JPS61265530A - Electromagnetic flowmeter - Google Patents

Abstract

PURPOSE:To enable the replacement of a measuring pipe, by fixing metal rings to the outer periphery of both opening end parts of a ceramic measuring pipe by shrinkage fit and engaging a metal case with the outer periphery of said measuring pipe through O-ring in a freely detachable manner to enlarge the selection width of the material of an exciting coil. CONSTITUTION:A ceramic measuring pipe 12 having flanges 12a provided at both end opening parts thereof is provided and a pair of exciting coils 13 formed into a saddle shape are fixed to the outer peripheral part of said pipe. A pair of electrodes 14 is fixed to a pair of electrode holes 12b provided to the wall of the pipe 12 in a liquid-tight state so that the leading ends of said electrodes 14 are contacted with a fluid. Metal rings 15 are engaged with the outer periphery of the flanges 12a by shrinkage fit. A metal case 16 is integrally formed of a cylinder part 16a and a exchanger support part 16b and mounted to the pipe 12 in a freely detachable manner and O-rings 17 are engaged with the ring shaped grooves provided to the side engaging surfaces of the flanges 12a. When the coils 13 are excited and the conductive fluid flows through the inner bore of the pipe 12, electromotive force proportional to an average flow speed is generated between electrodes 14 provided so as to cross a magnetic field direction and a flow passage direction at right angles and a flow rate can be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electromagnetic flowmeter equipped with a ceramic measuring tube.

[Conventional technology]

Electromagnetic flowmeters use Faraday's electromagnetic induction phenomenon to measure flow rates by converting the flow rate of a conductive fluid passing through a measurement tube into an electrical signal, and there are no moving parts during measurement. It is not a simple device and has advantages such as no pressure loss during measurement, and it is also possible to measure the flow rate of fluids containing corrosive fluids and slurry solids that are difficult to measure with other measuring devices. , is widely used in various fields.

The measuring tubes of this type of electromagnetic flowmeter have traditionally been metal tubes lined with synthetic resin such as Teflon, but in recent years ceramic measuring tubes with various features have become widely used. It's here. Conventionally, this type of ceramic measuring tube and metal case are generally fixed by shrink fitting. For example, Figure 5 shows the
This is a cross-sectional view of an electromagnetic flowmeter disclosed in Publication No. 01552, etc., in which a ceramic measurement tube 1 having seven flange 1a at both ends has a pipe 2.3 inserted through a gasket 4 made of a non-conductive material. A pair of excitation coils 5 are fixed to the outer periphery of the measurement tube 1. and,
A metal case 6 is fixed to the seven flange 1 of the measuring tube 1 by shrink fitting. γ is a pair of electrodes inserted and fixed into electrode holes in the outer wall of the measuring tube 1 with their axes perpendicular to the magnetic field direction of the excitation coil 5 and the fluid flow direction.

With this configuration, when the excitation coil 5 is excited and the conductive fluid flows through the inner hole of the measuring tube 1, an electromotive force proportional to the average flow rate is generated between the electrodes 7.
By measuring this, the flow rate can be obtained.

Also, the cross-sectional view shown in Fig. 6 is, for example,
An electromagnetic flowmeter disclosed in Publication No.-28219,
A ceramic pipe S is shrink-fitted into the inner hole of a metal measuring tube 8 having flanges 8 a at both ends, and pipes 2 and 3 are joined to the measuring tube 8 via a gasket 4 . The measuring tube 8 is equipped with an excitation coil 5 and an electrode T similar to those shown in FIG. 5, and the metal case 6 is fixed to the 7 flange 81 of the measuring tube 8 by shrink fitting. The operation is the same as shown in FIG.

[Problem that the invention seeks to solve]

However, among such conventional electromagnetic flowmeters, the one shown in FIG. 5 first requires attaching the excitation coil 5 and electrode T, and then shrink-fitting the metal case 6 to the measuring tube 1. Because the high heat caused by this is transmitted to the excitation coil 5, etc.
There is a problem that the material must be heat resistant, and once it is shrink-fitted, it cannot be disassembled, so the measurement tube 1
There was a problem in that the entire instrument had to be replaced because the instrument could not be replaced.

In addition, in the case shown in Fig. 6, the gasket 4, which is the sealing surface when joining the pipes 2 and 3, is in contact with the end face of the metal 7 flange 8a, so even if ceramic is used, it will not have good corrosion resistance. There was a problem that the superiority of ceramic could not be demonstrated.

[Means for solving problems]

In order to solve these problems, the present invention shrink-fits metal rings to the outer periphery of both open ends of the ceramic measuring tube.
A metal case was removably fitted onto the outer periphery of this ring via an O-ring.

[Effect]

With this configuration, the excitation coil is attached to the ceramic measuring tube after the metal ring is shrink-fitted, and the metal case is fitted with the OIJ ring interposed between the ring and the electromagnetic flowmeter. Once completed, connect the piping via gaskets. As a result, the gasket comes into contact with the ceramic surface, and the measuring tube can be removed from the metal case for replacement or other purposes.

