JPH03181833A - Pressure sensor for piping - Google Patents

Abstract

PURPOSE:To accurately detect the pressure change in piping by providing an inner tube having flexibility to the inside of a corrugated outer tube having flanges provided to both ends thereof and embedding an optical fiber strand in the wall of the inner tube to fix the same on the way of the piping through the flanges. CONSTITUTION:A pressure sensor is constituted of an outer tube 1 made of a corrugated steel pipe having flanges 2 fixed to both ends thereof, an inner tube having flexibility composed of rubber and the optical fiber strand 4 embedded in the wall of the inner tube 3 in the axial direction thereof. This pressure sensor is mounted on the way of a pipeline by connecting both flanges 2, 6 to the pipeline. A light pulse is sent to the strand 4 from the light pulse tester provided to one end of the strand 4 and the transmission loss of the light pulse is measured by the light pulse tester. When the internal pressure of the pipeline becomes abnormally high, the inner tube 3 expands and the curvature of the strand 4 becomes large and the transmission loss of the light pulse increases. The change of the transmission loss of the light pulse is detected by the light pulse tester and the abnormality of the internal pressure of the pipeline is detected.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a pressure sensor for piping, in particular, a pressure sensor for accurately detecting pressure changes in piping without using a power source, using an optical fiber wire. This article relates to a pressure sensor for piping that can be used.

[Conventional technology]

Conventionally used pressure sensors include the following:

(1) Introducing fluid into a semicircularly curved pressure receiving pipe,
Bourdon tube type pressure sensor that deforms the curvature of the pressure receiving tube and detects changes in fluid pressure based on the amount of deformation (2) Diaphragm type pressure sensor that deforms the diaphragm depending on the pressure of the fluid and detects changes in fluid pressure based on this amount of deformation Sensor (3) A bellows is placed in a casing, and fluid is introduced into the casing to deform the bellows. Bellows-type pressure sensor detects changes in fluid pressure based on the amount of deformation. (4) The spacing between electrode plates changes depending on the pressure. Capacitance type pressure sensor that electrically detects the pressure change of the fluid based on the amount of change (5) Semiconductor type sensor that electrically detects the pressure of the fluid using a semiconductor [Problem to be solved by the invention] ] However, the conventional pressure sensor described above has the following problems.

That is, since the pressure sensors (11 to (3)) do not have a pressure transmission function themselves, for example, when these sensors are used for remote monitoring of gas leaks from a natural gas pipeline, they do not have a pressure transmission function. Since a separate road is required, equipment costs are incurred.

On the other hand, the pressure sensors (4) and (5) above require a power source, so although they themselves have a pressure transmission function, they require incidental equipment such as a power cord and an amplifier.
Equipment costs still apply.

Therefore, an object of the present invention is to provide a pressure sensor for piping that can accurately detect pressure changes within piping without requiring a separate pressure transmission line or power source.

[Means to solve the problem]

This invention includes a wavy outer tube provided with flanges at both ends;
It consists of a flexible inner tube provided inside the outer tube, and an optical fiber strand embedded in the wall of the inner tube in the axial direction, and the outer tube is connected to the inner tube through the flange. It is characterized by being fixed in the middle of piping.

Next, one embodiment of the pressure sensor for piping according to the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the pressure sensor for piping according to the present invention.

As shown in FIG. 1, the piping pressure sensor of the present invention includes an outer tube I made of a corrugated steel tube with flanges 2 fixed at both ends, an inner tube 3 having flexibility made of rubber or the like, and an inner tube 3 made of a flexible material such as rubber. It consists of an optical fiber strand 4 embedded within the wall of 3 along its axial direction.

The flange 2 of the outer tube 1 is fixed to a flange 6 provided on a pipe 5 such as a pipeline.

Both ends of the optical fiber strand 4 are covered with a protective tube 7.

As the optical fiber wire 4, a conventionally known one is used. The reason why the optical fiber strand 4 is buried in the wall of the inner tube 3 is to prevent the optical fiber strand 4 from being damaged by the fluid flowing inside the pipe 5.

In this invention, the transmission loss of the optical fiber strand 4 changes according to its curvature, that is, the optical fiber strand 4
The transmission loss of increases as its curvature increases,
This utilizes the unique characteristic of the optical fiber 4 that the curvature decreases as the curvature becomes smaller.

According to the piping pressure sensor of the present invention configured as described above, a change in pressure within the piping is detected in the following manner.

For example, the piping pressure sensor described above is installed in the middle of the pipeline by joining the flange 2.6. Then, an optical pulse is sent to the optical fiber 4 from an optical pulse tester provided at one end of the optical fiber 4, and the transmission loss of the optical pulse is measured by the optical pulse tester. At this time, the optical pulse tester is adjusted in advance so that the transmission loss of the optical pulse transmitted within the optical fiber 4 becomes zero when the internal pressure of the pipeline is normal.

When the internal pressure of the pipeline becomes abnormally high, the inner pipe 3 swells. When the inner tube 3 expands, the curvature of the optical fiber wire 4 buried therein increases, and the transmission loss of optical pulses increases. This change in the transmission loss of the optical pulse is detected by an optical pulse tester, and an abnormality in the internal pressure of the pipeline is detected.

〔Effect of the invention〕

As explained above, the piping pressure sensor of the present invention has both a sensor function and a transmission path, so it is possible to accurately detect pressure changes in piping without requiring a separate signal cable or power source. This brings about useful effects such as being able to do things.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the piping pressure sensor of the present invention. In the drawings, 1 - outer tube, 2 - flange, 3 - inner tube, 4 optical fiber strand, 5 piping, flange, protection tube.

Claims (1)

[Claims] (1) A wavy outer tube with flanges at both ends, a flexible inner tube provided inside the outer tube, and an optical fiber element embedded in the wall of the inner tube along its axial direction. A pressure sensor for piping, characterized in that the outer tube is fixed in the middle of the piping via the flange.