JP2021117067A - Thermometer calibration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a calibration device capable of relatively easily controlling a temperature in an accommodation space for calibrating a thermometer to be calibrated. SOLUTION: A thermometer calibration device 1 of the present invention is arranged outside a container body 2 having a reference thermometer 61, a thermometer 62 to be calibrated, a storage space A for accommodating a refrigerant, and the container body 2. A second wall 3 that forms a first space B with the container body 2 and a second space C that is arranged outside the first wall 3 and forms a second space C between the first wall 3 and the first wall 3. The first space B is filled with gas, and the second space C is filled with liquefied gas. [Selection diagram] Fig. 2

Description

The present invention relates to an apparatus used to calibrate a thermometer.

Calibration of the thermometer at a low temperature is performed by the following method as described in Patent Document 1. A platinum resistance thermometer that meets the conditions of the international temperature scale (the current temperature standard, the international temperature scale is the 1990 international temperature scale set in 1990), has an international temperature scale in the low temperature range of 0 ° C or less. When calibrating by the specified method, the temperature fixed point of the international temperature scale (hereinafter, it may be simply referred to as "fixed point"), the triple point of water (0.01 ° C) and the triple point of mercury (-). 38.8344 ° C.), triple points of argon (-189.3442 ° C.), etc. are realized, and the resistance value of the thermometer, that is, the calibration value is obtained at those realized temperatures. Then, the arbitrary temperature between these fixed temperature points can be calibrated by interpolating from the calibration values at these fixed temperature points by a method determined by the international temperature scale.

Patent Document 1 provides a comparative calibration block provided with a storage unit for accommodating a reference thermometer and a thermometer to be calibrated in a space inside a heat insulating container in order to efficiently perform a calibration service at a triple point temperature of argon. A low temperature calibration device is disclosed that is provided with a stirrer that holds and stirs the mixed liquid while supplying a mixed liquid of liquid nitrogen and liquid oxygen for cooling so that the comparative calibration block is immersed.

Japanese Unexamined Patent Publication No. 2007-248277

However, in the calibration device of Patent Document 1, since a mixed liquid of liquid nitrogen and liquid oxygen is put in a container in which a thermometer is housed to cool the inside of the container, the temperature inside the container tends to drop sharply, and the inside of the container is squeezed. It is difficult to adjust the temperature to make the triple point of argon and maintain the triple point temperature.
Further, since the thermometers (reference thermometer and calibrated thermometer) are directly cooled by the mixed liquid of liquid nitrogen and liquid oxygen, the thermometer is exposed to a sudden temperature change. For example, a thermometer having a sensor unit such as a platinum resistance thermometer tends to cause an error when the sensor unit is exposed to a sudden temperature change (the quality of the thermometer may deteriorate).
Further, in recent years, liquefied hydrogen has been used in various fields, and a thermometer capable of accurately measuring the temperature of liquefied hydrogen (boiling point: about -253 ° C) is required. In this regard, in the calibration device of Patent Document 1, even if the mixing ratio of the mixed liquid is adjusted, it can be cooled only near the boiling point of nitrogen (about -195.8 ° C.), and the temperature to be calibrated is lower. It is also required to be able to calibrate the meter.

A first object of the present invention is to provide a thermometer calibration device capable of relatively easily controlling the temperature in the accommodation space for calibrating the thermometer to be calibrated.
A second object of the present invention is to provide a thermometer calibration device capable of calibrating at a lower temperature.

The calibrator device for the thermometer of the present invention has a first space between a container body having a storage space for accommodating a reference thermometer, a thermometer to be calibrated, and a refrigerant, and a first space arranged outside the container body and between the container body. It has a first wall forming the above and a second wall arranged outside the first wall and forming a second space between the first wall, and the first space is filled with gas. , The second space is filled with liquefied gas.

In the preferred calibration device of the present invention, the liquefied gas filled in the second space contains liquid hydrogen.
In the preferred calibration device of the present invention, the gas filled in the first space contains gaseous hydrogen.
In the preferred calibration device of the present invention, the refrigerant contained in the accommodation space contains nitrogen.
In a preferred calibration device of the present invention, the refrigerant contained in the accommodation space contains nitrogen, and the gas filled in the first space contains gaseous hydrogen, and the liquefied gas filled in the second space. However, it contains liquid hydrogen and the nitrogen in the containment space is cooled to the triple point temperature.

