Liquid sample feeding device of Karl Fischer moisture meter

Abstract

The utility model provides a Karl Fischer moisture meter liquid sample feeding device which comprises a reaction cup body, a fixing ring is fixed above the outer wall of the reaction cup body, a fixing plate is fixed on the inner side of the fixing ring, the fixing plate is connected with the top of the reaction cup body, the top of the fixing plate extends to the position above the fixing ring, and a sample feeding port is formed in the top of the fixing plate. A sample adding plug is in threaded connection with the inner side of the sample inlet, a needle hole is formed in the bottom of the sample adding plug, a threaded groove communicated with the needle hole is formed in the top of the sample adding plug, and a threaded connector is in threaded connection with the interior of the threaded groove. According to the utility model, a gap between the syringe needle and the sample inlet can be effectively avoided, external moisture is prevented from entering the reaction cup to influence a detection result, and when a sample in the syringe is injected into the reaction cup, the syringe needle of the syringe can be always kept in a vertically downward state, so that the situations such as shaking of the syringe needle are avoided, and the detection accuracy is improved. A sample is prevented from being in contact with the inner wall of the reaction cup when entering the reaction cup.

Description

Technical Field

[0001] The utility model relates to the technical field of sample injection devices, in particular to a liquid sample injection device for a Karl Fischer moisture analyzer. Background Art

[0002] The Karl Fischer moisture analyzer can be used to accurately analyze the crystal water, adsorbed water, and free water in solid, liquid, and gas samples, and can be widely used in many industries such as petroleum, chemical industry, pharmaceuticals, daily chemical industry, food, agriculture, and laboratories.

[0003] The Karl Fischer moisture determination method is a redox titration method in non-aqueous solution. The basic principle of the titration is that a certain amount of water is required to participate in the reaction when iodine oxidizes sulfur dioxide. The chemical reaction equation is as follows:

[0004] I2 + SO2 + 2H2O → 2HI + H2SO4

[0005] I2 + SO2 + H2O + 3RN + CH3OH → 2RNHI + RNSO4CH3

[0006] The Karl Fischer reagent contains molecular iodine and is dark brown. When a reagent or sample containing water is added, due to a chemical reaction, methyl sulfate compounds (RNSO4CH3) are generated, causing the solution to turn yellow. Therefore, the end point can be judged by the visual method, that is, from light yellow to orange. However, the visual method has a large error and will encounter trouble when measuring colored substances. Most national standards stipulate the use of the "dead-stop method" to determine the end point of the Karl Fischer reaction. The principle is as follows: A pair of platinum electrodes are inserted into the reaction solution, and a fixed voltage is applied between the two electrodes. If there is water in the solvent, there will be no electrode pair in the solution, and the solution will not conduct electricity. When the reaction reaches the end point, there are I2 and I- electrode pairs in the solution, that is: 2I- = I2 + 2e. Therefore, the conductivity of the solution will suddenly increase, and the current value between the pair of platinum electrodes with an applied voltage will suddenly increase and stabilize at a signal value we set in advance, and then it can be judged that the titration end point has been reached, and the machine will automatically stop titration, and then the water content of the sample can be calculated by the volume of the consumed KF reagent.

[0007] However, in actual operation, because the injection port diameter of the instrument reaction cup is relatively large, there is a large gap between the syringe needle and the injection port during the injection process, resulting in moisture in the external environment entering the reaction cup, thus increasing the drift value and affecting the test result; at the same time, due to the large injection port diameter, the injection needle is prone to shaking, causing the sample to be thrown onto the inner wall of the reaction cup along with the shaking of the needle, affecting the test result. Content of the Utility Model

[0008] The utility model discloses a liquid sample injection device for a Karl Fischer moisture analyzer, which solves the problems that the injection port diameter of the reaction cup of the instrument is too large, there is a large gap between the syringe needle and the injection port, resulting in moisture in the external environment entering the reaction cup and affecting the detection result. At the same time, the injection needle is prone to shaking, causing the sample to be thrown onto the inner wall of the reaction cup with the shaking of the needle and affecting the detection result.

