JPH03225229A - Electromagnetic flowmeter - Google Patents

Abstract

PURPOSE:To obtain a flowmeter capable of securing airtightness between a measuring pipe part and a magnetic casting main body and having improved explosion-proof structure by constituting the casting main body to cast the measuring pipe. CONSTITUTION:The magnetic casting body 1 is constituted to cast the measuring pipe part 5. Thereby, airtightness between the pipe part 5 and the body 1 can be secured and the strength of the main body 1 can be also secured. Thus, this flowmeter having the electrode rooms 5A, 5B of practically safe explosion- proof structure and the exciting coil room 3 of pressure-resistance explosion- proof structure can be obtained. The explosion-proof safety of the electrode rooms 5A, 5B can be checked from the outside of the device by opening/closing a cover 8. Since a signal extracting tube 25 is led out up to a terminal board 18, wiring can easily be executed without executing it in the main body 1. Signal lines 7A, 7B can be checked on the terminal board 18 to be easily opened/closed from the external. Since the signal lines 7A, 7B pass through the inside of the extracting tube 25 in a coil room 3, the lines 7A, 7B are prevented from coming into contact with the coil 3 and the safety of the flow meter can be improved.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to an electromagnetic flowmeter with an explosion-proof structure, and more specifically, the electrode part has an intrinsically safe explosion-proof structure, and the measuring tube part has a magnetic flowmeter. The present invention relates to an electromagnetic flowmeter that uses a space surrounded by body casting as an excitation coil storage part.

(Prior Art) An explosion-proof electromagnetic flowmeter is disclosed in Japanese Utility Model Publication No. 47-17024. The electromagnetic flowmeter disclosed in this publication has an electrode chamber with an intrinsically safe explosion-proof structure housed in an excitation coil chamber with a pressure-resistant explosion-proof structure. Further, a terminal box is arranged above the excitation coil chamber. Connected to electrodes? Ti&( passes through a high-energy excitation coil chamber and is led to a terminal box.

There are various types of fluids that can be measured with electromagnetic flowmeters.
The flow rate of lO2 water, c]2 water, acetic acid, ammonia water), etc. may be fixed at 4-1.

If these fluids leak or permeate into the electrode chamber from the electrode section, they may attack the electrode chamber, hermetic seal, electrode, etc., and the intrinsically safe explosion-proof structure may be destroyed.

For this reason, the inside of the electrode chamber of the electromagnetic flowmeter, its surrounding area, and the state of the wiring, I! ! need to be checked accordingly.

However, in the configuration of the electromagnetic flowmeter disclosed in the above-mentioned publication, in order to check whether the electrode chamber is functioning normally, the excitation coil chamber must be opened, which is extremely difficult. Ta.

(Problem to be solved by the invention) As mentioned above, the intrinsically safe explosion-proof structure part of the electromagnetic flowmeter,
It is necessary to check the surrounding area and the condition of the wiring as appropriate.

However, in the configuration disclosed in the above publication, in order to check the electrode chamber, which has an intrinsically safe explosion-proof structure, the excitation coil chamber must be opened. For this reason, conventionally, it has been extremely difficult to check the intrinsically safe explosion-proof structure parts.

This invention has been made in view of the above circumstances, and an object of the invention is to provide an electromagnetic flowmeter with an improved explosion-proof structure.

Another object of the present invention is to provide an explosion-proof electromagnetic flowmeter capable of checking a container for an intrinsically safe explosion-proof structure.

Still another object of the present invention is to provide an improved electromagnetic flowmeter with a quality-safe, explosion-proof electrode chamber and an explosion-proof excitation coil chamber.

[Configuration of the Invention (Means and Effects for Solving the Problems) To achieve the above object, an electromagnetic flowmeter according to the present invention is constructed of a non-magnetic material, 1-1 A measurement tube through which the constant magnetic flux passes and the API constant fluid passes; an electrode section attached to the measurement tube and having an intrinsically safe explosion-proof structure; and an excitation coil chamber which is made of magnetic casting, has an outer periphery of the electrode chamber encased, and accommodates an excitation coil that generates the magnetic flux for measurement. did.

