RU2735135C1 - Constant pressure sampler - Google Patents

Abstract

FIELD: aviation; astronautics.

SUBSTANCE: invention can be used for measurement of percentage composition of different gaseous media used in testing of aircraft and space equipment serviceability. Constant pressure sampler consists of cylindrical housing with flanges sealing it along ends, housing is divided into two volumes for placement of sample of gas medium and working gas, housing is equipped with pressure measuring devices and locking valves, in housing there are two resilient gas-impermeable partitions of same size, one partition divides housing into two equal sealed volumes - upper and lower, and second partition wall is tightly fixed under upper flange of housing, both partitions are interconnected rigidly with rod, and on upper protruding part of stock, fixed by locking nut, graduated scale is installed, upper and lower volumes of cylindrical housing are connected by pipelines with shutoff valves to vacuum pump and vessel with analysed gas medium, at that lower part of housing is connected via pipeline via shutoff valve to gas chromatograph.

EFFECT: technical result is simplification of design and provision of independent automatic support of constant pressure at supply of gas medium sample for analysis into gas chromatograph.

1 cl, 1 dwg

Description

The constant pressure sampler belongs to the field of mechanical engineering and can be used in the conditions of research and plant laboratories to measure the percentage composition of various gaseous media used in testing the performance of aviation and space technology.

The closest to the proposed sampler is an industrial constant pressure sampler of the PPD-0.150 type, which is a cylindrical chamber with a piston and end flanges. To separate the analyzed gas mixture, a piston is installed in the working part of the chamber and the inert gas. In each chamber of both working and inert gases, pressure measuring instruments, manometers and shut-off valves are installed. By supplying the required amount of working gas (helium or nitrogen) through the reducer, a constant pressure in the sampler is maintained.

The disadvantage of this sampler is the need for an external source of inert working gas regulating the pressure and the absence of an automatic system for maintaining a constant pressure of the gas medium when it is fed to the gas chromatograph for analysis.

The purpose of the invention is to simplify the design and provide autonomous automatic maintenance of constant pressure when supplying a sample of a gaseous medium for analysis to a gas chromatograph.

The technical problem posed is solved by the fact that the constant pressure sampler consists of a cylindrical body with flanges sealing it at the ends, the body is divided into two volumes for accommodating a sample of the gaseous medium and the working gas, the body is equipped with pressure measuring instruments and locking valves, and are installed in the sampler body. two elastic gas-tight partitions of the same size, one partition divides the body into two equal sealed volumes, upper and lower, and the second partition is hermetically fixed under the upper flange of the body, both partitions are rigidly connected to each other by a rod, and on the upper protruding part of the rod, fixed with a lock nut, is installed graduated scale, while the upper and lower volumes of the cylindrical body are connected by pipelines with shut-off valves with a vacuum pump and a container with the analyzed gas medium, while the lower part of the body is connected by a pipeline through a shut-off valve with a gas chromatograph m.

The proposed constant pressure sampler is shown in the drawing.

1 - cylindrical body

2, 3 - flanges

4 - lower elastic gas-tight partition

5 - lower volume

6 - upper volume

7 - upper elastic gas-tight partition

8 - stock

9 - lock nut

10 - guide sleeve for stem

11, 16, 19 - connecting pipelines

12, 13, 14, 17, 20 - shut-off valves

15 - vacuum pump

18 - container with the investigated gaseous medium

21 - gas chromatograph

22, 23 - manovacuum meters

24 - graduated scale

The constant pressure sampler consists of a cylindrical body 1, sealed at the ends by flanges 2 and 3, and is hermetically divided by a lower elastic gas-tight partition 4 into two equal sealed volumes, lower 5 and upper 6. Under the upper flange 2 of housing 1, an upper elastic gas-tight partition 7 is hermetically installed of the same size with partition 4 and is rigidly fastened to it by a rod 8, fixed to the upper flange 2 by a lock nut 9. Inside the upper volume 6 of the housing 1, a centering guide sleeve 10 for the rod 8 is installed, and a graduated scale 24 is installed on the upper protruding part of the rod 8. the volume 6 and the lower volume 5 of the housing 1 are connected by a pipeline 11 through shut-off valves 12, 13, 14, with a vacuum pump 15 and a pipeline 16 through a shut-off valve 17 with a container 18 containing a test gas medium under excess pressure. In this case, the lower volume 5 is connected by a pipeline 19 through a shut-off valve 20 with a gas chromatograph 21.

On the pipelines between the shut-off valves 12 and 13 and the upper 6 and lower 5 volumes, pressure gauges 22 and 23 are installed to control the pressure in them.

The constant pressure sampler works as follows.

When the shut-off valves 12, 13, 14 are open, air is simultaneously evacuated by a vacuum pump 15 through the connecting pipeline 11 from the upper 6 and lower 5 volumes. When the required vacuum value (≈1 mm Hg) is reached, valve 14 closes and valve 17 opens, and the gas medium from tank 18 through pipelines 16.11 fills equal volumes 5 and 6 to a given value of working pressure (≈1.2 atm .). In this case, the measurement and control of the magnitude of the vacuum and pressure in volumes 5 and 6 is carried out using manovacuum meters 22, 23. Before supplying the gaseous medium for analysis, elastic gas-tight partitions 4, 7 are in a horizontal position. Removing the lock nut 9 frees the stem 8 from the connection with the upper flange 2 of the body 1.

With the valve 20 open, through the pipeline 19, the gaseous medium, which is under excess pressure, enters from the lower volume 5 into the gas chromatograph 21, which measures its percentage.

When taking a sample, the deformation (bending) of the elastic partitions 4, 7 due to their rigid connection by the rod 8 with the centering guide sleeve 10 holding the rod will be carried out by the same amount, while the volume of the gas medium between the partitions 4, 7 and, consequently, the pressure in it will remain unchanged, equal to the original. Consequently, the source of constant pressure when taking a sample for analysis will be a gaseous medium, which is in a constant volume at constant pressure, between the walls of the housing 1 and elastic partitions 4, 7. With this mechanism, in the process of supplying a sample to the gas chromatograph, autonomous automatic maintenance will be carried out the pressure in the upper chamber is at a constant level. The number of samples taken for analysis during one filling of the sampler will be determined by the position in the housing of the lower elastic partition 4, which is visually fixed according to the graduated scale 24 installed on the upper protruding part of the stem 8.

This invention can be used with the greatest effect for accurate measurement of the percentage composition of the analyzed gaseous media used in testing the performance of aircraft and space technology products, in conditions without the use of an external source of creating a constant pressure of the working inert gas, while providing autonomous automatic maintenance of constant pressure during the passage of the sample gas through a gas chromatograph.

Claims (1)

A constant pressure sampler, consisting of a cylindrical body with flanges sealing it at the ends, the body is divided into two volumes for accommodating a sample of a gaseous medium and a working gas, the body is equipped with pressure measuring instruments and shut-off valves, it differs in that the body has two elastic gas-tight partitions of the same size, one baffle divides the body into two equal sealed volumes - upper and lower, and the second baffle is hermetically fixed under the upper flange of the body, both baffles are rigidly connected to each other by a stem, and a graduated scale is installed on the upper protruding part of the stem, secured by a lock nut, the upper and lower volumes of the cylindrical body are connected by pipelines with shut-off valves with a vacuum pump and a container with the analyzed gas medium, while the lower part of the body is connected by a pipeline through a shut-off valve with a gas chromatograph.

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