JPS63281986A - Underground tank having leakage detection means - Google Patents

Abstract

PURPOSE:To accurately detect leakages in an underground tank by sensing variations of liquid levels in a conducting pipe with its end open in a clearance between the inner and outer tanks accommodating fluid. CONSTITUTION:The exterior periphery of a cylindrical steel inner tank 1 is covered with a reinforced plastic outer tank 3 with a clearance 2 provided therebetween. From above the outer tank 3, a steel pipe 4 having an outside diameter of about 80 mm and a thickness of about 6 mm extends in an airtight condition therethrough with its end open in the clearance 2. The clearance 2 is filled with fluid such as water through the conducting pipe 4 and a means for detecting the fluid levels in the conducting pipe 4 is provided. The method of forming the clearance 2 between the inner tank 1 and the outer tank 3 is by, for example, providing a projection having a length of about 0.2 mm at a plurality of places on the exterior periphery of the inner tank 1 and by placing the outer tank 3 split into two sections in such a manner as to cover up the projections.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an underground tank having a leak detection mechanism.

(Prior art) Gasoline and other oil tanks buried underground in conventional oil facilities such as gas stations are made of steel according to the provisions of the Fire Service Act. There was a drawback that holes were easily formed (erosion) in the parts due to the pressure of the injected oil.

Furthermore, even when the outer periphery of the tank is rust-proofed with bituminous material such as coal tar, this rust-preventing layer is dissolved by oil seeping in from the ground, and the outer periphery of the tank is susceptible to soil corrosion.

In addition, in order to know the fact that there is a hole in such a tank buried underground, for example, inert gas is injected into the tank to maintain a predetermined pressure inside the tank, and leakage is detected from the change in this pressure over time. However, the tank generally has a large capacity and the amount of gas introduced into the tank is large, making the work cumbersome and increasing detection errors.

(Object of the Invention) An object of the present invention is to obtain an underground tank having a leakage detection mechanism that eliminates the above-mentioned drawbacks.

(Structure of the Invention) The underground tank having the leakage detection mechanism of the present invention includes an inner tank that holds fluid, an outer tank that can be covered with a slight gap on the outside of the inner tank, and a gap between the inner and outer tanks. The device is characterized by comprising a conduit opening into the gap, a mechanism for introducing liquid into the gap through the conduit, and a mechanism for detecting changes in the liquid level in the conduit.

(Example of the invention) The present invention will be explained in detail below with reference to the drawings.

In the present invention, as shown in FIGS. 1 and 2, for example, a cylindrical steel inner tank 1 having an inner diameter of about 2 m, a length of about 6 m, and a thickness of about 6 Ill.
Reinforced plastic (FRP) with a thickness of about 3mm through
A steel conduit 4 having an outer diameter of about 80 mm and a thickness of about 611II11 extends from the upper part of the outer tank 3 through the outer tank 3 in an airtight manner and opens into the gap 2.
A liquid such as water is filled into the gap 2 through the conduit 4, and a mechanism for detecting the level of the liquid in the conduit 4, such as a viewing window (not shown), is provided.

Reference numeral 5 designates a tank socket having an oil injection hole, a ventilation hole, etc., provided at the upper part of the inner and outer tanks 1.3 and passing through them.

In order to form the gap 2 between the inner and outer tanks 1.3 of the present invention, for example, protrusions with a length of about 0.2 rats are provided at a plurality of locations on the outer circumference of the inner tank 1, and the outer tank 3 is, for example, provided so as to cover these protrusions. You can split it in two and cover it.

However, the outer circumference of the inner tank 1 has a thickness of, for example, 0°2 mm.
For example, a sheet of polyvinylidene chloride mesh such as Saran Lavub (trade name) is wound intermittently or tightly, a glass fiber cloth is tightly wound on top of it, and an unsaturated polyester is applied on top of this and it hardens naturally. In this way, the unsaturated polyester penetrates into the glass fibers and these are naturally hardened to form the outer tank 3, and the polyvinylidene chloride sheet portion has a gap of about 0.2 mm. This leads to the formation of a gap.

Since the underground tank having the leak detection mechanism of the present invention has the above-described configuration, if a leak occurs in the inner tank 1, the liquid in the conduit 4 and the gap 2 will flow into the inner tank 1, A leak in the inner tank 1 is detected by detecting the drop in the level of liquid in the conduit 4.

Note that even if there is a leak in the outer tank 3, the level of the liquid in the conduit 4 will similarly drop, so if it is also detected at the same time whether the level of the contents in the inner tank 1 has risen, it will be more reliable to check the inner tank 1. It is possible to detect whether the leak is from the outside tank 3 or the outside tank 3.

(Effects of the Invention) As described above, the underground tank having the leak detection mechanism of the present invention has the great advantage of being able to easily and accurately detect tank leaks.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view of an underground tank having a leakage detection mechanism according to the present invention, and FIG. 2 is a longitudinal sectional side view. l...Inner tank, 2...Gap, 3...Outer tank, 4...Conduit, 5...Tank socket. +1 circle +20

Claims (2)

[Claims] (1) An inner tank that holds fluid, an outer tank that can be placed over the outside of the inner tank with a slight gap, a conduit that opens into the gap between these inner and outer tanks, and a conduit that opens into the gap between the inner and outer tanks, and a conduit that opens into the gap between the inner and outer tanks. 1. An underground tank having a leakage detection mechanism, comprising a mechanism for introducing liquid into the tank, and a mechanism for detecting changes in the liquid level in the conduit. (2) an inner tank for containing fluid, an outer tank covered by the inner tank, a thin sheet wrapped around the outer periphery of the inner and outer tanks to form a slight gap between the inner and outer tanks; Leak detection comprising: a conduit opening into the gap between the outer tanks; a mechanism for introducing liquid into the gap through the conduit; and a mechanism for detecting a change in the level of the liquid in the conduit. An underground tank with a mechanism.