JP2014085185A - Fixing device, fixing method, and flow rate measurement instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique which provides excellent stability of a temperature after heating due to a heat transfer part and excellent heat dissipation after the stop of the heat transfer part, is capable of fixing a pressure from the heat transfer part to piping, and prevents characteristics including the stability of temperature, heat dissipation, and fixing of the pressure from being varied by a skill level of a user.SOLUTION: A fixing device includes a fixing jig and a holder. The fixing jig includes: opposite portions which are installed in a lengthwise direction of piping and face each other with a prescribed gap therebetween in a direction orthogonal to the lengthwise direction; a body portion including a support part supporting the opposite portions; an elastic portion like an elastic tape which is stretched between piping-side end parts of the opposite portions across the opposite portions and fixes a heat transfer part for transferring heat to a fluid flowing in the piping by applying heat to the surface of the piping, to the surface of the piping. The holder holds the fixing jig so as to allow detachment from the piping of the fixing jig in a state where the fixing jig is attached to the surface of the piping.

Description

  The present invention relates to a fixing device, a fixing method, and a flow rate measuring device.

  As a method for measuring the flow rate of the fluid flowing through the pipe, there are a measurement method using an electromagnetic flow meter and a measurement method using an ultrasonic flow meter. In the measurement method using an electromagnetic flow meter, it is necessary to insert a sensor into the pipe, and therefore construction such as cutting the pipe and draining water is necessary. Moreover, in the measuring method using an ultrasonic flowmeter, it is possible to measure from the outer surface of the pipe, and construction such as cutting the pipe and draining water is unnecessary. However, if bubbles are mixed in the fluid or if rust or corrosion has occurred in the piping, the ultrasonic wave will be blocked or diffused at the location where bubbles, rust, or corrosion occurs, making measurement difficult. Is concerned.

  In addition, as a measurement method other than the above, the surface temperature of two pipes on the upstream side and the downstream side is measured, and the same temperature as the fluid temperature obtained from the measurement result at the upstream measurement point at a certain point in time, There is a method of calculating a flow rate based on a time difference obtained from a measurement result at a downstream measurement point (for example, Patent Document 1). Further, as a different measurement method, there is a measurement method using a thermal flow meter (for example, Patent Document 2).

Japanese Patent No. 4796283 JP 2004-69667 A No. 1-40013 Japanese Patent Laid-Open No. 10-82678 Japanese Patent Laid-Open No. 2005-233859 JP 2006-226996 A JP 2008-232620 A

In the technique of measuring the flow rate of the fluid flowing through the pipe from the surface of the pipe, for example, a heat transfer part (for example, a heater) is installed outside the pipe, and a change in the temperature distribution of the liquid near the heat transfer part is detected. The flow rate is measured based on the amount of heat consumed. Here, in the flow rate measuring device that measures the flow rate using the heat transfer unit, it is necessary to continuously apply heat by the heat transfer unit during measurement. Therefore, power consumption during measurement increases, and there is a concern about an increase in measurement running cost. This problem is particularly noticeable when measurement is performed over a long period of time, or when a flow rate measurement device is attached to a pipe for permanent installation. As a method for suppressing an increase in power consumption during measurement, it is conceivable to control the operation timing of the heat transfer section. For example, it is possible to control such that when the measurement time approaches, the heat transfer unit is operated to apply heat to the surface of the pipe, and the heat transfer unit is stopped after the measurement is completed. Specifically, the following conditions are preferably satisfied in controlling the operation timing of the heat transfer section. The first condition is that the time until the temperature stabilizes after the heat transfer section operates is short. The second condition is that the heat release time is short after the heat transfer section is stopped. The third condition is that when the heat transfer section is attached to the pipe, the pressure from the heat transfer section to the pipe (hereinafter also referred to as attachment pressure) is constant. The fourth condition is reproducibility. Since there are minute irregularities on the surface of the pipe, the mounting pressure is likely to change. When the mounting pressure changes, the contact area between the surface of the pipe and the heat transfer section changes, and the amount of heat taken to the pipe / fluid side changes accordingly. When the amount of heat lost is changed, there is a concern that the characteristics as a flow meter, that is, measurement accuracy may be affected.

  In view of the above problems, the present invention is excellent in temperature stability after heating by the heat transfer section, and heat dissipation after stopping the heat transfer section, and can make the pressure from the heat transfer section to the pipe constant, It is an object of the present invention to provide a technique in which characteristics including temperature stability, heat dissipation, and pressure uniformity do not change depending on the skill level of a user.

  In order to solve the above-described problems, the present invention uses the tension of the tape-like stretchable part to hold down the heat transfer part.

  Specifically, the fixing device according to the present invention is installed along the longitudinal direction of the pipe, and is opposed to each other at a predetermined interval in a direction orthogonal to the longitudinal direction, and a support portion that supports the opposed portion. A stretchable tape-like stretchable part stretched across the opposing part at the pipe-side end of the opposing part, and applies heat to the surface of the pipe In a state where the fixing jig includes an expansion / contraction part that fixes a heat transfer part that transfers heat to the fluid flowing in the pipe to the surface of the pipe, and the fixing jig is attached to the surface of the pipe, And a holding tool for detachably holding the fixing jig with respect to the pipe.

  According to the fixing device according to the present invention, the heat transfer section can be fixed to the surface of the pipe using the tension of the expansion and contraction section. By holding the heat transfer part using the tension of the expansion and contraction part, the heat transfer part comes into close contact with the surface of the pipe. Therefore, the heat from the heat transfer part is efficiently transmitted to the surface of the pipe, and the temperature stability after heating by the heat transfer part can be ensured. Moreover, since the tape-shaped expansion / contraction part has a large surface area exposed to the outside and is thin, the heat capacity is small, so that heat can be efficiently radiated after the heat transfer part is stopped. Moreover, a heat transfer part can be hold | suppressed with the tape surface of an expansion-contraction part, and the pressure from a heat transfer part to piping can be made constant. Furthermore, since the user only has to hold the fixing jig against the surface of the pipe and hold it with a holder, the characteristics including temperature stability, heat dissipation, and pressure uniformity depend on the skill level of the user. There is no change. Since the heat transfer unit only needs to be able to transmit the generated heat to the pipe or the fluid, the heat imparted by the heat transfer unit may be either hot or cold. Moreover, you may fix an expansion-contraction part other than a heat-transfer part, for example, a temperature sensor.

