KR20200101687A - Flow tube and gas meter comprising the same - Google Patents

Abstract

The present invention relates to a flow tube and a gas meter including the same. The gas meter comprises: a housing with a measuring space formed therein, and having an inlet and an outlet connected to the measuring space; and the flow tube defined in any one of claims 1 to 8 and located in the measurement space to be connected to the outlet. The flow tube comprises: a tube body which has a flow channel having an inlet and an outlet and passing therethrough; a pressure dropping unit which is disposed on the flow channel and in which a plurality of circular flow holes are formed to connect the inlet and the outlet; a sensor arrangement part formed on the tube body and having an arrangement space; a bypass channel formed on the sensor arrangement part and bypassing the flow of fluid flowing through the flow channel; and a filter part disposed at the inlet of the flow channel. Some of the fluid energy introduced into and flowing in the flow channel bypasses the pressure dropping unit through the bypass channel and is merged and discharged at the outlet.

Description

Flow tube and gas meter comprising the same

The present invention relates to a flow tube and a gas meter including the same.

The conventional gas meter metering method consists of the following volume equation. The volume equation is as follows.

Meter reading (m ³ )

Actual use capacity (m ³ ) = Reading amount (m ³ ) Ⅹ Temperature and pressure correction factor

Used calories (MJ) = Actual capacity (m ³ ) Ⅹ Unit calories (MJ/m ³ )

Charge (won) = Energy used (MJ) Ⅹ Unit price of heat (won/MJ)

Install the temperature-pressure compensator with the volume type as above and perform the temperature-pressure compensation using Boyle-Charles' Law. And it is a method of charging a fee by applying an energy conversion factor. Since the metering method uses a volumetric flowmeter that reads pulses and linearly corrects it, an error in actual energy use occurs. Due to the error, a fee dispute between the user and the supplier occurs.

Accordingly, there is a demand for the development of a gas meter for measuring mass energy from a volumetric type, but still has not deviated from the existing volumetric type.

And, in the case of high value-added flowmeters, according to the Korea International Trade Association's import and export statistics, the trade volume has averaged 7% growth since 2001, but in 2014, exports were 17,200 thousand dollars, imports 11,900 thousand dollars, and deficits were 5,300. It is recording a deficit of $1,000. In other words, the trade balance deficit of gas flow meters, including gas meters, has a very weak trade structure that is comparable to the size of exports, so the domestic economy is protected and exports revitalized by commercialization of the source technology for flow measurement of the most commonly used household gas meters. There is a need for economic and industrial structural improvement.

In order to secure the metering reliability of the energy output gas meter, stability of the flow rate must be secured over a wide flow range, and for this, it is necessary to improve the pressure drop element inserted into the flow tube.

Registration Utility Model No. 20-0432331 (2006.11.24.) Registered Patent No. 10-1536582 (2015.07.08.)

The present invention provides a gas meter in which a flow tube having high measurement accuracy and excellent reproducibility is applied in a mass gas meter.

The flow tube according to an embodiment of the present invention is a tube body through which a flow channel having an inlet and an outlet passes through the inside, and a plurality of circular flow holes connecting the inlet and the outlet are formed in the flow channel. Pressure drop, a sensor arrangement part formed in the tube body and having an arrangement space, a bypass passage formed in the sensor arrangement part and bypassing the flow of fluid flowing through the flow passage, and a filter disposed at the inlet of the flow passage Includes wealth.

Some of the fluid energy flowing into the flow channel may bypass the pressure drop through the bypass channel and merge at the outlet to be discharged.

The bypass passage may include a sensor passage formed at the bottom of the arrangement space, a first capillary connecting the inlet and one end of the sensor passage, and a second capillary connecting the outlet and the other end of the sensor passage.

A coating layer may be formed on the bypass channel.

The flow tube may further include a sensor unit disposed in the arrangement space.

The sensor unit may include a thermal sensor.

The pressure drop may be positioned between the first capillary tube and the second capillary tube in the flow passage, and the flow hole may be radially arranged based on an imaginary center of the pressure drop.

The flow tube may further include a suction nozzle connected to an inlet of the flow channel.

The inner circumference diameter of the suction nozzle may gradually increase as the distance from the tube body increases.

The flow tube may further include a guide blade arranged in a circumferential direction around the inner circumference of the suction nozzle and allowing an incoming fluid to be uniformly introduced.

