JPH0545946Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention is applicable to, for example, FID (Flame Ionization).
Detector) and CLD (Chemical Luminescence)
Detector) and other sampling devices in analyzers.

[Conventional technology]

Since the amount of sample supplied to analyzers such as FID and CLD is small at several to several cc/min, the flow rate is controlled in the sampling device using a very thin capillary with an inner diameter of 0.1 to 0.3 mm. However, it has the disadvantage that it may become clogged by impurities in the sample.

By the way, conventionally, as shown in FIGS. 3A and 3B, one capillary 42 is connected to the sample supply path 41 [FIG. 3A], or two capillaries 42, 42' are connected in parallel. Then, the two capillaries were selectively switched using a three-way switching valve 43 (FIG. B). Note that 44 in the figure indicates a detector.

[Problem that the invention attempts to solve]

In the conventional example shown in FIG. 3A, if the capillary 42 becomes clogged, it must be replaced to continue measurement work, but replacing the capillary is time-consuming and requires waiting for the temperature to stabilize after replacement. Or it may take several hours for the background to drop. For this reason, if the capillary becomes clogged during measurement, it will be impossible to measure for a long time while it is being repaired, which is a big problem, especially in line measurements such as automotive exhaust gas measurements.

Alternatively, simply connect the capillary 4 shown in Figure 3B.
In the same figure, if only two 2,42′ are connected in parallel,
Shaded flow path 45 and valve 4 used for switching
3 is large compared to the amount of sample sent to the detector 44 through the capillaries 42, 42', and this becomes a dead space, prolonging the gas replacement time and significantly reducing the response speed of the detector 44. The drawback was that it was slow.

Furthermore, if the two sample channels connected in parallel are switched by a valve as described above, the change in pressure drop in the piping (including the valve) will cause the sample supplied to the analyzer to change. Large variations in the flow rate occur, which in turn causes large variations in the output of the analyzer, such as curve B in Figure 2.
As shown in , the difference in indication increases as the sample flow rate increases.

The present invention was developed with the above-mentioned considerations in mind, and its purpose is to reliably reduce the output fluctuations of the analyzer due to pressure drop through a low-cost configuration, and to reduce the response delay of the detector. An object of the present invention is to provide a sampling device for an analyzer that can switch a capillary for a minute flow rate without incurring time.

[Means for solving problems]

In order to achieve the above object, the analyzer sampling device according to the present invention includes a first sample supply path.
A first branch flow path and a second branch flow path are connected through a switching section, and a second switching section connected to a bypass flow path is provided at the confluence point of both the branch flow paths. A capillary is connected to each of the channel and the second branch channel, a detector is connected to the downstream side of these capillaries, a pressure regulating mechanism is provided upstream of the first switching section, and a capillary is connected to the bypass channel. It is distinctive in that it has been established.

[Action]

According to the above configuration, when one capillary becomes clogged, the first switching section and the second switching section are switched respectively to stop the sample from flowing into one capillary, and the sample is detected through the other capillary. The sample gas in the branch flow path is introduced into the capillary in only the required amount, and the rest quickly flows to the bypass side, reducing the gas replacement time and increasing the response speed of the detector. In addition, since the pressure regulating mechanism is installed upstream of the first switching section at a location where there is no pressure loss due to changes in the flow rate, all pressure changes caused by changes in the sample flow rate are absorbed by this pressure regulating mechanism. It will be resolved. Further, the analyzer can maintain a predetermined response speed by the capillary provided downstream of the second switching section.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Fig. 1 shows an example of the configuration of a sampling device for an analyzer according to the present invention. The end is connected to a six-way valve 3.

This six-way valve 3 includes a rotatable valve body 5 inside a fixed block 4. Six connection ports 6, 7, 8, 9, 10, and 11 are formed in the fixed block 4. Two independent internal channels 12 and 13 are formed. The terminal end of the sample supply path 1 is connected to the connection port 6, and both ends of a first flow path 14 as a branch flow path are connected between the connection ports 7 and 8. Both ends of a second flow path 15 as a branch flow path are connected between the connection ports 9 and 10, and a starting end of a bypass flow path 16 is connected to the connection port 11. Then, connection ports 6 and 7, connection ports 11 and 10, and connection ports 8 and 1
1 and the connection ports 9 and 6, and furthermore, the connection port 6 and the connection port 11 are arranged so as to be 180 degrees symmetrical with each other. Therefore, by rotating the valve body 5 by 180 degrees, either the first flow path 14 or the second flow path 15 can be made to communicate with the sample supply path 1.