With the above configuration, the electrode chamber can be easily checked from the outside without opening the excitation coil chamber.

In the electromagnetic ammeter, a gap and a depth of the gap that satisfy explosion-proof safety standards may be provided between the electrode chamber and the excitation coil chamber. With this configuration, it is possible to make the excitation coil chamber have a pressure-resistant and explosion-proof structure.

Further, the electromagnetic flowmeter may include an open structural part that can be opened, and a narrow path connecting the electrode chamber and the open structural part, and through which a wiring connected to the electrode part extends. With this configuration, it is possible to prevent the lead wire from the electrode part constituting the intrinsically safe explosion-proof structure part from coming into contact with the electric wire for the excitation coil, and it is possible to improve the reliability of the apparatus. Moreover, since the narrow path extends to the open structure, there is no need to conduct wiring inside the excitation coil chamber, which cannot be opened, and wiring is easy.
The signal line can be easily checked from the openable structure without opening the excitation coil chamber.

Furthermore, when manufacturing the electromagnetic flowmeter, a part that is easily melted may be provided on the outer periphery of the electrode chamber, and the easily melted part may be melted during pouring, and the outer periphery of the electrode chamber and the excitation coil chamber may be welded together. Further, the interface between the electrode chamber and the excitation coil chamber may be welded or brazed with a metal whose ionization tendency is equal to or smaller than that of the non-magnetic material and the magnetic casting. With this configuration, the welded or brazed portions of the connecting portions between the magnetic casting, the measurement tube, and the electrode chamber will not be electrically corroded;
Airtightness is ensured.

(Example) An electromagnetic flowmeter according to a first example of the present invention will be described below with reference to the drawings. In the electromagnetic flowmeter of this embodiment, the electrode chamber has an intrinsically safe explosion-proof structure, and the excitation coil chamber has a pressure-resistant explosion-proof structure.

The structure of the electromagnetic flowmeter of this embodiment will be explained with reference to FIGS. 1 to 4. In addition, FIG. 1 is a partially cutaway sectional view showing the structure of the electromagnetic flowmeter according to this embodiment, FIG. 2 is a perspective view of the measurement tube section 5, and FIGS. FIG. 3 is a cross-sectional view for explaining the structure of a joint portion of body castings.

As clearly shown in FIG. 2, the measurement tube section 5 of the flowmeter of this embodiment is composed of a measurement tube 5 and electrode chambers 5A and 5B attached to the center of the measurement tube 5. The measuring tube 5 is made of a non-magnetic material, such as stainless steel. The measuring tube 5 is provided with a lining 28 on its inner surface.

The nj constant tube 5 electrode chambers 5A and 5B are surrounded by a magnetic casting body (container) 1, as shown in cross section in FIG. 1.3.4. The magnetic casting body 1 has the APL constant tube part 5 as a core, the measuring tube 5 and the electrode chamber 5A.

It is formed by casting 5B. The magnetic casting body 1 has a box-like shape with open upper and lower ends and portions corresponding to the electrode chambers 5A and 5B. The magnetic casting body 1 constitutes two excitation coil chambers and one terminal block chamber.

An electrode section 6 is arranged in the electrode chambers 5A and 5B.

The electrode section 6 seals the 4P1 constant tube 5. Electrode chamber 5A.

A lid 8 is attached to the lid 5B via a gasket 4A. Since the impedance between the electrode sections 6 is sufficiently high and the generated electromotive force is sufficiently small, the electrode chambers 5A and 5B satisfy the standards for intrinsically safe explosion-proof construction.

In an excitation coil chamber above the measuring tube 5, an upper magnetic flux generating section consisting of an excitation coil 3, a yoke 2, and a mounting section 3A is arranged. The yoke 2 has a magnetic flux expanding portion 2A at its tip. The mounting portion 3A is attached to the magnetic casting body 1 with screws 26A. The magnetic casting body 1 and the mounting portion 3A are closely attached at the joint surface 27A so that magnetic flux can be returned (transmitted).

