SU1575089A1 - Method of preparing trial gas mixtures - Google Patents

Abstract

The invention relates to the field of gas analysis - to methods of preparing calibration gas mixtures of known composition for calibration of gas analytical devices. The purpose of the invention is to simplify and reduce the preparation time while maintaining the dosing accuracy and life of the diffusion metering unit. The method consists in that a hermetically sealed vessel with a gas-permeable tube filled with a dosing gas is placed in a thermostatic device, blown by a stream of carrier gas in which the gas diffuses through the walls of the tube, and before sealing the vessel is filled with a chemically inert high molecular phase that does not diffuse through the walls of the tube, for example, silicone fluid. Saturate this liquid with a metered gas. 2 Il.

Description

With a pressure stabilizer 4 and a flow stabilizer 5, the flow rate of the carrier gas is measured with a rotameter 6.

FIG. 2 is a drawing of a diffusion dispenser consisting of a Glass ampoule 7 filled with phosgene saturated silicone fluid, permeable polyethylene pipe.

thermostating and maintaining consumption of the a-carrier gas.

The stability and reproducibility of gas dosing was checked at a constant temperature and flow rate of the carrier gas. The following materials were used as inert liquid for filling the dispensers: silicone liquid VZHK-94 and polyethylene

si 8, closed-plug 9 with otoysty-jQ Lenova IES-3, as dosed

to fill the dispenser with a screw 10.

The essence of the method is as follows.

TO

gas for obtaining gas mixtures with a given concentration used freon-12, phosgene. Control of the concentration of freon-12 in the gas mixture

The vessel with the saturated dosage liquid was gravimetrically. Stability

gas, hermetically sealed with a gas-permeable tube, which is closed with a plug made as a metal cylinder with an opening for filling the gas dispenser with gas 20; as it is exhausted. The diffusion dose-switch is placed in a mixing thermostat-controlled chamber, which is blown by a constant stream of carrier gas supplied from a balloon through stabilization, and is determined by chemical

analysis techniques. The stability and reproducibility of phosgene dosing was monitored by a gas analyzer at

phosgene Sirena-4. Accuracy prigotor consumption. The stability of the flow rate of the carrier gas is provided by a pressure stabilizer and is monitored with an exemplary manometer.

The method of dosing the microconcentration of gas mixtures of phosgene in the presence of gases is quite simple. The spirit of the proposed method in the interior, does not require complicated sealing equipment of the dispenser, does not require additional devices for liquefying gases, is very economical and especially suitable

35

tal 0.2-2 mg / m is + 4%,

An example, the proposed method for the preparation of gas mixtures is implemented in the Chemical Automation Design Bureau as follows. With the design documentation developed, three metering units were manufactured in which a glass vessel with gas-permeable pipes35

for dosing of toxic and corrosive gases. In addition, this method is more versatile than the known ones: as the dispenser is tested, the inert liquid modulated by polyethylene is 3/4 full, it can be re-saturated with the dispensed volume of polyethylene silicone fluid

An example, the proposed method for the preparation of gas mixtures is implemented in the Chemical Automation Design Bureau as follows. With the design documentation developed, three metering units were manufactured in which a glass vessel with a gas permeable pipe gas, which ensures a virtually unlimited service life of the dispenser and does not require its repeated individual calibration.

Filling a diffusion metering device with a chemically inert high molecular weight liquid saturated with a metered gas allows you to quickly and accurately determine the impurity concentration in the gas-air mixture by an independent gravimetric method: by the weight loss of the diffusion metering unit due to diffusion of pure gas into the flow for certain periods of time,

Thus the sample, the dosing error; gas consists only of the weighting error of the metering device

gas for obtaining gas mixtures with a given concentration used freon-12, phosgene. Monitoring the concentration of Chladone-12 in the gas mixture The reproducibility of dosing was monitored chromatographically using an electron capture detector. It was found that the accuracy of the preparation of Chladone-12 gas mixtures in the air by the proposed method is 4-5% in the concentration range 5-10 mg / m3.

The concentration of phosgene in the gas analysis smemetodiki. The stability and reproducibility of phosgene dosing was monitored by a gas analyzer at

phosgene Sirena-4. Error

- polyethylene silicone is filled with 3/4 volume polyethylene liquid

tal 0.2-2 mg / m is + 4%,

An example, the proposed method for the preparation of gas mixtures is implemented in the Chemical Automation Design Bureau as follows. In the course of the developed design documentation, three metering plants were manufactured in which a glass vessel with gas permeable pipes IDC-3 GOST 13004-67, weighed on an analytical balance, connected to a phosgene cylinder, filling them with PES-3 liquid. phosgene in a liquid. After saturation, the dispenser is sealed with a plug and placed in a thermostatted chamber blown by a gas flow of a gas. A nitrogen gas is used as a carrier gas, the flow rate is changed in the range of 100-200 l / min. The temperature in the mixing chamber is maintained

Constantly with an accuracy of + 0.2 ° C, the Carrier, has blown the metering device, is enriched in phosgene diffusing through the walls of the polyethylene tube, the concentration of phosgene in the gas mixture is determined

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Claims (1)

SUMMARY OF THE INVENTION A method for preparing calibration gas mixtures, namely, that a hermetically sealed vessel with a gas-permeable tube filled with a dosed gas is placed in a temperature-controlled device, purged with a carrier gas stream, in which gas diffuses through the walls of the tube, which differs by that, in order to simplify and shorten the cooking time while maintaining the accuracy of the dosage and the life of the diffusion dispenser, the vessel is filled with a chemically inert high-molecular phase before sealing d, which does not diffuse through the walls of the tube, for example, with a silicone fluid, and saturate this fluid with a metered gas.