JPH0438293Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is mainly based on gases remaining in the soil, for example, when the soil of fields, fields, etc. is fumigated with a soil fumigant, the presence or absence of component gases of the fumigant remaining in the soil can be easily detected. The present invention relates to a detection tool for measuring.

BACKGROUND OF THE INVENTION In order to exterminate harmful centipedes and/or other pathogenic bacteria in the soil before sowing or planting crops, it is common practice to fumigate the soil in advance. However, when a soil fumigant is used for this purpose, a considerable amount of component gas remains in the soil, and if crops are planted as they are, they will cause chemical damage. Therefore, in order to sufficiently dissipate this residual gas, the treated soil is usually plowed and a so-called "degassing" operation is carried out.
However, when actually planting crops, it is preferable to check whether the gas has been sufficiently dissipated.

However, to date, there is no simple and quick way to detect the residual gas in the soil from such fumigant agents, and conventional methods for detecting residual gas have been to collect local soil samples and subject them to instrumental analysis. Or, one has to rely on a germination test (cress test) using a specific seed (Cress test), and any of these methods is complicated and takes a considerable amount of time to obtain results. Was.

In view of these circumstances, the present invention primarily aims to provide a device that can easily and quickly detect residual gas in soil after soil fumigation treatment on site.

By the way, as a device that can be used for such a purpose, the "underground atmosphere measuring device" described in Japanese Utility Model Publication No. 54-26077 is publicly known. This device is
As stated in that publication, there are ventilation slits on the lower side of each of the inner and outer double-walled metal cylindrical tubes, which have a cap at the tip (a cap with a pointed tip) and a semiconductor detection element inside. It is constructed such that the slit can be closed when the cylindrical pipe is inserted into and removed from the ground, and the slit can be opened after being buried underground. This device has almost no practical problems, but since the ventilation slit is opened and closed by the relative rotation of two cylindrical tubes, when in use, the slit is inserted and removed, and the slit is opened and closed. It is necessary to open and close the double tube, that is, to rotate the double tube, and it is difficult to perform these operations at once.

The present invention relates to an improvement of the known measuring device of this type and aims to solve the operational difficulties thereof.

The present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 1, the gas detector of the present invention comprises a protective tube 2 housing a gas sensor 1 therein, an intake device (not shown) airtightly connected to an upper end opening 3 of the protective tube 2 via an intake tube 4, and
and its lower end opening 5
The protective tube 2 is made up of a cap 6 in the shape of an inverted cone having a pointed tip, which can close the cap 6, and the cap 6 has at least one fixed plate 7 on its side, which is stretched along the axial direction of the cap and can suppress the rotation of the cap. The protective tube 2 has an intake hole 9 drilled on the side of the screw-fitting portion with the cap 6 at its lower end, and the intake hole 9 is formed in the cap 6.
and the corresponding protective tube 2 are screwed together to be able to be opened and closed freely.

The protective tube 2 is preferably made of metal, such as stainless steel, with an outer diameter of 20 to 45 mm and a total length of 400 to 800 mm, and has a male thread cut at the lower end and a cap with a corresponding female thread. 6 and 10 are screwed together to close the upper and lower end openings 3 and 5 of the protective tube. However, the upper end opening 3 is ventilally connected to an intake device (not shown) via an intake pipe 4 attached to the cap 10. Therefore, the cap 10 may be, for example, a push-in rubber stopper or a cork stopper instead of the illustrated metal screw cap. A pair of handles 11 and 12 are attached to the upper side of the protective tube 2.

As the suction device, a publicly known suction device such as a small pump or a rubber balloon may be appropriately used.

The gas sensor 1 is a known semiconductor gas sensor (for example, TGS-812 manufactured by Figaro Giken Co., Ltd.,
813) is used and is installed slightly above the intake hole 9 of the protective tube 2. A lead wire 13 from the gas sensor 1 passes through the upper cap 10 and is connected to a predetermined display device (for example, a voltmeter, not shown).