  Since the facing portion is supported by the support portion, the heat transfer portion can be pressed against the surface of the pipe with a constant pressure. Note that the facing portion and the support portion may be configured as separate members, or may be configured integrally with the same member. That is, the main body portion may be configured by combining a plurality of members, or may be configured by molding one member.

  Moreover, the fixing device according to the present invention may further include a heat retaining unit that covers a surface of the stretchable unit. The surface means a surface opposite to the surface in contact with the surface of the pipe. By further providing the heat retaining part, it is possible to suppress the occurrence of condensation on the surface of the stretchable part. As a result, it is possible to suppress a decrease in the amount of heat transmitted to the pipe side due to the occurrence of condensation. Moreover, it can suppress that a heat | fever radiates from the surface side of an expansion-contraction part at the time of the heating by a heat-transfer part. As a result, heat can be transferred to the piping more efficiently.

  The main body may have a hollow portion inside. By forming the hollow portion, for example, contact between the upper surface (surface) of the heat retaining portion and the lower surface of the support portion, which is a concern when the diameter of the pipe is small, can be suppressed. In other words, by forming the hollow portion, the heat retaining portion can be freely deformed according to the shape of the pipe, and the heat transfer section and the surface of the pipe can be more closely attached.

  In the fixing device according to the present invention, the pipe may be made of a magnetic material, and the holder may be a magnet. When piping is comprised with magnetic bodies, such as iron and steel, a fixing jig can be easily fixed to piping by using a holder as a magnet. A magnet can be arrange | positioned along the edge part of an opposing part, for example. In addition, when piping is comprised with the nonmagnetic body, you may comprise a fixing | fixed part with a hook-and-loop fastener and an adhesive tape, for example.

  Here, the present invention can also be specified as a fixing method. Specifically, the fixing method according to the present invention is a fixing method for fixing a heat transfer section that transfers heat to a fluid flowing in a pipe by applying heat to the surface of the pipe, and the longitudinal direction of the pipe A tape-like stretchable part that stretches across the facing part is stretched over the pipe-side end of the facing part that is spaced along the longitudinal direction and faces the predetermined part in a direction perpendicular to the longitudinal direction. In the state where the heat transfer part is fixed by pressing the heat transfer part with the expansion / contraction part, and the heat transfer part is fixed to the surface of the pipe, the fixing jig including the facing part and the expansion / contraction part is Removably hold on the piping.

  According to the fixing method according to the present invention, the heat transfer section can be easily fixed to the surface of the pipe using the tension of the expansion and contraction section. Since the user only needs to hold the main body against the surface of the pipe, the characteristics including temperature stability, heat dissipation, and pressure uniformity do not change depending on the skill level of the user.

  Here, the present invention can also be specified as a flow rate measuring device including the above-described fixing device. Specifically, the present invention is a flow rate measuring device that measures a flow rate of a fluid flowing through a pipe, and includes a first temperature sensor that measures a temperature of the fluid that flows through the pipe, and a fluid temperature that is higher than that of the first temperature sensor. A heat transfer section which is provided downstream of the flow and at a predetermined interval from the first temperature sensor, and transfers heat to the fluid flowing in the pipe by applying heat to the surface of the pipe; A second temperature sensor for measuring the temperature of the surface at the heat transfer unit installation position, the amount of heat applied to the surface of the pipe by the heat transfer unit, the temperature measured by the first temperature sensor, and the second temperature sensor A processing unit that calculates a flow rate of the fluid flowing through the pipe based on a temperature difference from the temperature measured by the step, and a predetermined interval in a direction orthogonal to the longitudinal direction, which is installed along the longitudinal direction of the pipe Facing each other with a gap And a body part including a support part for supporting the opposing part, and a stretchable tape-like elastic part stretched across the opposing part on the pipe side end of the opposing part. A fixing jig including at least an expansion / contraction part that fixes the heat transfer part to the surface of the pipe, and the fixing jig is attached to the pipe with the fixing jig attached to the surface of the pipe. And a detachable holding tool.

  According to the flow rate measuring device according to the present invention, it is possible to measure the flow rate of the fluid flowing through the pipe from the outside of the pipe. Therefore, it is not necessary to separately provide a measurement pipe and a measurement bypass pipe, and it is not necessary to make a hole in the pipe for measurement. That is, in the flow rate measuring apparatus according to the present invention, the flow rate of the fluid flowing through the pipe can be measured without processing the pipe itself. Moreover, compared with the prior art described in Patent Document 1, for example, the distance between temperature measurement points can be shortened.

  Here, in the flow rate measuring apparatus according to the present invention, the second temperature sensor may be provided in the expansion / contraction part. By providing the second temperature sensor in the expansion / contraction section, the temperature at the heat transfer section installation position can be accurately measured. In addition, you may make it provide both said 1st temperature sensor and said 2nd temperature sensor in the said expansion-contraction part.

The heat transfer unit can apply heat so that the pipe surface temperature at the position where the heat transfer unit is installed is higher than the temperature of the fluid measured by the first temperature sensor. There must be a certain relationship between the heat applied to the pipe and fluid, in other words, the amount of heat released from the heat transfer section, the flow velocity of the fluid flowing through the pipe, and the temperature difference between the fluid temperature and the pipe surface temperature. If the temperature difference between the fluid temperature and the pipe surface temperature is made constant, the fluid flow rate can be calculated from the amount of heat released. Therefore, in the processing unit, for example, the flow rate of the fluid flowing through the pipe is calculated from the amount of heat released by the heat transfer unit, and the flow rate of the fluid can be calculated by multiplying the calculated flow rate by the cross-sectional area of the pipe.

  Here, the flow rate measuring device according to the present invention makes the amount of heat given by the heat transfer unit constant, and the processing unit measures the fluid temperature measured by the first temperature sensor and the second temperature sensor. The flow rate of the fluid flowing through the pipe may be calculated based on the temperature difference from the pipe surface temperature and the amount of heat.

  In the present invention, since the amount of heat applied by the heat transfer unit is constant, the flow rate of the fluid flowing through the pipe can be calculated based on the temperature difference obtained by the two temperature sensors. Since the amount of heat applied by the heat transfer unit may be constant, the processing load of heat transfer by the heat transfer unit is reduced.

