CN217006011U - Calibration device of turbine flowmeter - Google Patents

Abstract

The application provides a calibration equipment of turbine flowmeter, including steady voltage pond and measuring cell. And the tank wall of the pressure stabilizing tank is provided with a liquid inlet for injecting a checking medium into the pressure stabilizing tank. The measuring tank and the pressure stabilizing tank are arranged adjacently and communicated with each other through an overflow groove formed in the tank wall, an upper liquid level sensor and a lower liquid level sensor with height difference are arranged in the measuring tank, the checking medium overflows from the overflow groove and is poured into the measuring tank, and the lower liquid level sensor and the upper liquid level sensor respectively detect liquid level information in the measuring tank and send the liquid level information to an external controller. The utility model provides a calibration equipment is through setting up parts such as level sensor and lower level sensor to the level value in to the measuring tank carries out the record with data parameters such as the time of flowing through, compares artifical reading and the mode of timing more reliable and accurate, can guarantee the calibration accuracy better.

Description

Calibration device of turbine flowmeter

Technical Field

The application relates to the technical field of flowmeter verification devices, in particular to a verification device of a turbine flowmeter.

Background

In the existing calibration device of the turbine flowmeter, a measuring container consists of three main tank bodies of a pressure stabilizing tank, a measuring tank and an overflow tank, and the three tanks are sequentially attached to one another by the same wall and are respectively provided with overflow ports. And a liquid level measuring scale is arranged on the side wall of the measuring tank. During measurement, the check medium flows from the pressure stabilizing pool to the measuring pool, and timing is started at the moment. And when the water to be detected rises to the overflow ports of the measuring pool and the overflow pool and flows out, timing is finished. At this time, the flow rate of the check medium flowing through the turbine flowmeter to be tested is calculated by measuring the water amount and the time of the check medium flowing through the turbine flowmeter to be tested. And calculating the value of the current which should be theoretically output by the turbine flowmeter at the flow according to the flow of the verification medium flowing through the turbine flowmeter, the calibration range of the turbine flowmeter to be verified and the calibration output current of the turbine flowmeter. And after a checker calculates the value of the output current theoretically corresponding to a certain flow, the checker adjusts the value of the output current of the turbine flowmeter, so that the checking work of the turbine flowmeter is completed.

However, when the water flow is detected to be injected into the measuring pool in the checking process, the liquid level measuring scale is observed by the naked eyes, and the recording and timing are manually carried out, so that errors and time difference exist, and the checking accuracy is greatly reduced.

SUMMERY OF THE UTILITY MODEL

The application provides a calibration equipment of turbine flowmeter, through be equipped with last level sensor and lower level sensor that have the difference in height in measuring tank, make operations such as liquid level reading, record, timing all can realize automaticly to solve the big technical problem of manual operation error among the prior art.

The application provides a calibration equipment of turbine flowmeter, including steady voltage pond and measuring cell.

And the tank wall of the pressure stabilizing tank is provided with a liquid inlet for injecting a checking medium into the pressure stabilizing tank.

The measuring tank and the pressure stabilizing tank are arranged adjacently and communicated with each other through an overflow groove formed in the tank wall, an upper liquid level sensor and a lower liquid level sensor with height difference are arranged in the measuring tank, the checking medium overflows from the overflow groove and is poured into the measuring tank, and the lower liquid level sensor and the upper liquid level sensor respectively detect liquid level information in the measuring tank and send the liquid level information to an external controller.

According to the calibration device of the turbine flowmeter, the upper liquid level sensor, the lower liquid level sensor and other components are arranged, so that data parameters such as a liquid level value, flow-through time and the like in the measuring pool are recorded, compared with manual reading and timing modes, the calibration device is more reliable and accurate, and the calibration accuracy can be better guaranteed; meanwhile, the data parameters are measured through an automatic component, and the labor intensity of workers is also reduced.

