JP2003047837A - Mixing device and mixing method for gas for inspection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mixing device and mixing method for gas for inspection which are capable of regulating the gas for inspection to a set concentration with good accuracy and are capable of maintaining this concentration at the set concentration or setting the concentration at the different set concentrations even in replenishing the gas for inspection. SOLUTION: A stop valve 12a of a gaseous helium delivery pipe 12 connected to a mixing tank 11, a stop valve 13a of a pneumatic delivery pipe 13, a pressure gage 14 connected to the mixing tank 11, a gaseous helium integrator 16a connected to the gaseous helium delivery pipe 12 and an air integrator 18a connected to the pneumatic delivery pipe 13 are connected to a sequencer 17. The amounts of the gaseous helium and air supplied from the gaseous helium delivery pipe 12 and the pneumatic delivery pipe 13 to the mixing tank 11 are controlled by the sequencer 17 according to the measurement of the pressure gage 4, the gaseous helium integrator 16a and the air integrator 18a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection gas mixing apparatus and a mixing method used for inspecting a leak of a work such as a container or a pipe used to store or transfer gas or liquid. .

[0002]

2. Description of the Related Art Conventionally, some containers and pipes used for containing and transferring gas and liquid are required to be airtight, and such containers and pipes are generated. A leak test using a trace gas (inspection gas) is performed to check the leak. Although various gases can be used as such a trace gas, helium gas is generally used because it is harmless and has excellent detection resolution. Then, at the time of inspection, an inspection gas obtained by mixing this helium gas with air or nitrogen gas and diluting it is used.

In this case, the inspection gas is contained in the mixing tank 20 as shown in FIG.
Is supplied to the inspection device (not shown) via the. Further, the delivery pipe 2 to which the helium gas is supplied to the mixing tank 20.
2. Delivery pipe 23 and mixing tank 20 to which air is supplied
A pressure gauge 24 for measuring the internal pressure is connected. The delivery pipes 22 and 23 have open / close valves 22a and 23a, respectively.
Is provided, and the helium gas and the air can be supplied to the mixing tank 20 or the supply thereof can be stopped by opening / closing the opening / closing valves 22a and 23a.

The pressure gauge 24 is connected to a sequencer 25, and the sequencer 25 opens / closes the opening / closing valve 22a of the delivery pipe 22.
It is connected to the. Then, when the inspection gas decreases due to use and the pressure in the mixing tank 20 measured by the pressure gauge 24 decreases, the opening / closing valve 22a is opened by the control of the sequencer 25, and helium gas is supplied into the mixing tank 20. . At this time, the opening / closing valve 23a is also opened to supply the amount of air according to the amount of the replenished helium gas, and the air and the helium gas are mixed in the mixing tank 20 and the inspection gas having the concentration set is set. become. In this case, the inspection gas is set to have a constant concentration,
The supplied helium gas and air are supplied while being controlled by the value of the pressure gauge 24 so as to have a constant ratio.

[0005]

However, in the method of mixing the inspection gas using the above apparatus, the supply amounts of the helium gas and the air are controlled by the internal pressure of the mixing tank 20. Helium gas supplied to the mixing tank 20 when the helium gas is diluted to a large degree by mixing with air to set the helium gas to a low concentration, or when the amount of the inspection gas used in one inspection is small. When the amount is very small, it is difficult to control the supply amount, and there is a problem that the concentration of the inspection gas is not constant. Further, the accuracy of diluting the helium gas to the set concentration largely depends on the resolution and responsiveness of the pressure gauge 24, and there is a problem in that the reproducibility of constantly mixing the inspection gas having a constant concentration causes uncertainty. .

[0006]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and its purpose is to make it possible to accurately set the concentration of the inspection gas and to replenish the inspection gas. Another object of the present invention is to provide an inspection gas mixing apparatus and a mixing method capable of maintaining a constant concentration or setting different concentrations.