A gas meter according to an embodiment of the present invention includes a housing having a measuring space formed therein and having an inlet and an outlet connected to the measuring space, and a flow tube located in the measuring space and connected to the outlet.

The gas meter may further include a filter member disposed at the inlet.

According to an embodiment of the present invention, impurities contained in fluid energy are not introduced into the flow channel by the filter unit disposed at the inlet of the flow channel. Thus, the fine bypass channel is not blocked by impurities. Fluidity can be improved by bypassing fluid energy.

According to an embodiment of the present invention, friction between the fluid energy and the bypass channel is minimized by the coating layer of the bypass channel, so that fluidity of the fluid energy can be improved. Moreover, self-cleaning can be achieved by the coating layer.

According to an exemplary embodiment of the present invention, since the cross-sectional shape of the flow hole of the pressure drop was formed in a circular shape and arranged radially with respect to the center of the pressure drop, linear response was improved in a wide flow range and hysteresis characteristics were also excellent.

1 is a schematic diagram showing a gas meter according to an embodiment of the present invention.
Figure 2 is an enlarged view showing the flow tube of Figure 1;
Figure 3 is an exploded view of the flow tube of Figure 2;
Figure 4 is an enlarged view showing the bypass passage of Figure 3;
5 is a cross-sectional view of FIG. 3 taken along line VV.
6 is a schematic diagram showing a gas meter according to another embodiment of the present invention (fallopian tube)
7 is a flow analysis result diagram showing the velocity vector in the suction nozzle where the flow tube of FIG. 6 is located inside the housing.
8 is a flow analysis result diagram showing the pressure distribution in the suction nozzle in which the flow tube of FIG. 6 is located inside the housing.
Figure 9 is a front view showing the pressure drop of Figure 3;
10 to 12 are schematic diagrams showing a pressure distribution in the x plane of the discharge portion of the pressure drop of FIG. 9;
13 to 15 are schematic diagrams showing the pressure distribution in the z-plane within the tube body.
16 is a graph showing the front and rear pressures of the pressure drop according to the flow rate change.
17 is a graph showing the ratio of the mass flow rate at the inlet and the mass flow rate at the bypass channel according to the volume flow rate.
18 is a graph comparing measured values, which are electronic pulse values measured by a sensor unit.
19 is a graph in which the measured value is measured by increasing the flow rate with respect to the pressure drop, and conversely, by decreasing the flow rate.
20 is a schematic diagram showing a flow hole of a conventional pressure drop.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. The same reference numerals are assigned to similar parts throughout the specification.

A flow tube according to an embodiment of the present invention can be applied to a gas meter according to an embodiment of the present invention, and hereinafter, a gas meter to which a flow tube is applied will be mainly described.

Then, a gas meter according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4.

1 is a schematic diagram showing a gas meter according to an embodiment of the present invention, FIG. 2 is an enlarged view showing the flow tube of FIG. 1, FIG. 3 is an exploded view of the flow tube of FIG. 2, and FIG. 4 is a bypass of FIG. It is an enlarged view showing the flow path, and FIG. 5 is a cross-sectional view of FIG. 3 taken along line VV.

First, referring to FIG. 1, the gas meter 1 according to the present embodiment includes a housing 10 and a flow tube 20, and uses fluid energy in a mass manner so as not to cause a dispute between a fluid energy user and a supplier. Measure to prevent actual use errors. Here, the fluid energy may be natural gas, methane (CH ₄ ). It does not limit fluid energy to natural gas.

The housing 10 may be fixed to the wall by forming the outer shape of the gas meter. A measuring space 11 is formed inside the housing 10, and an inlet 11a and an outlet 11b connected to the measuring space 11 are formed on the upper surface. A supply pipe (not shown) for supplying fluid energy may be connected to the inlet 11a, and a use pipe (not shown) for supplying fluid energy to a user is connected to the outlet 11b. A filter member 12 having a mesh structure for removing impurities contained in fluid energy is disposed between the inlet 11a and the supply pipe. Accordingly, fluid energy from which impurities have been removed through the supply pipe and the inlet 11a is introduced into the measurement space 11 and supplied to the user through the outlet 11b and the use pipe. On the other hand, the front surface of the housing 10 is formed with a display unit 13 for displaying the amount of use.

Since a more detailed configuration of the housing 10 is the same as a gas meter of a known configuration, a detailed description will be omitted.