[0009] To solve the above technical problems, the utility model specifically adopts the following technical solutions:

[0010] A liquid sample injection device for a Karl Fischer moisture analyzer includes a reaction cup body. A fixing ring is fixed above the outer wall of the reaction cup body. Inside the fixing ring, a fixing plate connected to the top of the reaction cup body and extending above the fixing ring is fixed. An injection port is opened at the top of the fixing plate. A sample addition plug is threadedly connected inside the injection port. A needle hole is opened at the bottom of the sample addition plug. A threaded groove communicating with the needle hole is opened at the top of the sample addition plug. A threaded joint is threadedly connected in the threaded groove.

[0011] Compared with the prior art, the utility model has the following beneficial effects:

[0012] When the staff needs to add a sample into the reaction cup body, the threaded joint can be removed, and then the needle of an external syringe containing the sample is inserted into the needle hole on the sample addition plug through the threaded groove. After the needle of the syringe passes through the needle hole, the inner wall of the needle hole on the sample addition plug contacts the outer wall of the syringe needle, which can limit the position of the needle, prevent the needle from shaking randomly, keep the needle in a vertically downward state all the time, and effectively play a sealing role. The utility model can effectively avoid the gap between the syringe needle and the injection port, prevent external moisture from entering the reaction cup and affecting the detection result. When injecting the sample in the syringe into the reaction cup, the needle of the syringe can always be kept in a vertically downward state, avoiding the situation of the syringe needle shaking, and preventing the sample from contacting the inner wall of the reaction cup when entering the reaction cup. Description of the Drawings

[0013] Figure 1 It is a front view structural schematic diagram of the utility model;

[0014] Figure 2 It is a top view structural schematic diagram of the fixing plate of the utility model;

[0015] Figure 3 It is a cross-sectional structural schematic diagram of the sample addition plug of the utility model;

[0016] Figure 4 It is a structural schematic diagram showing the threaded joint of the utility model.

[0017] In the figure: 1. Reaction cup body; 2. Fixed ring; 3. Fixed plate; 4. Sampling port; 5. Sampling plug; 6. Thin tube; 7. Threaded groove; 8. Threaded joint; 9. Connecting column; 10. Magnet; 11. Connecting ring; 12. Jack; 13. Protective ring; 14. Annular groove; 15. Rubber seat. Detailed implementation manner

[0018] The following will combine the accompanying drawings and embodiments to elaborate in detail on the specific content of the present utility model.

[0019] As Figure 1 , Figure 2 , Figure 3 and Figure 4 shown, the present utility model provides a liquid sample injection device for a Karl Fischer moisture analyzer, including a reaction cup body 1. A fixed ring 2 is fixed above the outer wall of the reaction cup body 1. Inside the fixed ring 2, a fixed plate 3 is fixed, which is connected to the top of the reaction cup body 1 and extends above the fixed ring 2 at the top. A sampling port 4 is opened at the top of the fixed plate 3. A sampling plug 5 is threadedly connected inside the sampling port 4. A needle hole is opened at the bottom of the sampling plug 5, and a threaded groove 7 communicating with the needle hole is opened at the top of the sampling plug 5. A threaded joint 8 is threadedly connected in the threaded groove 7.

[0020] As Figure 1 , Figure 2 and Figure 4 shown, a connecting ring 11 that is threadedly connected and contacts the top of the fixed ring 2 is sleeved on the fixed plate 3. A jack 12 is opened at the top of the connecting ring 11, and an iron plate is fixed at the bottom inside the jack 12. A connecting column 9 is fixed at the top of the threaded joint 8, and a magnet 10 is fixed at the top of the connecting column 9. After the connecting ring 11 is threadedly connected to the fixed plate 3, when the staff removes the threaded joint 8 through the connecting column 9, the magnet 10 can be inserted into the jack 12, so that the magnet 10 contacts the iron plate inside the jack 12, and the magnet 10 is adsorbed on the iron plate, playing a role in fixing the threaded joint 8, preventing the threaded joint 8 from falling to the ground or being lost, and facilitating the subsequent staff to quickly remove the threaded joint 8 and then restore the threaded joint 8.

