JPH05126811A - Gas chromatograph - Google Patents

Abstract

PURPOSE:To omit the requirement for securing the setting space for a measuring tube around a sampling valve and to make it possible to reduce the cost by fixing the measuring tube in a groove provided in the sampling valve. CONSTITUTION:In a sampling valve 3, a sample-gas flow path and a carrier-gas flow path are switched with plungers 34A and 34B, which are arranged at both surfaces of a center plate 30, so as to a face to each other through a diaphragms 31 and 32. A measuring tube 1 is arranged in the sampling valve 3. Both ends of the tube are alternately connected to the sample-gas flow path and the carrier-gas flow path. A groove having the U-shaped cross section is provided in the surface of the cylinder of the sampling valve 3. The measuring tube 1 is contained and fixed in the groove 51. The groove 51 provided in the surface of the cylinder forms the containing part of the measuring tube 1. The attaching space of the measuring tube when the tube is externally attached to the sampling valve is not required.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas chromatograph suitable for high speed measurement in a process.

[0002]

2. Description of the Related Art A process gas chromatograph holds a sample gas and separates the gas components by passing the sample gas through a plurality of columns with a carrier gas to a detector to separate the separated gas components. Is measured, and as a cleaning for the next sampling, a series of operations of flushing the pipeline and the column with a carrier gas is automatically repeated according to the sequence. In order to improve the response speed, it is necessary to send a small amount of sample gas at high speed,
Therefore, it is desirable that the diameters of the flow paths such as the sample valve and the measuring pipe are small, and the sample valve is also small and has a small internal volume. Therefore, a pneumatically driven diaphragm valve is generally used as a sample valve of this type of gas chromatograph for a process, and a measuring pipe 1 is connected and fixed to the outer side thereof through a fitting 2 as shown in FIG. It was In addition, 3 is a sample valve.

[0003]

However, in the above-mentioned conventional gas chromatograph, since the measuring pipe 1 is externally attached to the sample valve 3 via the fitting 2, a space for the measuring pipe 1 is required. Also, since the two fittings 2 are connected, the number of parts increases correspondingly, which causes a problem of cost increase.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and it is an object of the present invention that there is no need to secure an installation space for the measuring tube around the sample valve. Another object is to provide a gas chromatograph that enables cost reduction.

[0005]

In order to achieve the above-mentioned object, the present invention provides a sample valve for switching between a sample gas flow path and a carrier gas flow path by means of plungers arranged oppositely on both sides of a center plate with a diaphragm interposed therebetween. The sample valve is provided with a metering tube whose both ends are alternately connected to the sample gas channel and the carrier gas channel, and a groove having a U-shaped cross section is provided on the cylinder surface of the sample valve. The measuring pipe is housed and fixed in.

[0006]

The groove provided on the surface of the cylinder forms a storage portion for the measuring pipe, and eliminates the need for a space for mounting the measuring pipe when externally attached to the sample valve.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the drawings. FIG. 1 is a schematic configuration diagram of a gas chromatograph according to the present invention. First, the schematic configuration of the gas chromatograph will be described. 11 is the analyzer body, 12 is a power supply,
Reference numeral 13 is a controller. The analyzer main body 11 is composed of a constant temperature bath 14 which is heated and held at a predetermined temperature (about 60 ° C. to 120 ° C.), a heater 15, an amplifier 16, a constant temperature bath temperature control device 17, a pressure reducing valve 18, and the like. Inside the constant temperature bath 14, a measuring tube 1, a sample valve 3, a column 19, and a detector 20 are arranged. Then, the analyzer main body 11 is housed in the internal pressure explosion-proof container 21 to be an explosion-proof type. During non-measurement, the flow path of the sample valve 3 is maintained in a state of a solid line so that the carrier gas CG made of an inert gas such as helium supplied from the first carrier gas inlet 23 passes through the column 19 and the detector. 20 while the sample gas SG introduced from the sample gas introduction port 24 is passed through the measuring pipe 1 and the vent port 25.
More discarded. When the flow path of the sample valve 3 is switched from the state of the solid line to the state of the broken line in the measurement, the sample gas SG collected by the measuring pipe 1 is introduced into the column 19 by the carrier gas CG introduced from the second carrier gas introduction port 26. Sent in. Although different depending on the sample gas SG, the column 19 is packed with powder having a uniform particle size such as activated carbon, activated alumina, and molecular sieve as a stationary phase. The stationary phase and each gas component in the sample gas SG are packed with each other. The gas components are separated from each other by utilizing the difference in the moving speed based on the difference in the adsorptivity and the distribution coefficient, and this is detected by a detector 20 such as a thermal conductivity detector or a hydrogen flame ionization detector to obtain an electric signal. Convert. The electric signal is proportional to the gas component concentration, and the controller 13 performs waveform processing to monitor or record the process steps.