  Here, the present invention can also be specified as a flow rate measuring method. For example, the present invention is a flow rate measuring method for measuring a flow rate of a fluid flowing through a pipe, and the heat transfer unit that transfers heat to the fluid flowing in the pipe by applying heat to the surface of the pipe is fixed as described above. A step of fixing with a jig; a temperature measuring step of measuring a surface temperature of the pipe by a first temperature sensor for measuring a temperature of the fluid flowing through the pipe; and a downstream side of the fluid flow from the first temperature sensor. A temperature measuring step of measuring a surface temperature of the pipe by a second temperature sensor provided at a predetermined interval from the first temperature sensor and measuring a temperature at the heat transfer portion installation position on the surface of the pipe; A pipe surface heating step for applying heat to the surface of the pipe by the heat transfer unit; an amount of heat applied to the surface of the pipe by the heat transfer unit; a temperature measured by the first temperature sensor; Comprising a temperature difference between the measured temperature by the temperature sensor, the processor for calculating the flow rate of the fluid flowing through the pipe based on a processing step of calculating the flow rate of the fluid flowing through the pipe, a.

  According to the flow rate measuring method according to the present invention, the flow rate of the fluid flowing through the pipe from the outside of the pipe can be measured. Therefore, it is not necessary to separately provide a measurement pipe and a measurement bypass pipe, and it is not necessary to make a hole in the pipe for measurement. That is, according to the flow rate measuring method according to the present invention, the flow rate of the fluid flowing through the pipe can be measured without processing the pipe itself.

  According to the present invention, the temperature after heating by the heat transfer section is excellent in heat stability and heat dissipation after the heat transfer section is stopped, the pressure from the heat transfer section to the pipe can be made constant, and the temperature stability Further, it is possible to provide a technique in which characteristics including heat dissipation and pressure uniformity do not change depending on the skill level of the user.

The perspective view of the fixing device concerning a first embodiment is shown. A mode that a heater is fixed with the fixing device concerning a first embodiment is shown. The state which fixed the fixing device to piping with the adhesive tape is shown. The state which fixed the fixing device to piping with the magnet is shown. The figure explaining the fixing state of a fixing device is shown. The schematic structure of the flow measuring device concerning a second embodiment is shown. The outline | summary of the measurement process in the flow measuring device which concerns on 2nd embodiment is shown. The measurement processing flow performed with the flow measuring device concerning a second embodiment is shown. The temperature characteristic graph according to fixing method is shown. The experimental result of confirmation of reproducibility is shown. The side view which closed the both ends of the longitudinal direction of the fixing device concerning a first embodiment with tape is shown.

  Next, embodiments of the present invention will be described with reference to the drawings. The embodiment described below is merely an example, and the present invention is not limited to the embodiment described below.

<First embodiment>
FIG. 1 is a perspective view of a fixing device according to the first embodiment. FIG. 2 shows how the heater 2 and the second temperature sensor 9 are fixed by the fixing device according to the first embodiment. The fixing device 200 according to the first embodiment includes an angle 201, a plate-like base member 202, and a tape 203. The heater 2 is pressed on the back side of the tape 203 to fix the heater 2 to the pipe 10. The back surface side of the tape 201 means a surface on the pipe 10 side. The angle 201 and the plate-like base member 202 constitute the main body of the present invention. The angle 201, the plate-like base member 202, and the tape 203 constitute the fixing jig of the present invention.

  The angle 201 corresponds to the facing portion of the present invention, is installed along the longitudinal direction of the pipe 10, and is installed so as to face with a predetermined interval in a direction perpendicular to the longitudinal direction (width direction of the pipe 10). Is done. The predetermined interval only needs to be larger than the width of the heater 2 and can be designed as appropriate. The angle 201 of the first embodiment has an L-shaped cross section and is designed to be longer in the longitudinal direction than the heater 2. Further, the upright surface of the angle 201 has a predetermined height, so that when the fixing device 200 is installed in the pipe 10, the angle 201, the plate-shaped base member 202, and the pipe 10 are hollow. Part is formed. By forming the hollow portion, the tape 203 can be freely deformed according to the shape of the pipe 10. As a result, the heater 2 and the surface of the pipe 10 can be more closely attached. The predetermined height can be appropriately designed according to the shape of the pipe 10 so that the tape 203 can be freely deformed according to the shape of the pipe 10. The angle 201 is preferably formed of a hard material such as metal or plastic.

  The plate-like base member 202 corresponds to the support portion of the present invention, is configured by a rectangular plate member, and supports the angle 201. Specifically, the angle 201 is connected along each of the two long sides of the rectangle. The angle 201 may be either an aspect in which the rising surface of the angle is positioned on the inner side in the width direction of the pipe 10 or an aspect in which the rising surface of the angle is positioned on the outer side in the width direction of the pipe 10 as shown in FIG. As shown in FIG. 1 and the like, by disposing the angle 201 so that the upright surface of the angle 201 is located outside the width direction of the pipe 10, a predetermined interval formed between the angles 201 is widened. The installation space of the heater 2 installed between the angles 201 can be widened. The plate-like base member 202 is also preferably formed of a hard material such as metal or plastic, like the angle 201. In the present embodiment, the angle 201 and the plate-like base member 202 are separately configured, but they may be integrated. Further, instead of the angle 201, a simple plate may be used as the facing portion of the present invention.

  The tape 203 corresponds to the expansion / contraction part of the present invention, and holds down the heater 2 and the second temperature sensor 9. Specifically, the tape 203 has stretchability and heat resistance, and is stretched at a constant tension so as to straddle the two angles 201 at the end of the angle 201 on the pipe 10 side. The constant tension may be such that the tape 203 is curved along the curved surface of the pipe 10 and can hold the heater 2. Examples of the tape 203 include a polyimide tape and a polyurethane film tape. Note that the tape 201 may hold only the heater 2.

The heater 2 corresponds to the heat transfer section of the present invention, is electrically connected to a power source (not shown), and heats the surface of the pipe 10. The heater 2 is preferably deformable along the shape of the pipe 10, and can be constituted by, for example, a film heater or a rubber heater.

  The second temperature sensor 9 is electrically connected to a processing device (not shown) for calculating a flow rate, and is installed at the lower part of the heater 2 to measure the surface temperature of the pipe 10 at the lower part of the heater 2. The second temperature sensor 9 is preferably deformable along the shape of the pipe 10 (curved surface in the first embodiment), and can be constituted by, for example, a film-type temperature sensor. The second temperature sensor 9 may be a thermocouple as long as the wire diameter is thin enough to be sufficiently deformable along the pipe surface. 2 and 3, the second temperature sensor 9 is emphasized for convenience of explanation. Actually, the thickness of the second temperature sensor 9 can be made much thinner than that of the heater 2. The second temperature sensor 9 can be fixed to the lower part of the heater 2 with, for example, aluminum tape.

