阅读说明：本技术 气相色谱仪 (Gas chromatograph ) 是由 小森优辉 中野茂畅 冈田昌之 于 2017-05-09 设计创作，主要内容包括：气相色谱仪(1)包括冷却装置(8)。在冷却装置(8)中包含内部供给管(83)。内部供给管(83)延伸到柱恒温箱(3)内的配置有柱(2)的区域附近。从外部供给管(81)朝向柱恒温箱(3)内供给的制冷剂向内部供给管(83)流入,之后从喷出口(83A)向柱恒温箱(3)内喷出。此时,利用在内部含有制冷剂的内部供给管(83)对柱恒温箱(3)内进行冷却并且借助内部供给管(83)供给制冷剂从而对柱恒温箱(3)内进一步进行冷却。这样,利用内部供给管(83)自身和从内部供给管(83)供给的制冷剂对柱恒温箱(3)内阶段性地进行冷却。其结果,能够利用冷却装置(8)高精度地对柱恒温箱(3)内进行温度调节。(The gas chromatograph (1) comprises a cooling device (8). The cooling device (8) includes an internal supply pipe (83). The internal supply pipe (83) extends to the vicinity of the region in the column oven (3) where the column (2) is disposed. The refrigerant supplied from the external supply pipe (81) into the column oven (3) flows into the internal supply pipe (83), and is then discharged from the discharge port (83A) into the column oven (3). At this time, the inside of the column oven (3) is cooled by an internal supply pipe (83) containing a refrigerant therein, and the inside of the column oven (3) is further cooled by supplying the refrigerant through the internal supply pipe (83). Thus, the inside of the column oven (3) is cooled in stages by the internal supply pipe (83) itself and the refrigerant supplied from the internal supply pipe (83). As a result, the temperature in the column oven (3) can be accurately adjusted by the cooling device (8).)

1. A gas chromatograph, characterized in that,

the gas chromatograph includes:

a column oven in which a column is housed; and

a cooling device for cooling the inside of the column oven by discharging a refrigerant from a discharge port into the column oven,

the cooling device includes a supply pipe extending to the vicinity of a region in the column oven where the column is arranged, for supplying the refrigerant to the discharge port.

2. Gas chromatograph according to claim 1,

the gas chromatograph also comprises a heater which is arranged in the column constant temperature box and used for heating the column constant temperature box,

the supply tube extends to a region between the heater and the column.

3. Gas chromatograph according to claim 1,

the supply pipe is formed in a curved shape in the vicinity of a region where the column is arranged.

4. Gas chromatograph according to claim 3,

the supply pipe is formed in a curved shape corresponding to the shape of the column.

5. Gas chromatograph according to claim 1,

the cooling device includes a resistance tube having a resistance portion with a smaller inner diameter than the supply tube and communicating with the supply tube at a position upstream of the supply tube.

6. Gas chromatograph according to claim 5,

the gas chromatograph further includes a switching unit configured to switch between a 1 st supply state in which the refrigerant is supplied to the supply pipe via the resistance unit and a 2 nd supply state in which the refrigerant is supplied to the supply pipe without the resistance unit.

7. Gas chromatograph according to claim 5,

the cooling device includes a flow rate adjustment valve for adjusting the flow rate of the refrigerant supplied to the supply pipe at a position upstream of the supply pipe.

Technical Field

The present invention relates to a gas chromatograph including a cooling device for cooling the inside of a column oven.

Background

Conventionally, a gas chromatograph including a cooling device that introduces a refrigerant into a column oven to cool the inside of the column oven to a predetermined temperature has been used. In the gas chromatograph, the inside of the column oven is heated to a high temperature by the heater due to the analysis operation. Thereafter, the column oven is cooled to a predetermined temperature by the cooling device for the next measurement. In this way, in the gas chromatograph, the inside of the column oven is appropriately cooled by the cooling device, and the analysis operation is repeated (for example, see patent document 1 below).

