JPH0612958U - Gas chromatograph - Google Patents

Abstract

(57) [Summary] [Purpose] Prevents dew condensation due to sudden temperature changes and makes it easier to read the display value on the display board. A front opening of a cylindrical case 1 for accommodating electric equipment members such as a printed circuit board 2, a decorative board (display board) 8 and a connector 10 is hermetically closed by a lid 6 having a glass plate 13. Inside the glass plate 13, a transparent resin plate 40 having a smaller thermal conductivity than that is arranged.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a gas chromatograph that performs gas analysis by utilizing the difference in adsorptivity between a packing material packed as a stationary phase in a column and a measurement gas, and particularly relates to a gas chromatograph designed to prevent dew condensation at an opening. Is.

[0002]

[Prior art]

 Gas chromatographs have been commonly used as detectors for analyzing the components of process gases in petrochemical processes, steel processes, etc., and monitoring each process step and performing various controls based on the analysis results. . In this type of industrial gas chromatograph, a sample gas is continuously sampled from a process line to be measured by a sampling device and fed into a column by a carrier gas, and each gas component is separated into a stationary phase in this column. Separation is performed using the difference in the moving speed based on the difference in the component's adsorptiveness (affinity) and the partition coefficient, the detection is performed by the detector, the electric signal is processed by the controller, and the process is performed based on this. It is configured to control and print out the chromatogram waveform.

FIG. 5 and FIG. 6 show a conventional example showing the structure of an electric equipment part for accommodating electric equipment members such as a printed circuit board, a display board and a connector in a small process gas chromatograph. This is a cylindrical case connected and fixed to a main body case (not shown) of the tograph. The cylindrical case 1 is made of a metal such as an aluminum alloy and has a plurality of, for example, three printed circuit boards 2 as electric device members inside. Is held and arranged by a pair of upper and lower board fixing brackets 3 and 4, and a lid 6 is attached to the opening 5 on the case side opposite to the main body to hermetically close the cylindrical case 1. Retaining grooves 7 for retaining the upper and lower ends of each printed circuit board 2 are formed on the surfaces of the board fixing brackets 3 and 4 facing each other at a predetermined interval in the longitudinal direction. Further, a decorative plate 8 is screwed and fixed to the end portions of the board fixing brackets 3 and 4 on the side of the lid body 6 via grounding metal fittings 9.

A connector 10 is attached to the innermost printed circuit board 3 among the three printed circuit boards 3, and the connector 10 accommodates the printed circuit board 3 in the cylindrical case 1 together with the board fixing brackets 3 and 4. Then, it is connected to the main body side connector 11 arranged in the case 1.

The lid 6 is made of a metal such as aluminum alloy, and an opening 12 is provided in the center of the front surface. The opening 12 is hermetically closed by a glass plate 13 arranged in the lid 6. ing. On the outer peripheral surface of the lid body 6, a male screw portion 15 that is screwed into a female screw portion 14 formed on the inner peripheral surface of the opening end portion of the cylindrical case 1 is formed.

As shown in FIG. 7, the decorative plate 8 serves as a display plate by including a liquid crystal display device 16 and a light emitting diode 17, and the order of the component gases to be measured and the measured values (analytical values). ), Component ratio, carrier gas pressure, temperature of constant temperature bath, remaining time of measurement time, etc. can be selectively displayed as needed, and the displayed value can be visually confirmed from the outside through the glass plate 13 of the lid 6. You can do it. Further, since the decorative plate 8 is formed of a metal plate, the electrical circuit of the printed board 3 malfunctions or fails due to electrical noise that enters the cylindrical case 1 through the opening 12 through the glass plate 13. It functions as an electromagnetic shielding plate for preventing electric shock and is electrically connected to the grounding fitting 9. The tip of the grounding metal 9 is in contact with the inner peripheral surface of the lid 6, and electromagnetic noise from the outside that hits the decorative plate 8 is guided to the cylindrical case 1-main body case via the lid 6. I am trying. The body case is grounded.

[0007]

[Problems to be solved by the device]

 However, in the structure of the electric equipment in the conventional small process gas chromatograph described above, the water contained in the air in the cylindrical case 1 becomes supersaturated due to the rapid decrease in the ambient temperature. If dew condensation forms water drops and adheres to the inner surface of the glass plate 13, there is a problem that the display value on the decorative plate 8 cannot be read. This was especially noticeable when there was a temperature change during the day and night under high humidity conditions. Therefore, it is required to take some measures against dew condensation on the cylindrical case.

The present invention has been made in view of the above-mentioned problems and demands of the related art, and an object of the present invention is to prevent dew condensation due to a rapid temperature change with a simple structure, An object of the present invention is to provide a gas chromatograph capable of easily reading the display plate.

[0009]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention provides a main body case containing a column, a valve, a detector, a pressure reducing valve, etc., and a cylindrical case projecting on a side portion of the main body case and accommodating a display board, a board, a connector, etc. And a transparent resin plate disposed between the glass plate and the display plate provided in the opening of the cylindrical case opposite to the main body case.

[0010]

[Action]

 In the present invention, the transparent resin plate is made of acrylic resin or the like and has a lower thermal conductivity than that of the glass plate, so that it is difficult for the outside air temperature to be transmitted to the inside of the cylindrical case, and abrupt changes in the temperature difference between the inside and outside are reduced. Further, when a space is provided between the glass plate and the transparent resin plate, this space forms a heat insulating space, which further enhances the heat insulating effect and prevents the occurrence of dew condensation.

[0011]

【Example】

 Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. 1 is a partially cutaway side view of a gas chromatograph according to the present invention, FIG. 2 is a front view, and FIG. 3 is a sectional view taken along line III-III of FIG. The same components as those of the conventional structure shown in FIGS. 5 to 7 are designated by the same reference numerals, and the description thereof will be omitted. In these figures, a small process gas chromatograph indicated by the whole numeral 20 is connected and fixed to a sample conditioner device 21, an analyzer 22 installed on the sample conditioner device 21, and the front face of the analyzer 22. It is composed of an electric device section 23.

The sample conditioner device 21 is provided with a box-shaped housing 24 having an open top center portion, and inside thereof, a vaporizer, a flow meter, a filter, and a standard for vaporizing a sample liquid from a process not shown. A changeover switch for switching the flow path of gas and carrier gas, a needle valve, etc. are stored.

The analyzer 22 is provided with a main body case 25 which is formed of a metal such as an aluminum alloy into a substantially egg shape and which is installed and fixed on the sample conditioner device 21 with its long axis facing forward and backward. Inside, a sample valve 28 that switches between the flow paths 26 and 27 of the sample gas and the carrier gas, a column 29 that separates the sample gas by utilizing the difference in adsorptivity, and a detector 30 that detects each separated gas component. A constant temperature bath 31 surrounding them, a pressure reducing valve 32 for reducing the pressure of the carrier gas to a predetermined pressure, a transformer 33 and the like are provided. Since the sample conditioner device 21 and the analyzer 22 themselves are not directly related to the present invention, further detailed description will be omitted.

The electric device section 23 includes a cylindrical case 1 protruding from the front surface of the main body case 25. The cylindrical case 1 is made of aluminum die-cast, and has a printed circuit board 2 for driving and controlling the gas chromatograph 20, such as a thermostatic chamber temperature control circuit, which faces the upper and lower sides holding the printed circuit board 2 like the conventional structure described above. The board fixing brackets 3 and 4, the decorative plate (display plate) 8, the grounding metal 9, the connectors 10 and 11 and the like are stored and arranged. The case side connector 11 and the analyzer 22 are electrically connected by a cord 35. Further, in the upper and lower portions of the inner peripheral surface of the cylindrical case 1, detents and guide grooves 36 and 37 that are long in the axial direction are formed corresponding to the board fixing brackets 3 and 4, respectively. Protrusions 38 and 39, which are inserted into the anti-rotation and guide grooves 36 and 37, are provided at the inner ends of the board fixing brackets 3 and 4, respectively. When mounting the printed circuit board 2 in the cylindrical case 1, the protrusions 38 and 39 are inserted into the anti-rotation and guide grooves 36 and 37, and the printed circuit board 2 is inserted into the cylindrical case 1 together with the board fixing brackets 3 and 4. To do. Then, the board-side connector 10 is inserted and connected correspondingly to the case-side connector 11, and when completely connected, the protrusions 38 and 39 come into contact with the inner walls of the rotation-stopping and guide grooves 36 and 37, and are further connected. Insertion is blocked. Next, the lid body 6 is screwed into the open end of the cylindrical case 1 to complete the work of attaching the print substrate 2 and the lid body 6. In this screwing operation of the lid body 6, a rotational moment acts on the printed circuit board 2 and the board fixing brackets 3 and 4 due to a frictional force between the lid body 6 and the grounding metal 9, but the rotation preventing / guide grooves 36 and 37 and the protrusion 38 Since the brackets 3 and 4 are prevented from rotating by 39, the printed circuit board 2, the brackets 3 and 4, and the connectors 10 and 11 are not twisted or damaged.