In the calibration device of the present invention, since the gas filled in the first space is interposed between the liquefied gas filled in the second space and the refrigerant filled in the accommodation space, the refrigerant is rapidly cooled. Can be prevented. Since sudden temperature changes can be prevented, the temperature inside the accommodation space can be easily controlled.
The preferred calibration device of the present invention can also calibrate the thermometer to be calibrated at the triple point temperature of nitrogen.

Top view of the calibration device of the thermometer of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II of FIG.

In the present specification, when simply described as "gas", it means a gas of a substance that is in a gas phase at normal temperature and pressure, and "liquefied gas" means that the gas is in a liquid state (liquid phase). ) Means that it is. "Gas + substance name (element name or compound name)" such as gaseous hydrogen means a substance in a gaseous state (gas phase), and "liquid + substance name (element name or compound name)" such as liquid hydrogen. "Name)" means a substance in a liquid state (gas phase). Further, when only the "substance name" is described, it means any substance in at least one state selected from those three phases without distinguishing between gas, liquid and solid.

[Thermometer calibration device]
In FIGS. 1 and 2, the calibrator 1 of the thermometer of the present invention includes a container body 2 having a reference thermometer 61, a thermometer 62 to be calibrated, a storage space A for accommodating a refrigerant (a refrigerant is not shown), and a container body 2. Between the first wall 3 arranged outside the container body 2 and forming a first space B with the container body 2 and the first wall 3 arranged outside the first wall 3 and forming a first space B with the container body 2. It has a second wall 4 and a second wall 4 forming a second space C. If necessary, it further has a third wall 5 that is arranged outside the second wall 4 and forms a third space D with the second wall 4.
The accommodation space A of the container body 2 is filled with a refrigerant that cools the reference thermometer 61 and the thermometer 62 to be calibrated. Further, the second space C is filled with a liquefied gas (liquefied gas is not shown) which is a cooling agent for cooling the refrigerant. The first space B is filled with a gas (gas is not shown) interposed between the liquefied gas and the refrigerant.
The refrigerant in the accommodation space A is cooled by the liquefied gas that is the coolant in the second space C (in other words, the heat of the refrigerant is taken away by the liquefied gas), and the reference thermometer 61 reaches a predetermined low temperature by the refrigerant. At that time, the thermometer 62 to be calibrated is calibrated.

<Accommodation space and container>
The container body 2 has an upper surface opening type concave body 21 and a lid material 22 that airtightly closes the opening of the concave body 21, and the lid material 22 is detachably attached to the concave body 21. There is. The container body 2 in which the lid member 22 is attached to the concave body 21 has a storage space A inside thereof. The accommodation space A is filled with a refrigerant (details of the refrigerant will be described later). Since the lid material 22 is airtightly attached to the concave body 21, the refrigerant in the accommodation space A does not leak.
In the illustrated example, the container body 2 is formed in a cylindrical shape, and for example, the lid member 22 is airtightly attached to the upper portion of the concave body 21 by a screw action. In this case, by turning the lid material 22 with respect to the concave body 21, the lid material 22 can be removed and the accommodation space A can be opened. On the other hand, by screwing the lid material 22 into the concave body 21, the accommodation space A of the concave body 21 is sealed by the lid material 22. A packing (not shown) may be provided in order to make the lid member 22 and the concave body 21 airtight.

From the viewpoint of strength, it is preferable that the container body 2 made of the concave body 21 and the lid material 22 has pressure resistance.
From the viewpoint of heat transfer, the concave body 21 is preferably formed of a material having excellent heat conductivity, and particularly preferably formed of a material having excellent heat conductivity at least at a low temperature. Examples of materials having excellent thermal conductivity at low temperatures include copper, aluminum, silver, and gold. Since the concave body 21 is made of a material having excellent heat conduction, the liquefied gas effectively cools the refrigerant in the accommodation space A.
Here, in the present invention, the low temperature means 0 ° C. or lower, preferably −30 ° C. or lower.
On the other hand, the lid material 22 is formed of a material that is difficult to conduct heat, and is particularly preferably formed of a material that is difficult to conduct heat at least at a low temperature. Materials that do not easily transfer heat at low temperatures include, for example, synthetic resins such as acrylic resin and epoxy resin, ceramics, materials containing heat insulating materials (for example, metal plates in which foamed resin is laminated or filled inside), glass fibers, and the like. Can be mentioned. Since the lid material 22 is made of a material that does not easily transfer heat, it is possible to effectively prevent heat from flowing into the accommodation space A through the lid material 22.

The container body 2 is provided with an inlet for inserting a refrigerant into the accommodating space A and an outlet for expelling gas or the like in the accommodating space A. For example, valve bodies 2a and 2b are provided at the inlet and the outlet, respectively. Hereinafter, the valve body provided at the inlet is referred to as an “injection valve 2a”, and the valve body provided at the outlet is referred to as a “pouring valve 2b”. In the illustrated example, the injection valve 2a and the injection valve 2b are provided on the lid material 22.

Further, the lid material 22 is formed with an opening 2c for inserting the reference thermometer 61 and the thermometer 62 to be calibrated into the accommodation space A of the container body 2. At least two openings 2c are formed. At least one opening 2c is for inserting the reference thermometer 61, and at least one opening 2c is for inserting the thermometer 62 to be calibrated. In the illustrated example, four openings 2c are provided. In this case, by inserting the reference thermometer 61 into one opening 2c and inserting the thermometer 62 to be calibrated into the remaining three openings 2c, three thermometers 62 to be calibrated can be calibrated at the same time. In the case of having three or more openings 2c, for example, (a) the reference thermometer 61 is inserted into the two openings 2c, and the thermometer 62 to be calibrated is inserted into the two openings 2c (b). ) Insert the reference thermometer 61 into one opening 2c, insert the thermometer 62 to be calibrated into one opening 2c, close the remaining opening 2c to make a blank, and so on. Can be used.
A connector 7 for suspending and holding the thermometers (reference thermometer 61 and thermometer 62 to be calibrated) is attached to the opening 2c. The connector 7 has a through hole 7a. By inserting the thermometer into the through hole 7a, the thermometer is held by the connector 7 on the lid material 22 without leaking the refrigerant from the opening 2c.

Further, the comparative calibration block 8 is accommodated in the accommodation space A. This comparative calibration block 8 is similar to the comparative calibration block of Patent Document 1 (Japanese Patent Laid-Open No. 2007-248277).
The comparative calibration block 8 has a storage unit 81 for accommodating the reference thermometer 61 and the thermometer 62 to be calibrated. The storage unit 81 is formed in a tubular shape with an opening at the top, and a thermometer (reference thermometer 61 and thermometer 62 to be calibrated) can be inserted into the storage unit 81 through the opening.
The comparative calibration block 8 is formed of a material having a high thermal conductivity at a low temperature such as copper or aluminum in order to make the temperature uniform.
The diameter of the storage portion 81 is designed so as to create a gap between the storage portion 81 and the thermometer so that the sensor portion of the thermometer can be easily taken in and out. Although it depends on the thickness of the thermometer, the diameter of the storage portion 81 is, for example, about 8 to 15 mm. The depth (length in the vertical direction) of the storage portion 81 is also not particularly limited, but is, for example, twice or more the total length of the sensor portion in order to ensure the reliability of calibration.

The comparative calibration block 8 is preferably arranged in the central portion of the accommodation space A. Therefore, the comparative calibration block 8 is suspended from the lid member 22 by using, for example, a fixture 82. The fixture 82 is made of a material that does not easily transfer heat at low temperatures in order to prevent heat from flowing into the refrigerant in the accommodation space A through the fixture 82. For example, the fixture 82 is made of a material having a low thermal conductivity, such as stainless steel or nylon.
Specifically, the fixture 82 is made of a rod-shaped member on which a screw is formed. The lower portion of the fixture 82 is fixed to the comparative calibration block 8, and the upper portion of the fixture 82 penetrates the lid material 22 and protrudes from the lid material 22. By attaching the nut member 83 to the upper portion of the protruding fixture 82, the comparative calibration block 8 is suspended and supported by the lid member 22 via the fixture 82.