In the gas chromatograph described in patent document 1, a supply pipe (supply line) for cooling gas is connected to a column oven. The supply pipe is provided with a valve for adjusting the supply amount of the cooling gas. Then, by appropriately opening the valve, the cooling gas is introduced into the column oven through the supply pipe, thereby cooling the inside of the column oven.

Disclosure of Invention

Problems to be solved by the invention

In the above-described conventional gas chromatograph, there is a problem that it is difficult to stabilize the temperature when the inside of the column oven is cooled.

Specifically, the above-described gas chromatograph is provided with a sensor for detecting the temperature in the column oven, and the cooling gas is introduced into the column oven through the supply pipe based on the temperature in the column oven detected by the sensor. In the cooling device having such a structure that the inside of the column oven is cooled only by the cooling gas introduced thereinto, a time lag occurs between the introduction of the cooling gas and the reduction of the temperature of the atmosphere around the sensor under the influence of the gas.

For example, even when a required amount of gas is introduced into the column oven, the temperature of the atmosphere around the sensor does not completely decrease (become unstable) immediately after the introduction of the gas. Therefore, if the gas continues to be introduced into the column oven based on the detected temperature of the sensor, a required amount or more of gas is introduced into the column oven when the detected temperature of the sensor reaches the target temperature. As a result, even if the supply of the gas is stopped thereafter, the ambient gas temperature around the sensor further decreases, resulting in a final significant decrease from the target temperature. As described above, the above-described configuration of the gas chromatograph has a problem that the internal temperature is difficult to stabilize.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a gas chromatograph capable of accurately adjusting the temperature in a column oven.

Means for solving the problems

(1) The gas chromatograph of the present invention includes a column oven and a cooling device. The column oven houses a column therein. The cooling device cools the inside of the column oven by discharging a refrigerant into the column oven from a discharge port. The cooling device includes a supply pipe extending to the vicinity of a region in the column oven where the column is arranged, for supplying the refrigerant to the discharge port.

With this configuration, the interior of the column oven is cooled by the supply pipe containing the refrigerant therein. Then, the coolant is supplied into the column oven through the supply pipe, thereby further cooling the inside of the column oven. That is, the inside of the column oven is cooled in stages by the supply pipe itself and the refrigerant supplied from the supply pipe.

Therefore, the temperature in the column oven can be accurately adjusted by the cooling device.

(2) Further, the gas chromatograph may further include a heater. The heater is arranged in the column thermostat and used for heating the interior of the column thermostat. The supply pipe may extend to a region between the heater and the column.

With this configuration, the region between the heater and the column can be cooled by the supply pipe containing the refrigerant therein.

(3) Further, the supply pipe may be formed in a curved shape in the vicinity of a region where the column is arranged.

With this configuration, the atmosphere around the column can be efficiently cooled by the supply pipe containing the refrigerant therein.

(4) Further, the supply pipe may be formed in a curved shape corresponding to the shape of the column.

With this configuration, the column itself can be efficiently cooled by the supply pipe containing the refrigerant therein.

(5) The cooling device may further include a resistance tube having a resistance portion with a smaller inner diameter than the supply tube and communicating with the supply tube at a position upstream of the supply tube.

With this configuration, the refrigerant passes through the resistance portion and is then supplied into the column oven through the supply pipe. Therefore, even when the supply pressure of the refrigerant is high, the flow rate of the refrigerant can be adjusted by passing the refrigerant through the resistance portion.

(6) Further, the gas chromatograph may further include a switching unit. The switching unit is switchable between a 1 st supply state in which the refrigerant is supplied to the supply pipe via the resistance unit and a 2 nd supply state in which the refrigerant is supplied to the supply pipe without the resistance unit.

With this configuration, the supply state can be appropriately switched by the switching unit, and the refrigerant can be supplied into the column oven in an appropriate supply state (supply path).

(7) Further, the cooling device may include a flow rate adjustment valve. The flow rate adjustment valve adjusts the flow rate of the refrigerant supplied to the supply pipe at a position upstream of the supply pipe.

