Method for controlling concentration of test substance in under-suit space of chemical protective clothing

Abstract

FIELD: personal protective equipment.SUBSTANCE: use: for controlling the concentration of a test substance in the under-suit space of chemical protective clothing. The essence of the invention lies in placing measuring sensors in the under-suit space of the chemical protective clothing on a test subject, after which the test subject wearing the chemical protective clothing set is placed in a chamber filled with ethanol vapour, and then the concentration of ethanol vapour in the under-suit space of the chemical protective clothing worn by the test subject is monitored continuously in real time.EFFECT: ability to increase the industrial and environmental safety of controlling the concentration of a test substance in the under-suit space of chemical protective clothing.1 cl, 2 tbl

Description

[0001] Field of technology to which the invention relates

[0002] This invention relates to the field of research and analysis of the quality indicators of materials and articles of personal protective equipment (PPE) against chemical hazards. This invention can find application in military, chemical, medical, microbiological, and other industries where it is necessary to evaluate the tightness of personal protective equipment (PPE).

[0003] Technology Level

[0004] At present, the main indicators characterizing the protective properties of personal protective equipment against physiologically active substances (PAS) are: the protective action time of the package of materials from which it is made, as well as the tightness of the product as a whole.

[0005] The methodology for assessing the tightness of PPE from FAS consists of determining the amount of test substance (simulator or FAS) entering the under-suit space due to diffusion through a package of protective materials, as well as penetration in areas of design leakage, which is captured using indicator underwear, passive adsorption dosimeters or air sampling devices from the under-suit space of PPE.

[0006] In accordance with GOST B 21969-83, leak testing of personal protective equipment (PPE) is conducted using model gases of chlorine and sulfur dioxide. When these gases enter the undersuit during the tester's simulation of typical physical exercises in a test chamber, they cause a color change in the indicator garment. Determining the amount of test substance that has penetrated the undersuit space of the PPE involves experts visually comparing the color of the indicator garment after testing with pre-prepared standards.

[0007] The main disadvantage of using chlorine and sulfur dioxide as test substances is their toxicity (chlorine - hazard class 2, sulfur dioxide - hazard class 3), which entails the possibility of harm to the life and health of persons involved in the tests, and also implies the use of PPE and special equipment, high requirements for the tightness of the test chamber and the presence of supply and exhaust ventilation.

[0008] A method for studying the protective properties of personal protective equipment is known, where benzene is used as a test substance. ("Setup for studying the protective properties of a set of personal protective equipment", patent No. 2153658 C1: IPC G01M 3 / 20 -2000).

[0009] Another disadvantage of using benzene as a test substance is its toxicity (hazard class 2), due to its carcinogenic effect.

[0010] The closest in technical essence and achieved positive effect and adopted by the authors as a prototype is the method for assessing the tightness of PPE kits (“Method for determining the tightness of personal protective equipment kits as a whole under simultaneous exposure to an aerosol and vapor of physiologically active substances”, patent RU 2425347 C1: IPC G01M 3 / 00 - 2011), in which chlorine (vapor phase of FAS) and standard oil mist (SOM), having a particle dispersion of 0.2-0.3 μm (aerosol phase) are used as test substances.

[0011] The disadvantage of the closest analogue is the use of chlorine (hazard class 2) as one of the test substances.

[0012] In view of the above, a search was conducted for low-toxicity chemical compounds suitable for conducting studies of the tightness of personal protective equipment and capable of indication by qualitative and quantitative analysis methods.

[0013] As a result of theoretical and experimental studies, it was found that ethanol meets the specified requirements.

[0014] Table 1 presents comparative data on the hazard classes of substances used to assess the tightness of personal protective equipment.

[0015]

[0016] It's worth noting that the lower flammability limit of ethanol vapor is 3.28% or 62.8 mg / L, and the upper flammability limit is 19% or 364 mg / L. Therefore, a gas-air mixture of ethanol vapor in this concentration range will be explosive. However, the methodology for testing the tightness of the SIZK does not require the use of these concentrations.

[0017] The technical result of the claimed invention consists in increasing the industrial and environmental safety of the process of assessing the tightness of sanitary protective equipment by using ethanol as a test substance simulating the vapor phase of the FAS.

[0018] The essence of the claimed invention consists in measuring the concentration of ethanol vapors in the under-suit space of the personal protective equipment and the test chamber by the method of electrochemical analysis using a concentration control system (CCS) consisting of a microcontroller with a wireless data transmission module, a power source, connecting wires and a set of sensors based on electrochemical sensors (ECS).

[0019] The range of measurement of ethanol vapor concentrations by the used EHS is from 0.05 mg / l to 10 mg / l, which allows for the assessment of the protective properties of personal protective equipment in accordance with the requirements of regulatory documents.