In addition, the measuring tank and the pressure stabilizing tank are communicated through the overflow groove, the checking medium is injected into the measuring tank in an overflow mode, air bubbles can be prevented from being generated when liquid is injected into the measuring tank, and therefore errors of the degree of the liquid level sensor caused by the fact that the air bubbles are contained in the checking medium are avoided, and checking accuracy is further improved.

In addition, the double liquid level sensors are adopted for measuring to measure the liquid level height of the middle end, the influence of irregular bottom space volume of the measuring pool and residual volume in the valve on the measured volume is not needed to be considered, and the interference factors in the measuring process are reduced.

In a possible design, a turbulence member is arranged in the pressure stabilizing pool, and the arrangement position of the turbulence member is higher than the liquid inlet.

In one possible design, the turbulence member is a grid mesh made of acrylic.

In a possible design mode, a liquid outlet for discharging the checking medium is formed in the bottom of the pressure stabilizing pool, and the liquid outlet is provided with a first valve.

In one possible embodiment, the first valve is a solenoid valve which can be actuated by the control unit.

In a possible design mode, a monitoring liquid level sensor which is higher than the upper liquid level sensor and lower than the overflow groove is further arranged in the measuring tank, and liquid level information in the measuring tank is detected by the monitoring liquid level sensor and is sent to the controller.

In a possible design mode, a liquid outlet is formed in the bottom of the measuring pool, and a second valve is arranged on the liquid outlet.

In one possible embodiment, the second valve is a solenoid valve that can be actuated by the controller.

In one possible embodiment, the bottom of the measuring tank has a slope surface that gradually slopes downward toward the drain opening.

In a possible design, the pool bottom of the pressure stabilizing pool has a slope surface which gradually inclines downwards towards the liquid outlet.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.

FIG. 1 is a schematic diagram of an example of a turbine flow meter prover provided by an embodiment of the present application;

FIG. 2 is a schematic connection diagram of an upper liquid level sensor, a lower liquid level sensor and a controller provided in the embodiments of the present application;

fig. 3 is a schematic connection diagram of the monitoring liquid level sensor, the controller and the second valve provided in the embodiment of the present application.

Reference numerals are as follows: 10. a pressure stabilizing pool; 11. a liquid inlet; 12. a turbulence member; 13. a liquid outlet; 20. a measuring cell; 21. an overflow trough; 22. an upper liquid level sensor; 23. a lower liquid level sensor; 24. monitoring a liquid level sensor; 25. a liquid discharge port; 26. a controller; 27. and a second valve.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise. In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can include, for example, fixed connections, removable connections, or integral parts; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through intervening media. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature "under," "beneath," and "under" a second feature may be directly under or obliquely under the second feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description of the present application, it is to be understood that the terms "inner," "outer," "upper," "bottom," "front," "back," and the like, when used in the orientation or positional relationship indicated in FIG. 1, are used solely for the purpose of facilitating a description of the present application and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be considered as limiting the present application.

It should be noted that the same reference numerals are used to denote the same components or parts in the embodiments of the present application, and for the same parts in the embodiments of the present application, only one of the parts or parts may be given the reference numeral, and it should be understood that the reference numerals are also applicable to the other same parts or parts.

The turbine flowmeter is the main type of speed flowmeter, when the measured fluid flows through the turbine flowmeter sensor, the impeller is forced to rotate under the action of the fluid, the rotating speed of the impeller is in direct proportion to the average flow speed of the pipeline, meanwhile, the blades periodically cut the magnetic force lines generated by the electromagnet, the magnetic flux of the coil is changed, according to the electromagnetic induction principle, a pulsating potential signal, namely an electric pulse signal, is induced in the coil, the frequency of the electric pulse signal is in direct proportion to the flow of the measured fluid, and the flow of the fluid can be measured through the relationship. The turbine flowmeter has the advantages of simple structure, light weight, large flow capacity and the like, and is widely applied to the following measurement objects: petroleum, organic liquids, inorganic liquids, liquefied gases, natural gases, coal gases, cryogenic fluids, and the like.

