JP3336543B2 - Gas collection device for leak inspection in leak detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a closed underground buried object which is isolated from the surroundings of underground buried water pipes, sewer pipes, gas pipes, fuel transport pipes, etc. or underground buried tanks such as gas stations. The present invention relates to a leak test gas collection device used for a leak detector that mainly detects leak of a transport fluid or a storage fluid from a test object by using a rare gas leak test gas.

[0002]

2. Description of the Related Art Conventionally, when investigating a leaked portion of a closed underground object such as a water supply and sewage pipe, the underground water leakage sound is performed by relying on human hearing. It is performed at night with little noise. However, in this method of examining the sound of water leakage, the noise of driving noise from automobiles and compressors from vending machines etc. enters as noise even at night. And the working environment is poor and the working efficiency is poor.

In order to solve these drawbacks, the applicant has injected a rare gas leakage inspection gas such as helium gas into an inspection object a of a closed underground object such as a water pipe as shown in FIG. And a rare gas leaking from a leak location such as a crack generated in the inspection object is swept by a leak inspection gas collecting device c of a leak detecting device d mounted on a truck b running on the ground surface above the noble gas. A part of the collected gas was introduced into an inspection device e mounted on the cart, and the concentration of the rare gas was measured to find the leaked portion. As the inspection device e, for example, as shown in FIG. 2, a rare gas introduction port i is connected to a vacuum pump m via an exhaust pipe l provided with a test port j and a rotary valve k. Connected to the vacuum pump m via a valve n, a turbo-molecular pump o and a foreline valve p, and an analysis tube q between the throttle valve n and the turbo-molecular pump o
A known helium leak detector connected to is used. r is a Pirani gauge and s is a Penning gauge.

[0004]

As the gas collecting device for leak inspection, as shown in FIG. 1, a duct f for sucking gas on the ground surface and a rubber mat g for cushion provided at the tip thereof.
The gas near the ground surface that has entered the duct f is sucked by the nozzle h of the inspection device e provided in the duct f. However, the sand and the dust near the ground surface enter the duct f. However, there is a defect that dust enters the inspection apparatus e from the nozzle h and hinders the analysis. Further, the suction amount of a vacuum pump such as a rotary pump provided in the inspection device e is small, and a large amount of gas near the surface of the ground cannot be collected. Insufficient, small suction volume makes it impossible to introduce gas with a large surface area, and narrow suction range makes it difficult to quickly detect leaks over a wide area.
Is slow, and as a result, there is a disadvantage that the detection time is prolonged. If the detection time is long, when the leak detection device d is moved to perform the search, a position shift occurs between the rare gas suction place and the rare gas detection place, and it becomes difficult to specify the leak point.

[0005] The first object of the present invention is to remove dust from a gas for leakage inspection and dust from the atmosphere and to supply the same to an inspection device. The second object of the present invention is to improve detection sensitivity and to speed up detection. It is a third object of the present invention to collect leakage inspection gas and send it to an inspection device to shorten the detection time.

[0006]

According to the present invention, leakage of a gas for leak inspection injected into a test object buried underground is collected together with the atmosphere on the surface of the ground by a gas collection device of a leak detector, and the collected gas is collected. A part of the gas detector is introduced into an inspection device of the leak detector to analyze and measure the concentration of the gas for leak inspection, wherein the gas collecting device is provided with a lower intake opening directed to the ground surface and A casing provided with an upper exhaust opening for discharging a gas mixture of the leak inspection gas and the atmosphere introduced from the intake opening by the suction fan to the outside, and a flexible material surrounding the front of the intake opening. Skirt, a mesh filter provided between the intake opening and the skirt, and a gas retaining portion toward the upper exhaust opening formed by providing a partition plate inside the casing. , The exhaust By providing the inlet in front of the opening leads to a part of said gas to said inspection device, and to achieve the above object. It is preferable to provide a flow control device for controlling the flow rate at the intake opening and the exhaust opening.