With this configuration, the flow rate of the refrigerant can be adjusted by the resistance portion in addition to the adjustment of the flow rate of the refrigerant by the flow rate adjustment valve.

Therefore, the flow rate of the refrigerant can be appropriately adjusted.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the inside of the column oven is cooled in stages by the supply pipe itself and the refrigerant supplied from the supply pipe. Therefore, the temperature in the column oven can be accurately adjusted.

Drawings

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

Fig. 2 is a front view showing an internal supply pipe used in the cooling apparatus of fig. 1.

Fig. 3 is a front view showing an internal supply pipe used in a cooling device of a gas chromatograph according to embodiment 2 of the present invention.

Fig. 4 is a schematic diagram showing a configuration example of a gas chromatograph according to embodiment 3 of the present invention.

Detailed Description

1. Structure of gas chromatograph

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

The gas chromatograph 1 is used for analyzing by supplying a sample gas and a carrier gas into a column 2, and includes a column oven 3, a heater 4, a fan 5, a sample introduction unit 6, a detector 7, a cooling device 8, and the like in addition to the column 2.

The column 2 is housed in a column oven 3. The column 2 is formed by a capillary column, for example.

The column oven 3 is formed in a box shape.

The heater 4 is for heating the inside of the column oven 3, and is disposed inside the column oven 3. The heater 4 is disposed at a distance from the column 2. In the column oven 3, a partition plate 9 is provided between the column 2 and the heater 4. Partition plate 9 has holes through which air passes and holes through which a part of cooling device 8 passes.

The fan 5 is disposed in the column oven 3. The fan 5 is provided on the side opposite to the side on which the column 2 is provided with respect to the heater 4. In the gas chromatograph 1, the side where the fan 5 is provided is the rear side, and the side where the column 2 is provided is the front side.

The sample introduction section 6 is for introducing a carrier gas and a sample gas into the column 2, and a sample vaporization chamber (not shown) is formed inside the sample introduction section 6. A liquid sample is injected into the sample vaporization chamber, and the sample vaporized in the sample vaporization chamber is introduced into the column 2 in the same direction as the carrier gas. The gas supply channel 11 and the flow dividing channel 12 communicate with the sample vaporizing chamber.

The gas supply channel 11 is a channel for supplying the carrier gas into the sample vaporization chamber of the sample introduction unit 6.

The split flow path 12 is a flow path for discharging a part of the gas (mixed gas of the carrier gas and the sample gas) in the sample vaporization chamber to the outside at a predetermined split ratio when the carrier gas and the sample gas are introduced into the column 2 by the split introduction method.

The detector 7 is formed of, for example, a hydrogen Flame Ionization Detector (FID), a Flame Photometric Detector (FPD). The detector 7 sequentially detects each sample component contained in the carrier gas introduced from the column 2.

The cooling device 8 is a device for discharging a refrigerant into the column oven 3 to cool the inside of the column oven 3. The refrigerant discharged from the cooling device 8 is, for example, N₂Gas, CO₂Cooling gas such as gas. A part of the cooling device 8 is disposed in the column oven 3. The details of the cooling device 8 will be described later.

When a sample is measured in the gas chromatograph 1, first, the temperature in the column oven 3 is lowered to a set temperature (room temperature or lower) using the cooling device 8. In this state, a sample to be analyzed is injected into the sample introduction portion 6. The sample is vaporized in the sample vaporization chamber. Further, the carrier gas is supplied to the sample vaporization chamber of the sample introduction section 6 through the gas supply passage 11.

The sample vaporized in the sample vaporizing chamber is introduced into the column 2 in the same direction as the carrier gas. After the sample is introduced into the column 2, the heater 4 and the fan 5 are driven to heat the inside of the column oven 3, thereby gradually raising the temperature inside the column oven 3. The respective sample components contained in the sample are separated while passing through the column 2, and are sequentially introduced into the detector 7.

Then, each sample component contained in the carrier gas introduced from the column 2 is sequentially detected by the detector 7. In the gas chromatograph 1, a chromatogram is generated based on a detection signal of the detector 7. The user confirms the obtained chromatogram and performs various analyses. After confirmation of the chromatogram, high-temperature air was discharged to the outside of the system, thereby cooling the column oven 3 to the initial temperature.

Thereafter, the coolant is discharged from the cooling device 8 into the column oven 3. Thereby, the column oven 3 is cooled to a predetermined temperature (target temperature). Then, the above analysis operation is repeated. In this way, when the analysis operation is repeated in the gas chromatograph 1, the temperature is appropriately adjusted by the cooling device 8.

2. Structure of cooling device

The cooling device 8 includes a flow rate adjustment valve 80, an external supply pipe 81, a resistance pipe 82, and an internal supply pipe 83.

The flow rate adjustment valve 80 is provided on a side wall (rear wall) of the column oven 3. The flow rate adjustment valve 80 is a valve for adjusting the flow rate of the refrigerant. An external supply pipe 81 and a resistance pipe 82 are connected to the flow rate adjustment valve 80. That is, the flow rate adjustment valve 80 is interposed between the external supply pipe 81 and the resistance pipe 82. The opening degree of the flow rate adjustment valve 80 is adjusted by a control unit, not shown. The flow rate adjustment valve 80 may be configured to manually adjust the opening degree thereof.

The external supply pipe 81 is disposed outside the column oven 3. The downstream end of the external supply pipe 81 is connected to the flow rate adjustment valve 80. Although not shown, an upstream end of the external supply pipe 81 is connected to a storage unit such as an air tank in which refrigerant is stored. Then, the refrigerant is supplied from the reservoir.

The resistance tube 82 is disposed inside the column oven 3. An upstream end of the resistance pipe 82 is connected to the flow rate adjustment valve 80. The resistance tube 82 is a tubular member having a flow path resistance corresponding to the length thereof. The resistance tube 82 has an inner diameter smaller than that of the inner supply tube 83. As described later, the resistance tube 82 is a detachable member. The resistance tube 82 is an example of a resistance portion.

The internal supply pipe 83 is disposed inside the column oven 3. Specifically, the internal supply pipe 83 is disposed (extended) in a region between the column 2 and the heater 4, more specifically, between the column 2 and the partition plate 9. The inner supply pipe 83 is an example of a supply pipe.

Fig. 3 is a front view showing the inner supply pipe 83.

The inner supply pipe 83 is formed in a curved shape (circular arc shape). The internal supply pipe 83 includes a tubular portion 831 and a connecting portion 832.

The tubular portion 831 is formed in a tubular shape. The tubular portion 831 is curved in an arc shape in a range from an upstream end portion thereof to a central portion thereof, and is formed in a shape extending linearly from the central portion (a portion slightly downstream of the central portion) to a downstream end portion thereof. That is, the tubular portion 831 includes a portion formed in an arc shape and a portion formed in a linear shape. The inner space of the downstream end portion (the tip end portion of the straight portion) of the tubular portion 831 is the ejection port 83A. The central portion of the tubular portion 831 is held to the fixing member 20. A connecting portion 832 is attached to an upstream end portion of the tubular portion 831.

The connection portion 832 is formed in a cylindrical shape. The inner space of the connecting portion 832 communicates with the inner space of the tubular portion 831. The tip end (upstream end) of the connection portion 832 is configured to allow the resistance tube 82 to be attached thereto.

In fig. 1, although not shown, the fixing member 20 is attached to the partition plate 9. Then, the fixing member 20 holds the internal supply tube 83 (the tubular portion 831). Thereby, the internal supply pipe 83 is maintained in a state of being disposed between the partition plate 9 and the column 2. In this state, the downstream end of the internal supply pipe 83 is disposed at the lower portion in the column oven 3. Further, the discharge port 83A of the internal supply pipe 83 faces in the horizontal direction. Thus, the refrigerant discharged from the discharge port 83A does not directly impinge on the column 2, but collides with the inner wall of the column oven 3 and spreads.

The internal supply pipe 83 is provided in the vicinity of the region where the column 2 is disposed, in a state of being held in the column oven 3. Specifically, the internal supply pipe 83 is disposed behind the column 2 with a space from the column 2. Further, the shape of the internal supply pipe 83 corresponds to the shape of the column 2. Specifically, the size of the outer shape of the internal supply pipe 83 is approximately the same as the size of the outer shape of the column 2, and the internal supply pipe 83 and the column 2 overlap when viewed in the front-rear direction.

3. Operation of the cooling device

In the gas chromatograph 1, a resistance tube 82 (a resistance tube 82 having an appropriate flow path resistance) having an appropriate length according to the usage state of the gas chromatograph 1 is selected, and the resistance tube 82 is used.

For example, in the case where the remaining amount of the refrigerant is large, the supply pressure of the refrigerant is large, and therefore the supply amount is large even if the opening degree of the flow rate adjustment valve 80 is the same. In this case, the user selects the resistance tube 82 having a long length (having a large flow path resistance), and connects the resistance tube 82 to the internal supply tube 83 and the flow rate adjustment valve 80. For example, when the remaining amount of the refrigerant is small, the supply pressure of the refrigerant is small. Therefore, in such a case, the user selects the resistance tube 82 having a short length (having a small flow path resistance), and connects the resistance tube 82 to the internal supply tube 83 and the flow rate adjustment valve 80.

A downstream end of the resistance tube 82 is connected to a connection portion 832 of the internal supply tube 83, and an upstream end of the resistance tube 82 is connected to the flow rate adjustment valve 80. Thereby, the resistance pipe 82 and the inner supply pipe 83 communicate with each other via the connection portion 832, and the resistance pipe 82 and the outer supply pipe 81 communicate with each other via the flow rate adjustment valve 80. Thus, the resistance pipe 82 is disposed upstream of the internal supply pipe 83. The flow rate adjustment valve 80 is disposed upstream of the resistance pipe 82 and the internal supply pipe 83.

When the interior of the column oven 3 is cooled, a refrigerant is supplied from the external supply pipe 81 into the column oven 3. The refrigerant having passed through the external supply pipe 81 flows into the resistance pipe 82 via the flow rate adjustment valve 80. After passing through resistance tube 82, the refrigerant flows into internal supply tube 83, and is then discharged from discharge port 83A to the lower portion in column oven 3.

In this way, the refrigerant is discharged from the discharge port 83A of the internal supply pipe 83 after the flow rate of the refrigerant is adjusted by the resistance pipe 82. Then, the inside of the column oven 3 (column 2) is cooled by the refrigerant. At this time, the inside of the column oven 3 is cooled not only by the refrigerant but also by the internal supply pipe 83 containing the refrigerant therein. That is, the interior of the column oven 3 is cooled in stages by the internal supply pipe 83 and the refrigerant.

In addition, in the gas chromatograph 1, as a result of repeating the cooling in the column oven 3 by the cooling device 8, the supply pressure of the refrigerant decreases, and in this case or the like, the opening degree of the flow rate adjustment valve 80 is adjusted to adjust the flow rate of the refrigerant. This allows the flow rate of the refrigerant to be adjusted without changing the type of the resistance tube 82. In this way, in the cooling device 8 of the gas chromatograph 1, the flow rate of the refrigerant is adjusted by the resistance tube 82 and the flow rate adjustment valve 80.

4. Effect of action

(1) According to the present embodiment, as shown in fig. 1, the cooling device 8 of the gas chromatograph 1 includes an internal supply pipe 83. The internal supply pipe 83 extends to the vicinity of the region in the column oven 3 where the column 2 is arranged.

Therefore, the inside of the column oven 3 is cooled by the internal supply pipe 83 containing the refrigerant therein, and the inside of the column oven 3 is further cooled by supplying the refrigerant through the internal supply pipe 83. That is, the inside of the column oven 3 is cooled in stages by the internal supply pipe 83 itself and the refrigerant supplied from the internal supply pipe 83.

