JPH06324025A - Drain valve of liquid-feeding pump for liquid chromatography - Google Patents

Abstract

PURPOSE:To achieve switching according to a simple key operation and an external control with the switching of channels in an electric switching mechanism. CONSTITUTION:A sensitive part of a pressure sensor 4, a liquid-feeding channel to an injector, a drain channel 15, a switching seal 22 for switching the channels are constituted in one branching block 17 and the switching seal 22 is provided with a control circuit 23 and a switching drive mechanism 24 which can be operated freely. Therefore, since the channels are formed in one branching block 17, an introduction port 12 of a pressure sensor part 4 and a solvent, an exit 14 of a solvent, a drain channel 15 are minimized, thus reducing the dead volume of the channels. Also, by adding switching drive mechanism 24 for switching the channels, switching by key operation and external control is enabled for an improved handling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drain valve for a liquid feed pump for liquid chromatography.

[0002]

2. Description of the Related Art In a conventional liquid chromatograph flow path system, as shown in FIG. 1, a solvent sucked from a liquid feed pump cylinder 1 through a solvent filter passes through a pump cylinder 2 and a pressure sensor is connected thereto. It is connected to the pressure-sensitive part and a flow path for sending liquid to the column. An injector for injecting a sample is provided immediately before the column, and the sample is introduced by a predetermined sample introduction operation, and each measurement component is detected by various detectors through the column. Here, the liquid feed pump needs to accurately feed a certain amount of various solvents, but there are cases in which constant liquid feed cannot be performed due to bubbles dissolved in the solvent or bubbles attached to the flow path system. In this case, a drain valve is provided immediately after the pressure sensor in order to normally send the liquid, and the solvent is discharged without being sent to the column side. The drain valve was provided on the outlet side of the liquid feed pump, and the drain valve was manually operated by the measurer.

[0003]

In the above-mentioned conventional liquid feed pump, the drain valve is manually operated. It is operated when the flow path in the pump becomes dry and liquid cannot be delivered at the time of starting to start the analysis. In this case, the drain valve is set to the open position to rapidly feed a large amount of liquid to enable liquid feeding. In addition, the solvent may be changed to a different one due to changes in analysis conditions, and in this case as well, the drain valve is opened to fast-forward a large amount of liquid for rapid solvent exchange. Further, the air dissolved in the solvent may grow in the flow path system, hinder the constant liquid supply, and cause a pressure fluctuation. In these cases as well, the drain valve is opened to discharge the bubbles in the flow path, and then the normal liquid transfer flow path is switched to. All of these drain valves are manually operated while confirming the state of the flow path, the presence or absence of fluctuations in the pressure of the liquid to be sent, and whether or not the pressure has reached a predetermined value. In addition, after seeing that these conditions have fallen, it is done manually. The operation settings for fast-forwarding, which is performed at the same time as the operation of the drain valve, are keyed in, and one-touch operation is possible. However, if the drain valve is not opened, it is common for the pressure to rise and the rapid-forward operation to become impossible.
The operation of the drain valve that removes air bubbles in the liquid flow path, which is essential for stable analysis of liquid chromatographs like this, is performed manually by the operator.
The operability is bad. In particular, a strong tightening force is required for opening and closing the valve of the high-pressure flow path, and the opening and closing of each analysis and the operation of multiple times imposes a burden on the measurer. However,
If a switching valve is added to the flow path system just for automatic switching, the pressure sensor section and the drain valve switching valve will be separate and the dead volume of the piping and connection will increase, causing air bubbles to adhere and changing the solvent. The retention part of the solvent is easily formed. Further, recent liquid chromatographs are becoming more automated and systematic, and there is a problem in that the liquid delivery pump cannot be automated because the opening / closing of the drain valve is a manual operation and external control is impossible.

[0004]

As means for solving the above-mentioned problems, as a flow path for analysis of a main flow path of a drain valve, which is connected from the pump cylinders 1 and 2 via a pressure sensitive portion of a pressure sensor, A drain valve that opens to the atmosphere and discharges the solvent mixed with air bubbles, and a switching seal that switches between these channels in an integrated branch block. To do. In addition, one end of the switching seal is achieved by providing a drive mechanism for switching the flow path by a motor or the like to enable automatic switching and easy operation by key operation or the like.

[0005]

The flow path is connected to the column side from the pump cylinders 1 and 2 side through the pressure sensors provided at the solvent inlet and the solvent outlet and the pressure sensitive parts of the pressure sensor. It is composed of a body of a branch block that branches into an outlet of the solvent and a drain flow path of the open flow path, a push spring that holds the surface pressure of the switching seal in pressure contact with the body, and a drive mechanism that switches the switching seal. The pressure sensor and the drain valve mechanism were integrated into the branch block to minimize the length of the piping system and minimize dead volume at the pipe-pipe connection. In addition, by adding an automatic switching drive mechanism for switching the flow path and operating the keys on the keyboard, it is possible to easily open and close the valve. Furthermore, by providing a circuit that enables external control, external control from a PC (personal computer), controller, or the like can also be possible.

[0006]

EXAMPLE FIG. 2 shows an example of the present invention.

The drain valve provided in the liquid delivery pump is a pressure sensor 4, a solvent introducing port, a solvent outlet, and an integral branch block 17 having a drain passage 15, a switching seal 22 for switching to each passage, and a switching seal 22. It is composed of a switching drive mechanism 24 for performing.