[0021] As Figure 3As shown, a thin tube 6 is inserted into the needle hole on the sample addition plug 5. The thin tube 6 includes a vertical pipe and an annular plate. The annular plate is located at the bottom inside the thread groove 7. The outer wall of the pipe is fixed on the inner ring surface of the annular plate. After the annular plate is placed into the thread groove 7, the pipe is inserted into the needle hole on the sample addition plug 5, playing a role in fixing the pipe. Subsequently, when the staff inserts the needle of the syringe into the thin tube 6, it can prevent the needle of the syringe from being inserted into the inner wall of the needle hole on the sample addition plug 5 due to the operation error of the staff (the sample addition plug 5 is made of rubber). The thin tube 6 is made of hard metal material. After the needle is inserted into the thin tube 6, it contacts the inner wall of the thin tube 6, and the situation that the needle is inserted into the inner wall of the thin tube 6 will not occur, ensuring that the needle can smoothly pass through the thin tube 6 and enter the reaction cup body 1.

[0022] As Figure 2 and Figure 3 shown, a protective ring 13 is threadedly connected to the top of the fixed plate 3, and the sample inlet 4 is located inside the protective ring 13; an annular groove 14 adapted to the protective ring 13 is provided on the sample addition plug 5. When the staff removes the sample addition plug 5, the protective ring 13 can prevent external moisture or impurities from entering the reaction cup body 1 through the sample inlet 4; when the sample addition plug 5 is threadedly connected to the sample inlet 4, the protective ring 13 is inserted into the annular groove 14, which can further seal the sample inlet 4.

[0023] As Figure 1 shown, a rubber seat 15 is fixed to the bottom of the reaction cup body 1. The rubber seat 15 can increase the stability of the reaction cup body 1 when placed.

[0024] During use, when it is necessary to inject the sample in the external syringe into the reaction cup body 1, only need to remove the threaded joint 8, first insert the needle of the external syringe into the thread groove 7, and then make the needle continue to pass through the needle hole on the sample addition plug 5. The inner wall of the needle hole contacts the outer wall of the needle, effectively limiting the needle and keeping the needle in a vertically downward state all the time. When injecting the sample in the syringe into the reaction cup body 1, the needle will not shake, and there will be no excessive gap between the needle and the needle hole, preventing external moisture or impurities from entering the reaction cup body 1; after the sample injection is completed, the threaded joint 8 can be restored to seal the thread groove 7 and the needle hole.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A liquid sample injection device for a Karl Fischer titrator, comprising a reaction cup body (1), characterized in that: A fixing ring (2) is fixed above the outer wall of the reaction cup body (1); a fixing plate (3) connected to the top of the reaction cup body (1) and extending to the top of the fixing ring (2) is fixed inside the fixing ring (2); a sample injection port (4) is provided on the top of the fixing plate (3); a sample injection plug (5) is threadedly connected to the inside of the sample injection port (4); a pinhole is provided at the bottom of the sample injection plug (5); a thread groove (7) connected to the pinhole is provided at the top of the sample injection plug (5); a threaded joint (8) is threadedly connected to the inner thread of the thread groove (7).

2. A liquid sample injection device for a Karl Fischer titrator according to claim 1, characterized in that: The fixing plate (3) is sleeved with a connecting ring (11) which is threadedly connected and contacts the top of the fixing ring (2); a plug hole (12) is provided at the top of the connecting ring (11); an iron plate is fixed at the bottom of the plug hole (12); a connecting column (9) is fixed at the top of the threaded joint (8); and a magnet (10) is fixed at the top of the connecting column (9).

3. The liquid sample injection device for a Karl Fischer titrator according to claim 1, characterized in that: A thin tube (6) is inserted into the pinhole on the sample adding plug (5).

4. The liquid sample injection device for a Karl Fischer moisture analyzer according to claim 1, characterized in that: The top of the fixing plate (3) is threadedly connected with a protective ring (13), and the sample inlet (4) is located on the inner side of the protective ring (13); and the sample adding plug (5) is provided with an annular groove (14) adapted to the protective ring (13).

5. The liquid sample injection device for a Karl Fischer titrator according to claim 1, characterized in that: A rubber seat (15) is fixed to the bottom of the reaction cup body (1).

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