A lower magnetic flux generating section consisting of an exciting coil 30, a yoke 10, and a mounting section 30A is arranged in an exciting coil chamber below the measuring tube 5. For installation, part 30A has magnetic flux expansion part 10A at the tip.
has. The attachment portion 30A is attached to the magnetic casting body 1 via a gasket 4B and a screw 26B.

The magnetic casting body 1 and the mounting portion 30A are closely attached at the joint surface 27B so that magnetic flux can return (transmit).

The magnetic flux generated by the excitation coil 3.30 is transferred to the measuring tube 5.
, and induces an electromotive force in the fluid to be measured, and returns through the magnetic casting body 1 .

That is, the measuring tube 5 functions as a magnetic flux transmission window, and the magnetic casting body 1 functions as a magnetic flux passage.

A signal terminal block (low energy) 18 and an excitation terminal block (high energy) 20 are arranged in the terminal block room. The signal terminal block 18 and the excitation terminal block 20 are clearly separated by a partition wall 19.

The electrode chamber 5A and the electrode chamber 5B are connected by a crossover pipe 9 made of, for example, stainless steel. The crossover pipe 9 is the electrode chamber 5
It is fixed to A and 5B by welding or the like. The electrode chamber 5A and the signal terminal block 18 are connected by a signal line extraction tube 25 passing through the upper excitation coil chamber. Signal line extraction tube 25
is made of stainless steel or the like, and one end thereof is fixed to the electrode chamber 5A by welding or the like. A vermetic terminal housing portion 24 is formed at the tip of the signal line extraction tube 25 . The terminal storage part 24 is the projection welding part 2
3 is welded to the signal terminal block 18.

A vermetic terminal 22 is attached to the storage portion 24. The hermetic terminal 22 is a terminal that satisfies explosion-proof standards. Of course, the terminal has gaps and depths. The wiring 7B connected to the electrode part 6 arranged in the electrode chamber 5B passes through the crossover pipe 9 and is led to the electrode chamber 5A. Electrode chamber 5
The signal line 7B led to A and the signal line 7A connected to the electrode part 6 disposed in the electrode chamber 5A are connected to the hermetic terminal 22 through the signal line extraction tube 25. Vermetic terminal 24 is connected to signal terminal block 18 .

The lid 17 is attached to the terminal chamber using the gasket 4C. The lid 17 is formed with a protrusion 17A for hooking a screw tightening tool. A signal cabtire cable outlet 14A and an excitation cabtire cable outlet 14B are formed in the terminal room. Gaskets 15A and 15B are attached to the outlet 14A and 114B. The signal cabtire cable 13A1 and the excitation cabtire cable 13B are led out of the flowmeter through the gaskets 15A and 15B.

An earth ring 12 is attached to the Jllll fixed tube 5 with a screw 11.

The electromagnetic flow port type of the above structure may be either a sandwich type as shown in FIG. 5 or a flange type as shown in FIG. 6.

In the structure shown in FIGS. 1 to 5, the intrinsically safe explosion-proof container includes the electrode chambers 5A, 5B, the lid 8, the crossover pipe 9, the signal line take-out pipe 25, the hermetic terminal 22, the hermetic terminal storage pipe part 24, and the signal It is composed of a wire extraction tube 25. On the other hand, the pressure-resistant explosion-proof container includes a magnetic casting body 1, a measuring tube 5
, electrode chambers 5A, 5B, yoke mounting portion 30A, packing 15A, 115B1, lid 17, hermetic terminal 22, and signal line extraction tube 25.

Since the impedance between the electrode parts 6 is sufficiently high and the generated electromotive force is sufficiently small, the electrode part 6 adopts an intrinsically safe structure.

In addition, in order to make the excitation coil chamber have a pressure-resistant explosion-proof structure, the magnetic casting body 1 has a depth (Y 2 +
, 5B is cast inside. Similarly, the magnetic casting body 1 has a depth that satisfies the flameproof explosion-proof standard (X3 shown in Fig. 4).
The tP1 fixed tube 5 is cast inside. Furthermore, regarding the joint portion between the magnetic casting body 1 and the lid 17, the gap 21 and the depth Z are formed so as to satisfy the pressure-proof and explosion-proof standards. In addition, the magnetic casting body 1 and the yoke are attached to the part 30.
Regarding the joint part A, the gap and the depth of the gap (Y1+X1 shown in FIG. 1) are also formed so as to satisfy the pressure-proof and explosion-proof standards. In order to improve safety, the dimensions of each gasket 4A, 4B, and 4C are ensured to be other than the depth of the joint surface.