<1st space and 1st wall>
The first wall 3 is arranged outside the container body 2 and forms a first space B with the container body 2. The first space B is filled with gas. The gas filled in the first space B will be described later.
The first wall 3 has a first concave wall 31 that surrounds the concave body 21 of the container body 2, and a first lid wall 32 that airtightly closes the opening of the first concave wall 31.
The first space B is formed inside the first lid wall 32, the first concave wall 31, and the concave body 21 of the container body 2.
The first lid wall 32 is detachably attached to the first concave wall 31, and is preferably airtightly attached to the first concave wall 31. Since the first lid wall 32 is airtightly attached to the first concave wall 31, the gas sealed in the first space B is prevented from leaking.
In the illustrated example, the first concave wall 31 is formed in a bottomed cylindrical shape, and for example, the first lid wall 32 is airtightly attached to the upper portion of the first concave wall 31 by a screw action. The inner edge of the first lid wall 32 is fixed to the outside of the upper portion of the concave wall of the container body 2 (for example, fixed by means such as welding or adhesion using an adhesive). Through the first lid wall 32, the container body 2 and the first concave wall 31 are integrated while having a first space B between them. By turning the first lid wall 32 with respect to the first concave wall 31, the first lid wall 32 can be removed together with the container body 2. A packing (not shown) may be provided in order to make the first lid wall 32 and the first concave wall 31 airtight.
The first lid wall 32 is not removable and may be fixed to the first concave wall 31.

From the viewpoint of strength, the first wall 3 composed of the first concave wall 31 and the first lid wall 32 preferably has pressure resistance for the same reason as the container body 2.
From the viewpoint of heat transfer, the first concave wall 31 is formed of a material having excellent heat conductivity for the same reason as the concave body 21 of the container body 2, and is particularly formed of a material having excellent heat conductivity at least at a low temperature. Is preferable. Since the first concave wall 31 is made of a material having excellent heat conduction, the liquefied gas effectively cools the refrigerant in the accommodation space A.
The first lid wall 32 is formed of a material that is difficult to conduct heat, and is particularly preferably formed of a material that is difficult to conduct heat at least at a low temperature, for the same reason as the lid material 22 of the container body 2.

The first wall 3 is provided with an inlet (for example, an injection valve 3a) for entering gas into the first space B and an outlet (for example, an injection valve 3b) for removing gas or the like in the first space B. ing. In the illustrated example, the injection valve 3a and the injection valve 3b are provided on the first lid wall 32.

<Second space and second wall>
The second wall 4 is arranged outside the first wall 3 and forms a second space C with the first wall 3. The second space C is filled with liquefied gas. The liquefied gas filled in the second space C will be described later.
The second wall 4 has a second concave wall 41 that surrounds the first concave wall 31 and a second lid wall 42 that airtightly closes the opening of the second concave wall 41.
A second space C is formed inside the second lid wall 42, the second concave wall 41, and the first concave wall 31.
The second lid wall 42 is detachably attached to the second concave wall 41, and is preferably airtightly attached to the second concave wall 41. Since the second lid wall 42 is airtightly attached to the second concave wall 41, gas or the like generated in the second space C is prevented from leaking.
In the illustrated example, the second concave wall 41 is formed in a bottomed cylindrical shape, and for example, the second lid wall 42 is airtightly attached to the upper portion of the second concave wall 41 by a screw action. The inner edge of the second lid wall 42 is fixed to the outside of the upper portion of the first concave wall 31. Through the second lid wall 42, the first concave wall 31 and the second concave wall 41 are integrated while having a second space C between them. By turning the second lid wall 42 with respect to the second concave wall 41, the second lid wall 42 can be removed together with the first wall 3. A packing (not shown) may be provided in order to make the second lid wall 42 and the second concave wall 41 airtight.
The second lid wall 42 is not removable and may be fixed to the second concave wall 41.