In order to achieve the above object, the feature of the inspection gas mixing apparatus according to the present invention is that a tank for containing an inspection gas formed by mixing an inspection high-concentration gas and a dilution gas is provided. An inspection high-concentration gas supply means for supplying an inspection high-concentration gas, a dilution gas supply means for supplying a dilution gas to the tank, and a pressure gauge for measuring the pressure in the tank,
Inspection connected to inspection high-concentration gas supply means, dilution gas supply means, and the pressure gauge, and supplied to the tank from the inspection high-concentration gas supply means and dilution gas supply means according to the measurement result of the pressure gauge In a mixing device for an inspection gas provided with a control means for controlling the amounts of the high concentration gas for dilution and the diluting gas, the high concentration gas supply means for inspection and the control means are connected, and the tank is connected from the high concentration gas supply means for inspection. A high concentration gas flow meter for inspection which measures the amount of high concentration gas for inspection supplied to and is sent to the control means is provided.

According to the features of the present invention configured as described above, the inspection high-concentration gas flow meter for measuring the amount of the inspection high-concentration gas supplied from the inspection high-concentration gas supply means to the tank is provided. It is provided in a state of being connected to the high-concentration gas supply means and the control means, and the measurement result measured by the high-concentration gas flow meter for inspection is transmitted to the control means. Therefore,
Actually, since the high concentration gas for inspection supplied to the tank can be supplied while being measured by the high concentration gas flow meter for inspection, an accurate amount of high concentration gas for inspection can be supplied to the tank.

Another feature of the inspection gas mixing apparatus according to the present invention is that a tank for holding an inspection gas prepared by mixing an inspection high concentration gas and a dilution gas is used, and the tank has a high inspection concentration. High concentration gas supply means for inspection that supplies gas, dilution gas supply means that supplies dilution gas to the tank, pressure gauge that measures the pressure in the tank, and supply gas from the high concentration gas supply means for inspection to the tank High-concentration gas flow meter for measuring the amount of high-concentration gas for inspection, diluting gas flow meter for measuring the amount of diluting gas supplied from the diluting gas supply means to the tank, and high-concentration gas for inspection Supply means, dilution gas supply means, pressure gauge, high concentration gas flow meter for inspection and dilution gas flow meter connected, depending on the measurement results of pressure gauge, high concentration gas flow meter for inspection and dilution gas flow meter Supply high concentration gas for inspection In that a control means for controlling the amount of high concentration gas and the diluent gas for inspection is supplied to the tank from the stage and the dilution gas supply means.

In this case, the inspection high-concentration gas flow meter detects the flow rate of the inspection high-concentration gas supplied from the inspection high-concentration gas supply means to the tank per unit time and the flow rate sensor. It is preferable to include an integrating meter for integrating the flow rate of the inspection high-concentration gas.

According to the features of the present invention configured as described above, the amount of the inspection gas to be replenished is obtained from the measurement result of the pressure in the tank by the pressure gauge, and a constant high concentration gas for inspection and dilution are obtained from the amount. To supply the inspection high-concentration gas and the dilution gas that are actually supplied to the tank while measuring the inspection high-concentration gas flow meter and the dilution gas flow meter, rather than determining the supply amount of the inspection gas As a result, the concentration of the inspection gas in the tank can be grasped, an accurate amount of gas can be supplied to the tank, and the concentration can be changed appropriately.

Further, even if the control means allows the concentration of the inspection gas to be used to be set to a desired value and the inspection is performed while appropriately changing the concentration, the concentration of the inspection gas in the tank is Since the high-concentration gas for inspection and the diluting gas can be supplied to the tank so that the concentration becomes the set concentration, it is possible to perform inspection using different concentrations of the inspection gas by using one tank. That is, it is not necessary to prepare a plurality of tanks containing the inspection gas having different concentrations and use the tanks properly according to the set concentration of the inspection gas.

Further, the inspection high-concentration gas flow meter is provided with a flow sensor for detecting the inspection high-concentration gas and an integrating meter for integrating the flow rate of the inspection high-concentration gas, whereby the accuracy is improved. The high-concentration gas for inspection can be supplied with good quality, and the amount of high-concentration gas for inspection supplied to the tank can be accurately grasped.

Further, for example, a diluting gas flow meter is a flow sensor for detecting the diluting gas supplied from the diluting gas supply means to the tank, and an integrator for integrating the flow rate of the diluting gas detected by the flow sensor. It is also possible to supply the diluent gas with high accuracy and to accurately grasp the amount of the diluent gas supplied into the tank.

The feature of the inspection gas mixing method according to the present invention is that the pressure of the inspection gas is measured by measuring the pressure in the tank containing the inspection gas prepared by mixing the inspection high-concentration gas and the dilution gas. The process of calculating the remaining amount and the flow rates of the high concentration gas for inspection and the dilution gas supplied to the tank are integrated, and the accumulated value of the high concentration gas for inspection and the integrated value of the diluted gas The process of calculating the concentration of the inspection gas, the results calculated from both of the above processes, and the amount of the inspection high-concentration gas and the dilution gas depending on the set concentration are calculated, and the inspection high-concentration gas and the dilution gas to be supplied It consists of the step of calculating the amount of gas, the step of supplying the calculated amount of high-concentration gas for inspection to the tank, and the step of supplying the calculated amount of dilution gas to the tank.

In addition, for example, the step of supplying the calculated high-concentration gas for inspection to the tank, the step of supplying the high-concentration gas for inspection to the tank while reading the flow rate, and the step of integrating the flow rates Can be configured to stop the supply when the amount of high-concentration gas for inspection to be supplied is reached, and further, the step of supplying the calculated amount of dilution gas to the tank can be performed while reading the flow rate. It can also be configured by a step of supplying gas to the tank and a step of integrating the flow rates and stopping the supply when the integrated flow rate reaches the amount of dilution gas to be supplied. This also makes it possible to supply the high-concentration gas for inspection and the diluting gas with high accuracy, and as a result, the inspection by the leak inspection device can be performed with high accuracy.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an inspection gas mixing apparatus 10 according to the same embodiment. This mixing device 10 is provided with a mixing tank 11 for containing an inspection gas, and a helium gas delivery pipe 12, an air delivery pipe 13, a pressure gauge 14 and an inspection gas delivery pipe 15 are connected to the mixing tank 11. Has been done. The helium gas delivery pipe 12 supplies helium gas, which is a high concentration inspection gas, to the mixing tank 11,
The air delivery pipe 13 supplies air, which is a diluting gas for diluting the helium gas, to the mixing tank. In addition, the pressure gauge 14 measures the pressure in the mixing tank 11, and the inspection gas delivery pipe 1
Reference numeral 5 is connected to a leak inspection device (not shown) and supplies the inspection gas in the mixing tank 11 to the leak inspection device.

The helium gas delivery pipe 12 is provided with an opening / closing valve 12a, a helium gas flow rate adjusting valve 12b, a helium gas flow rate sensor 16 and a pressure reducing valve 12c. The pressure reducing valve 12c connects the helium gas delivery pipe 12 to the helium gas delivery pipe 12. It is connected to a helium gas supply device 12d that supplies helium gas to the mixing tank 11 via. Therefore, from the helium gas supply device 12d to the helium gas delivery pipe 12
The helium gas delivered to the mixing tank 11 is supplied to the mixing tank 11 by opening the open / close valve 12a while controlling the pressure and flow rate by adjusting the pressure reducing valve 12c and the helium gas flow rate adjusting valve 12b, and closing the open / close valve 12a. Supply is stopped. The helium gas delivery pipe 12, the opening / closing valve 12a, the helium gas flow rate adjusting valve 12b, the pressure reducing valve 12c, and the helium gas supply device 12d constitute the inspection high-concentration gas supply means of the present invention.

Further, the helium gas flow sensor 16 includes
A helium gas integrator 16a is connected. The helium gas flow sensor 16 detects the helium gas passing through the helium gas delivery pipe 12 and calculates the instantaneous flow rate thereof. The helium gas integrator 16a receives a signal from the helium gas flow sensor 16 and delivers the helium gas. Tube 1
The flow rate of helium gas per unit time passing through 2 is integrated and the integrated flow rate of helium gas is displayed. The helium gas integrator 16a is connected to the sequencer 17, which is a control means, and the sequencer 17 is connected to the pressure gauge 14 and the opening / closing valve 12a.

The sequencer 17 includes a CPU, ROM, RA
M and the like are provided, and a basic unit that stores various programs and data and executes arithmetic processing based on the programs and data, an input unit, and an output unit are provided.
In addition, the basic unit also stores data regarding the state of the mixing tank 11 set by the user, for example, various data such as the pressure inside the mixing tank 11, the concentration of the inspection gas, and the helium gas amount.

Then, the input unit receives the measurement result of the pressure in the mixing tank 11 measured by the pressure gauge 14 as a signal and the integrated value of the helium gas supply amount integrated by the helium gas integrator 16a as a signal. To do. Then, the amount of the residual inspection gas in the mixing tank 11 is calculated from the measurement result of the pressure gauge 14, and the calculated value of the amount of the residual inspection gas and the preset amount of the inspection gas and the inspection gas are set. The amount of helium gas required to be supplied to the mixing tank 11 is calculated by comparing the ratios of helium gas and air (concentration of helium gas).

Then, a signal is transmitted from the output section to open the on-off valve 12a and send the helium gas from the helium gas supply device 12d to the mixing tank 11 via the helium gas delivery pipe 12. At that time, the helium gas flow rate sensor 16
The helium gas supplied to the mixing tank 11 is detected by the helium gas integrator 16a, and the supply amount thereof is calculated and sent to the sequencer 17 as data. Therefore, when the necessary helium gas is supplied to the mixing tank 11, the opening / closing valve 12a is closed and the supply of the helium gas to the mixing tank 11 is completed under the control of the sequencer 17.

Further, the air delivery pipe 13 has an opening / closing valve 1
3a, an air flow rate adjusting valve 13b, an air flow rate sensor 18, and a pressure reducing valve 13c are provided, and the pressure reducing valve 13c is connected to an air supply device 13d that supplies air to the mixing tank 11 via an air delivery pipe 13. There is. Therefore, the air sent out from the air supply device 13d is
c and the air flow rate adjusting valve 13b are controlled to control the pressure and the flow rate, and the open / close valve 13a is opened to supply the mixed tank 11 with the open / close valve 13a.
The supply is stopped by closing the. The air delivery pipe 13, the opening / closing valve 13a, the air flow rate adjusting valve 13b, the pressure reducing valve 13c, and the air supply device 13d constitute the dilution gas supply means of the present invention.

An air integrator 18a is connected to the air flow rate sensor 18. The air flow rate sensor 18 detects the air passing through the air delivery pipe 13 and calculates the instantaneous flow rate thereof, and the air integrator 18a receives the signal from the air flow rate sensor 18 and passes through the air delivery pipe 13 by a unit. Display the cumulative flow rate of air by integrating the flow rate of air per hour. The air integrator 18a is the sequencer 1
7, and the sequencer 17 is connected to the opening / closing valve 13a.

The sequencer 17 is a mixture calculated from the measurement result when the pressure gauge 14 measures the pressure in the mixing tank 11, the pressure in the mixing tank 11 preset by the user, the concentration of the inspection gas, and the like. The required amount of air to be supplied to the tank 11 is supplied to the mixing tank 11 by opening the opening / closing valve 13a. Further, when the air flow rate sensor 18 and the air integrator 18a determine that the air supplied into the mixing tank 11 has reached the required air amount, the opening / closing valve 13a is closed and the air supply is terminated. . The supplied air is mixed with helium gas in the mixing tank 11 to become a test gas having a set concentration.

The inspection gas is supplied to the leak inspection device through the inspection gas delivery pipe 15 and used for inspection. The inspection gas delivery pipe 15 has an opening / closing valve 15
a is attached, and by opening and closing the opening / closing valve 15a, it is possible to supply the inspection gas to the leak inspection device or to stop the supply thereof.

Next, the inspection gas in the mixing tank 11 is reduced, and the high-concentration helium gas and the diluting air are supplied by using the inspection gas mixing apparatus 10 configured as described above. The case will be described. First, mixing tank 1
When the inspection gas in 1 decreases due to use, pressure gauge 1
The measurement of 4 shows that the pressure in the mixing tank 11 is decreasing. Next, the sequencer 17 calculates the inspection gas amount in the mixing tank 11, and the amount of helium gas and air to be supplied is calculated from the calculation result.

In this case, when the test gas having the same concentration as the residual test gas in the mixing tank 11 is replenished, the supply amounts of helium gas and air are calculated at the same ratio. Also, when replenishing so that the concentration of the remaining inspection gas becomes different from that of the inspection gas, the helium gas and the air should be mixed so that the mixed gas of the remaining inspection gas and the inspection gas to be supplemented has the set concentration. Calculate the supply amount of.
This calculation is based on the helium gas integrator 16a and the air integrator 1
8a, the concentration of the residual inspection gas in the mixing tank 11 is calculated from the values of the supply amounts of the helium gas and the air that have already been supplied, and what is the amount of the helium gas and the air to be newly replenished? For example, it is performed by calculating whether the total density reaches the set value.