As a result, the temperature in the column oven 3 can be accurately adjusted by the cooling device 8.

(2) Further, according to the present embodiment, as shown in fig. 1, the internal supply pipe 83 extends to the region between the heater 4 and the column 2.

Therefore, the region between the heater 4 and the column 2 can be cooled by the internal supply pipe 83 containing the refrigerant therein.

(3) Further, according to the present embodiment, as shown in fig. 1, the internal supply pipe 83 is formed in a curved shape in the vicinity of the region where the column 2 is arranged.

Therefore, the atmosphere around the column 2 can be efficiently cooled by the internal supply pipe 83 containing the refrigerant therein.

(4) Further, according to the present embodiment, as shown in fig. 1 and 2, the internal supply pipe 83 is formed in a curved shape corresponding to the shape of the column 2. Specifically, the size of the outer shape of the internal supply pipe 83 is approximately the same as the size of the outer shape of the column 2, and the internal supply pipe 83 and the column 2 overlap when viewed in the front-rear direction.

Therefore, the column 2 itself can be efficiently cooled by the internal supply pipe 83 containing the refrigerant therein.

(5) Further, according to the present embodiment, as shown in fig. 1, the resistance tube 82 is included in the cooling device 8. The resistance tube 82 is disposed upstream of the internal supply tube 83, and communicates with the internal supply tube 83.

Therefore, the refrigerant supplied through the external supply pipe 81 passes through the resistance pipe 82 and is then discharged into the column oven 3 through the supply pipe.

As a result, even when the supply pressure of the refrigerant is high, the flow rate of the refrigerant can be adjusted by passing the refrigerant through the resistance tube 82.

(6) Further, according to the present embodiment, as shown in fig. 1, the cooling device 8 includes a flow rate adjustment valve 80. The flow rate adjustment valve 80 adjusts the flow rate of the refrigerant at a position upstream of the internal supply pipe 83 and the resistance pipe 82.

Therefore, the flow rate of the refrigerant can be adjusted by the resistance tube 82 in addition to the flow rate of the refrigerant adjusted by the flow rate adjustment valve 80.

As a result, the flow rate of the refrigerant can be appropriately adjusted.

5. Embodiment 2

A gas chromatograph 1 according to another embodiment of the present invention will be described with reference to fig. 3 and 4. Note that the same reference numerals as those used above are used for the same components as those in embodiment 1, and the description thereof is omitted.

Fig. 3 is a front view showing an internal supply pipe 85 used in the cooling device 8 of the gas chromatograph 1 according to embodiment 2 of the present invention.

In embodiment 2, the cooling device 8 uses an internal supply pipe 85 instead of the internal supply pipe 83 described above. The inner supply pipe 85 has a shape different from the shape of the inner supply pipe 83 of embodiment 1.

Specifically, the inner supply pipe 85 includes a tubular portion 851 and a connecting portion 852.

The tubular portion 851 is formed in a tubular shape and in a spiral shape. Specifically, the tubular portion 851 is formed in a shape that curves in a convolute manner from the upstream-side end portion toward the downstream and is away from the center as it goes toward the downstream. The downstream end of the tubular portion 851 extends linearly downward. The inner space of the downstream end portion (tip end portion of the straight portion) of the tubular portion 851 is the ejection port 85A. The intermediate portion of the tubular portion 851 is held by the fixing member 20. A connecting portion 852 is attached to an upstream end portion of the tubular portion 851.

The connecting portion 852 is formed in a vertically long cylindrical shape. The inner space of the connecting portion 852 communicates with the inner space of the tubular portion 851. A resistance tube 82 is attached to a distal end portion (upstream end portion) of the connecting portion 852.

The fixing member 20 is attached to the partition plate 9 (see fig. 1) in the column oven 3. The fixing member 20 holds the internal supply pipe 85 (the tubular portion 851). In this state, the discharge port 85A of the internal supply pipe 85 faces downward. Thus, the refrigerant discharged from the discharge port 85A does not directly impinge on the column 2, but collides with the bottom wall of the column oven 3 and spreads.