From the viewpoint of strength, the second wall 4 composed of the second concave wall 41 and the second lid wall 42 preferably has pressure resistance for the same reason as the container body 2.
From the viewpoint of heat transfer, the second concave wall 41 is formed of a material that is difficult to conduct heat. This is to effectively prevent heat inflow into the liquid gas in the second space C through the second concave wall 41. However, as will be described later, when a heat insulating layer is provided on the outside of the second concave wall 41 so as to cover the second concave wall 41, the second concave wall 41 may be formed of a material that is difficult to conduct heat. , It may be formed of a material having excellent heat conductivity.
For the same reason as described above, the second lid wall 42 is formed of a material that is difficult to conduct heat, and is particularly preferably formed of a material that is difficult to conduct heat at least at a low temperature.

The second wall 4 is provided with an inlet (for example, an injection valve 4a) for entering gas into the second space C and an outlet (for example, an injection valve 4b) for removing gas or the like in the second space C. ing. In the illustrated example, the injection valve 4a and the discharge valve 4b are provided on the second lid wall 42.

<Third space and third wall>
The third wall 5 is arranged outside the second wall 4 and forms a third space D with the second wall 4. The third space D of the third wall 5 functions as a heat insulating layer for making it difficult for heat from the outside to flow into the second space C. Therefore, as described above, when the second wall 4 is formed of a material that is difficult to conduct heat and the inflow of heat from the outside into the second space C is prevented (it is difficult for heat to be applied to the liquefied gas in the second space C). Case), the third wall 5 can be omitted.
The third wall 5 has a third concave wall 51 that surrounds the second concave wall 41, and a third lid wall 52 that airtightly closes the opening of the third concave wall 51.
A third space D is formed inside the third lid wall 52, the third concave wall 51, and the second concave wall 41.
The third lid wall 52 is detachably attached to the third concave wall 51, and is preferably airtightly attached to the third concave wall 51.
In the illustrated example, the third concave wall 51 is formed in a bottomed cylindrical shape, and for example, the third lid wall 52 is airtightly attached to the upper portion of the third concave wall 51 by a screw action. The inner edge of the third lid wall 52 is fixed to the outside of the upper portion of the second concave wall 41. Through the third lid wall 52, the second concave wall 41 and the third concave wall 51 are integrated while having a third space D between them. By turning the third lid wall 52 with respect to the third concave wall 51, the third lid wall 52 can be removed together with the second wall 4. A packing (not shown) may be provided in order to make the third lid wall 52 and the third concave wall 51 airtight.
The third lid wall 52 is not removable and may be fixed to the third concave wall 51.

From the viewpoint of strength, it is preferable that the third wall 5 composed of the third concave wall 51 and the third lid wall 52 has pressure resistance for the same reason as the container body 2.
From the viewpoint of heat transfer, the third concave wall 51 and the third lid wall 52 may be formed of a material having excellent heat conduction, or may be made of a material having difficulty in heat conduction.
The third wall 5 is provided with an outlet (for example, a discharge valve 5b) for venting gas or the like in the third space D. In the illustrated example, the discharge valve 5b is provided on the third lid wall 52.
The inside of the third space D is in a vacuum state. Since the third space D is in a vacuum state, it is possible to prevent heat from flowing into a space inside the third space D (such as the second space C) from the outside.

[Use of calibration device]
The present invention calibrates the thermometer to be calibrated using the calibration device 1. In particular, according to the calibration device 1 of the present invention, the thermometer to be calibrated can be calibrated in a low temperature range.
The thermometer calibration method of the present invention includes a step of accommodating the reference thermometer and the thermometer to be calibrated in the accommodation space, a step of filling the accommodation space with a refrigerant, a step of filling the first space with gas, and a step of liquefying the second space. It has a step of filling gas and a step of measuring the temperature of the thermometer to be calibrated when the reference thermometer reaches a predetermined temperature and calibrating the thermometer to be calibrated.
The order of the steps of accommodating the reference thermometer and the thermometer to be calibrated in the accommodating space, filling the accommodating space with the refrigerant, filling the first space with gas, and filling the second space with liquefied gas is as follows. The present invention is not particularly limited, and either of them may be performed first, or may be performed simultaneously.
Hereinafter, a specific description will be given.