Next, under the control of the sequencer 17,
The open / close valves 12a and 13a are opened, helium gas is supplied from the helium gas supply device 12d to the mixing tank 11 via the helium gas delivery pipe 12, and mixed from the air supply device 13d via the air delivery pipe 13. Tank 1
1 is supplied with air. And helium gas integrator 1
When the integrated flow rate of helium gas displayed on 6a reaches the calculated value, the opening / closing valve 12a is closed by the control of the sequencer 17 and the supply of helium gas is stopped. Further, when the integrated flow rate of air displayed on the air integrator 18a reaches the calculated value, the opening / closing valve 13a is closed by the control of the sequencer 17 and the air supply is stopped.

As a result, the residual inspection gas in the mixing tank 11 is mixed with the newly supplemented helium gas and air, and the mixing tank 11 is filled with the inspection gas of the set concentration in the set amount. become. When supplying the helium gas and the air into the mixing tank 11, as described above,
Helium gas and air may be supplied at the same time, helium gas may be supplied first and then air may be supplied, or air may be supplied and then helium gas may be supplied. Further, other gas may be used as the inspection high-concentration gas instead of helium gas, and nitrogen gas or the like may be used instead of air as the dilution gas.

Further, in this embodiment, the mixing tank 11
On the other hand, the helium gas and the air are separately supplied using the helium gas delivery pipe 12 and the air delivery pipe 13, and the helium gas flow rate sensor 16 and the helium gas integrator 16a are supplied to the delivery pipes 12 and 13, respectively. Also, an air flow rate sensor 18 and an air integrator 18a are provided. However, the helium gas delivery pipe 12 and the air delivery pipe 13 are
Mixing tank 11 that joins from the middle to form one delivery pipe
The helium gas and the air can be supplied by the same delivery pipe.

In this case, the helium gas delivery pipe 12 and the air delivery pipe 13 are provided with opening / closing valves which are controlled to be opened / closed by the sequencer 17, and the portions of the helium gas delivery pipe 12 and the air delivery pipe 13 on the downstream side of the both opening / closing valves are connected. Join. The device can be simplified by providing one flow rate sensor and one integrator at each of the converging portions of the delivery pipe.

As described above, in the mixing apparatus 10 according to the present embodiment, the supply amount of helium gas to the mixing tank 11 is controlled not only by using the measurement value of the pressure gauge 14, but also by the helium gas flow sensor 16 and With a high-concentration gas flow meter for inspection consisting of a helium gas integrator 16a,
The amount of helium gas actually supplied to the mixing tank 11 is measured, and when the amount reaches the set value, the supply is stopped. Therefore, the supply amount of helium gas can be accurately controlled.

Similarly, the air is supplied to the mixing tank 11 by the dilution gas flow meter including the air flow sensor 18 and the air integrator 18a.
The amount of air supplied to No. 1 is measured, and when the amount reaches a set value, the supply is stopped. Therefore, the supply amount of air can also be accurately controlled, and as a result, the mixed gas of helium gas and air supplied to the mixing tank 11 becomes the inspection gas having the set concentration.

Further, according to the mixing apparatus 10, not only the concentration of the inspection gas is kept constant, but also the concentration of the inspection gas can be changed by appropriately setting the concentration of the inspection gas. Therefore, it is not necessary to prepare a plurality of mixing tanks containing inspection gases having different set concentrations and use the tanks properly according to the purpose of use. A user-friendly device that can use gas can be obtained.
That is, the helium gas integrator 16a and the air integrator 18
By using a, the concentration of the inspection gas already supplied into the mixing tank 11 can be calculated,
By appropriately changing the amounts of helium gas and air to be replenished, it is possible to freely mix test gases having different concentrations.

Further, the helium gas delivery pipe 12 is provided with a helium gas flow rate adjusting valve 12b and a pressure reducing valve 12c so that the pressure and flow rate of the helium gas supplied to the mixing tank 11 can be controlled. The amount of gas supplied can be controlled within a minute range. Similarly, the air delivery pipe 13 is provided with an air flow rate adjusting valve 13b and a pressure reducing valve 13c so that the air supplied to the mixing tank 11 can be controlled within a very small range. Therefore, even if the inspection gas is set to a low concentration or the inspection gas is used in a small amount, the concentration becomes stable.

Further, according to the mixing apparatus 10, since the opening / closing valves 12 and 13a can be simultaneously opened to supply the helium gas and the air at the same time, the helium gas and the air can be supplied to the mixing tank 11 in a short time. This can be done and work efficiency is greatly improved.

[Brief description of drawings]

FIG. 1 is a schematic view of an inspection gas mixing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic view of an inspection gas mixing device according to a conventional example.

[Explanation of symbols]

10 ... Mixing device, 11 ... Mixing tank, 12 ... Helium gas delivery pipe, 12a, 13a ... Open / close valve, 13 ... Air delivery pipe, 14 ... Pressure gauge, 16 ... Helium gas flow sensor,
16a ... Helium gas integrator, 17 ... Sequencer, 18
... air flow rate sensor, 18a ... air integrator.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Seiya Nishimura             Yamafa, 283 Aoyamachi, Hamamatsu City, Shizuoka Prefecture             Inside Intec Co., Ltd. F term (reference) 2G067 CC04 CC11 CC13 DD02 DD04                 4G035 AB01 AE02 AE13 AE19                 4G037 BA02 BB06 BC04 BD01 BD04

Claims (4)

[Claims] 1. A tank for containing an inspection gas formed by mixing an inspection high-concentration gas and a dilution gas, an inspection high-concentration gas supply means for supplying the inspection high-concentration gas to the tank, and the tank. Dilution gas supply means for supplying a dilution gas to, a pressure gauge for measuring the pressure in the tank, connected to the inspection high-concentration gas supply means, the dilution gas supply means and the pressure gauge, Depending on the measurement result of the pressure gauge, control means for controlling the amounts of the high concentration gas for inspection and the dilution gas supplied from the high concentration gas for inspection gas supply means and the dilution gas supply means to the tank,
In an inspection gas mixing device, the device is connected to the inspection high-concentration gas supply means and the control means, and measures the inspection high-concentration gas amount supplied from the inspection high-concentration gas supply means to the tank. And an inspection gas mixing device, characterized in that an inspection high-concentration gas flow meter for transmitting the measurement result to the control means is provided. 2. A tank for containing an inspection gas, which is a mixture of an inspection high-concentration gas and a dilution gas, an inspection high-concentration gas supply means for supplying the inspection high-concentration gas to the tank, and the tank. A dilution gas supply means for supplying a dilution gas to the tank, a pressure gauge for measuring the pressure in the tank, and an amount of the inspection high-concentration gas supplied from the inspection high-concentration gas supply means to the tank. Inspection high-concentration gas flow meter, dilution gas flow meter for measuring the amount of dilution gas supplied from the dilution gas supply means to the tank, inspection high-concentration gas supply means, dilution gas supply means ,
Connected to a pressure gauge, a high concentration gas flow meter for inspection and a dilution gas flow meter, and according to the measurement results of the pressure gauge, a high concentration gas flow meter for inspection and a dilution gas flow meter, the high concentration gas for inspection And a control unit for controlling the amounts of the high concentration gas for inspection and the dilution gas supplied from the supply unit and the dilution gas supply unit to the tank. 3. A flow sensor, wherein the inspection high-concentration gas flow meter detects a flow rate of the inspection high-concentration gas supplied from the inspection high-concentration gas supply means to the tank per unit time, and the flow rate. 3. An integrator for integrating the flow rate of the high-concentration gas for inspection detected by the sensor.
The inspection gas mixing device described in 1. 4. A step of measuring the pressure in a tank containing an inspection gas containing a mixture of an inspection high-concentration gas and a dilution gas to calculate the remaining amount of the inspection gas, and the step of supplying the inspection gas to the tank. Integrating the flow rates of the inspection high-concentration gas and the dilution gas, and calculating the concentration of the inspection gas in the tank from the integrated value of the integrated inspection high-concentration gas and the integrated value of the dilution gas, and A step of calculating the results calculated from both steps and the amounts of the high concentration gas for inspection and the dilution gas depending on the set concentration, and calculating the amounts of the high concentration gas for inspection and the dilution gas to be supplied, A method of mixing an inspection gas, comprising: a step of supplying an amount of high concentration gas for inspection to the tank; and a step of supplying a calculated amount of dilution gas to the tank.