At the solvent inlet 12, a pump cylinder 2,
The solvent 1 sent from 3 enters the branch block 17, passes through the flow path inside the branch block 17, passes through the pressure sensing portion 16 of the pressure sensor 4, and is pressed against the stator 26 surface of the branch block 17 by the pressure of the pressing spring 18 to achieve a high pressure resistance. The liquid is sent to the injector 7 and the column 9 through the switching groove 19 communicating with the switching seal 22 having 500 kgf / cm ² and through the flow path filter 13 provided at the solvent outlet 14 part. These flow paths are formed by high pressure resistant connections and seals in the high pressure section. One of the drain flow paths 15 to be opened is an exhaust flow path for degassing and solvent replacement, and is opened to the atmosphere, and is a low-pressure pipe. As described above, the integrated branch block 17 without connecting pipes
A flow path and a mechanism were provided in the structure to minimize the dead volume generated in the pipe-to-pipe connection. In this structure, the switching of the flow path is performed by the branch block 17 and the stator 2.
This is performed by switching the angles of the switching seal 22 and the switching groove 19 that are in pressure contact with 6. The switching seal 22 switches the angle by a drive mechanism 24 using a motor or the like via the coupling 21. The coupling 21 is provided with a photo interrupter 20 for detecting the switching angle to rotate and stop the motor at a predetermined rotation speed. The operation command of the drive motor is the control circuit 23.
This is easily performed by operating the keys of the keyboard 25 via the. The keyboard 25 is provided with a PURGE key (the one in which the fast-forwarding of the flow path is linked with the opening / closing of the drain valve) and the VALVE key (the key for turning the valve ON / OFF), and the opening / closing operation can be freely performed by the key operation. It also has the function of opening and closing the drain valve by external control by connecting to a PC (personal computer) or controller. The drain valve formed as described above is provided between the liquid pump 8 of the liquid chromatograph and the injector 7 or the autosampler for injecting the sample in the flow channel configuration according to the present embodiment as shown in FIG. The pressure of the solvent 1 sent at 8 is sensed to switch between the analysis flow path 27 and the drain flow path 15 for drainage, one of which is the injector 7,
It is sent to the column 9 and the analysis is developed. The conventional drain valve 28, which was manually operated, can be easily operated by an easy key operation. In particular, the drain valve 28 requires a strong tightening force because it is a high-pressure switching valve, and the conventional manual operation that is repeated a number of times places a burden on the measurer, and the operability in this respect can be significantly improved. did it.

Further, the drain valve 2 is programmed by a device that enables external control of an automatic switching drive mechanism.
It was possible to open and close 9 at a predetermined time. For example, it is possible to purge air bubbles adhering to the inside of the flow path by purging for a predetermined time after completion of each analysis. This is particularly effective when the analysis time is long or when a solvent in which bubbles are easily generated (for example, n-hexane or a mixed solution of water and an organic solvent) is used, and the reliability of analysis is improved. With these, it is possible to provide the liquid delivery pump 8 having the drain valve 29 capable of constructing true automation and systemization.

[0010]

EFFECTS OF THE INVENTION According to the present invention, the main flow path for analysis and air bubbles connected from the injector to the column via the pressure-sensitive part of the pressure sensor from the flow path of the solvent introduction port from the pump cylinder are provided in the integral branch block. A switching drive mechanism that drives the switching between the switching seal and the switching seal installed in this flow path by providing a drain flow path that discharges to the drain without being sent to the flow path on the analysis side in the case of inflow or solvent replacement It is possible to form a drain valve that is incorporated in an integral branch block. As a result, by integrating the conventional pressure sensor and the drain valve switching valve as separate parts, the piping system can be shortened and the dead volume generated in the piping and the connecting portion of the piping can be reduced.

Furthermore, by providing a switching drive mechanism for switching the flow paths and enabling the switching by a simple key operation, the conventional hand operation is made into a one-touch operation by key operation, and the handleability is improved. In addition, the drain valve can be opened / closed by external control so that the drain valve can be opened / closed at a predetermined time by programming. This makes it easy to perform the purge operation for each analysis cycle and the purge operation before the start of analysis by programming. This enabled the construction of recent automation and systemization, and was able to provide the optimal liquid delivery pump for automation and systemization.

[Brief description of drawings]

FIG. 1 is a diagram showing a flow channel system of a conventional liquid chromatograph.

FIG. 2 is a structural diagram of a drain valve for a liquid chromatograph according to an embodiment of the present invention.

FIG. 3 is a diagram showing a flow channel system of a liquid chromatograph according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Solvent, 2 ... Pump cylinder 1, 3 ... Pump cylinder 2, 4 ... Pressure sensor, 5 ... Connection pipe, 6 ... Sample loop, 7 ... Injector, 8 ... Liquid delivery pump, 9 ... Column, 10 ... Detector, 11 ... Data processing, 12 ... Solvent introduction port, 13 ... Flow path filter, 14 ... Solvent outlet, 15 ... Drain flow path, 16 ... Pressure sensitive part, 17 ... Branch block, 18 ...
Push spring, 19 ... switching groove, 20 ... photo interrupter,
21 ... Coupling, 22 ... Changeover seal, 23 ... Control circuit, 24 ... Drive mechanism, 25 ... Keyboard, 26 ... Stator, 27 ... Analysis flow path, 28 ... Drain valve (conventional type), 29 ... Drain valve (improved type) ), 30 ... Solvent filter, 31 ... Tightening screw, 32 ... Mounting panel.

Claims (2)

[Claims] 1. A drain valve provided between an outlet of a liquid-sending pump of a liquid chromatograph and an injector, which passes to the injector via a pressure sensing portion of a pressure sensor for sensing the pressure in a pipe flow path. Features a piping channel system that has a channel and a drain channel for drainage, and has a structure that can be freely opened and closed by a switching seal provided in the channel and the channel in an integrated block The drain valve of the liquid feed pump for liquid chromatography. 2. The switching seal provided in the flow path has a switching drive mechanism and a control circuit, and is capable of freely opening and closing by itself and externally. Drain valve of the liquid feed pump for liquid chromatography.