Next, the mounting structure of the measuring pipe will be described in detail with reference to FIGS. 2 is a sectional view of the sample valve, FIG.
Is a bottom view of the valve, and FIG. 4 is a sectional view taken along line IV-IV of FIG. The sample gas flow path formed inside and the carrier gas flow path (flow paths a to f shown by the solid line and the dotted line in FIG. 1) are switched, the sample gas SG is guided to the detector 20 during measurement, and the carrier gas is flowed during non-measurement. As the sample valve 3 for guiding the gas CG to the detector 20, a conventionally known pneumatically driven diaphragm valve is used. The sample valve 3 includes a center plate 30 and a center plate 3
A plurality of plungers 34A and 34B, which are arranged to face each other on the front and back surfaces of 0 through the diaphragms 31 and 32,
The lower plunger plates 35, 36 and the plunger 3 support the plungers 34A, 34B in a slidable manner.
4A and 34B are alternately operated, and lower piston 37,
38, the return spring 39 for the pistons 37, 38, and the plungers 34A, 34B, the plunger plates 35, 3 which are arranged to face each other with the center plate 30 in between.
6, the pistons 37 and 38, the return spring 39 and the like are housed, and the lower cylinders 40 and 41 and the like are provided. A plurality of concentric fluid passages (a to f) are formed on the front and back surfaces of the center plate 30, and the plungers 34A and 34B are arranged corresponding to these fluid passages. .. The upper and lower diaphragms 31, 32 are elastically deformed alternately by the gas pressures of the sample gas SG and the carrier gas CG supplied to the sample valve 3, and the plungers 34A, 34B are operated by the pistons 37, 38 to alternate between the diaphragms 31, 32. By pressing against, the upper route and the lower route of the fluid passages a to f are alternately switched. In other words, this sample valve 3
Is a system in which the diaphragm on the plunger OFF side is elastically deformed by the gas pressure to switch between the lower route and the upper route of the fluid passages a to f so that the fluid flows.
The column 19 is arranged around the sample valve 3.

A column 19 is provided inside the lower cylinder 41.
Is incorporated with a heater 50 for heating and keeping the same at a constant temperature, and a groove 51 for housing and fixing the measuring pipe 1 is formed on the lower surface as shown in FIG. Groove 51 is for lower cylinder 4
Two vertical holes 51a, 51b penetrating the upper and lower surfaces of the first cylinder 1 and two vertical holes 51a, 51b formed on the lower surface of the lower cylinder 41.
and a communication groove 51c that communicates the lower end opening of b with a U-shaped cross section, and the upper end openings of the vertical holes 51a and 51b are respectively connected to one end of the fluid passages c and d (FIG. 1). It is connected. The measuring pipe 1 has a length of 60 mm,
It is formed by bending a thin tube with an outer diameter of about 1.6 mm and an inner diameter of about 0.8 mm into a U-shape. Both ends are inserted and fixed in the vertical holes 51a and 51b via the bush 52, and the central portion is 1
It is fixed to the groove bottom surface of the communication groove 51c by one set screw 55. Therefore, the measuring pipe 1 is connected to the sample valve 3
It does not project to the outside of the column and facilitates the assembly of the column 19. The set screw 55 preferably has a large head outer diameter, and the measuring pipe 1 is pressed and fixed by a part of the lower surface of the head.

[0010]

As described above, according to the gas chromatograph of the present invention, since the measuring tube is housed and fixed in the groove provided in the sample valve, a space for installing the measuring tube is secured around the sample valve. It is possible to effectively use the space in the constant temperature bath without the need to do so, and it is possible to downsize the device itself.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a gas chromatograph according to the present invention.

FIG. 2 is a sectional view of a sample valve.

FIG. 3 is a bottom view of the sample valve.

4 is a sectional view taken along line IV-IV of FIG.

FIG. 5 is a view showing a conventional measuring tube and a sample valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Measuring pipe 3 Sample valve 19 Column 20 Detector 30 Center plate 31, 32 Diaphragm 34A, 34B Plunger 40, 41 Cylinder 51 Groove af Fluid flow path

Claims (1)

[Claims] 1. A sample valve for switching between a sample gas flow channel and a carrier gas flow channel by plungers arranged opposite to each other on both sides of a center plate via a diaphragm,
The sample valve is provided with both ends of the metering pipe which are alternately connected to the sample gas channel and the carrier gas channel, and a groove having a U-shaped cross section is provided on the cylinder surface of the sample valve. A gas chromatograph characterized in that the measuring pipe is housed and fixed in a groove.