However, these are not necessarily necessary. For example, in a structure with heavy inkstone in dark blue, if reliable welding (adhesion) is achieved by controlling the temperature of the casting water, etc., the welded part (adhesion) can be considered as an integral structure. It has been confirmed through experiments that, in such a case, there is no need to ensure the depth between gaps.

The gap between the magnetic casting body 1 and the measuring tube section 5 is also set to satisfy pressure-proof and explosion-proof standards. For this reason, the materials of the magnetic casting body 1 and the AFI fixed tube part 5 and the dimensions of the cast-in part are designed so that the gap caused by the difference in thermal expansion between the magnetic casting body 1 and the all J fixed tube part 5 satisfies the explosion-proof regulations. is determined. To explain specifically, if the outer diameter of the electrode chamber or TPJ fixed tube is d, and the inner diameter of the cast-in part of the magnetic casting body 1 is D, then the change in inner diameter ΔD and the change in outer shape at any temperature with respect to the reference temperature are The minute Δd is determined by the following formula.

ΔD area DO・α or ΔT Δ d−dOφ β fist ΔT DO=dimensions of cast-in part at reference temperature, dO: dimensions of outer periphery of measuring tube or electrode chamber at reference temperature, α:
Thermal expansion coefficient of the magnetic casting body, β: Thermal expansion coefficient of the measuring tube, ΔT: If the difference between the reference temperature and the current temperature is ΔD>Δd, the gap is ΔD−Δd.

In the case of ΔD less Δd, the limit is ΔD−Δd.

Therefore, the material and dimensions are determined so that the gap value determined by the above equation satisfies the pressure-proof and explosion-proof standards within the operating temperature range of this electromagnetic flowmeter.

The magnetic casting body 1 is made of, for example, FDC-4 which is a magnetic material.
Constructed from 5 ductile cast iron.

FDC-45 can be welded using a Ni welding rod, silver soldered using an Ag solder, etc. However, welded structures are not suitable for flameproof construction. In this embodiment, since the magnetic body casting body 1 has a structure in which the measuring tube portion 5 is cast, the measuring tube portion 5
The airtightness of the magnetic casting body 1 can be ensured, and the strength of the magnetic casting body 1 can also be ensured.

As described above, according to this embodiment, an electromagnetic flowmeter is obtained in which the electrode chamber has an intrinsically safe explosion-proof structure and the excitation coil chamber has a pressure-resistant explosion-proof structure. Moreover, the explosion-proof safety of the electrode chamber can be easily checked from outside the device by opening and closing M8. In addition, the signal line take-out tube 25 is connected to the terminal block 18.
Since the wire is pulled out to the end, there is no need to conduct wiring inside the magnetic body casting body 1, which cannot be opened, and wiring is easy. The signal lines 7A and 7B can be checked on a signal terminal block 18 that can be easily opened from the outside. Signal lines 7A, 7B
passes inside the signal line take-out tube 25 in the excitation coil chamber, and is prevented from coming into contact with the excitation coil 3, resulting in extremely high safety.

The ΔP1 constant tube section 5 in this embodiment includes electrode chambers 5A and 5B. For this reason, when placing the measuring tube section 5 inside the container, the container is divided into two parts. Store the lp1 fixed tube part 5 in a container,
The usual construction method is to bolt or weld the container. However, containers manufactured by this method are not suitable for pressure-resistant and explosion-proof construction.

In this embodiment, since the container of the electromagnetic flowmeter is constructed by casting the measuring pipe portion 5, a container (magnetic casting body 1) with strong pressure resistance can be obtained.

Next, a method of manufacturing the electromagnetic flowmeter having the above configuration will be explained with reference to FIGS. 7A to 7E (for easy understanding,
Figures 7A to 7E show only the main parts).