2 to 5, the flow tube 20 includes a tube body 21, a filter part 22, a sensor arrangement part 23, a bypass channel 25, and a pressure drop 26, and is measured. It is located in the space 11 and connected to the outlet 11b, and it measures fluid energy use as a mass measurement method to ensure flow rate repeatability and reproducibility.

The tube body 21 is connected to the outlet 11b in a state erected in the measurement space 11. A flow passage 211 connecting the measurement space 11 and the outlet 11b is formed inside the tube body 21. The fluid energy in the measurement space 11 may be introduced into the outlet 11b through the flow passage 211. The lower end of the tube body 21 forms an inlet 211a of the flow passage 211, and the upper end connected to the outlet 11b forms an outlet 211b. The tube body 21 may be made of metal.

The filter unit 22 is disposed at the inlet 211a and filters impurities contained in the fluid energy flowing into the flow channel 211. Impurities contained in fluid energy are removed in two steps through the filter member 12 and the filter unit 22, so that impurity filtering performance may be improved.

The filter part 22 has a mesh structure. Here, the diameter of the filter hole (not shown) does not exceed 0.5 mm. The diameter of the filter hole may be smaller than the diameter of the filter hole (not shown) of the filter member 12. The filter unit 22 is not limited to a mesh structure. It can be applied in various ways as long as it can filter impurities without disturbing the flow of fluid energy.

Meanwhile, the filter unit 22 may be separated from the inlet 211a of the flow path 211. Accordingly, the filter unit 22 can be inspected and replaced. When the filter unit 22 is damaged, the flow tube 20 is not completely replaced, but only the filter unit 22 is replaced, so that the cost of maintenance of the gas meter 1 can be reduced.

The sensor arrangement part 23 is formed on the outer surface of the tube body 21 and has a planar arrangement space 231 by a central portion of the upper surface being recessed. The sensor arrangement part 23 is formed in the center portion of the tube body 21 in the longitudinal direction. The formation position of the sensor arrangement part 23 may be variously changed according to the design of the flow tube 20.

The bypass channel 25 includes a sensor channel 251, a first capillary tube 252, and a second capillary tube 253, and is formed in a portion of the tube body 21 where the sensor arrangement unit 23 is located.

The sensor flow path 251 is formed by recessing the bottom of the arrangement space 231. The sensor flow path 251 is formed in a predetermined length along the length direction of the tube body 21 in the arrangement space 231.

The first capillary tube 252 connects one side of the sensor channel 251 and the flow channel 211. The diameter of the first capillary tube 252 is smaller than the diameter of the sensor flow path 251. Part of the fluid energy flowing into the flow channel 211 from the measurement space 11 through the inlet 211a may flow into the sensor channel 251 by bypassing the first capillary tube 252.

The second capillary tube 253 connects the other side of the sensor flow path 251 and the flow path 211. The diameter of the second capillary tube 253 is smaller than the diameter of the sensor flow path 251. Fluid energy that flows through the sensor flow path 251 by bypassing through the first capillary tube 252 flows back into the flow channel 211 through the second capillary tube 253 and flows into the outlet 11b through the outlet 211b. It can flow outside the gas meter (1).

A coating layer 254 is formed around the bypass channel 25. The coating layer 254 is a hydrophobic coating and may include Teflon, silicone, or an olefin-based polymer. The coating layer 254 minimizes frictional resistance that hinders the flow when fluid energy flows through the bypass channel 25. In addition, the coating layer 254 has a self-cleaning function. Accordingly, impurities that obstruct the flow of fluid energy are not generated on the bypass channel 25.

The sensor unit 24 is disposed in the arrangement space 231 and is connected to the sensor flow path 251. The sensor unit 24 includes a thermal sensor. The sensor unit 24 measures the mass flow rate of fluid energy flowing through the sensor flow path 251 by bypassing the bypass flow path 25. The sensor unit 24 is connected to a control unit (not shown).

The control unit includes a central processing unit such as a micro controller unit (MCU) and a central processing unit (CPU). The control unit may further include a memory, an application program, and a communication means. The control unit receives a count output value according to the flow rate from the circuit of the sensor unit 24 and displays it on the display unit 13. In addition, the measured value may be transmitted to the portable terminal through a communication means.

The pressure drop 26 is located between the first capillary tube 252 and the second capillary tube 253 in the flow passage 211. Here, one side of the pressure drop 26 is connected to the inlet 211a to form an inlet area (not shown), and the other side is connected to the outlet 211b to form a discharge area (not shown). The inlet region is connected to the first capillary tube 252 and the discharge region is connected to the second capillary tube 253.