Further, a transparent resin plate 40 for preventing dew condensation is arranged inside the cylindrical case 1. This transparent resin plate 40 is a resin having a thermal conductivity sufficiently smaller than that of the glass plate 13 (1.1 W · m ⁻¹ · K ⁻¹ ), such as an acrylic resin (thermal conductivity: 0.15 W · m ⁻¹ · K ⁻¹ ) and the like, and is disposed between the glass plate 13 that hermetically closes the front opening 12 of the lid 6 and the decorative plate 8. In this case, the present embodiment shows an example in which the transparent resin plate 40 is closely arranged on the glass plate 13, but as shown in FIG. A space 42 may be provided between the members.

Thus, in the electric device section 23 having such a configuration, since the transparent resin plate 40 having a smaller thermal conductivity than the glass plate 13 is disposed behind the glass plate 13, the heat insulating effect is large. When the external temperature drops sharply, it is difficult for the external temperature to be transmitted into the cylindrical case 1, and the occurrence of dew condensation can be reliably prevented. Moreover, when a space 42 is provided between the glass plate 13 and the transparent resin plate 40 as shown in FIG. 4, the space 42 has a thermal conductivity of air (0.0241 W · m ⁻¹ · K ⁻¹ ). Since the heat insulation space is formed due to its small size, the heat insulation effect is further increased, and the formation of dew condensation can be prevented more reliably. However, there is a risk that the moisture contained in the air confined in the space 42 will be in a supersaturated state due to a sudden decrease in the ambient temperature, and will be condensed to form water droplets and adhere to the inner surface of the glass plate 13. Since the volume of the space 42 is small, even if dew condensation occurs, the amount thereof is very small, and there is no influence on the reading of the displayed value by the decorative plate 8.

[0017]

[Effect of device]

 As described above, the gas chromatograph according to the present invention has a transparent resin plate located between the glass plate and the display plate in a cylindrical case accommodating various electric device members such as a printed circuit board, a connector, and a display plate. The heat insulation effect can be enhanced by the difference in heat conductivity between the glass plate and the transparent resin plate, and when the ambient temperature changes suddenly, the moisture inside the case condenses and the inner surface of the glass plate is exposed. It is possible to prevent the adhesion. Therefore, the display value of the display plate can be read well through the glass plate and the transparent resin plate. Moreover, since it is only necessary to dispose a resin plate such as an acrylic resin inside the case, the structure is simple and existing products can be easily modified.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view showing an embodiment of a gas chromatograph according to the present invention.

FIG. 2 is a front view.

3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a sectional view showing another embodiment in which a heat insulating space is provided.

FIG. 5 is a cross-sectional view of an electric device section in a conventional gas chromatograph.

6 is a sectional view taken along line VI-VI of FIG.

FIG. 7 is a front view of a decorative plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical case 2 Printed circuit board 6 Lid body 8 Decorative plate (display board) 10 Connector 12 Lid opening 13 Glass plate 25 Main body case 28 Sample valve 29 Column 30 Detector 32 Pressure reducing valve 40 Transparent resin plate 42 Space

Claims (1)

[Scope of utility model registration request] 1. A main body case containing a column, a valve, a detector, a pressure reducing valve, etc., and a cylindrical case projecting from a side portion of the main body case and accommodating a display plate, a substrate, a connector, etc., A gas chromatograph characterized in that a transparent resin plate is arranged between a glass plate and a display plate provided in an opening of the cylindrical case opposite to the main body case.