<Preparation process for reference thermometer and thermometer to be calibrated>
As the reference thermometer 61, for example, a thermometer provided by the National Institute of Advanced Industrial Science and Technology (such as a platinum resistance thermometer) or a thermometer calibrated by the thermometer can be used.
The thermometer 62 to be calibrated is a thermometer to be calibrated.
The lid material 22 is removed from the concave body 21, the reference thermometer 61 and the thermometer 62 to be calibrated are inserted into the connector 7, and at least the sensor portion of the reference thermometer 61 and the thermometer 62 to be calibrated is stored in the comparative calibration block 8. It is inserted into the portion 81. By attaching the lid material 22 to the concave body 21, the reference thermometer 61 and the thermometer 62 to be calibrated can be accommodated in the accommodation space A.

<Refrigerant filling process in the accommodation space>
The refrigerant is filled in the accommodation space A that accommodates and seals the thermometer.
The refrigerant is not particularly limited, and a refrigerant that can bring the inside of the accommodation space A into a low temperature environment is used. Examples of the refrigerant include hydrogen (H), nitrogen (N), oxygen (O), fluorine (F), neon (Ne), chlorine (Cl), argon (Ar), bromine (Br), and krypton (Kr). , Xenon (Xe), mercury (Hg), radon (Rn), carbon dioxide (CO ₂ ) and the like. Since it is easy to control the predetermined triple point temperature (triple point temperature peculiar to the substance), the refrigerant is preferably one kind alone. However, two or more kinds may be selected and filled in the accommodation space A on condition that they do not react.
The refrigerant may be filled with a liquid (liquid phase state) or a gas (gas phase state). When filling with a liquid refrigerant, it is preferable to put the liquid refrigerant in the accommodation space A when the above-mentioned thermometer is accommodated in the accommodation space A. When filling with a gaseous refrigerant, the thermometer is accommodated in the accommodating space A, the lid material 22 is closed, and then the accommodating space A is filled from the injection valve 2a. At the time of filling, it is possible to prevent the inside of the accommodation space A from being boosted by injecting the refrigerant of the gas while removing the air (gas) existing in the accommodation space A from the discharge valve 2b.
After filling the liquid refrigerant and closing the lid material 22, if necessary, the gaseous refrigerant is discharged from the injection valve 2a while removing the air (gas) existing in the accommodation space A from the injection valve 2b. It may be injected. The white arrows in FIG. 2 indicate the inflow and outflow directions of the refrigerant and the like.

<Gas filling process in the first space>
The gas filled in the first space B is not particularly limited, and gas hydrogen, gas nitrogen, gas oxygen, gas fluorine, gas neon, gas chlorine, gas argon, gas bromine, gas krypton, gas xenone, gas carbon dioxide and the like are used. Can be mentioned. The gas to be filled in the first space B is preferably one type alone because it is easy to manage. However, two or more kinds of gases may be selected and filled in the first space B on condition that they do not react.
Further, since it is easy to manage, the gas filled in the first space B is preferably the same substance as the liquefied gas filled in the second space C.
The gas is filled into the first space B from the injection valve 3a. At the time of filling, by injecting the gas while removing the air (gas) existing in the first space B from the discharge valve 3b, it is possible to prevent the pressure in the first space B from increasing.

<Liquefied gas filling process in the second space>
The liquefied gas filled in the second space C is not particularly limited, but a substance having a relatively low boiling point is preferable in order to cool the refrigerant. Examples of the liquefied gas include liquid hydrogen, liquid helium, liquid nitrogen, liquid argon and the like.
The liquefied gas is filled into the second space C from the injection valve 4a. At the time of filling, by injecting the liquefied gas while removing the air (gas) existing in the second space C from the discharge valve 4b, it is possible to prevent the pressure inside the second space C from increasing.

<Vacuum process in the third space>
When the calibration device 1 is provided with the third wall 5, the inside of the third space D is evacuated.
For example, by drawing out the air (gas) existing in the third space D from the discharge valve 5b with a vacuum pump, the inside of the third space D can be evacuated.