  For fixing the fixing device 200 and the pipe 10, an adhesive tape, a magnet, or the like can be used. As shown in FIG. 3, when the adhesive tape 204 is used, the fixing device 200 can be fixed to the pipe 10 by binding the fixing device 200 and the pipe 10 with the adhesive tape 204. As shown in FIG. 4, in the case of using the magnet 6, the magnet 6 can be attached to the upright surface of the angle 201 and fixed using magnetic force. In the example shown in FIG. 4, the cross-sectional shape of the magnet 6 is processed into a trapezoid according to the shape of the pipe 10, but when the diameter of the pipe 10 is large, the cross-sectional shape of the magnet 6 may be square or rectangular. Good. Moreover, you may use a well-known binding band and a hook-and-loop fastener for fixation with the fixing apparatus 200 and the piping 10. FIG.

[Fixing method]
Next, a fixing method will be described. When fixing the fixing device 200 to the pipe 10, the longitudinal direction of the angle 201 and the longitudinal direction of the pipe 10 are matched. As a result, the reaction force generated on the tape 203 becomes constant and reproducibility is ensured. Here, FIG. 5 shows a diagram for explaining a fixing state of the fixing device. FIG. 5 (a) shows a state in which the heater 203 is normally fixed, that is, a state in which the tape 203 is deformed along the curved surface of the pipe 10 and the heater 2 is brought into close contact with the surface of the pipe 10, and FIG. Shows the state that could not be fixed. As shown to Fig.5 (a), the state fixed so that the longitudinal direction of the angle 201 and the longitudinal direction of the piping 10 may correspond is a state normally fixed. On the other hand, as shown in FIG. 5 (b), the state in which the longitudinal direction of the angle 201 and the longitudinal direction of the pipe 10 do not coincide with each other is a state where the fixing cannot be performed normally. In this case, the angle 201 of the fixing device 200 floats from the surface of the pipe 10 and becomes unstable. In other words, when the fixing device 200 is fixed to the pipe 10, it can be determined whether the fixing device 200 is normally fixed by checking whether the fixing device 200 is stable and does not wobble. The heater 2 is preferably attached to the back surface of the tape 203 in advance, but may be disposed on the surface of the pipe 10. Once the fixing device 200 is fixed to the pipe, it is fixed with an adhesive tape 204 or the like so that the fixed state can be maintained. As described above, the fixing device 200 can be fixed to the pipe.

[effect]
According to the fixing device 200 according to the first embodiment, the heater 2 can be fixed to the surface of the pipe 10 using the tension of the tape 203. By fixing the heater 2 using the tension of the tape 203, the heater 2 can be pressed by the surface of the tape 203, and the heater 2 is in close contact with the surface of the pipe 10. Therefore, the heat from the heater 2 is efficiently transmitted to the surface of the pipe 10, and the temperature stability after heating by the heater 2 can be ensured. Further, since the tape 203 is thin and has a large exposed surface area, it is possible to efficiently dissipate heat after the heater 2 is stopped. Further, by pressing the heater 2 with the surface of the tape 203, the pressure from the heater 2 to the pipe 10 can be made constant. Furthermore, since the user only needs to press the tape 203 against the surface of the pipe 10 in a state where the longitudinal direction of the angle 201 and the longitudinal direction of the pipe 10 coincide with each other, temperature stability, heat dissipation, and constant pressure are maintained. Characteristics including sex do not change depending on the skill level of the user. In other words, the fixing device 200 according to the first embodiment is also excellent in reproducibility.

<Second embodiment>
[Constitution]
2nd embodiment demonstrates the case where the fixing device 200 which concerns on 1st embodiment is used for a flow measuring device. FIG. 6 shows a schematic configuration of the flow rate measuring device according to the second embodiment. The flow rate measuring device 103 according to the second embodiment includes a fixing device 200 ′, a first temperature sensor 1, a heater 2, a second temperature sensor 9, an ammeter 3, an output regulator 8, and a processing device 20. In the flow rate measuring device 103, the fixing device 200 ′ is installed in the steel pipe 10 and measures the flow rate of the fluid (cold water, hot water) flowing through the pipe 10. The cross-sectional shape of the pipe 10 is not limited to a circle, and may be a rectangle, for example. The fluid may be a liquid other than water or a gas.

  The fixing device 200 ′ according to the second embodiment is designed to be longer than the fixing device 200 according to the first embodiment, and the first temperature sensor 1 is further provided on the back surface of the tape 203. The back surface of the tape 203 means a surface in contact with the pipe 10.

  The first temperature sensor 1 is preferably deformable along the shape of the pipe 10 (curved surface in the first embodiment), and can be constituted by, for example, a film-type temperature sensor. The first temperature sensor 1 measures the surface temperature of the pipe 10 at a position away from the second temperature sensor 9 and indirectly measures the temperature of the fluid. The first temperature sensor 1 may be fixed by means different from the fixing device 200 ′, but the first temperature sensor 1 and the second temperature sensor are provided by providing the first temperature sensor 1 on the tape 203 of the fixing device 200 ′. The distance between and is kept constant. Therefore, the measurement value does not change depending on the skill level of the installation worker. In addition, if the first temperature sensor 1 and the second temperature sensor 9 are arranged in advance along the longitudinal direction of the angle 201, when installed on the pipe 10, the axial direction of the pipe (that is, the fluid in the pipe) Therefore, the measurement value does not change depending on the skill level of the installation operator.

  The heater 2 is electrically connected to a power source (not shown) via the processing device 20 and heats the surface of the pipe 10. Specifically, the heater 2 is installed downstream of the first temperature sensor 1 in the fluid flow direction and on the back surface of the tape 203 at a predetermined interval from the first temperature sensor 1 and is in contact with the surface of the pipe 10. Thus, the surface of the pipe 10 is heated and the fluid is indirectly heated. The distance between the heater 2 and the first temperature sensor 1 can be determined as a distance at which the first temperature sensor 1 is not affected by the heat of the heater 2. In the present embodiment, the temperature at the position where the heater 2 is installed (the temperature measured by the second temperature sensor 9) is designed to be a temperature obtained by adding a certain value to the temperature measured by the first temperature sensor 1. ing. For example, when adding 5 degreeC, if the temperature measured with the 1st temperature sensor 1 is 10 degreeC, it will heat so that it may become 15 degreeC. Similarly to the first temperature sensor 1, the heater 2 is preferably deformable along the shape of the pipe 10, and can be constituted by, for example, a film heater or a rubber heater.