The turbine flowmeter inevitably generates the problems of scaling, bearing abrasion, internal clearance change and the like in long-term operation, and simultaneously, in the measurement process, the turbine rotating speed corresponding to the same flow rate is different along with the change of the physical properties of the medium such as the temperature, the pressure, the density, the viscosity and the like of the measured medium. Therefore, turbine flow meters need to be serviced and verified periodically.

In some special fields, for example, to overhaul the fuel turbine flowmeter in the auxiliary boiler room in the nuclear power station, because there is no standard instrument, the maintainer can only carry out zero calibration to the turbine flowmeter when overhauing it, and can not check its measuring range, so at the overhaul scene, can't accomplish the check-up work of turbine flowmeter, can only carry out maintenance calibration to the original factory.

In order to solve the problem, a device capable of verifying a turbine flowmeter on site appears in the prior art, and the device mainly comprises a pressure stabilizing tank, a measuring tank and three main tank bodies of an overflow tank, wherein the three tank bodies are sequentially attached to the same wall, and are respectively provided with an overflow port. And a liquid level measuring scale is arranged on the side wall of the measuring tank. During measurement, the check medium flows from the pressure stabilizing pool to the measuring pool, and timing is started at the moment. And when the water to be detected rises to the overflow ports of the measuring tank and the overflow tank and flows out, timing is finished. At this time, the flow rate of the check medium flowing through the turbine flowmeter to be tested is calculated by measuring the water amount and the time of the check medium flowing through the turbine flowmeter to be tested. And calculating the value of the current which should be theoretically output by the turbine flowmeter at the flow according to the flow of the verification medium flowing through the turbine flowmeter, the calibration range of the turbine flowmeter to be verified and the calibration output current of the turbine flowmeter. And after the calibration personnel calculates the value of the output current theoretically corresponding to a certain flow, the calibration personnel adjusts the value of the output current of the turbine flowmeter, so that the calibration work of the turbine flowmeter is completed.

However, when the water flow is detected to be injected into the measuring pool in the checking process, the liquid level measuring scale is observed by the naked eyes, and the recording and timing are manually carried out, so that errors and time difference exist, and the checking accuracy is greatly reduced.

Therefore, the application provides a calibration equipment of turbine flowmeter, through last level sensor and lower level sensor that is equipped with the difference in height in the measuring pond, makes operations such as liquid level reading, record, timing all can realize automaticly to solve the big technical problem of manual operation error among the prior art.

Fig. 1 is a schematic diagram of an example of a turbine flowmeter verification device according to an embodiment of the present application. Fig. 2 is a schematic connection diagram of the upper liquid level sensor 22, the lower liquid level sensor 23, and the controller 26 provided in the embodiment of the present application.

As shown in fig. 1 and fig. 2, a calibration apparatus for a turbine flowmeter according to an embodiment of the present application includes a pressure stabilizing pool 10 and a measurement pool 20.

The pool wall of the pressure stabilizing pool 10 is provided with a liquid inlet 11 for injecting a checking medium into the pressure stabilizing pool 10, the liquid inlet 11 can be connected with a liquid storage pool storing the checking medium through a pipeline, a turbine flowmeter to be checked is arranged on the pipeline in front of the liquid inlet 11, and the checking medium in the liquid storage pool sequentially flows through the turbine flowmeter to be checked and the liquid inlet 11 through a pump and then is injected into the pressure stabilizing pool 10.

The measuring tank 20 and the pressure stabilizing tank 10 are arranged adjacently, overflow grooves 21 are formed in the tank walls of the measuring tank 20 and the pressure stabilizing tank 10, the measuring tank 20 is communicated with the pressure stabilizing tank 10, an upper liquid level sensor 22 and a lower liquid level sensor 23 with height differences are arranged in the measuring tank 20, a checking medium in the pressure stabilizing tank 10 overflows from the overflow grooves 21 and is filled into the measuring tank 20, and the lower liquid level sensor 23 and the upper liquid level sensor 22 respectively detect liquid level information in the measuring tank 20 and send the liquid level information to an external controller 26.