A plurality of circular flow holes 261 are formed in the pressure drop 26. The flow holes 261 are arranged radially with respect to the virtual center of the pressure drop 26 as shown in the drawing [Fig. 9 b)]. That is, the flow holes 261 are regularly arranged with a specific pattern. However, the flow holes 261 may not be radially arranged as shown in the drawing [Fig. 9 a)] and may be formed to be symmetrically vertically and horizontally based on an imaginary center.

The fluid energy introduced into the flow passage 211 through the inlet 211a passes through the flow hole 261, and a part of the fluid energy flows into the first capillary tube 252 from the inlet region and bypasses it. The fluid energy passing through the flow hole 261 merges with the fluid energy discharged from the second capillary tube 253 to the discharge area and flows into the discharge port 11b through the outlet 211b.

The pressure drop 26 generates a pressure difference between the first capillary tube 252 connected to the inlet region and the second capillary tube 253 connected to the discharge region. Here, the actual flow rate is measured by measuring the mass flow rate of the fluid energy flowing through the sensor flow path 251 with the sensor unit 24.

Meanwhile, the flow tube 20 may further include a suction nozzle 27 and a guide blade 28 as shown in FIG. 6.

The suction nozzle 27 is connected to one side of the tube body 21, and the inner circumference diameter gradually increases as the distance from the tube body 21 increases. Accordingly, the cross-sectional shape of the suction nozzle 27 is a trumpet shape. The fluid energy in the measurement space 11 may be introduced into the tube body 21 through the suction nozzle 27.

The guide blades 28 protrude from the inner circumference of the suction nozzle 27 in a virtual center direction and are arranged along the circumferential direction. The virtual diameter formed by the guide blades 28 is the same as the inner circumference diameter of the tube body 21. The guide blade 28 guides the fluid flowing into the suction nozzle 27 from the measurement space 11 uniformly.

Next, the numerical analysis of the gas meter described above will be described with reference to FIGS. 7 to 19.

Here, the flow governing equation used in numerical analysis is expressed in the x, y, z Cartesian coordinate system as follows. [Equation 1] represents the conservation of mass equation, [Equation 2] represents the equation of conservation of the momentum of flow, and [Equation 3] represents the equation of conservation of energy. Each equation represents a steady state.

[Equation 1]

[Equation 2]

[Equation 3]

In [Equation 1], [Equation 2], and [Equation 3], u, v, and w are the velocity components in the x, y, and z directions, respectively, P is pressure, ρ is density, g is gravitational acceleration, ν is the dynamic viscosity coefficient , α is the temperature diffusion coefficient, and T is the temperature.

The numerical solution of the above governing equation was obtained using a commercial CFX program using ANSYS as a platform. The convective term in [Equation 2] was discretized using the QUICK difference method, and the diffusion term used a typical central difference method.

The gas meter 1 according to the present embodiment provides a pressure drop 26 of the flow tube 20 having high accuracy and excellent reproducibility in a mass gas meter.

Accordingly, the flow stability of the mass-type gas meter is secured by designing the optimum shape of the pressure drop 26 of the flow tube 20 through computational fluid analysis. In addition, by installing an optimized pressure drop 26 and a thermal sensor (sensor unit 24), the temperature difference of the thermal sensor generated by the flow of the capillary tube (bypass channel 25) is tested to collect stable data on repeatability and reproducibility. It can be applied as a commercial product.

First, the flow tube 20 of the gas meter is installed in the housing 10, and the fluid energy flowing into the housing 10 fills the measuring space 11 and then flows into the flow tube 20, some of which is bypassed. After being diverted to the flow path 25, it is again combined with the flow rate passing through the pressure drop 26 and then discharged. The mass flow rate of fluid energy flowing through the sensor flow path 251 formed in the sensor unit 24 is directly measured.

When the flow tube 20 is located inside the housing 10 and analyzed as the maximum flow condition, the velocity vector at the suction nozzle 27 of the flow tube 20 (see Fig. 7) and the pressure distribution (see Fig. 8) ). Looking at the velocity vectors in the x plane (Fig. 7a) and y plane (Fig. 7b), the fluid energy flow entering the flow path 211 of the flow tube 20 is the guide blade 28 of the suction nozzle 27 ), it can be seen that it changes uniformly in the z direction.