  The second temperature sensor 9 is electrically connected to the processing device 20 and is installed in the lower part of the heater 2 to measure the surface temperature of the pipe 10 in the lower part of the heater 2. By adjusting the output of the heater 2 with the output regulator 8 so that this temperature becomes a set value, the surface of the pipe 10 can be heated to an arbitrary temperature as described above. For example, the output of the heater 2 is adjusted by controlling the voltage value, current value, or power value of the heater 2, and in this embodiment, the voltage is kept constant and the current value is controlled. The second temperature sensor 9 can have the same configuration as the first temperature sensor 1.

The heat insulating material 205 is affixed to the surface of the tape 203 and suppresses a reduction in the amount of heat transmitted to the pipe 10 due to condensation that occurs when, for example, a low-temperature fluid such as cold water or cold / hot water flows in the pipe 10. . When the heat insulating material 205 is pasted, the height of the angle 201 is preferably set so that the heat insulating material 205 does not interfere with the plate-like base member 202. Thereby, a sufficient hollow portion can be secured, the heat insulating material can be freely deformed, and the heater 2 and the surface of the pipe 10 can be sufficiently adhered. The heat insulating material 205 is preferably a material having flexibility and low thermal conductivity so that it can be deformed along with deformation of the tape 203 when the fixing device 200 ′ is installed in the pipe 10. Registered trademark) and Aeroflex (registered trademark). The thickness may be set to a level that can prevent dew condensation. However, if the thickness is too large, the efficiency of heat dissipation after the heater 2 is stopped is reduced. Therefore, it is preferable to make the thickness as thin as possible. Then, it was set to 3 mm. The heat insulating material 205 may be attached so as to cover at least the upper surface of the heater 2. By sticking the heat insulating material 205, it is possible to suppress the occurrence of condensation on the surface of the tape 203. As a result, it is possible to suppress a decrease in the amount of heat transmitted to the pipe 10 side due to the occurrence of condensation, and the measurement accuracy can be further improved. Moreover, the heat release from the surface of the tape 203 by the heater 2 during heating can be suppressed. As a result, heat can be transferred to the piping more efficiently.

  The ammeter 3 is supplied with power via the processing device 20 and measures the current supplied to the heater 2.

The processing device 20 is electrically connected to a power source (not shown), the temperature of the fluid measured by the first temperature sensor 1, and the surface temperature of the pipe 10 at the heater 2 installation position measured by the second temperature sensor 9. Based on the current value measured by the ammeter 3, the flow rate of the fluid flowing through the pipe 10 is calculated. The processing device 20 can be configured by a CPU (Central Processing Unit), a memory, a display unit, and an operation unit. The CPU calculates the flow rate of the fluid flowing through the pipe 10 based on a program stored in the memory, that is, a flow rate calculation program. The calculation result can be displayed on the display unit. The display unit can also display the temperature added by the heater 2 and the measurement results obtained by the first temperature sensor 1 and the second temperature sensor 9. The temperature added by the heater 2 can be set, for example, via an operation unit (numeric keypad, keyboard, switch, etc.). Details of the fluid flow rate calculation process will be described later.

  The processing device 20, the output regulator 8, and the ammeter 3 can be accommodated in a housing, for example. The processing device 20, the output regulator 8, and the ammeter 3 only need to be electrically connected to the first temperature sensor 1, the second temperature sensor 9, and the heater 2. The processing device 20, the output regulator 8, and the ammeter 3 may be attached to the pipe 10 or installed in a place other than the pipe 10. The electrical connection may be either wired or wireless.

[Measurement process]
Next, the measurement process will be described. FIG. 7 shows an outline of measurement processing in the flow rate measuring device 100 according to the second embodiment. FIG. 8 shows a measurement processing flow executed by the flow rate measuring device 100 according to the second embodiment. In FIG. 7, for convenience of explanation, the second temperature sensor 9 is highlighted. Actually, the thickness of the second temperature sensor 9 can be made much thinner than that of the heater 2.

The outline will be described based on FIG. 7. First, (1) the temperature of the fluid flowing through the pipe 10 is measured by the first temperature sensor 1 measuring the surface temperature of the pipe 10. Next, (2) the processing device 20 adds a constant value to the measured temperature of the fluid. Next, (3) the temperature measured by the second temperature sensor 9 provided at the lower part of the heater 2 by the output adjuster 8 becomes “temperature to which a constant value is added (hereinafter referred to as temperature after addition)”. The output of the heater 2 is adjusted so that heat is radiated toward the pipe 10. In addition, since the temperature to add (henceforth addition temperature) is constant, the amount of heat radiation is proportional to the flow velocity of the fluid which flows through the piping 10. FIG. (4) The current value of the heater 2 is acquired by the processing device 20, and the flow rate of the fluid flowing through the pipe 10 is calculated by a program stored in the memory of the processing device 20.

  Hereinafter, it demonstrates in detail based on FIG. In step 01, the temperature (TW) of the fluid flowing through the pipe 10 is measured by the first temperature sensor 1. Specifically, the surface temperature of the pipe 10 is measured by the first temperature sensor 1, and the measured surface temperature is input as a fluid temperature to the processing device 20 electrically connected to the first temperature sensor 1. The When the temperature of the fluid is acquired by the first temperature sensor 1, the process proceeds to step 02.

In step 02, the temperature (addition temperature) (A) added by the heater 2 is input. Specifically, the addition temperature may be set in advance and may be automatically calculated by the processing device 20 (for example, + 5 ° C.), or input may be received each time via the operation unit. When the processing device 20 acquires the added temperature, the process proceeds to step 03. The additional temperature may be a temperature at which the capacity of the heater 2 can cover the amount of heat sufficient to raise the pipe temperature by a predetermined temperature after heat is taken away by the fluid flowing in the pipe.

  In step 03, the processing apparatus 20 calculates the temperature after addition. Specifically, the processing device 20 adds the added temperature (A) to the temperature (TW) of the fluid flowing through the pipe 10 acquired via the first temperature sensor 1, and calculates the added temperature. For example, when the temperature of the fluid is 10 ° C. and the addition temperature is + 5 ° C., the temperature after addition is 15 ° C. When the post-addition temperature is calculated, the process proceeds to step 04.