The cross-sectional area of the measuring cell 20 is a fixed value S, the liquid level height h1 measured by the lower liquid level sensor 23 and the liquid level height h2 measured by the upper liquid level sensor 22, and the time for the verification medium to flow through the lower liquid level sensor 23 and the upper liquid level sensor 22 is t, then the controller 26 obtains the flow rate Q of the verification medium through calculation, wherein the flow rate Q is V/t (h2-h1) S/t, and the verification is performed after the comparison with the flow rate measured by the turbine flowmeter to be verified on the pipeline.

According to the verification device of the turbine flowmeter, the upper liquid level sensor 22, the lower liquid level sensor 23 and other components are arranged to record data parameters such as a liquid level value and flowing time in the measuring pool 20, compared with manual reading and timing modes, the verification device is more reliable and accurate, and verification accuracy can be better guaranteed; meanwhile, the data parameters are measured through an automatic component, and the labor intensity of workers is also reduced.

In addition, the measuring cell 20 and the pressure stabilizing cell 10 are communicated through the overflow groove 21, and the checking medium is injected into the measuring cell 20 in an overflow mode, so that bubbles can be prevented from being generated when the liquid is injected into the measuring cell 20, errors of degrees of the liquid level sensor caused by bubbles contained in the checking medium can be avoided, and checking accuracy is further improved.

In addition, the double liquid level sensors are adopted for measuring the liquid level height of the middle end, the irregular volume of the bottom space of the measuring pool 20 and the influence of the residual volume in the valve on the measured volume do not need to be considered, and the interference factors in the measuring process are reduced.

Alternatively, the upper limit level sensor and the lower limit level sensor may be commercially available ball float laser level gauges, laser level sensors, hydrostatic drop-in level sensors, etc., with in-situ display and HART protocols for connection to the controller 26.

Alternatively, the controller 26 may be a PLC, a PC, or the like.

Alternatively, the lower level sensor 23 is located at a distance from the bottom of the measuring cell 20.

Alternatively, the upper level sensor 22 and the lower level sensor 23 are sized themselves, thus resulting in the upper level sensor 22 and the lower level sensor 23 having a certain intrusion volume r within the verification medium, resulting in the finally calculated volume V having a certain error, and thus, this portion of the intrusion volume r can be subtracted during the flow calculation. The specific formula is Q ═ V-r)/t ═ h2-h 1S-r ]/t.

Alternatively, the verification medium may be water, oil, solution or a mixture of the three.

Optionally, an overflow pool can be additionally arranged on one side of the measuring pool 20 away from the pressure stabilizing pool 10, so that the risk of liquid overflow is reduced, and the safety performance is improved; alternatively, an overflow-preventing monitoring device is added to the measuring cell 20, as described in detail in the following examples.

In one embodiment, the turbulence member 12 is disposed in the surge tank 10, and the turbulence member 12 is disposed at a position higher than the liquid inlet 11.

In this embodiment, a turbulent member 12 is disposed in the pressure stabilizing tank 10, and the turbulent member 12 is disposed on the upper side of the liquid inlet 11 for stabilizing the liquid level of the fluid and reducing the fluctuation of the water level.

Alternatively, the turbulators 12 may be a mesh-like structure, a sheet-like structure, or the like.

In one embodiment, the turbulence member 12 is a grid mesh made of acrylic.

The material of the turbulence member 12 is selected to satisfy the following points: firstly, the water is not absorbed, no residue is left, and the reaction with the liquid to be detected is avoided; secondly, the density is larger than the density of the measured liquid. Therefore, in the embodiment, the turbulent component 12 is made of a transparent acrylic material, and the acrylic material has the characteristics of low price, high transparency (convenient for observing the bottom of the pool), strong hardness, corrosion resistance, insolubility in water, and the like.

The turbulence member 12 of the grid mesh structure has the best effect of stabilizing the fluid level and reducing the water level fluctuation.

In one embodiment, a liquid outlet 13 for discharging the calibration medium is formed in the bottom of the pressure stabilization tank 10, and the liquid outlet 13 is provided with a first valve.