As shown in FIG. 7A, a 4-1 fixed tube 5 made of, for example, 5US316 is formed. Electrode chambers 5A and 5B are attached to this apI fixed tube 5, for example, by welding. Further, a crossover pipe 9 and a signal line extraction pipe 25 are attached to the electrode chambers 5A and 5B by welding or the like. Signal line extraction tube 2
5 may be installed by manufacturing a casting, cutting it and then fixing it by welding or the like.

Next, as shown in FIG. 7B, the hollow portion of the measuring tube 5 and the electrode chambers 5A and 5B are filled with sand or the like 41 to form a baseboard.

As shown in FIG. 7C, a sand core 42 containing the measuring tube portion 5 and used to form the inner surface of the magnetic casting body 1 is formed.

Next, as shown in FIG. 7D, the sand core 42 is placed in the upper mold 4.
4 and a lower mold 43.

The fried material 46 is injected into this mold from the sprue 45. After a certain period of time has elapsed and the hot water is cooled, the magnetic casting body 1 is formed.

By removing the formed product from the mold and balancing the sand core 42, the measuring tube 5 and the electrode chamber 5 are formed, as shown in FIG. 7E.
A magnetic casting body 1 containing A and 5B is obtained.

Next, parts that require dimensional accuracy are processed. For example, as shown in FIG. 4, the end of the ΔPI constant tube 5 and the end of the magnetic casting body 1 are cut into a predetermined shape and size.

Further, the inner tube 5 lining 28 is formed, a hole for attaching the electrode section 6 to the measurement tube 5 is formed, the electrode section 6 is attached to this hole, wiring is provided, and assembly is performed.

Through the above steps, the electromagnetic flowmeter of the first embodiment is completed.

When forming the magnetic casting body 1, it is desirable to weld the surface portion of the measuring tube portion 5 and the joint portion of the magnetic casting body 1 in order to obtain a pressure-resistant and explosion-proof structure.

If you want to reliably weld the outer periphery of the electrode chambers 5A, 5B, the measuring tube 5, and the magnetic casting body 1, for example, as shown in FIGS. 5D and 5E may be formed. The protrusions 5D and 5E have a small heat capacity and are easily melted during pouring. Therefore, when the protrusions 5D and 5E are formed, the magnetic casting body 1 and the electric chamber 5
The outer circumferences of the A, 5B, and 4Pj fixed tubes 5 are more likely to be welded.

Furthermore, A g s A u
By plating s P or the like, the protrusions 5D and 5E will be more easily melted, and a highly reliable welded portion can be obtained. In order to make it easier to form lava, it is necessary to increase the heat capacity of the part of the magnetic casting body 1 near the measuring tube part 5 (make the magnetic casting body 1 thick and large), and to make the A-j fixed tube large. Reduce the heat capacity of the part you want to weld (make the part you want to weld thinner)
It is desirable to do so. If you make the part you want to weld thinner,
It is not necessary to provide the protrusions 5A, 5D, and 5E shown in FIGS. 8A and 8B, and a structure without protrusions can be used like the electrode chamber 5A in FIG. 3.

In addition, if it is difficult to weld the magnetic casting body 1 and the measuring tube part 5, the boundary part between the magnetic casting body 1 and the measuring tube part 5, for example, the part surrounded by broken lines 47 and 48 in FIGS. 8A and 8B, Ni
Airtightness may be ensured by welding with a welding rod or brazing with Ag. If the ionization tendency of the material of the welding rod or brazing material is smaller than that of the base material, electrochemically, the welded part and additional parts of the brazing part will not be corroded, but the base material (large part) will be damaged. This has the effect of protecting corroded parts of small additional members. Therefore, airtightness between the magnetic casting body 1 and the measuring tube 5 can be ensured.

Next, an electromagnetic flowmeter according to a second embodiment of the present invention will be explained with reference to FIG. FIG. 9 is a partially cutaway sectional view of an electromagnetic flowmeter according to a second embodiment. Note that in FIG. 9, the same parts as in FIG. 1 are given the same reference numerals, and their explanation will be omitted.