In addition, it can be seen that the pressure distribution also changes uniformly as the fluid energy passes through the nozzle portion of the suction nozzle 27.

The pressure drop 26 according to the present exemplary embodiment eliminates the randomness of the conventional pressure drop grid and forms a flow hole 261 having a small circular cross section of a uniform size, thereby providing uniformity of flow.

Here, the drawing [Fig. 9 a)] is a form in which the flow hole 261 is symmetrical with respect to the bypass channel 25 (Porous1), and the drawing [Fig. 9 b)] shows the flow hole 261 It shows that it is in a radial shape based on the center of the pressure drop 26 (Porous2).

The drawings [FIG. 10] to [FIG. 12] show the discharge portion of the pressure drop 26 from the x plane, (a) shows [Fig. 9(a)], and (b) shows [Fig. b)], showing a uniform pressure distribution throughout.

에서의 압력분포를 나타낸 것으로 전체적으로 균일한 압력분포를 뛰고 있는 것을 확인할 수 있다. 도면 [도 12의 (a)와 (b)]는 최대유량일 때 압력분포를 나타낸 것으로 (a)는 이웃한 유동홀(261)의 간격이 넓은 부분에서 낮은 압력을 띄고, (b)는 벽 주변에서 낮은 압력을 띄고 있는 것을 확인할 수 있다.The drawings [Fig. 10(a) and (b)] show the pressure distribution at the minimum flow rate, and it can be seen that they have almost the same distribution. The drawings [Fig. 11 (a) and (b)] are

By showing the pressure distribution at, it can be confirmed that the overall pressure distribution is uniform. Figures [Fig. 12 (a) and (b)] show the pressure distribution at the maximum flow rate, where (a) shows low pressure in the wider gap between adjacent flow holes 261, and (b) shows the wall You can see that there is low pressure around it.

13 to 15 show the pressure distribution in the flow tube 20 viewed from the z plane. Here, (a) shows [Fig. 9(a)], and (b) shows [Fig. 9(b)].

에서의 압력분포를 나타낸 것으로 압력 강하기(26)의 배출부에서 압력이 균일하게 유지되는 것을 확인할 수 있다. 도면 [도 14의 (a)와 (b)]는 최대유량일 때 압력분포를 나타낸 것으로 (b)가 (a)보다 압력분포가 좀 더 균일한 것을 확인할 수 있다.The drawings [Fig. 13 (a) and (b)] are

It can be seen that the pressure is uniformly maintained at the discharge portion of the pressure drop 26 by showing the pressure distribution at. Figures [Fig. 14 (a) and (b)] show the pressure distribution at the maximum flow rate, and it can be seen that (b) has a more uniform pressure distribution than (a).

And it can be seen that the drawings [Fig. 14(a) and (b)] show the velocity distribution at the maximum flow rate, and are uniform and symmetric.

In addition, numerical analysis was performed by forming the flow hole 261 of the pressure drop 26 into two porous shapes as shown in the drawings [Fig. 9 (a) and (b)].

From the results of numerical analysis, it was found that the flow at the discharge part was more uniform in the porous shape than in the conventional shape. Accordingly, it was determined based on the ratio of the pressure drop characteristics at the pressure drop 26 according to the change in flow rate and the mass flow rate at the inlet and the mass flow rate flowing along the bypass channel 25.

Fig. 16 is a graph showing the pressure drop before and after the pressure drop according to the flow rate change. Original (flow hole is formed in a lattice shape, see Fig. 20 (existing)), Porous1 (Fig. 9a), Porous2 (Fig. 9b) all show the form of a quadratic function, but Porous2 shows a form close to linear. The closer it is to the linearity, the more advantageous it is to calibrate the actual measurement value, so Porous2 was relatively superior.

Fig. 17 is a graph showing the ratio of the mass flow rate at the inlet 211a and the mass flow rate at the bypass channel 25 according to the volume flow rate. In the case of the conventional model, it can be seen that the mass ratio has a very small value and shows an irregular value at a high flow rate. Porous1 has a logarithmic function and becomes linear as the flow rate increases. Porous2 also showed relatively excellent because it has a linear function form with a constant slope overall.

Through such a numerical analysis result, it can be seen that the flow hole 261 of the pressure drop 26 is formed in a circular shape and arranged in a radial shape based on the center of the pressure drop 26.