[0007]

The leak detector is mounted on, for example, a trolley and travels on the ground surface above the burial place of the test object into which the gas for leak test has been injected. The leaked test gas together with the gas on the ground surface is discharged to the outside from the lower intake opening through the upper exhaust opening by a suction fan in the casing of the gas collecting device, and the inspection device is disposed in front of the exhaust opening. A part of the gas sucked into the casing from the provided inlet is introduced to measure the concentration of the test gas. Gases such as the inspection gas are collected together with dust near the ground surface, but dust having a large particle size is removed by a mesh filter provided in front of the intake opening, and the gas has a low flow velocity in the stagnation portion. When this occurs, dust having a relatively small particle size is separated from the gas by its own weight, so that the amount of dust entering the inspection device from the inlet is reduced. Further, a skirt provided in front of the intake opening and surrounding the intake opening defines a gas intake space, and the gas in the space is forcibly transported to the exhaust opening by a suction fan. Since the gas flow rate and the suction amount increase without the influence of the gas, the measurement can be quickly performed by the inspection device, and the gas can be efficiently transported without giving the gas a lot of stirring by the suction fan. Activating the flow control device provided at the intake opening to reduce the amount of suction can clean up the gas accumulated inside the casing, and operate the flow control device at the exhaust opening to reduce the gas inside the casing. By controlling these two flow rate control devices, a constant flow rate can be suctioned by the suction fan, and the detection sensitivity can be made accurate.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
In FIG. 3, reference numeral 1 denotes an inspection object of a closed underground buried object isolated from the surroundings such as a water pipe, a sewer pipe, a gas pipe, a fuel transport pipe, etc. buried underground like the one shown in FIG. There is shown a self-propelled or towed trolley running on the surface above the inspection object injected with a leak inspection gas such as helium gas, and the trolley 1 has a gas collection device 2 behind the trolley. A leak detector 4 including an inspection device 3 on a trolley 1 for introducing a part of the collected gas to measure the concentration of the leak test gas is mounted. When the leak inspection gas is helium gas, a helium leak detector having a configuration as shown in FIG.

The gas collecting device 2 collects a leak inspection gas leaking from the inspection object to the ground surface together with the atmosphere. The details thereof are as shown in FIGS. A casing 7 having an intake opening 5 and an upper rectangular exhaust opening 6 is attached to the carriage 1, and a suction fan 8 for transporting gas from the intake opening 5 to the exhaust opening 6 is provided inside the casing 7. At a position facing the intake opening 5. As the suction fan 8, for example, a sirocco fan having a large number of blades 8 a that are long in the rotation axis direction and extend in the radial direction is used, and the gas is not agitated from the intake opening 5 to the exhaust opening 6 without giving much agitation to the gas. Ship quickly. An extension casing 9 having an opening width is provided in front of the intake opening 5, and a skirt 10 formed of a flexible material such as rubber is attached around a tip of the extension casing 9, and the intake opening of the extension casing 9 is provided. The mesh filter 11 was attached at a position between the skirt 5 and the skirt 10. The skirt 10 is located close to the surface of the ground, and the suction fan 8 draws the gas in the enclosed space unaffected by the wind by the exhaust opening 6.
Transport to

A partition plate 12 for partitioning the inside of the casing 7 into a plurality of sections is provided inside the casing 7 to form a plurality of vertical compartments 13a and 13b communicating with each other at an upper portion.
In the illustrated example, the compartment is divided into two compartments, an inlet 14 from the suction fan 8 is formed below the compartment 13a in front of the compartment, and an exhaust opening 6 is formed above the compartment 13b in the rear serving as the retaining portion 17. did. A plurality of gas inlets 18 to the inspection apparatus 3 are provided in front of the exhaust opening 6 and a rectangular opening 15 is provided below.
The gas sent from the cross flow fan 8 rises in the front compartment 13a and stays in the retaining portion 17 of the rear compartment 13b, where dust in the gas is removed by its own weight. Is discharged to the outside through the exhaust opening 6, and at that time, a part of the gas with little dust is sent to the inspection device 3 from the inlet 18 in front of the exhaust opening 6, and the leakage in the gas is performed. The concentration of the test gas was analyzed and measured. The inlet 18 is provided with a filter to prevent dust from entering the vacuum system of the inspection device 3. If the dust in the gas is large, the filter becomes clogged in a short time and stops leak detection. However, by adopting the configuration of the gas collecting device 2 as described above, much of the dust in the gas is removed, and a long-term leak detection can be performed.

The intake opening 5 and the exhaust opening 6 are provided with flow control devices 19 and 20 comprising shutters so as to control the passing flow rate. The intake opening 5 is closed by the flow control device 19 and By exhausting the inside of the casing 7 so as to clean it, and by controlling the opening areas of the intake opening and the exhaust opening 6 with the flow control devices 19 and 20 to flow a constant flow rate, the gas inside the casing 7 is discharged. The concentration of the gas for leak inspection can be adjusted by adjusting the degree of accumulation.