The cap 6 has an inverted conical tip for convenient insertion and removal into the soil.
It has at least one (two in the example of the drawing) fixed plate 7 (a kind of baffle plate or resistance plate) stretched along the axial direction of the cap and capable of suppressing rotation of the cap. As mentioned above, it is screwed into the lower end opening 5 of the protective tube, and depending on the degree of screwing (advancement), a hole is drilled into the side surface 8 of the protective tube at the screwed part, that is, the male threaded part. The air intake hole 9 can be opened and closed. Here, the fixing plate 7 stretched over the cap 6 functions to suppress the cap from rotating in response to the rotation of the protection tube 2 after being inserted into the soil. . In addition, it is also possible to adopt other fixing means such as a fixing claw, for example, without being limited to the fixing plate shown in the illustrated example.

The larger the size of the fixing plate 7 (width of the flat plate part), the more reliable the fixing action of the cap becomes, but on the other hand, it becomes somewhat inconvenient to insert and remove it into the soil. It is preferable to design the cap to be as small as possible to ensure the above-mentioned effects under the condition of the soil to be tested, especially its hardness. Incidentally, according to experiments conducted by the present inventors on a prototype like the one shown in the figure, the total length: 600 mm, and the outer diameter of the protective tube:
For a 30mm detector, the short diameter (upper side) of the fixing plate
The above purpose can be completely achieved by attaching two pieces with L: 10 mm, major axis (lower side) L: 20 mm, and height (axial length) H: 40 mm, and also makes it easy to insert into soil. There was no problem in taking it off.

The method for measuring residual gas in soil using the detection device of the present invention is as follows.

First, in the state shown in FIG. 1, the protective tube 2 of this detector is inserted into the test soil after fumigation by grasping the handles 11 and 12. In this case, it is convenient if a scale is attached to the outer surface of the protective tube, since the insertion depth of the protective tube 2 can be easily determined using the scale as a guide. Lower the protective tube 2 to the specified depth (approximately 15 to 20
cm), then gently rotate the handles 11 and 12 to the left. At this time, since the cap 6 in the soil is fixed by the rotation restraining action of the fixing plate 7 on the cap 6, the threaded engagement with the protective tube 2 becomes loose. When the handles 11 and 12 are thus turned leftward by 1/2 to 1 turn, the intake hole 9, which had been closed by the cap 6, opens, as shown in FIG. Therefore, the protective tube 2
The threaded pitch between the cap 6 and the threaded joint and the position of the intake hole 9 in the threaded joint are closely related to the opening/closing operation of the intake hole 9, so each should be set to optimal conditions so that the opening/closing operation can be performed as quickly as possible. Needless to say, this must be designed.

Next, when an intake device (not shown) communicating with the intake pipe 4 is operated, gas in the soil flows into the protective tube 2 through the intake hole 9, and this gas comes into contact with the gas sensor 1. The gas that comes into contact with the gas sensor changes the electrical resistance of the sensor depending on its concentration. The presence of gas is therefore detected by a conventional display device (eg, a voltmeter, not shown) to which the gas sensor lead 13 is connected.

After detecting the gas in this way, rotate the handles 11 and 12 to the right to close the intake hole 9 again as shown in Figure 1, and then pull out the protective tube 2 from the test soil. Bye.

As described above, according to the present invention, gas remaining in the soil can be detected easily and quickly on-site. In particular, since the protective tube 2 of the present detection device is a single-tube type, it is not only lightweight and easy to carry, but also combines with its unique intake hole opening/closing mechanism to make gas detection extremely easy. . That is, the suction hole is opened and closed simply by rotating the handle after inserting and removing the protective tube into the soil, which is extremely convenient in terms of operation.

[Brief explanation of the drawing]

FIG. 1 is a half-longitudinal cross-sectional side view showing the main parts of the detection tool of the present invention, and FIG. 2 is a side view of the main parts. 1...Gas sensor, 2...Protective tube, 3...
Upper end opening, 4... Intake pipe, 5... Lower end opening,
6...Cap, 7...Fixing plate, 9...Intake hole,
11, 12...handle.

Claims (1)

[Scope of utility model registration request] A protective tube housing a gas sensor therein and having an open lower end, an intake device airtightly connected to the upper opening, and a lower end screwable to the lower end of the protective tube. It consists of an inverted conical cap with a pointed tip that can close the opening,
The cap has on its side surface at least one fixed plate stretched along the axial direction of the cap and capable of suppressing rotation of the cap itself;
Further, the protective tube has an intake hole bored on the side surface of the threaded part with the cap at its lower end, and the intake hole can be opened and closed by the screwing action of the cap and the corresponding protective tube. 1. A soil gas detection device characterized by being made by: