JPH01203931A - Small-sized leak testing instrument for tank, pipe, or the like - Google Patents

Abstract

PURPOSE:To speedily confirm whether or not there is a leak by transducing whether or not pressure drops into an electric signal by the displacement of a core coupled directly with a pressure receiving diaphragm which is strained by pressure variation. CONSTITUTION:The branch pipe 4 of the testing device T is coupled by a hose 3 with an opening part 2 which is linked with the tank, pipe, etc., whose leak is to be tested. A selector valve 9 and a changeover switch 13 are switched according to a fine pressure drop test, a fine pressure rise test, or a pressure rise test to select differential transformer type transducers 7 and 8. Then a valve 6 is opened and the vacuum push button or pressure application push button of a pump 5 is pressed to drive the pump 5, thereby reducing or increasing finely the pressure in the tank, pipe, or the like. The finely pressure reduced or applied state or pressure applied state which is produced by said operation is maintained for a constant time and it is decided whether or not there is a leak according to data displayed on an indicating recorder 11 and a digital display meter 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a small-sized leak testing device for tanks and pipes that tests whether or not there are leakage points in tanks and pipes.

[Prior art]

In general, tanks and pipes that store or transport liquids need to be periodically tested for leakage.

As a leakage test device according to the prior art, all openings leading into the tank and pipes to be tested are closed to make the tank and pipes airtight, and in this state, for example, nitrogen gas is injected into the tank and pipes. Tanks and pipes are filled with inert gas to maintain a constant pressure, and if there is a leak, the nitrogen gas inside will leak out over time. Testing equipment that directly leads to a large Bourdon tube type pressure gauge to determine leakage is often used.

[Problem that the invention seeks to solve]

However, in such a test device, the tank,
The response speed to small leaks in pipes is extremely slow.
For this reason, it is necessary to leave the product for more than ten hours in order to confirm whether there is a leak, making it impossible to perform the intended test quickly.Also, if the product is left for a long time, the volume of the gas may change due to temperature changes, etc. There is a great possibility that this will occur, making it impossible to conduct tests accurately.

Furthermore, since the presence or absence of pressure drop is tested using a measuring device such as a manometer or a Bourdon tube pressure gauge that is directly connected to the piping, the device is bulky, heavy, and large, and cannot be moved unless it is mounted on a special vehicle, for example. Therefore, leakage tests are severely restricted depending on where tanks and pipes are installed.

The present invention has been made to solve the above-mentioned problems, and by having the features shown in the following items,
The object of the present invention is to provide a slight depressurization, slight pressurization, or pressurization testing device for tanks and pipes that solves the above-mentioned problems.

(1) When performing a slight depressurization test on tanks and pipes buried underground, if satisfactory test results cannot be obtained due to the effects of evaporation of internal liquid, a slight pressurization or pressurization test can be performed.

(n) The presence or absence of pressure drop is determined by a differential transformer type converter that converts into an electrical signal by the displacement of the core directly connected to the pressure-receiving diaphragm that causes distortion, and the gas flowing forward to the tank and pipe is connected to the pressure-receiving diaphragm by a hose. It is safe because it is insulated from inside the device. In addition, since this device is a test equipment that includes an electric signal circuit and measuring instruments (recorder, display meter), etc., it is not bulky, lightweight, compact, and easy to handle.

(m) A differential transformer converter detects the displacement of the core directly connected to the pressure-receiving diaphragm, which is distorted by pressure changes, and generates an AC output voltage that is inversely proportional to the pressure. Since it converts to a high-quality DC voltage output, its performance is good.Also, differential transformer type converters are selected and tested depending on the test method, such as for slight depressurization, slight pressurization, and pressurization, so the response to minute leakage is improved. It is also fast, accurate, and reduces testing time.

[Means for solving problems]

The structure of the present invention to achieve the above object is to provide a branch pipe connected by a hose to an opening that communicates with the tank and the pipe to be tested for leakage.

A pump that slightly depressurizes, slightly pressurizes, or pressurizes the forward direction of the tank or pipe is connected to one end of this branch pipe, and the other end is directly connected to a pressure receiving diaphragm that is distorted due to slight depressurization, slight pressurization, or pressure changes. A differential transformer type converter that converts the core displacement into an electrical signal is connected via a switching valve for micro-depressurization, micro-pressure testing, and pressurization testing, and records or displays the electrical signal of pressure changes. The gist is that a recorder or indicator is provided to

〔Example〕

Hereinafter, the leak test device of the present invention will be explained in detail based on one illustrated embodiment.

FIG. 1 is a conceptual diagram of an apparatus for carrying out a tank and pipe leakage test according to the present invention. In the figure, 1 is a tank and pipes, and an opening 2 for testing is provided in the tank and pipes 1. The opening 2 is connected to a branch pipe 4 of the testing device T by a hose 3.

A pump 5 for reducing, slightly pressurizing, or pressurizing the inside of the tank and pipes 1 is connected to one end of the branch pipe 4 of the test apparatus T of the present invention via a valve 6. The pump 5 is preferably a rotary pump because it has low noise, high performance, and is small in size, and is driven to generate a slight decrease in pressure, slight increase in pressure, or increase in pressure within the tank and pipes 1. Normally, the slight pressure test is -200 to -1000 Aq, the slight pressure test is 200 muA9, and the pressure test is 0.2 kgf/cd.
It will be held in

The other end of the branch pipe 4 is a slight pressure reduction, a slight pressure increase, or a slight pressure reduction in the pipes 1 that converts the pressure into an electrical signal.
A differential transformer type converter 7 for slight pressurization and a differential transformer type converter 8 for pressurization are connected via a switching valve 9. This differential transformer type converter for slight depressurization, slight pressurization and pressurization 7.8
The switching valve 9 is used by switching depending on whether the leakage test is to be carried out under slightly reduced pressure, slightly increased pressure, or increased pressure inside the tank and pipes 1.