As a result of the performance test of the pressure drop, the original (conventional) pressure drop and the Porous2 pressure drop 26 were installed in the flow tube 20, passed through a wide range of flow rates, and compared with the measured values, which are electronic pulse values measured by the sensor unit.

As shown in the comparative graph of Fig. 18, the existing pressure drop shows a large change in slope by drawing an s-curve in a small flow range, whereas the newly developed pressure drop shows a gentle and consistent slope in all flow ranges. Considering that the measured value is converted to mass flow rate through a calibration process, the pressure drop with a small calibration variable is evaluated to be much better. Accordingly, it can be seen that the pressure drop 26 in which the circular flow hole 261 is formed is superior to the existing pressure drop (flow hole is formed in a grid shape).

And the drawing [Fig. 19] shows the measured value by increasing the flow rate for the pressure drop 26 and measuring the measured value, and decreasing the flow rate on the contrary. Through this, the hysteresis characteristics of the pressure drop 26 were tested, and a very good result was confirmed that there was no hysteresis effect at all.

Accordingly, as shown in the drawing [Fig. 20], the V-shaped groove below the original (existing) pressure drop element is a portion in which the bypass flow path is formed. Due to this pressure drop, a pressure difference is generated between the inlet and the outlet of the bypass channel and flow through the bypass channel is formed. The actual flow rate is obtained indirectly by measuring the mass flow rate of the bypass channel with a flow sensor. This conventional pressure drop has a grid shape of an approximately square shape and is partially blocked. In the drawing [FIG. 20], it can be seen that the part represented by the dark color is a blocked part, and the pattern is very arbitrary. Due to this randomness, the flow rate measurement is unstable and the reproducibility of the measurement is deteriorated.

However, in the case of this embodiment, since the cross-sectional shape of the flow hole 261 of the pressure drop 26 is formed in a circular shape and is arranged radially with respect to the center of the pressure drop 26, linear response is improved in a wide flow range and hysteresis characteristics It was also excellent.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention defined in the following claims are also present. It belongs to the scope of rights of

1: gas meter 10: housing
11: measuring space 11a: inlet
11b: outlet 12: filter member
13: display unit 20: flow tube
21: tube body 211: flow channel
211a: entrance 211b: exit
22: filter unit 23: sensor arrangement unit
231: arrangement space 24: sensor unit
25: bypass flow 251: sensor flow
252: first capillary 253: second capillary
254: coating layer 26: pressure drop
261: flow hole 27: suction nozzle
28: guide feather

Claims (10)

A tube body through which a flow channel having an inlet and an outlet passes through the inside,
A pressure drop in which a plurality of circular flow holes disposed in the flow passage and connecting the inlet and the outlet are formed,
A sensor arrangement part formed in the tube body and having an arrangement space,
A bypass passage formed in the sensor arrangement portion and bypassing the flow of fluid flowing through the flow passage; and
A filter unit disposed at the inlet of the flow channel
Including,
Some of the fluid energy flowing into the flow channel bypasses the pressure drop through the bypass channel and merges and discharges at the outlet.
Flow tube. In claim 1,
The above bypass passage
A sensor flow path formed on the floor of the arrangement space,
A first capillary tube connecting one end of the inlet and the sensor flow path, and
A second capillary tube connecting the outlet and the other end of the sensor flow path
Flow tube comprising a. In paragraph 2,
A flow tube in which a coating layer is formed in the bypass channel. In paragraph 2,
Flow tube further comprising a sensor unit disposed in the arrangement space. In claim 4,
The sensor unit flow tube including a thermal sensor. In paragraph 2,
The pressure drop is located between the first capillary tube and the second capillary tube in the flow channel, and the flow hole is a flow tube arranged radially with respect to an imaginary center of the pressure drop. In claim 1,
A flow tube further comprising a suction nozzle connected to an inlet of the flow channel, and the inner circumference diameter of the suction nozzle gradually increases as the distance from the tube body increases. In clause 7,
The flow tube further comprises a guide blade arranged in a circumferential direction around the inner circumference of the suction nozzle and allowing the incoming fluid to be uniformly introduced. A housing having an inlet and an outlet connected to the measuring space and having a measuring space formed therein, and
A flow tube defined in any one of claims 1 to 8 located in the measurement space and connected to the outlet
Gas meter comprising a. In claim 9,
Gas meter further comprising a filter member disposed at the inlet.

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