When a leak detector 4 equipped with the gas collecting device 2 of the illustrated embodiment is mounted on the bogie 1 and runs on the ground surface above the inspection object, the gas collecting device 2 The gas mixture for leakage inspection and the atmosphere is sucked by the suction fan 8 without much agitation and the mesh filter 1 is used.
1 and the stagnation portion 17 removes dust and is rapidly discharged to the exhaust opening 6. The gas leaking into the inspection device 3 from the inlet 18 provided at the place where the flow velocity of the gas in front of the gas is weakened. Since the leak detection is performed by guiding a part of the gas mixed with the gas, the probability of catching the leak test gas is improved, and the sensitivity of the test apparatus 3 is improved. The air accumulated in the casing 7 is supplied to the flow control device 1 at the intake opening 5.
When we clean up by closing and exhausting 9,
A change in detection sensitivity due to residual gas in the detection device 3 can be prevented to perform accurate measurement, and the flow control devices 19 and 20 in the intake opening 5 and the exhaust opening 6 are adjusted to flow a constant flow evenly. 2 allows accurate measurement.

[0013]

As described above, according to the present invention, a gas detector for a leak detector that collects a leak test gas and checks the leak of a test object is provided with a lower intake opening and an upper exhaust opening. , A mesh filter and a skirt in front of the intake opening, and a gas retaining portion formed by a partition plate inside the casing, and the inspection is performed in front of the exhaust opening. Since an inlet for guiding a part of the gas to the apparatus is provided, it is possible to remove the gas for leakage inspection sucked from the intake opening and dust from the atmosphere and supply them to the inspection apparatus. The concentration of the leak test gas is improved by the stagnation portion, and the detection sensitivity of the test device can be improved, and the leak test gas can be quickly collected by the suction fan and sent to the test device with little stirring. Short detection time Detection sensitivity it is possible to also have effects such that the better.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a device for detecting leakage of a closed underground object using a rare gas.

FIG. 2 is a diagram of a leak detector inspection device.

FIG. 3 is a side view of a main part of the embodiment of the present invention.

FIG. 4 is a side view of the gas collecting device of FIG. 3;

FIG. 5 is a sectional view taken along line 5-5 in FIG. 4;

[Explanation of symbols]

1 cart 2 gas collection device 3
Inspection device 4 Leak detector 5 Intake opening 6
Exhaust opening 7 Casing 8 Suction fan 10
Skirt 11 Mesh filter 12 Divider 17
Retention part 18 Inlet 19, 20 Flow control device

──────────────────────────────────────────────────続 き Continuation of the front page (72) Eijiro Ochiai 2500, Hagizono, Chigasaki-shi, Kanagawa Prefecture Inside Japan Saka Engineering Co., Ltd. (56) Reference JP-A-7-181096 (JP, A) (JP, U) Actually open 60-156438 (JP, U) Actually open 60-6056437 (JP, U) Actually open 60-120346 (JP, U) Actually open 60-120345 (JP, U) Actually open 50-124988 (JP, U) 50-123384 (JP, U) 50-123382 (JP, U) 48-792 (JP, U) 6-7043 (JP, U) JP, U) Jikken 49-2231 (JP, Y1) Table 9-506705 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 1/22 G01M 3/04 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. A leak detecting gas injected into a test object buried underground is collected together with the atmosphere on the surface of the ground by a gas collecting device of a leak detector, and a part of the collected gas is collected by the leak detector. In the apparatus for analyzing and measuring the concentration of the gas for leak inspection by introducing into the inspection apparatus of the above, the gas collecting apparatus is introduced by a suction fan from the lower intake opening directed to the surface of the ground and the intake opening. A casing having an upper exhaust opening for discharging the leaked test gas and the mixed gas of the atmosphere to the outside, a skirt formed of a flexible material surrounding a front part of the intake opening, and the intake opening A mesh filter provided between the portion and the skirt, and a gas retaining portion toward the upper exhaust opening formed by providing a partition plate inside the casing, and in front of the exhaust opening. To the inspection device A leak inspection gas collecting device in a leak detector, wherein an inlet for introducing a part of the gas is provided. 2. The gas collection device for leak inspection in a leak detector according to claim 1, wherein a flow control device for controlling a flow rate is provided at the intake opening and the exhaust opening.