  In step 04, the surface temperature of the pipe 10 below the heater 2 is measured by the second temperature sensor 9. If measured, the process proceeds to step 05. In step 05, the output regulator 8 controls the heater 2 and the output is controlled. Specifically, the output adjuster 8 measures the surface temperature of the pipe 10 measured by the second temperature sensor 9 provided in the lower part of the heater 2 measured in step 04 (the surface temperature of the pipe 10 at the installation position of the heater 2). ) Is controlled to a predetermined value (temperature after addition). When the temperature measured by the second temperature sensor 9 is adjusted to the post-addition temperature by the output control of the heater 2, the process proceeds to Step 06.

  In step 06, the processing device 20 acquires the output value of the heater 2. In the present embodiment, the processing device 20 acquires the current value of the heater 2 via the ammeter 3. When the output value of the heater 2 is acquired, the process proceeds to Step 07.

  In step 07, the processing apparatus 20 acquires the cross-sectional area of the pipe 10. The cross-sectional area of the pipe 10 is a cross-sectional area of the inner diameter of the pipe 10 in a plane orthogonal to the axial direction of the pipe. The cross-sectional area of the pipe 10 is input to the processing device 20 in advance and stored in a predetermined area of the memory, and after the current value of the heater 2 is measured, the processing apparatus 20 accesses the predetermined area of the memory and acquires it. May be. Moreover, you may make it input the cross-sectional area of the piping 10 via an operation part. When the cross-sectional area of the pipe 10 is acquired, the process proceeds to step 08.

  In step 08, the processing apparatus 20 calculates the flow rate of the fluid flowing through the pipe 10 based on the added temperature (A), the output value of the heater 2 acquired in step 06, and the pipe cross-sectional area acquired in step 07. Specifically, the calculation of the flow rate of the fluid flowing through the pipe 10 can be executed based on the heat transfer theory. Hereinafter, the heat transfer theory will be described.

A passing heat quantity Q from the heater 2 to the fluid (for example, water) per unit area is expressed by the following equation (1). That is, the passing heat amount is proportional to the temperature difference between the fluid and the heater 2. The temperature of the fluid can be measured by the first temperature sensor 1, and the temperature of the heater can be measured by the second temperature sensor 9. In the present embodiment, the temperature difference (T _h −T _w ) is not calculated from the measured value, but the added temperature (A) is used.

[Equation 1]
Q = (T _h −T _w ) / R
_Th : Heater temperature (° C)
T _w : temperature of fluid (° C.)
R: Thermal resistance (K / W)

  Here, the thermal resistance R per unit length of the pipe 10 is expressed by Equation 2. That is, the thermal resistance R is represented by the sum of the resistance of heat (heat transfer) moving from the inner surface of the pipe 10 to the fluid and the resistance of heat (heat conduction) moving from the heater 2 to the inner surface of the pipe 10. The heat transfer resistance is a variable value that varies depending on the state of the fluid, and the heat conduction resistance is a fixed value determined by the attributes (material and diameter) of the pipe 10.

[Equation 2]
R = 1 / πr _i h + 1 / πλ _s × ln (r _o / r _i )
Heat transfer Heat conduction r _i : Pipe inner diameter (m)
h: Heat transfer coefficient (W / m ² · K)
λ _s : thermal conductivity of pipe (W / m · K)
r _o : Piping outer diameter (m)

Here, when a fluid flows through the pipe 10, forced convection occurs between the pipe 10 and the fluid. The heat transfer coefficient (h) at that time is expressed by Equation 3. Further, the thermal conductivity (λ _w ) of the fluid is determined by the type of fluid and the temperature of the fluid.

[Equation 3]
_{h = N u × λ w /} r i
N _u : Nusselt number λ _w : Thermal conductivity of fluid (W / m · K)
r _i : Pipe inner diameter (m)

  Further, the Nusselt number is expressed by a function of the Reynolds number (Re) and the Prandtl number (Pr) as shown in Formula 4 in the case of turbulent flow with Re> 10,000. Here, the Reynolds number (Re) is expressed by Equation 5. The kinematic viscosity coefficient (ν) is determined by the type of fluid and the temperature of the fluid. In piping used for air conditioning, since the flow rate is generally 1 to 3 m / s and Re> 10,000, Equation 4 can be used to calculate the Nusselt number. However, even in a piping for air conditioning, since Re <10,000 at an extremely slow flow rate, it is preferable to set a lower limit flow rate to be measured. The Prandtl number (Pr) is determined by the type of fluid and the temperature of the fluid.

[Equation 4]
Nu = f (Re, Pr) = 0.023 × Re ^0.8 × Pr ^0.4

[Equation 5]
Re = V × _{r i} / ν
V: Flow velocity (m / s)
r _i : Pipe inner diameter (m)
ν: Kinematic viscosity coefficient (m ² / s)

From the above, in Equation 1, the passing heat quantity Q can be expressed by the temperature difference (T _h −T _w ) and the thermal resistance R. In Equation 2, the thermal resistance R can be expressed by a numerical value (heat transfer coefficient λ _s ) determined by the pipe diameter, pipe material, and heat transfer coefficient h. In Equation 3, the heat transfer coefficient h has a pipe diameter, a numerical value determined by the temperature of the fluid type and the fluid (thermal conductivity lambda _w), represented by Nusselt number N _u. In Equation 4, Nusselt number N _u is a numeric value that is determined by the temperature of the fluid type and fluid (Prandtl number Pr), expressed in the Reynolds number Re. In Equation 5, the Reynolds number Re can be expressed by the pipe diameter, the numerical value (ν) determined by the type of fluid and the temperature of the fluid, and the flow velocity. That is, from the equations (1) to (5), the passing heat quantity Q is determined by the temperature difference (T _h −T _w ), the fluid flow velocity (V), the pipe diameter, the pipe material, the fluid type, and the fluid temperature. It can be expressed numerically. Here, the type of fluid, the material of the pipe, and the pipe diameter can be specified in advance. Therefore, when calculating the flow velocity of the fluid, the temperature of the fluid, the temperature difference (T _h −T _w ), and the passing heat amount are variables at the time of measurement. In the first embodiment, since the temperature difference is fixed, the flow velocity of the fluid is affected only by the output of the heater 2 and the temperature of the fluid. That is, the heater 2 is controlled so that the added temperature is constant, and the heat dissipation amount of the heater 2 matches the passing heat amount Q. Therefore, the heat dissipation amount of the heater 2 is calculated from the heat dissipation amount of the heater 2, that is, the current amount of the heater 2. By calculating, the flow velocity of the fluid can be calculated.