<Calibration process of thermometer to be calibrated>
When the second space C is filled with liquefied gas, the heat in the accommodation space A flows into the second space C via the gas in the first space B. That is, the heat in the accommodation space A is taken by the liquefied gas via the gas in the first space B, and the refrigerant in the accommodation space A is cooled. When the temperature of the refrigerant drops and the reference thermometer 61 reaches a predetermined temperature fixed point, the temperature of the thermometer 62 to be calibrated is checked, and if there is a difference from the reference thermometer 61, the temperature is calibrated. Calibrate the thermometer 62.

According to the present invention, since the gas filled in the first space B is interposed between the liquefied gas filled in the second space C and the refrigerant filled in the accommodation space A, the refrigerant is rapidly cooled. Can be prevented.
When a sudden temperature drop occurs, there is a possibility that the sensor portion of the thermometer will be out of order, and it is also difficult to control the inside of the accommodation space A to a predetermined temperature fixed point (for example, the triple point temperature of nitrogen). In this respect, in the present invention, since the gas in the first space B interposed between the liquefied gas and the refrigerant acts as a buffer, the temperature in the accommodation space A does not drop sharply, and the degree of the drop does not occur. The temperature in the accommodation space A can be easily controlled.
Further, since the accommodation space A is cooled by the liquefied gas, the internal pressure of the accommodation space A does not increase during calibration (during operation of the device), and the inside of the accommodation space A can be kept below atmospheric pressure. Since the internal pressure of the accommodation space A does not increase in this way, the calibration device 1 of the present invention is not limited in terms of high pressure gas safety.

During calibration (during operation of the device), the gas in the first space B also approaches the temperature of the liquid gas with the passage of time (in this case, a part of the gas in the first space B is liquefied). By newly injecting a gas into the first space B, the temperature in the first space B can be easily controlled. For example, when the temperature of the accommodation space A drops relatively quickly, if the amount of gas injected into the first space B is increased, the temperature of the first space B rises accordingly, so that the temperature in the accommodation space A rises. The degree of decrease can be slowed down. On the other hand, when the temperature of the accommodation space A does not decrease so much, if the gas is not injected into the first space B or the amount of gas injected is reduced, the temperature of the first space B will decrease or will not easily increase. The degree of decrease in temperature in A can be accelerated. When the gas is additionally injected, it is possible to prevent the internal pressure of the first space B from increasing by drawing out the gas existing in the first space B.
Further, with the passage of time, a part of the liquefied gas in the second space C is vaporized, but the vaporized gas in the second space C (the liquefied gas is vaporized) during the operation of the apparatus. Can be prevented from increasing the internal pressure of the second space C by pulling out the gas from the discharge valve 4b. If necessary, liquefied gas may be added to the second space C during the operation of the device. When the same substance is used as the gas to be filled in the first space B and the liquefied gas to be filled in the second space C, the gas extracted from the second space C (the liquefied gas is liquefied) is used in the first space. It can be reused as a gas to be injected into B.
According to the present invention, it is possible to operate the first space B and the second space C so that the internal pressure does not become very high, so that it is possible to provide the calibration device 1 which is not limited in terms of high pressure gas safety. It becomes.

[Example of combination of gas and liquefied gas]
Hereinafter, some combinations of the gas to be filled in the first space B and the liquefied gas to be filled in the second space C will be illustrated.
(1) First Example Gas filled in the first space B: gaseous hydrogen.
Liquefied gas filled in the second space C: liquid hydrogen.
The boiling point of liquid hydrogen is about -253 ° C. When the gaseous hydrogen filled in the first space B is cooled until it is almost liquefied, theoretically, the accommodation space A can be cooled to about -253 ° C.
The refrigerant to be filled in the accommodation space A is not particularly limited, and as described above, hydrogen, nitrogen, oxygen, fluorine, neon, chlorine, argon, bromine, krypton, xenon, mercury, radon, carbon dioxide and the like may be used. It is possible. When calibrating with the triple point as a fixed point, a refrigerant whose triple point temperature is higher than the boiling point of liquid hydrogen is used.