In this embodiment, in order to facilitate emptying of the residual checking medium in the pressure stabilization tank 10 after the measurement is completed, the tank bottom of the pressure stabilization tank 10 is provided with the liquid outlet 13, and the liquid outlet 13 may be directly aligned to the water tank for discharging, or may be connected to the liquid storage tank through a pipeline to circulate the residual checking medium.

Alternatively, valve one may be a manual valve, operated manually.

In one embodiment, valve one is a solenoid valve that may be actuated by controller 26.

In this embodiment, the valve is a solenoid valve that is driven by the controller 26 to increase the level of automation and reduce the labor intensity.

In one embodiment, a monitor level sensor 24 is further disposed in the measuring tank 20 and is located above the upper level sensor 22 and below the overflow tank 21, and the monitor level sensor 24 detects the level information in the measuring tank 20 and sends the level information to the controller 26.

In this embodiment, in order to monitor the liquid level of the calibration medium in the measurement tank 20 in real time, reduce the risk of liquid overflow, and increase safety performance, the monitoring liquid level sensor 24 is disposed at a position higher than the upper liquid level sensor 22 and lower than the overflow tank 21 in the measurement tank 20, if the liquid level of the calibration medium reaches the monitoring liquid level sensor 24, the monitoring liquid level sensor 24 sends information to the controller 26, and the controller 26 sends an alarm to the outside to inform a person in the central control room to perform a corresponding operation, such as closing the liquid inlet 11 of the pressure stabilization tank 10.

Alternatively, the monitoring level sensor 24 may be a commercially available ball float laser level gauge, laser level sensor, hydrostatic drop-in level sensor, or the like, having an in-situ display and HART protocol for connection to the controller 26.

In one embodiment, the measuring cell 20 has a liquid outlet 25 at the bottom, and the liquid outlet 25 is provided with a second valve 27.

In this embodiment, in order to facilitate evacuation of the residual calibration medium in the measurement pool 20 after the measurement is completed, or to avoid danger in time when overflow occurs, the liquid outlet 13 is provided at the bottom of the measurement pool 20, and the liquid outlet 13 may be directly aligned to the water tank for discharge, or may be connected to the liquid storage pool through a pipeline to circulate the residual calibration medium.

Alternatively, the second valve 27 may be a manual valve, which is operated manually.

In one embodiment, the second valve 27 is a solenoid valve that can be actuated by the controller 26.

In this embodiment, the second valve 27 is an electromagnetic valve driven by the controller 26 to improve the automation level and reduce the labor intensity.

Fig. 3 is a schematic diagram illustrating the connection of the monitoring liquid level sensor 24, the controller 26 and the second valve 27 according to the embodiment of the present application.

As mentioned above, an anti-overflow monitoring device may be added to the measuring cell 20. That is, in this embodiment, as shown in fig. 3, the second valve 27, the controller 26, the monitoring liquid level sensor 24, and the like constitute a monitoring device, and if the monitoring liquid level sensor 24 monitors that the liquid level has an overflow risk, the liquid level information is sent to the controller 26, and the second valve 27 is driven by the controller 26 to open, so as to automatically discharge the verification medium in the measurement tank 20 in time.

Compared with the prior art, the overflow tank needs to be added to reduce the risk of liquid overflow, the monitoring device is adopted to replace the overflow tank in the embodiment, the whole volume of the checking device can be greatly reduced, and the automatic part can drain water more quickly and conveniently, so that the safety performance is further improved.

In one embodiment, the bottom of the measuring tank 20 has a slope that gradually slopes downward toward the drain port 25.

In this embodiment, in order to facilitate evacuation of the residual calibration medium in the measurement tank 20, the tank bottom has a slope surface gradually inclining downward toward the drain port 25.

Specifically, the bottom slope of the measuring cell 20 is about 15 °.

In one embodiment, the bottom of the pressure stabilizing tank 10 has a slope surface gradually inclined downwards towards the liquid outlet 13.

