Bi by the diffusion mechanism for a fixed time t with a definite efficiency are deposited on the surface of aerosol particles. Further, the aerosol with the tracer is brought to the collector 16, for example, a fiber filter, and is deposited. At the same time, at a fixed time of diffusion deposition of radioactive atoms on particles t and a constant concentration of the ST-P tracer, the radioactivity of sediment collected on the filter 9 is determined by the concentration of aerosol particles. Ensuring the constancy of the Ci-p-t value determines the possibility of a transition from the radioactivity of the sediment at the collector to the concentration of aerosol according to the calibration schedule obtained using standard aerodisperse systems. The C-pp-t parameter determines the amount of background radioactivity at the collector and is chosen to be minimal, since the background determines the lower limit of the recorded concentrations of aerosols.

252

Example. In order to transfer the nuclei No, 02 formed by the nuclear reaction Sy ,, 5n), from the irradiation zone to the recording equipment 1, the instrumentation and actin are allowed to pass a stream of carrier gas, for example N, Ar or air, and the gaseous product is displaced from it radioactive transformation. In the first case it is 55.6 s), and in the second - (T, / 2. 3.9 s). By stabilizing the temperature of the ampoule and volume

the carrier gas flow rate in the rhodon gas is maintained at a constant concentration of rhodon and, accordingly, the radioactivity A. The mixture of radon and the carrier gas is passed through a filter 13,

5 is shifted in the tee 14 with the aerosol jet being analyzed and the resulting gas flow is directed to a special chamber 15. The ratio between the chamber volume and the volumetric flow rate for the carrier must be sufficient for the accumulation of daughter nonvolatile radioactive products (tracer) in the chamber these are members of p yes:

five .

1g

0

five

0

45

50

55

. ,four%)

 10.6 h T (/ 60.4 t-shnary aerosol is used on the struts. The aerosol generator 4 is a two-section, ion quartz column. (FIG.) Heated by two furnaces 6 and 7 to 780 and 740 ° C. NaCl crystals with sizes 1.2–1.8 mm are placed at the top of the generator, and a carrier gas (argon) is continuously passed through the generator at a flow rate of 1 l / min. At the output of the generator, the concentration of particles 0.1-0.2 µm in size about 5-10 cm. The aerosol stream is then passed through a probe — a chamber in which the hot products of nuclear reactions are inhibited, and after cooling down they are sorbed on aerosol and neperfo-particles with a vehicle in the recorder (its device.

Throughout the experiment (with a duration of up to 2 days), the transfer efficiency should be constant, which can be ensured by maintaining the concentration of aerosols at the same level. The concentration of aerosols is monitored periodically using the apparatus shown in FIG. 1,

As an emanating source, ThOj is used, which is placed at 12. During the measurement, the ampoule is heated by a furnace 11 to 150 ° C, passed through more purified argon with

a flow rate of 50 cm is mixed with the aerosol stream, and the mixture of gases is directed to the chamber 15 with a volume of 10 liters. To reduce the level of aerosol concentration, a dilution circuit 8 is used with a dilution factor K 510. Radioactive - aerosols are collected (on an AFA-PCM fiber filter (collector 16); for 15 minutes - in idle mode (to establish equilibrium in the system), and after changing the filter - for 20 minutes - in working mode. After the collection of aerosols O-activity of the drug is measured (on the 2nd filter) and according to the previously plotted graph (FIG. 2), the C, f (No () dependencies find the Cj value, and the desired concentration C is determined by the formula: С К-С;, Иде К tangent of the straight line angle in Fig. 2. For 2 days the generator performance remained at the level ( 3.75-fO, 35) 10 cm The deviation from the average value does not exceed 10%. Consequently, the fluctuations in the efficiency of nuclear reaction do not exceed this value.

To determine the concentration of aerosols in an aerosol stream purified using a fiber filter (diameter 25 mm) of the FPPS type, gas (flow rate 1 l / min) is mixed with the gas flow (flow rate 50), containing and fed to chamber 15; The idling is conducted for 15 minutes, and then an aerosol fraction is collected on an AFA-PCM fiber filter for 20 minutes (collector 16} and measured on an o-meter counter.

Measurement results: installation background 5.0 imp min; sample 7.4 and 6.6 imp min; activity on the substrate 2.4 and 1.6 imp-min; slope of C; f (Nn /) (Fig. 2) is described by the equation Direct C, 4.66-10 Nj from here CJj 1.1 10 C i, 0.75-10 cm -; C, - (0.92 ± 0.18) to

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Claims (1)

Invention Formula The method for determining the aerosol counting concentration, which includes passing a stream of aerosol particles through the chamber with a tracer, selecting aerosol particles after the chamber at the collector, and then measuring the resulting impulse from the collector due to the fact that, in order to increase the sensitivity of the calculated aerosol concentration, radioactive isotopes of nonvolatile elements formed during the decay of gaseous short-lived radioisogonon radon5 which introduced into the chamber simultaneously with the aerosol stream, ps: keep the tracer constant parameter of the aerosol, defined as the product of the tracer concentration and the time of diffusion deposition of the atoms of daughter radioisotopes on the surface of the particles, are passed through the collector through the fixed flow volume of aerosols and the tracer and according to the linear calibration dependence of the amount of aerosol particles on the alpha activity of the atoms of the daughter radioisotopes on the collector, the countable concentration of aerosols is judged. PU "./ . 200 2 10 310 lO Na.MUH-fus. g