FIG. 2 is a schematic diagram showing the structure of this differential transformer type converter 7.8. 15 is a pressure receiving diaphragm that receives the pressure inside the tank and pipes 1; 16 is a pressure receiving diaphragm 1;
This is the core that is directly connected to 5. The pressure-receiving diaphragm 15 is called a capsule, a chamber, etc., and is, for example, two metal diaphragms bonded together. When pressure P enters from inside the tank or pipes 1, the core 16 is distorted and displaced at the same time.

The characteristics vary depending on the diaphragm's joining method, shape, size, effective pressure receiving area, etc. In the present invention, the pressure receiving diaphragms 15 of the differential transformer type converter 7 for slight depressurization and slight pressurization and the differential transformer type converter 8 for pressurization are most accurate and quick for the pressure of slight depressurization, slight pressurization, or pressurization test. A diaphragm with a thickness that responds to the

The rod-shaped core 16 is provided in a bobbin in which, for example, a primary coil 17 is wound around the center of the bobbin, and secondary coils 18a and 18b are wound on both sides of the primary coil 17. Therefore, when the core 16 is moved and displaced, the magnetic flux increases in one secondary coil while the magnetic flux in the other decreases, so that the differential connection between the two secondary coils 18a and 18b causes an AC output voltage that is inversely proportional to the pressure. can get.

The displacement of the core 16 by the pressure receiving diaphragm 15 is determined by the differential transformer type converter 7 for slight pressure reduction, slight pressurization, and pressurization.
．． Along with 8, there is a large linear displacement of several planes to several planes,
When connected to the recorder 11 and/or display meter 12, only the change excluding the excitation frequency with good current sensitivity is detected as an output, and for example, the rectifier circuits 19a, 19b and the output adjustment circuit 20 are used to detect the change with good linearity. Convert to DC voltage output for recording and display.

The primary voltage applied to the primary coil 17 is oscillation 2
1 is 24V at 2 KHz. Since fluctuations in voltage affect sensitivity, a constant voltage or constant current 24V DC power source is used as the power source.

Note that 10 is a connecting pipe connected to the switching valve 9, and 13 is a connecting pipe connected to the switching valve 9.
is a differential transformer type converter 7 for slight depressurization, slight pressurization, and pressurization.
．． 8 changeover switch.

[Action of the invention]

When conducting a test using the leak test device T of the present invention configured as described above, the branch pipe 4 of the test device T is connected to the opening 2 leading into the tank and pipes 1 to be tested for leakage. Connect with hose 3.

Depending on whether it is a slight depressurization test, a slight pressurization test, or a pressurization test, the switching valve 9
and the selector switch 13, the differential transformer type converter 7
．． Select 8. Next, the valve 6 is opened, the vacuum push button or pressurization push button of the pump 5 is pressed to drive the pump 5, and the inside of the tank and pipes 1 is slightly reduced, slightly increased, or pressurized.

The state of slight decompression, slight pressurization, or pressurization generated by this operation is left for a certain period of time, and during that time, the indicator recorder 11
The presence or absence of leakage is determined based on the data displayed on the digital display meter 12.

〔Effect of the invention〕

As explained above, the leak test device of the present invention has excellent performance because it detects the presence or absence of a pressure drop by converting it into an electrical signal by the displacement of the core directly connected to the pressure receiving diaphragm, which is distorted by pressure changes.

In addition, a pressure receiving diaphragm for slight depressurization and slight pressurization is used in the slight depressurization and slight pressurization test methods, and a pressure receiving diaphragm for pressurization is used in the pressurization test method, so the response is quick even to small leaks. It is accurate, the test time can be shortened to about 30 to 60 minutes, it is not easily affected by temperature changes, and the presence or absence of leakage can be quickly confirmed.

In addition, unlike conventional manometers and Bourdon tube pressure gauges that directly introduce gas to detect the presence or absence of a pressure drop, a pressure-receiving diaphragm separates the gas flowing forward from the tank and pipes from the electrical parts. This makes it safe for testing tanks and pipes that handle hazardous materials, and it is compact and easy to operate and carry.

Furthermore, it is possible to carry out both tests using a device using slight decompression, slight pressurization, and pressurization by simply switching operations, and it is convenient because the test method can be selected depending on the conditions.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of an apparatus for carrying out a tank and pipe leakage test according to the present invention. FIG. 2 is a schematic diagram showing one embodiment of a differential transformer type converter. 1...Tank, pipes 2...Opening 3...
Hose 4... Branch pipe 5... Pump 6... Valve 7... Differential transformer type converter for slight pressure reduction and slight pressurization 8...
・Pressure differential transformer type converter 9...Switching valve 10...Connecting pipe 11...Indication recorder 12...Digital display meter 13...Selector switch 15...Pressure receiving diaphragm 16...・Core 1
7... Secondary coil 18a, 18b... Secondary coil 19a, 19b... Rectifier circuit 20... Output adjustment circuit 21... Oscillator T... At the time of leakage test device Permit applicant Toyama inspection Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] 1) A branch pipe connected by a hose is installed at the opening leading into the tank or pipes to be tested for leakage, and a pump is installed at one end of this branch pipe to slightly reduce or slightly pressurize the inside of the tank or pipes. A differential transformer type converter that converts into an electrical signal by the displacement of the core directly connected to the pressure-receiving diaphragm, which generates distortion due to pressure changes due to slight vacuum, slight pressurization, or pressurization, is connected to the other end. A small leak in a tank or pipe, characterized in that the test and pressurization tests are connected via switching valves, and are equipped with a recorder or indicator that records or displays electrical signals of pressure changes. Test equipment.