〔Example〕

FIG. 1 is a longitudinal sectional view showing an embodiment of the electromagnetic flowmeter according to the present invention, and the electromagnetic flowmeter 11 is equipped with a ceramic measuring tube 2 having flanges 12 at both end openings.
A pair of excitation coils 13 formed in a saddle shape are fixed to the outer periphery of the coil. In addition, a pair of electrode holes 12bK provided in the wall of the measurement tube 12 are provided with a pair of electrodes 14 whose axes are perpendicular to the direction of the magnetic field of the excitation coil 13 and the direction of the flow path within the measurement tube 12. It is inserted and fixed fluid-tightly in contact with liquid. A metal ring 15 is fitted and fixed to the outer periphery of the flanges 12&, which are both open ends of the measurement tube 12, by shrink fitting. 16ti is a metal glue integrally formed with the cylindrical part 16h and the exchanger support part 16b, and by fitting the inner circumferential surface of the cylindrical part 16& with the outer circumferential surface of the 7 flange 12m,
The 7 lunges 12 are removably fitted to the
& An O-ring 1T is fitted into the annular groove provided on the side fitting surface to prevent rainwater from entering from the outside. Further, piping (not shown) is connected to both open end surfaces of the measurement tube 12 via seal gaskets. Also, case 1
A converter, a terminal box, etc. are supported on the exchanger support part 6.

With the above configuration, the excitation coil 1
3 is excited and a conductive fluid flows inside the inner hole of the measuring tube 12, an electromotive force proportional to the average flow velocity of the fluid is generated between the electrodes 7 provided perpendicular to the direction of the magnetic field and the direction of the flow path. So,
By guiding this to a converter and converting it, the flow rate can be measured.

In this type of electromagnetic flowmeter, the case is fitted onto a metal ring that has been shrink-fitted into a ceramic measuring tube and is kept at room temperature. Since the temperature does not rise even when the device is attached, there is no need to consider heat resistance when selecting the material.

Further, in the case of replacing or maintaining the measuring tube, the case 16 can be easily disassembled by moving it in the axial direction.

Note that unlike ceramic, the metal ring 15 is easy to process, so a screw hole is provided in the metal ring 15 as shown in FIG. By screwing into this screw hole, the case 16 can be detachably and firmly fixed to the metal ring 15.

In addition, as shown in Fig. 3, which is a cross-sectional view near the metal ring,
When shrink-fitting the metal ring 15 to the flange 12& of the measuring tube 12, if the step 12e is provided on the flange 12&, positioning can be easily and reliably performed.

Furthermore, FIG. 4 is a longitudinal sectional view of an electromagnetic flowmeter showing another embodiment of the present invention corresponding to FIG. A metal ring 15A having a larger diameter than that shown in FIG. 1 is shrink-fitted to the open end portions on both sides thereof. The rest of the configuration is the same as that shown in FIG. The operation and effect are the same as those shown in FIG.

〔Effect of the invention〕

As is clear from the above description, in an electromagnetic flowmeter according to the present invention, a metal ring is shrink-fitted to the outer periphery of the opening at both ends of a ceramic measuring tube, and a metal case is attached to and detached from the outer periphery of this ring via an O-ring. By fitting freely,
The excitation coil, electrodes, etc. are attached to the measurement tube at room temperature after shrink-fitting the metal ring, and the temperature of the excitation coil, etc. does not rise, so consider heat resistance etc. when selecting these materials. There is no need for this, expanding the range of material selection.

In addition, since the metal ring of the metal case is a metal ring, it is easy to process O-ring grooves, etc., unlike in the case of ceramics, which reduces processing costs compared to processing ceramics, and improves the characteristics of ceramics. able to demonstrate.

Furthermore, since the case and the measuring tube are not shrink-fitted and can be easily attached and detached, the measuring tube can be replaced and maintained, resulting in cost savings compared to conventional systems in which the entire meter has to be replaced.

Furthermore, since the sealing gasket for piping connection comes into contact with the ceramic, corrosion resistance is improved and the superiority of ceramic can be demonstrated.

[Brief explanation of the drawing]

1 to 4 show an embodiment of an electromagnetic flowmeter according to the present invention, FIG. 1 is a longitudinal sectional view thereof, and FIGS. 2 and 3 are metal rings showing other embodiments of the present invention, respectively. A nearby sectional view, FIG. 4 is a longitudinal sectional view showing another embodiment of the present invention corresponding to FIG. 1, and FIGS. 5 and 6 are longitudinal sectional views of a conventional electromagnetic flowmeter, respectively. . 11... Electromagnetic flowmeter, 12... Measuring tube, 121
...-flange, 15e@φ・metal ring, 16...
-・Case, 1T...O-ring.

Claims (1)

[Claims] An electromagnetic flowmeter characterized in that a metal ring is shrink-fitted to the outer periphery of both open ends of a ceramic measuring tube, and a metal case is removably fitted to the outer periphery of the ring via an O-ring.