Next, the triple point temperatures of some substances that can be used as refrigerants are listed (the triple point temperatures are listed up to the second decimal place).
Triple point temperature of hydrogen: 259.31 ° C.
Neon triple point temperature: -248.58 ° C.
Triple point temperature of oxygen: -218.79 ° C.
Triple point temperature of nitrogen: -209.97 ° C.
Triple point temperature of argon: 189.34 ° C.
Triple point temperature of krypton: 157.39 ° C.
Triple point temperature of xenon: -111.80 ° C.
Triple point temperature of carbon dioxide: -56.60 ° C.
In this example in which the first space B is filled with gaseous hydrogen and the second space C is filled with liquid hydrogen, if a refrigerant having a triple point temperature higher than the boiling point of the liquid hydrogen is used, the triple point temperature of the refrigerant is used. Can be calibrated with. Among these refrigerants, it is preferable to use an inert gas such as nitrogen or argon because it has a relatively low triple point temperature and is easy to handle, and it is economical to use nitrogen. More preferred. By putting a refrigerant containing nitrogen into the accommodation space, the accommodation space can be cooled to the triple point temperature of nitrogen.
Since the triple point temperature of nitrogen is −209.97 ° C., the thermometer to be calibrated can be calibrated at a lower temperature.

(2) Second Example Gas filled in the first space B: gaseous helium.
Liquefied gas filled in the second space C: liquid helium.
The boiling point of liquid helium is about -269 ° C. In the case of this example, the accommodation space A can theoretically be cooled to about -269 ° C.
Also in this example, the refrigerant to be filled in the accommodation space A is not particularly limited, but if liquid helium is used, it is possible to realize the triple point temperature of hydrogen. That is, by filling the accommodation space A with hydrogen, the thermometer to be calibrated can be calibrated at the triple point temperature of hydrogen. A thermometer calibrated at such a temperature can accurately measure the temperature of liquefied hydrogen.

(3) Third Example Gas filled in the first space B: gaseous nitrogen.
Liquefied gas filled in the second space C: liquid nitrogen.
The boiling point of liquid nitrogen is about -196 ° C. In the case of this example, theoretically, the accommodation space A can be cooled to about -196 ° C.
Also in this example, the refrigerant to be filled in the accommodation space A is not particularly limited, but it is preferable to use a refrigerant having a triple point temperature higher than the boiling point of liquid nitrogen.

(4) Example 4 Gas filled in the first space B: gaseous argon.
Liquefied gas filled in the second space C: liquid argon.
The boiling point of liquid argon is about -186 ° C. In the case of this example, the accommodation space A can theoretically be cooled to about -186 ° C.
Also in this example, the refrigerant to be filled in the accommodation space A is not particularly limited, but it is preferable to use a refrigerant having a triple point temperature higher than the boiling point of liquid argon.

1 Thermometer calibration device 2 Container 3 1st wall 4 2nd wall 61 Reference thermometer 62 Thermometer to be calibrated A Accommodation space B 1st space C 2nd space

Claims (5)

A container body having a storage space for accommodating a reference thermometer, a thermometer to be calibrated, and a refrigerant,
A first wall arranged outside the container body and forming a first space between the container body and the first wall.
It has a second wall that is arranged outside the first wall and forms a second space with the first wall.
A thermometer calibration device in which the first space is filled with gas and the second space is filled with liquefied gas. The thermometer calibration device according to claim 1, wherein the liquefied gas filled in the second space contains liquid hydrogen. The thermometer calibration device according to claim 1 or 2, wherein the gas filled in the first space contains gaseous hydrogen. The thermometer calibration device according to any one of claims 1 to 3, wherein the refrigerant contained in the accommodation space contains nitrogen. The refrigerant contained in the accommodation space contains nitrogen, the gas filled in the first space contains gaseous hydrogen, and the liquefied gas filled in the second space contains liquid hydrogen.
The thermometer calibration device according to claim 1, wherein the nitrogen in the accommodation space is cooled to the triple point temperature of nitrogen.

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