Also in this embodiment, the magnetic body casting body 1 has electrode chambers 5A and 5B.
And the i'ipI fixed tube 5 is formed into the fixed color 5.

Projections are formed in the electrode chambers 5A and 5B, and the outer peripheries of the magnetic casting body 1 and the electrode chambers 5A and 5B are welded together.

The terminal chamber 16 is formed separately from the magnetic casting body 1. The terminal chamber 16 is fixed to the magnetic casting body 1 with screws or the like while satisfying the gap-to-gap depth relationship in explosion-proof standards, and the terminal chamber 16 serves as a lid for the upper excitation coil chamber.

The yoke 2.10 is an internal type, and the magnetic flux expansion part 2A'
IOA' is fixed to the 71$1 constant tube 5.

In order to make the excitation coil chamber have a pressure-resistant explosion-proof structure, the terminal chamber 16 is attached as a lid to the upper excitation coil chamber as described above so as to satisfy explosion-proof regulations. Similarly, in the lower excitation coil chamber, a lid 51 is fixed to the magnetic casting body 1 with a gap and a gap depth X5 that satisfy explosion-proof regulations.

A hermetic terminal 22 is arranged in the signal line take-out tube 25 in the electrode chamber 5A, and no such explosion-proof terminal is provided in the terminal chamber 16.

Even with this configuration, an electromagnetic flowmeter can be obtained in which the electrode chambers 5A and 5B have an intrinsically safe structure, the excitation coil chamber has a pressure-resistant explosion-proof structure, and the intrinsically safe structure can be easily checked from the outside.

In the above practical example, there are two electrode chambers and a signal terminal block 18.
were connected with a metal tube 9.25. This invention is not limited to this. For example, if there are four electrode chambers, as shown in FIG.
5B' and the signal terminal block can be connected using tube 9.25.

It is not necessary to use metal tubes for wiring; for example, tubes made of other materials may be used. Additionally, extraneous configurations may be used for wiring. A third embodiment that employs a structure that does not use metal tubes for wiring will be described with reference to FIG. 11. Note that in FIG. 11, the same parts as in FIG. 1 are given the same reference numerals, and explanations thereof will be omitted.

In FIG. 11, a groove 51 is formed in the measuring tube 5. In FIG. On the groove 51 on the lower side of the measuring tube 5, for example, 5US316
A metal band 53 consisting of is arranged by welding.

Between this groove 51 and the metal band 53 is an electrode chamber 5B (not shown).
The wiring 7B from is led to the electrode chamber 5A. Also, the 11th
In the figure, a narrow passage 55 is formed inside the magnetic casting body 1 instead of the signal line extraction pipe 25. A hermetic terminal 57 is fixed to the narrow path 55, and the signal lines 7A and 7B are guided through the narrow path 55 to the signal terminal block. Note that the hermetic terminal may be placed inside the terminal chamber.

Note that no wiring or the like passes through the groove 51 on the upper side of the measurement tube 5.

Therefore, the upper groove 51 is not covered with the metal band 53- etc. and is exposed. Therefore, the groove 51 may be formed only around half the circumference of the measuring tube 5.

The present invention is not limited to the above-mentioned embodiments, and can be modified and applied in many ways. For example, in the above embodiment, the electrode chamber has an intrinsically safe structure and the excitation coil chamber has a pressure-resistant explosion-proof structure, but the excitation coil chamber may have an increased-safety explosion-proof structure, for example. Here, increased safety explosion-proof construction, as is commonly known, is a structure that buries high-energy parts such as excitation coils with filler such as resin or sand, reducing the hazardous space to zero. This structure avoids precision structures and uses a rough structure to ensure safety. In order to employ the safety-enhancing structure in the configuration shown in FIG. 1, the pressure-resistant explosion-proof structure portion shown in FIG. 1 may be filled with resin, sand, or the like. In this case, the relationship between the gap and the depth of the gap at the joint between the measuring tube portion 5 and the magnetic casting body 1 does not need to be as strict as in the case of a pressure-resistant and explosion-proof structure.

