JPH02259543A - Gas pipe and gas leakage detector - Google Patents

Abstract

PURPOSE:To detect the leakage of gas from the surface of a metallic gas pipe by providing three layers of a dielectric material, conductor and insulator enclosing the outer periphery of the gas pipe successively from the inside to the outside. CONSTITUTION:The layers L successively consisting of the dielectric material (material is mica) 2, the conductor 3 and the insulator 4 are provided on the outer periphery of the gas pipe 1. The dielectric material 2 is merely brought into pressurized contact with the outer periphery of the pipe 1 so as to be easily detached therefrom in the event of the gas leakage. Terminals 5 and 6 are respectively electrically connected to the pipe 1 and the conductor 3 and are the terminals which project to the outside of the insulator 4. The terminals are held and fixed to the pipe 1 from both sides by means of two terminal fixtures and are connected to a capacitance meter 7 by a cord 10 consisting of electric wires 8 and 9. The dielectric material 2 floats from the surface of the pipe 1 and the layers L become inflated when the pipe 1 is bored with a hole 20 and the gas leaks to the outside therefrom. The electrostatic capacity between the pipe 1 and the conductor 3, therefore, changes. This change can be detected by a change in the frequency of the meter 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas leak detection device for detecting gas leak from a gas pipe, and a gas pipe used therefor.

[Prior art]

Gas pipes for gas supply are either buried underground or installed indoors or outdoors.

In recent years, as the demand for safety against gas leaks has increased, detection of gas leaks from the surface of gas pipes has become necessary. In particular, there is an increasing demand for detecting gas leaks from gas pipes installed indoors or outdoors in high-rise buildings.

[Problems to be solved by the present invention]

In view of the above, an object of the present invention is to propose a gas pipe and a gas leak detection device used to detect gas leakage from the surface of the gas pipe.

[Means to solve the problem]

In order to achieve the above object, in the gas pipe of the present invention, three layers of a dielectric material, a conductive material, and an insulating material are provided in order from the inside to the outside to wrap the outer periphery of the metal gas pipe, and the gas pipe and the conductive material are separated from each other in order from the inside to the outside. A terminal is provided that protrudes outside the insulator.

Further, it is convenient to provide the three layers on the outer periphery of the gas pipe excluding the two ends, and to set the outer diameter of both ends to be larger than the outer diameter of the insulator.

A capacitance meter may be connected to the electrode of the gas pipe to provide a gas leak detection device that constantly monitors gas leaks.

Further, it is advantageous for the capacitance meter to include an oscillation circuit that oscillates at a frequency depending on the capacitance between the metal gas pipe and the conductor.

[Effect]

When a hole is made in the gas pipe and gas leaks from the surface of the pipe, the dielectric material partially separates from the surface of the metal gas pipe and the three layers swell up.

Therefore, the capacitance between the metal gas pipe and the conductor changes. By measuring this change electrically,
Gas leakage from the surface of the gas pipe can be detected.

If the above three layers are not provided at both ends of the gas pipe (and the outer diameter of both ends is increased), the gas pipe is
When connecting adjacent pipes, it is possible to perform the connection work by grasping both ends.

Connect a capacitance meter to the terminal of the gas pipe,
By constantly monitoring the capacitance between the metal gas pipe and the conductor, gas leakage can be detected from changes in capacitance.

〔Example〕

In FIG. 1, reference numeral 1 denotes a metal gas pipe, and a dielectric 2, a conductor 3, and an insulator 4 are provided in this order around the outer periphery of the pipe. Dielectric 2 easily connects the gas pipe in the event of a gas leak.
It is only pressed so that it can be separated from the outer periphery.

These three layers are collectively indicated by a symbol. Although FIG. 1 shows an enlarged cross section of a part of the gas pipe in order to show the three-layer structure, FIG. 2 shows the entire gas pipe.

In FIG. 2, reference numeral 1 denotes a gas pipe, and the outer periphery of the gas pipe is provided with layers made of a dielectric, a conductor, and an insulator. Both ends 1a and 1b are not provided with a layer, and are set to have a larger diameter than the outer diameter of the layer, that is, the outer diameter of the insulator 4. lc,
ld is a female thread carved into the inner diameter portion of both ends of the gas pipe. 5 and 6 are metal gas pipe 1 and conductor 3 respectively
This terminal is electrically connected to the capacitance meter 7 and protrudes outside the insulator 4, and is connected to the capacitance meter 7 by a cord 10 consisting of electric wires 8 and 9.

The terminal 6 has a shape as shown in FIG. 3, and as shown in FIG. 4, is sandwiched inside a thin layer (sheet) of an insulator 4 and comes into contact with the conductor 3 for electrical connection. Note that terminal 5 is not visible as it is behind gas pipe l in Figure 4, but
Terminal 6 for electrical connection to metal gas pipe 1
are abutted in a similar manner. Both terminals 5.6 are held and fixed from both sides by two terminal fixing fittings 11.12, as shown in FIG. Terminal fixing fittings 11 and 12 are studs 13
It is fixed at 14. In this way, the terminals 5 and 6 can be attached to arbitrary positions in the longitudinal direction of the gas pipe.