[0020] An example of a specific implementation of the proposed invention

[0021] During the first stage of the research, the SCC sensors were calibrated using ethanol vapor. Throughout the experiments, the SCC measuring sensors were kept in a sealed box with a volume of 150 dm3. 3, and new technical control equipment was installed for each experiment.

[0022] Sampling and analysis were carried out in accordance with MUK 4.1.3170-14.

[0023] Air at a speed of 0.5 dm 3 / min was aspirated through two series-connected absorption devices with porous plates containing 5 cm 3 distilled water each, for 25 minutes. The volume of air sampled was 12.5 dm3 3 In each experiment, two samples were collected simultaneously.

[0024] The absorption devices were cooled with a mixture of ice and water at a temperature of 4°C.

[0025] After sampling, the ends of the absorption devices were fixed with glass plugs.

[0026] When sampling, the ambient temperature and pressure were recorded.

[0027] Determination of ethanol concentrations collected from the test box into absorption solutions was carried out by capillary gas chromatography using flame ionization detectors (GC-FID).

[0028] To establish the calibration characteristics, the absolute calibration method was used, which relates the peak area on the chromatogram, obtained as a result of dosing the equilibrium vapor of ethanol into the chromatograph, with its concentration in the analyzed aqueous solution.

[0029] The ethanol vapor concentrations in the cabinet were created using bubbling (passing a controlled air flow through an ethanol solution of known concentration). To create low concentrations (up to 1 mg / L), a 10% ethanol solution was used. To create concentrations from 1 mg / L to 10 mg / L, a 70% ethanol solution was used (due to the optimal bubbling time). The bubbling time for obtaining concentrations in the studied range was determined by calculation using a formula derived from Henry's law and Raoult's law, which has the final form:

[0030]

[0031] where:

[0032] t - operating time of the bubbling unit, sec;

[0033] R - universal gas constant;

[0034] T - temperature, K;

[0035] V - volume, l;

[0036] C камера - concentration created in the chamber, mg / l;

[0037] x этанол- molar fraction of ethanol in the liquid;

[0038] P° этанол - pressure of saturated vapors of ethanol at a given temperature (tabular value), atm;

[0039] M - molecular weight of ethanol, g / mol;

[0040] Q - air flow rate passed through the ethanol solution, l / min.

[0041] After each generation of ethanol vapor, the box was stirred with a fan for one minute.

[0042] Simultaneously with the start of ethanol vapor sampling, the readings from the SCC measuring sensors were recorded in ADC counts for one minute. The sensor sampling frequency was set to 1 Hz (one measurement per second). The arithmetic mean of each sensor reading was then calculated, which was subsequently taken as the ethanol vapor concentration determined by the GC-FID method.

[0043] Based on the measurement results, a calibration graph of the dependence of sensor signals on the concentration of ethanol vapors was constructed and the linear regression data was approximated.

[0044] After each experiment, the box was ventilated until it was completely clear (at least 5 minutes).

[0045] To control the air purity in the box, a sample was taken before generating ethanol vapor.

[0046] In the second stage of work in a test chamber with a volume of 6.8 m 3 SCC #2 was installed with three calibrated measuring sensors located at different heights. An ethanol vapor concentration of 3±0.1 mg / L was then generated. Concentrations in the chamber were monitored continuously.

[0047] When the concentration in the test chamber reached 10% higher than the value specified by the test conditions, the generation of ethanol vapor stopped and the tester entered the chamber wearing respiratory and skin PPE.

[0048] The test subject's personal protective equipment (PPE) contained SCC #1, with ten measuring sensors positioned at the most likely locations for test substance penetration. The test subject performed a set of standard physical exercises for 10 minutes.

[0049] The concentration of ethanol in the under-suit space of the personal protective equipment worn by the test subject was monitored continuously in real time.

[0050] Data from the measuring sensors of the SCC were displayed on the control panel for collecting, processing and storing information.

[0051] Next, using formula (2), the partial coefficients of suction of the test substance into the under-suit space of the personal protective equipment in the area of ​​the i-sensor were determined.

[0052]

[0053] where

[0054] K под_i - coefficient of test substance suction into the under-suit space of the personal protective equipment, %;

[0055] C подг_i - concentration of the test substance determined on the i-sensor, mg / l;

[0056] C возд- concentration of test substance in the test chamber, mg / l.

[0057] The technical result obtained during the tests is shown in Table 2.

[0058]

[0059] The data obtained during the study indicate that the use of ethanol as a test substance simulating the vapor phase of a pharma-active substance allows for an assessment of the tightness of the PPE design.

[0060] Based on the data presented in the table, it can be concluded that the values ​​of the suction coefficients determined for ethanol vapors and for chlorine (GOST B 21969-83) have close values, which indicates a high convergence of the results.

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