  When the flow velocity of the fluid is calculated, the flow rate of the fluid flowing through the pipe 10 is calculated by multiplying this by the cross-sectional area of the pipe.

  The flow rate calculation processing based on the heat transfer theory described above will be described as processing by the processing device 20. In step 08, the processing device 20 calculates the current value of the heater 2 calculated in step 06 and the pipe cross-sectional area acquired in step 07. In addition to the above, various types of fluid flow, the inner diameter of the pipe 10, the outer diameter of the pipe 10, the material of the pipe 10, the Nusselt number, the Reynolds number, the Prandtl number, etc. Get parameters. Various parameters can be input through the operation unit. In addition, numerical values such as the thermal conductivity, Reynolds number, and Prandtl number of the fluid can be obtained from publicly known literatures (for example, Air Conditioning and Sanitation Engineering Handbook 14th Edition Volume 1 Basics p59-63). It is also possible to use the numerical values shown, and when a table corresponding to this is stored in the memory for each type of fluid and temperature of the fluid and the flow rate is calculated, the processing device 20 accesses the memory and sets the necessary parameters. May be obtained. For the calculation of flow rate, the relationship between the heater output, temperature difference, and fluid flow rate is tested for each pipe material, pipe diameter, fluid type, and fluid temperature without using the above theoretical formula. What is obtained from the result may be stored in the memory in advance. And the processing apparatus 20 calculates the flow volume of the fluid which flows through the piping 10 by multiplying the cross-sectional area of the piping 10, after calculating the flow velocity of a fluid, for example, displays on a display part.

[Measurement method]
Next, a measurement method will be described. First, the fixing device 200 ′ is attached to the pipe 10. When the fixing device 200 ′ is attached to the pipe 10, the above-described measurement process is executed. That is, the flow measuring device 100 is turned on, and the flow measuring device 100 is caused to execute the above-described steps 01 to 08. When the measurement is completed, the flow measuring device 100 is turned off and the fixing device 200 ′ is removed from the pipe 10. Thus, measurement by the flow rate measuring device 100 is completed.

[effect]
According to the flow rate measuring device 103 according to the second embodiment, the flow rate of the fluid flowing through the pipe 10 from the outside of the pipe 10 can be measured. Therefore, it is not necessary to separately provide a measurement pipe and a measurement bypass pipe, and it is not necessary to make a hole in the pipe 10 for measurement. Therefore, the flow rate measuring device 103 can measure the flow rate of the fluid flowing through the pipe 10 without processing the pipe itself. Further, the tape 203 is provided with the first temperature sensor 1, the second temperature sensor 9, and the heater 2, which can be deformed according to the shape of the pipe 10, so that the pipe 1
It can be attached in close contact with the 0 surface.

  Further, by fixing the heater 2 and the like using the tension of the tape 203, the heater 2 can be pressed by the surface of the tape 203, and the heater 2 is in close contact with the surface of the pipe 10. Therefore, the heat from the heater 2 is efficiently transmitted to the surface of the pipe 10, and the temperature stability after heating by the heater 2 can be ensured. Further, since the tape 203 is thin and has a large exposed surface area, it is possible to efficiently dissipate heat after the heater 2 is stopped. Further, by pressing the heater 2 with the surface of the tape 203, the pressure from the heater 2 to the pipe 10 can be made constant. Furthermore, since the user only has to press the tape 203 on the surface of the pipe 10 in a state where the longitudinal direction of the angle 201 and the longitudinal direction of the pipe 10 coincide with each other, temperature stability, heat dissipation, and constant pressure are maintained. Characteristics including sex do not change depending on the skill level of the user. In other words, the fixing device 200 ′ according to the second embodiment is also excellent in reproducibility.

<Consideration of temperature characteristics of fixing device>
Next, temperature characteristics of the fixing device 200 according to the first embodiment will be described based on experimental results. In this experiment, a heater was actually installed on the surface of the pipe, and the stability of the temperature after heating the heater and the heat dissipation to the pipe side after power-off were verified. The verification is based on the fixing device 200 according to the first embodiment, Comparative Example 1 in which the heater is fixed with a heat insulating material (thickness: 25 mm) having a closed cell structure, and aluminum having an adhesive surface on one surface. It carried out about the comparative example 2 which fixes a heater with a tape. In both Comparative Examples 1 and 2, the second temperature sensor 9 was previously fixed to the lower portion of the heater 2 with aluminum tape.

  The data consists of a first temperature sensor consisting of a thin-film platinum resistance thermometer located between the surface of the pipe and the heater 2 and upstream of the heater 2 at a sufficient distance. The temperature difference obtained from the temperature detected by the temperature sensor and the second temperature sensor 9 (heater lower temperature-pipe surface temperature) was summarized.

  The experimental conditions are: water temperature in the pipe: 20.0 ° C. ± 0.2 ° C., flow velocity in the pipe: 0.5 m / s, diameter of the pipe to be measured: 100 A (outer diameter dimension: 114.3 mm), material of the pipe to be measured : SGP (carbon steel pipe for piping). The ambient temperature around the pipe is 25 ° C. In the experiment, a film type heater (50 W, 2 W / cm) having a thin heating line was used. The surroundings of the heater, the fixing device, the heat insulating material (Comparative Example 1), and the aluminum tape (Comparative Example 2) were insulated with glass wool.

  Here, FIG. 9 shows a temperature characteristic graph for each fixing method. As shown in FIG. 9, when the fixing device 200 according to the first embodiment was used, the temperature was stabilized about 60 seconds after the heater was heated. In addition, it was confirmed that heat dissipation was good after the heater power was turned off (after 150 seconds in FIG. 9), and the heat was completely dissipated in about 90 seconds. Note that the heat dissipation was completed when the temperature difference was “0”, that is, when the heater bottom temperature and the pipe surface temperature were equal. Moreover, when fixing a heater with the method (aluminum tape) of the comparative example 2, it was confirmed that the heat dissipation after heater power-off shows the characteristic which is hardly different from the case of the fixing device 200 according to the first embodiment. . However, with regard to the stability after heating the heater, the temperature continued to rise slightly, but it took about 120 seconds to stabilize. This is presumably because the heat generated from the heater was continuously absorbed by the glass wool applied to the surroundings, and as a result, it took time to balance the temperature. Further, when the heater is fixed by the method (heat insulating material) of Comparative Example 1, both the stability after heating the heater and the heat dissipation after the heater power is turned off require more time than the fixing device 200 according to the first embodiment. It was confirmed that The reason why it takes time to stabilize the temperature after heating is presumed that the heat of the heater continues to be absorbed by the cushioning material and the temperature balance is not obtained, and the reason why it takes time for heat dissipation is the heat absorbed by the cushioning material. It is presumed that it took time to radiate heat.