Similarly, the excitation coil chamber may have, for example, an internal pressure explosion-proof structure. In this case, the excitation coil and the excitation coil terminal block blade, which serve as the ignition source, are isolated from the surrounding explosive atmosphere by a protective gas.

In addition, the present invention is not limited to the specific examples and drawings shown in the above embodiments, and various modifications and applications are possible.

[Effects of the Invention] As explained above, the electromagnetic flowmeter of the present invention includes an excitation coil chamber formed by casting a magnetic casting on the side surface of an electrode chamber having an intrinsically safe structure.

By adopting such a structure, the electrode chamber having an intrinsically safe structure can be easily checked without opening the magnetic casting. In addition, since the excitation coil chamber is integrally constructed by casting with the measuring tube section as the core, sufficient strength can be obtained.

Therefore, the explosion-proof flow meter according to the present invention has high reliability.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway sectional view showing the structure of an electromagnetic flowmeter according to a first embodiment of the present invention, and FIG. 2 is a perspective view showing the configuration of an Apj fixed tube of the electromagnetic flowmeter shown in FIG. Figures 3 and 4 are cross-sectional views for explaining the structure of the joint between the 71pj fixed pipe section and the magnetic casting.
Figure 4 is a side view of the measuring tube, Figure 5 is a side view of the electromagnetic flowmeter shown in Figure 1, and Figure 6 is a side view of the electromagnetic flowmeter shown in Figure 1. Figures 7A to 7E are side views showing other examples of the side surfaces of the electromagnetic flowmeter shown in Figure 1;
Figures A and 8B are diagrams showing an embodiment in which a welded portion is formed in the APJ fixed pipe portion, and Figure 9 is a partially cutaway sectional view showing the structure of an electromagnetic flowmeter according to a second embodiment of the present invention. , FIG. 10 is a diagram showing an example of the configuration of a tube connecting the electrode chamber and the terminal block,
FIG. 11 is a sectional view showing the structure of an electromagnetic flowmeter according to a third embodiment of the invention. 1...Magnetic casting body, 2.10...Yoke, 3.
・・Exciting coil, 4A, 4B, 4C, 15A, 15B・
・Packing, 5...Measuring tube section, 5...Measuring tube, 5A
. 5B-electrode chamber, 6... electrode section, 7A, 7B... signal line, 817... lid, 9.25... tube, 13A, 13
B... Cabtire cable, 14A, 14B...
Cabtire cable outlet, 18... Signal terminal block, 19... Bulkhead, 20... Excitation terminal block, 22
... Hermetic terminal, 28... Lining.

Claims (5)

[Claims] (1) A measuring tube made of a non-magnetic material, through which the magnetic flux for measurement passes and the fluid to be measured passes, an electrode section attached to the measuring tube and having an intrinsically safe explosion-proof structure, and an electrode section attached to the measuring tube and having an intrinsically safe explosion-proof structure. , an electrode chamber that encloses the electrode part and forms an intrinsically safe explosion-proof container; and an excitation coil chamber that is made of a magnetic casting, that has an outer periphery of the electrode chamber that is cast-wrapped, and that houses an excitation coil that generates the magnetic flux for measurement. Equipped with an electromagnetic flowmeter. (2) The electromagnetic flowmeter according to claim 1, wherein a gap and a depth of the gap satisfying explosion-proof safety standards are provided between the electrode chamber and the excitation coil chamber. The electromagnetic flowmeter according to claim 1, further comprising: (3) an open structure that can be opened; and a narrow passage connecting the electrode chamber and the open structure and through which wiring connected to the electrode extends inside. (4) providing a melting part that is easy to melt on the outer periphery of the electrode chamber;
2. The electromagnetic flowmeter according to claim 1, wherein during pouring to form the excitation coil chamber, the molten portion is melted and the outer periphery of the electrode chamber and the excitation coil chamber are welded. (5) The interface between the electrode chamber and the excitation coil chamber is constructed by welding or brazing with a metal whose ionization tendency is equal to or smaller than that of the non-magnetic material and the magnetic casting. The electromagnetic flowmeter according to claim 1.