JPH0144966B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is used as an explosion-proofing means for electrical equipment used in places where explosive gas is present, and as a method for preventing gas explosions in the middle of flammable gas transport pipes. This invention relates to narrow gap explosion-proof structural materials used to locally limit propagation.

[Prior art] Although the structure shown in JIS-C-0901 in which flat metal plates are stacked at equal intervals or the structure in which sintered metal is used as a narrow gap element exhibits an excellent explosion-proof effect,
It has the disadvantage that it easily loses its explosion-proof function due to external impact.

On the other hand, a wire-mesh-type narrow plate made of several layers of expanded metal is strong against external shocks, but if explosive concentration gas is applied to the narrow plate with high wind pressure, its explosion-proof function will easily deteriorate. It has the disadvantage of losing .

To explain this point more specifically, the present inventors have conducted various experiments and studies on the explosion-proof performance using a narrow gap plate made by laminating several sheets of expanded metal. When an explosion was caused inside an explosion-proof container while flowing a high-velocity, explosive-concentration gas into the container, the residual flame could persist for a long time, causing the gap plate to become red-hot. In this case, the red heat of the gap plate does not necessarily ignite the explosive concentration of gas outside the container, but it can be said to be on the verge of ignition.

The long-term survival of such residual flames is due to the fact that when a narrow gap plate attached to an explosion-proof container is exposed to high wind speed and explosive concentration gas, the remaining flames scattered on the surface of the narrow gap plate inside the vessel are This is thought to be because gas is often smoothly supplied from multiple sides of the plate, increasing the possibility that localized flames will exist along the narrow gap plate for a long time.

[Problems to be Solved by the Invention] The present inventors have developed an explosion-proof function when strong wind pressure of explosively concentrated gas is applied to the narrow gap plate, such as in an installation in a mine shaft where there is constant ventilation. In order to increase the flame resistance, an attempt was made to shorten the time from the occurrence of an explosion to the extinguishment of residual flame, and when a flame extinguishing grid made of metal strips arranged in a lattice shape was closely attached to the inner surface of the narrow gap plate, It was found that the gas supply to the local flame was thereby disturbed and became unsmooth, and the residual flame was extinguished in a relatively short time.

The present invention is based on this knowledge, and therefore, the problem to be solved by the present invention is to extinguish the residual flame at an early stage.
The objective is to obtain a narrow-gap explosion-proof structural material that exhibits an explosion-proof function equal to or better than that of the conventional type or sintered metal type, and is resistant to external shocks.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the narrow-gap explosion-proof structural material of the present invention has a flame-extinguishing grid made of metal strips arranged in a lattice shape, and several pieces of expanded metal that are tightly bonded together. The present invention is characterized in that it comprises a narrow gap plate laminated in a state that the flame-extinguishing grid and the narrow gap plate are brought into close contact with each other.

[Function] With the narrow gap explosion-proof structure material attached to the explosion-proof container,
If an explosion is caused inside the explosion-proof container while flowing a high-velocity, explosive-concentration gas into the container, residual flame will persist for a long time near the inner surface of the narrow gap plate if a flame-extinguishing grate is not provided. However, if a flame-extinguishing grid is provided as in the present invention, the supply of gas from outside the container to the local flame will be obstructed by the grid-like strips, making it unsmooth. Any remaining flame will be extinguished in a short time.

Therefore, a narrow-gap explosion-proof structural material that exhibits excellent explosion-proof function and is resistant to external impacts can be obtained.

[Examples] Examples of the present invention will be described in detail below with reference to the drawings.

1 to 4 show the structure of the narrow gap explosion-proof structural material according to the present invention. As shown in FIG. 1, this narrow-gap explosion-proof structure material is mainly composed of a flame-extinguishing grid 1 and a narrow-gap plate 2.
As illustrated in the figures and FIG.
0 is fixed within a frame 12 for attachment to an explosion-proof container 3. Further, the narrow gap plate 2 is constructed by laminating a plurality of expanded metal sheets 20 in close contact as shown in FIG. 4 and fixing them together.

The flame-extinguishing grid 1 and the narrow gap plate 2 are installed and used with the flame-extinguishing grid 1 on the inside and the narrow gap plate 2 on the outside of the explosion-proof container 3, etc., but in this case,
The flame-extinguishing grid 1 and the narrow gap plate 2 are attached with their joint surfaces brought into close contact.

In addition, in FIG. 1, 4 indicates a gasket, and 5 indicates a metal frame for a presser foot.

When the narrow-gap explosion-proof structure material having the above structure is installed in the explosion-proof container 3 and explodes inside the container while flowing gas with high explosive concentration into the container, the container will be exposed to local flames. The gas supply from the lattice-shaped strip 11 is obstructed and becomes uneven, and the residual flame does not persist for a long time and disappears in at least several tens of seconds.

In this case, as the mesh size of the flame-extinguishing grid 1 becomes smaller, the flame-extinguishing effect becomes better. For methane grade, the level shown in the experimental example below is sufficient, but for ethylene,
As the hydrogen grade increases, the width of the flame-extinguishing grid needs to increase and the squares become smaller.

FIG. 5 shows an experimental example of the explosion-proof effect conducted by the present inventor.

The expanded metal used in this experiment had a mesh as shown in FIG. The flame-extinguishing grate consists of 24 strips with a length of 193 mm and a thickness of 2.3 mm.
The strips are combined in a grid pattern, and in order to compare the effects, the width of the strips was 30 mm and 40 mm. The internal volume of the explosion-proof container is 12.

When comparing the critical wind speed of 120 to 180 m/min when using a narrow gap plate alone without using a flame-extinguishing grid, the limit wind speed when using a flame-extinguishing grid is 360 to 540 m/min, compared to the case without it. It turns out that it can withstand wind speeds more than three times faster.

Furthermore, in other experiments, as the number of layers of expanded metal increases, and as the width of the strip used for the flame-extinguishing grid increases, the area of the narrow gap plate per unit internal volume of the explosion-proof container also increases. As a result, it has been confirmed that the influence of wind speed on explosion protection ability can be moderated.

[Effects of the Invention] As detailed above, according to the narrow gap explosion-proof structure material of the present invention, by quickly extinguishing the residual flame after an explosion, it is possible to exhibit excellent explosion-proof function. A narrow-gap explosion-proof structural material that is resistant to external impacts can be obtained.

[Brief explanation of drawings]

Fig. 1 is an exploded side view showing a part of the narrow gap explosion-proof structure material according to the present invention in cross section, Fig. 2 is a front view of the flame-extinguishing grate, Fig. 3 is a perspective view thereof, and Fig. 4 is a narrow gap FIG. 5 is a front view of the expanded metal constituting the plate, FIG. 5 is a diagram showing the experimental results, and FIG. 6 is a partial front view of the expanded metal used in the experiment. 1... Flame-extinguishing grid, 2... Narrow plate, 11... Band plate, 20
…Expanded metal.

Claims (1)

[Claims] 1. A flame-extinguishing lattice made of metal strips arranged in a lattice pattern,
A narrow-gap explosion-proof structure material comprising a narrow-gap plate made of several sheets of expanded metal laminated in close contact, and a joint surface between the flame-extinguishing grid and the narrow-gap plate is brought into close contact.