Figure 6 is an enlarged view of the part where two gas pipes 1 and 1'' are connected via a joint 15. Connecting work is performed by grasping each end 1b and 1a' of both gas vibrators 1 and 1''. in,
layering and damage to L' can be avoided.

In Fig. 7, 1, 1'' and 1'' are gas pipes each having the above-mentioned three layers on the outer periphery, and are connected at a connecting part 16.17. 10.10' and 10'' are gas pipes 1.1
a cord that electrically connects ' to the capacitance meter,
18 and 19 are the floors of the building.

Gas leakage from the surface of the gas pipe occurs when there is a hole 20 in the gas pipe 1 and the gas inside the gas pipe leaks from the hole 20 to the outside of the pipe, as shown in FIG.
When gas leaks from the hole 20, the dielectric 2 rises from the surface of the gas pipe 1, causing the layer to swell.

The dielectric 2 is pressure-welded to the outer periphery of the gas pipe 1 so that it can be lifted up from the gas pipe 1 due to such gas leakage.

The length of the three FiLs installed outside gas pipe 1 is 3m.
, when the thickness of the dielectric 2 is 0.001 m and the material of the dielectric 2 is mica, the capacitance C between the gas pipe 1 and the conductor 3 is as follows: the dielectric constant of vacuum is 8.855X10F/m, and the material of the dielectric 2 is mica. Since the dielectric constant of air is approximately 4 and 1.00, C=8. ass
θ,001.

Note that in the above formula, A is the opposing area of the electrode plates. As mentioned above, if the length of the layer (this length is almost the same as the length of gas pipe 1) is 3 m, and the outer diameter of gas pipe 1 is 0.03 m, then A is approximately 0.28:M, so 0 The capacitance C of the formula
is c= 8.855xlOx 4 x O, 283÷0.
001 (F) = 1.0023X10 (F) = 0
．． 01 (μF).

The capacitance of the swollen area due to gas leakage becomes extremely small. The area of the part that is swollen now is 0.
Assuming that IX O,1 = 0.01 m, the capacitance changes by a ratio of 0.01÷0.283'-1÷28 with respect to the capacitance C of one gas pipe = 0.01 μF. Since this ratio is about 3.6%, it can be easily detected by the frequency change of the capacitance meter 7.

The capacitance meter 7 uses a tank circuit part that constitutes an oscillation circuit as the capacitance to be measured, and detects changes in the capacitance by changing the oscillation frequency. Some systems detect this as a change in the balance of the bridge.

Alternatively, a commercially available portable measuring device capable of measuring from several PF to several 100 μF may be used.

In the embodiment of FIG. 7 there are three gas pipes 1.1' and 1".
The terminals of each are connected to the capacitance meter 7 to monitor and detect the capacitance of each gas pipe, so depending on which gas pipe's capacitance changes, it can be determined which gas pipe has caused a gas leak. Gas pipes can be classified and detected.

〔Effect of the invention〕

According to the gas pipe of the present invention, by monitoring the capacitance of each gas pipe with a capacitance meter, it is possible to divide the gas piping into each gas pipe and immediately detect in which division a gas leak has occurred.

Furthermore, since large diameter portions are provided at both ends of the gas pipe, connection work can be performed without damaging the conductor layer.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a partially enlarged sectional view of a gas pipe, and FIG. 2 is a schematic diagram of a gas leak detection device, with the gas pipe portion showing a longitudinal section. Figure 3 is a slope view of the terminal.
Fig. 4 is a perspective view illustrating how the terminal is attached to the gas pipe, Fig. 5 is a perspective view of the gas pipe with the terminal attached, Fig. 6 is a partially enlarged joint view showing the connection state of the gas pipe, and Fig. 7. 8 is an overall view of the gas leak detection device of the present invention with a gas pipe installed in a building, and FIG. 8 is an enlarged sectional view illustrating gas leakage from the surface of the gas pipe. DESCRIPTION OF SYMBOLS 1... Gas pipe, 1a, 1b... End of gas pipe, 2... Dielectric, 3... Conductor, 4... Insulator, 5.6... Terminal, 7... capacitance meter

Claims (1)

[Claims] 1. A dielectric (2) that wraps around the outer periphery of a metal gas pipe (1)
, three layers of a conductor (3) and an insulator (4) are provided in order from the surface of the metal gas pipe (1) to the outside,
A gas pipe provided with terminals (5) and (6) projecting from the gas pipe (1) and the conductor (3) to the outside of the insulator (4), respectively. 2. Both ends (1a) and (1b) of the metal gas pipe (1)
), the above three layers are provided on the outer periphery of the part excluding the both ends (1
The gas pipe according to claim 1, wherein the outer diameters of a) and (1b) are set larger than the outer diameter of the insulator (4). 3. Terminals (5) and (6) of the gas pipe according to claim 1 or 2.
A gas leak detection device with a capacitance meter (7) connected to it.