In this embodiment, in order to facilitate emptying of the residual checking medium in the pressure stabilizing tank 10, the tank bottom has a slope surface gradually inclined downward toward the liquid outlet 13.

Specifically, the slope of the bottom of the pressure stabilization tank 10 is about 15 °.

The verification device of the turbine flowmeter in the embodiment of the application comprises the following specific implementation methods:

when the measurement work is needed, the liquid outlet 13 of the pressure stabilizing pool 10 and the liquid outlet 25 of the measurement pool 20 are closed. Then, the detection is started, the checking medium flows into the pressure stabilizing pool 10 through the liquid inlet 11 of the pressure stabilizing pool 10 and continues to rise after overflowing the turbulent flow member 12, when the liquid level overflows the overflow groove 21, the liquid level flows into the measuring pool 20, the liquid level rises in the measuring pool 20, when the liquid level overflows the lower liquid level sensor 23, the timing is triggered to start, the liquid level continues to rise, when the liquid level overflows the upper liquid level sensor 22, the timing is triggered to end, and the time t is recorded. At which point the measurement action is complete. Manual termination may be selected and automatic termination triggered. The conditions for triggering the automatic ending are that when the liquid level rises to the monitoring liquid level sensor 24, the automatic draining function is triggered, the liquid inlet 11 of the pressure stabilizing pool 10 is closed, and the liquid outlet 13 of the pressure stabilizing pool 10 and the liquid outlet 25 of the measuring pool 20 are opened. When the liquid level is completely emptied, the measurement is finished. The height difference deltah between the liquid level sensor 23 and the upper liquid level sensor 22 is recorded by the detection personnel, and the cross-sectional area S of the tank wall of the measuring tank 20 is measured. And calculating the volume V of the checking medium as S delta h. The flow Q of the measured piece is V/t and S delta h/t.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (10)

1. A verification device for a turbine flow meter, comprising:

the pressure stabilizing pool (10), the pool wall is equipped with a liquid inlet (11) for injecting the checking medium into the pressure stabilizing pool (10);

the device comprises a measuring pool (20), the measuring pool is arranged adjacent to the pressure stabilizing pool (10) and is communicated with the pressure stabilizing pool (10) through an overflow groove (21) formed in the pool wall, an upper liquid level sensor (22) and a lower liquid level sensor (23) with height difference are arranged in the measuring pool (20), the checking medium overflows from the overflow groove (21) and is poured into the measuring pool (20), and the lower liquid level sensor (23) and the upper liquid level sensor (22) respectively detect liquid level information in the measuring pool (20) and send the liquid level information to an external controller (26).

2. The verifying device according to claim 1, characterized in that a turbulence member (12) is arranged in the pressure stabilizing pool (10), and the turbulence member (12) is arranged at a position higher than the liquid inlet (11).

3. The verification device according to claim 2, wherein the turbulence member (12) is a grid mesh made of acrylic.

4. The checking apparatus according to claim 1, wherein a liquid outlet (13) for discharging the checking medium is formed at a bottom of the pressure stabilizing tank (10), and the liquid outlet (13) is provided with a first valve.

5. The verification device according to claim 4, wherein the first valve is a solenoid valve actuatable by the controller (26).

6. The verifying device according to any one of claims 1-5, wherein a monitoring level sensor (24) is further disposed in the measuring tank (20) and is positioned above the upper level sensor (22) and below the overflow tank (21), and the level information in the measuring tank (20) is detected by the monitoring level sensor (24) and sent to the controller (26).

7. The verification device according to claim 6, wherein a liquid discharge port (25) is formed in the bottom of the measuring cell (20), and a second valve (27) is arranged at the liquid discharge port (25).

8. The verification device according to claim 7, wherein the second valve (27) is a solenoid valve actuatable by the controller (26).

9. The verification device according to claim 7, wherein the bottom of the measuring cell (20) has a slope gradually sloping downward toward the drain port (25).

10. The checking apparatus according to claim 4 or 5, wherein the bottom of the pressure stabilizing tank (10) has a slope surface gradually inclined downwards towards the liquid outlet (13).

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