  Here, in the heat conduction type flow meter, heating by the heater is indispensable at the time of measurement, and the measurement running cost accompanying heating becomes an issue. Measurement running costs can be reduced by intermittently measuring at time intervals (for example, 5 minutes). When the measurement is intermittently performed at a predetermined time interval as described above, the measurement is performed after the temperature difference reaches a predetermined value after the heater is heated and is stabilized, but according to the fixing device 200 according to the first embodiment, the heater is used. Since the time until the temperature stabilizes after heating can be shortened, the heating time of the heater at the time of measurement can be shortened, and the measurement running cost can be further reduced.

  Next, the reproducibility of the fixing device 200 according to the first embodiment was confirmed. For confirmation of reproducibility, measurement is performed in a state where the fixing device 200 is fixed to the pipe, and after the measurement is completed, the fixing device 200 is once removed from the pipe and the measurement is performed by fixing the fixing device 200 to the pipe again and performing measurement. It was decided.

  Here, FIG. 10 shows an experimental result of confirmation of reproducibility. As shown in FIG. 10, the temperature difference and the time were almost the same in the three fixing operations. Thereby, it was confirmed that the fixing device 200 which concerns on 1st embodiment is excellent also in the reproducibility of fixing work.

<Other embodiments>
Instead of the heater 2 (heater) in the embodiment described above, a cooler such as a Peltier element may be used.

  If a device error occurs between the first temperature sensor 1 and the second temperature sensor 9, an error occurs in the calculated fluid flow rate. Therefore, before the measurement by the first temperature sensor 1 and the second temperature sensor 9, correction may be performed from the temperature measured by each temperature sensor in a state where the heater 2 is not heated. For example, when the temperature measured by the first temperature sensor 1 is 20.0 ° C. and the temperature measured by the second temperature sensor 9 is 20.1 ° C., the correction temperature is set to 0.1 ° C. For the display of temperature and the calculation of the flow rate, a value obtained by subtracting 0.1 ° C. from the value actually measured by the second temperature sensor 9 is used as the value of the true second temperature sensor 9.

  Both ends in the longitudinal direction of the fixing device 200 may be closed with the tape 203. FIG. 11: shows the side view which closed the both ends of the longitudinal direction of the fixing device 200 which concerns on 1st embodiment with the tape. Thereby, temperature stability can be improved more and generation | occurrence | production of dew condensation can be reduced more. The means for closing both ends in the longitudinal direction of the fixing device 200 may be any material that can be deformed along the surface shape of the pipe while keeping both ends closed when installed on the pipe, and has heat resistance. There is no particular limitation.

  Although the preferred embodiments of the present invention have been described above, the fixing device, the fixing method, the flow rate measuring device, and the flow rate measuring method according to the present invention are not limited to these, and can include combinations thereof as much as possible.

DESCRIPTION OF SYMBOLS 1 ... 1st temperature sensor 2 ... Heater 3 ... Ammeter 6 ... Magnet 8 ... Output regulator 9 ... Second temperature sensor 10 ... Pipe 20 ... Processing apparatus 103 ... Flow rate measuring device 200, 200 '... Fixing device 201 ... Angle 202 ... Plate-shaped casing 203 ... Tape 205 ... Heat insulating material

Claims (5)

A main body including a facing portion that is installed along the longitudinal direction of the pipe and is opposed to each other at a predetermined interval in a direction orthogonal to the longitudinal direction, and a support portion that supports the facing portion,
It is a stretchable tape-like stretchable part stretched across the facing part at the end of the facing part on the pipe side, and flows through the pipe by applying heat to the surface of the pipe. An expansion / contraction part that fixes a heat transfer part that transfers heat to the fluid to the surface of the pipe, and a fixing jig,
A fixing device comprising: a holding tool that detachably holds the fixing jig with respect to the pipe in a state where the fixing jig is attached to the surface of the pipe.   The fixing device according to claim 1, further comprising a heat retaining portion that covers a surface of the stretchable portion.   The fixing device according to claim 1, wherein the main body portion has a hollow portion therein. A fixing method for fixing a heat transfer section that transfers heat to a fluid flowing in the pipe by applying heat to the surface of the pipe,
Stretchable tape that is installed along the longitudinal direction of the pipe and extends across the facing portion at the end of the facing portion facing the piping at a predetermined interval in a direction orthogonal to the longitudinal direction. The heat transfer part is pressed by the expansion / contraction part to fix the heat transfer part, and the heat transfer part is fixed to the surface of the pipe and includes the facing part and the expansion / contraction part. A fixing method in which a fixing jig is detachably held with respect to the pipe. A flow rate measuring device for measuring a flow rate of a fluid flowing through a pipe,
A first temperature sensor for measuring the temperature of the fluid flowing through the pipe;
Provided downstream of the first temperature sensor and at a predetermined distance from the first temperature sensor, heat is transferred to the fluid flowing in the pipe by applying heat to the surface of the pipe. A heat transfer section,
A second temperature sensor for measuring the temperature at the heat transfer section installation position on the surface of the pipe;
Fluid flowing through the pipe based on the amount of heat applied to the surface of the pipe by the heat transfer unit and the temperature difference between the temperature measured by the first temperature sensor and the temperature measured by the second temperature sensor A processing unit for calculating the flow rate of
A main body part that is installed along the longitudinal direction of the pipe and is opposed to each other with a predetermined interval in a direction orthogonal to the longitudinal direction, and a support part that supports the opposed part,
A stretchable tape-shaped stretchable portion stretched across the facing portion at the end of the facing portion on the pipe side, the stretchable portion fixing at least the heat transfer portion to the surface of the piping And a fixing jig including
A flow rate measuring device comprising: a holder that removably holds the fixing jig with respect to the pipe in a state where the fixing jig is attached to the surface of the pipe.

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