In the six-way valve 3, the connection ports 6, 7, and 9 constitute a first switching section, and the connection ports 8, 10, and 11 constitute a second switching section.

One end of each of 17 and 18 is the first flow path 14,
These are capillaries (hereinafter referred to as a first capillary 17 and a second capillary 18) that are connected to the second flow path 15 and are in a parallel relationship with each other. 19 is a capillary (hereinafter referred to as the third capillary 19) provided in the bypass flow path 16, and a flow meter 2 is installed downstream of the capillary 19.
0 is set. 21 is the first capillary 1
7. An analyzer installed downstream of the confluence P on the downstream side of the second capillary 18.

22 is a pressure regulating mechanism provided in a flow path 23 branched from the sample supply path 1 on the upstream side of the six-way valve 3; for example, a high-precision pneumatic regulator 24;
and a secondary pressure regulator 25, and the pneumatic regulator 24 controls the opening and closing of the six-way valve 3 to maintain the inlet pressure at a predetermined pressure by applying an appropriate control pressure to the secondary pressure regulator 25. .

According to the above configuration, the bypass flow path 1
A predetermined response speed in the analyzer 21 can be obtained by the third capillary 19 provided in the analyzer 6 . on the other hand,
Changes in pressure loss caused by changes in the flow rate of the sample S are eliminated by the pressure regulating mechanism 22 provided upstream of the six-way valve 3, so fluctuations in the output of the analyzer 21 due to the changes in flow rate are almost eliminated. For example, as shown by the solid line A in FIG. 2, even if the flow rate of the sample S changes, the difference in indication remains almost zero, and a stable output can be obtained.

In the present invention, in addition to the six-way valve having the structure as in the above embodiment, two commercially available three-way valves may be combined to form a six-way valve.

[Effect of idea]

As explained above, the sampling device of the analyzer according to the present invention connects the first branch channel and the second branch channel to the sample supply channel via the first switching part,
A second switching section connected to the bypass flow path is provided at the confluence point of both the branch flow paths, and capillaries are connected to the first branch flow path and the second branch flow path, respectively, and the downstream side of these capillaries is connected to the first branch flow path and the second branch flow path. Since a detector is connected to the first switching section, a pressure regulating mechanism is provided upstream of the first switching section, and a capillary is provided in the bypass flow path, the following effects are achieved.

That is, when one of the capillaries connected to the first branch flow path and the second branch flow path becomes clogged, the flow path is switched, and the accumulation in the first and second switching parts is promptly discharged to reduce the delay in response to startup. Measurement can be continued immediately without any occurrence of gas leakage, and even in steady state, the remaining gas introduced into the capillary is quickly discharged from the bypass line, so new sample gas is introduced into the capillary in the required amount, resulting in a response time. No delays. A clogged capillary can be replaced or repaired in a timely manner, such as when the line is stopped, or even while the line is in operation, reducing line operational problems. Also, by switching the capillary from time to time, it is possible to check whether the capillary is clogged, and it is possible to predict when the capillary should be replaced. Further, in the present invention, there is no dead space and response delay caused by the dead space as in the prior art shown in FIG. 3B, and accurate measurements can be performed.

Furthermore, in the present invention, since the pressure regulating mechanism is provided upstream of the first switching section at a location where there is no pressure loss due to changes in the flow rate, all pressure changes caused by changes in the sample flow rate are eliminated in this pressure regulating mechanism.
Further, the analyzer can maintain a predetermined response speed by the capillary provided downstream of the second switching section.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of a sampling device according to the present invention, Fig. 2 is a characteristic diagram showing the relationship between sample flow rate and indicated difference, and Figs. 3A and 3B are block diagrams showing the prior art. It is. 1...Sample supply path, 3...Six-way valve, 1
6... Bypass flow path, 17, 18... Capillary, 19... Capillary, 21... Analyzer, 22
...Pressure regulating mechanism, S...Sample.

Claims (1)

[Scope of utility model registration request] A first branch channel and a second branch channel are connected to the sample supply channel via a first switching section, and a second switching section connected to the bypass channel is provided at the confluence of the two branch channels. , connecting capillaries to the first branch flow path and the second branch flow path, connecting a detector to the downstream side of these capillaries, and further providing a pressure regulating mechanism upstream of the first switching part, A sampling device for an analyzer, characterized in that a capillary is provided in the bypass flow path.