The internal supply pipe 83 is provided in the vicinity of the region where the column 2 is disposed, in a state of being held in the column oven 3. Specifically, the tubular portion 851 of the internal supply pipe 83 faces the column 2 and is disposed in the column oven 3 in a manner similar to the column 2.

When the refrigerant is supplied from the external supply pipe 81 into the column oven 3, the refrigerant having passed through the external supply pipe 81 passes through the flow rate adjustment valve 80 and the resistance pipe 82, and then is discharged from the discharge port 83A toward the bottom wall in the column oven 3 through the internal supply pipe 83.

Thus, according to embodiment 2, in the cooling device 8, the tubular portion 851 of the internal supply pipe 85 is formed in a spiral shape. Therefore, the tubular portion 851 of the internal supply pipe 83 can be disposed in the column oven 3 so as to face the column 2 and so as to be similar to the column 2.

As a result, the column 2 can be efficiently cooled by the internal supply pipe 85.

6. Embodiment 3

Fig. 4 is a schematic diagram showing a configuration example of the gas chromatograph 1 according to embodiment 3 of the present invention. Embodiment 3 is different from embodiment 1 in that the supply path for supplying the refrigerant to the internal supply pipe 83 can be appropriately changed.

Specifically, in embodiment 3, a flow path switching valve 90 and a bypass pipe 91 are provided. The flow rate adjustment valve 80 is provided so as to be interposed at a position slightly upstream of the downstream end of the external supply pipe 81.

The flow path switching valve 90 is interposed at the downstream end of the external supply pipe 81. That is, the flow path switching valve 90 is disposed downstream of the flow rate adjustment valve 80. The flow path switching valve 90 is connected to an upstream end of the resistance pipe 82 and an upstream end of the bypass pipe 91. The flow path switching valve 90 is a valve capable of switching the supply path of the refrigerant supplied to the external supply pipe 81 to either the resistance pipe 82 or the bypass pipe 91.

The bypass pipe 91 has an inner diameter larger than that of the resistance pipe 82, and has a flow path resistance smaller than that of the resistance pipe 82. The downstream end of the bypass pipe 91 is connected to the connection portion 832.

Thus, by switching the flow path switching valve 90, the refrigerant supplied to the external supply pipe 81 can be discharged into the column oven 3 through either a path (1 st supply state) through which the refrigerant flows into the internal supply pipe 83 via the resistance pipe 82 or a path (2 nd supply state) through which the refrigerant flows into the internal supply pipe 83 via the bypass pipe 91 without passing through the resistance pipe 82.

In this way, according to the gas chromatograph 1 of embodiment 3, the refrigerant can be supplied into the column oven 3 in an appropriate supply state by appropriately switching the supply state (supply path) by the flow path switching valve 90.

7. Modification example

In the above embodiment, the gas chromatograph 1 has been described with the resistance pipe 82 interposed between the internal supply pipe 83 and the flow rate adjustment valve 80. However, the gas chromatograph 1 may be configured such that the upstream end of the internal supply pipe 83 is connected to the flow rate adjustment valve 80 without providing the resistance pipe 82.

In the above embodiment, the case where the internal supply pipes 83 and 85 are provided in the vicinity of the column 2, specifically, in the rear of the column 2 (the region between the column 2 and the heater 4) has been described. However, the internal supply pipes 83 and 85 may be provided in front of the column 2 (on the opposite side of the column 2 from the side where the heater 4 is provided) as the vicinity of the column 2.

Description of the reference numerals

1. A gas chromatograph; 2. a column; 3. a column oven; 4. a heater; 8. a cooling device; 80. a flow rate regulating valve; 82. a resistance tube; 83. an inner supply tube; 83A, an ejection port; 85. an inner supply tube; 85A and an ejection port; 90. a flow path switching valve.