Metal shell water triple point bottle and its manufacturing method and freezing storage method

Abstract

The present invention relates to the field of temperature measurement technology, and specifically to a metal shell water triple point bottle and a freezing and preservation method thereof. The metal shell of the metal shell water triple point bottle is a cylindrical barrel with a height of 10 cm to 50 cm, made of corrosion-resistant metal, and the upper and lower ends are closed to form a cavity. The cavity is filled with ultrapure water, evacuated, and a vacuum sealing interface is installed on the shell. A thermometer well is provided in the shell. The present invention uses corrosion-resistant metal to make the shell of the water triple point bottle, and the inner cavity is coated with an anti-ion penetration coating. The overall durability is greatly improved compared to the glass bottle body, and it is repairable. Since the metal shell water triple point bottle can withstand the stress caused by the complete freezing of ultrapure water and the "ice bridge", the bottle body will not be damaged. When freezing, it can enter a "full ice" state, so that a freezing method different from the traditional one can be used. The professional requirements for use are low, and the technical process is simple.

Description

Technical Field

[0001] The invention relates to the technical field of temperature measurement, in particular to a metal shell water triple point bottle, a manufacturing method and a freezing and storage method. Background Art

[0002] Temperature is one of the basic units of the International System of Units. Temperature measurement is widely used in daily life and various industries of the national economy. In order to ensure the accuracy of temperature measurement, the International Committee for Weights and Measures has established the international highest temperature standard, namely the International Temperature Scale. The current international temperature scale is the International Temperature Scale of 1990, namely ITS-90. ITS-90 defines several fixed temperature points and temperature interpolation methods to achieve temperature reproduction.

[0003] The triple point temperature of water is the most important fixed point temperature defined in ITS-90 and is also the reference point for the definition of thermodynamic temperature. The triple point temperature of water is the temperature when water is in solid, liquid and gas phase equilibrium, defined as 0.01℃, and the thermodynamic temperature is 273.16K. The triple point temperature of water has good reproducibility and is an important temperature point for temperature tracing and verification.

[0004] The water triple point bottle is a specially made device used to reproduce the temperature of the water triple point. At present, most water triple point bottles use glass to make the outer shell and thermometer well. The inner cavity of the outer shell is filled with pure water and evacuated. There is a glass tube at the top of the bottle mouth that goes deep into the bottle body and the tail end is sealed, which serves as a measurement well for inserting the thermometer, that is, the thermometer well. The overall structure is shown in Figure 1 (Wherein, 101 is a glass container, 102 is a thermometer well, 103 is a vacuum, and 104 is pure water). Some triple point bottles are designed with a vacuum gauge for checking the vacuum level of the water triple point bottle.

[0005] There are two main types of water triple point bottles in terms of freezing methods:

[0006] The first is the internal freezing method. After precooling the triple point bottle, a low-temperature medium, such as liquid nitrogen, dry ice, low-temperature alcohol, etc., is placed from the thermometer well for freezing. An ice sheath of a certain thickness will be gradually frozen around the thermometer well. When the ice sheath reaches the required thickness, the freezing is stopped and the water triple point bottle is placed in ice water or a low-temperature liquid at the storage temperature for storage.

[0007] The second method is the external freezing method, in which the water triple point bottle is placed in a low-temperature constant-temperature liquid tank for cooling. After a specified period of time, when the pure water in the water triple point bottle reaches a certain supercooled temperature, the water triple point bottle is taken out for artificial vibration to induce ice crystal formation, forming a water three-phase equilibrium state, and the freezing is completed. Alternatively, the temperature in the thermometer well is monitored during the freezing process. When the temperature continues to drop and reaches a certain supercooled temperature, a spontaneous phase change occurs to form a water three-phase equilibrium state. At this time, the temperature in the thermometer well quickly rises to 0.01°C, and the freezing is stopped. Adjust the low-temperature constant-temperature liquid tank to the storage temperature, or store the water triple point bottle in ice water to complete the freezing. Based on the second method, automatic freezing and preservation devices are currently available.

[0008] The water triple point bottle made of glass currently has the following disadvantages in use:

[0009] 1. Glass products are relatively fragile and are easily broken when subjected to external forces or when the freezing stress is large; the stress at the bottom of the air extraction point is concentrated, and cracking and air leakage are likely to occur during use;

[0010] 2. When freezing, the water in the bottle cannot be completely frozen into ice. During the freezing process, an "ice bridge" cannot be formed from the central thermometer well to the outer wall of the bottle, otherwise it is easy to cause the bottle to break;

[0011] 3. Due to the use of glass containers, after long-term use, trace elements in the glass, such as boron, dissolve into pure water, causing the temperature of the water triple point to change;

[0012] Fourth, the production is complex and the degree of specialization is high, resulting in a high manufacturing cost for the triple point of water bottle. The use of low-temperature liquids, automatic freezing and storage devices, etc. all require the configuration of professional equipment, which is costly to use.

[0013] 5. High requirements for use. The internal freezing method requires high professional experience of personnel, and it is easy to cause problems such as freezing of personnel by low-temperature liquid and damage to the bottle. The external freezing method of low-temperature liquid also requires personnel to closely monitor the temperature changes of the thermometer well and adjust the temperature in time, otherwise it is easy to damage the bottle.

[0014] 6. If the bottle is broken or leaking, it is not economically worth repairing.

[0015] In general, since the water triple point bottle is currently made of glass, its durability, ease of use and cost of use are subject to certain limitations. It is mostly used in metrological technical institutions and is rarely used in industrial and other fields. Summary of the invention

[0016] The invention aims to provide a metal shell water triple point bottle and a manufacturing method and a freezing storage method thereof, so as to solve the problems of durability, usability and maintainability of the glass shell water triple point bottle.

[0017] In order to solve the above technical problems, this application provides the following technical solutions:

[0018] The metal shell water triple point bottle described in the present invention comprises a metal shell with a vacuum sealing interface, a thermometer well is arranged in the metal shell, a certain amount of ultrapure water is filled in the closed cavity inside the metal shell, and the closed cavity is evacuated and placed vertically when in use.

[0019] Furthermore, the metal shell is a cylindrical body with a height of 10 cm to 50 cm, and is made of high-strength corrosion-resistant metal; the upper and lower ends of the metal shell are closed, and a closed cavity is formed inside.

[0020] Furthermore, the thermometer well is made of the same type of metal as the metal shell, and is a semi-closed tube with a closed lower end and an open upper end; the thermometer well passes through the bottleneck on the upper end sealing wall and penetrates into the cavity of the metal shell.

[0021] Furthermore, the metal shell is provided with a vacuum sealing interface, one end of which passes through the metal shell and communicates with the inner cavity of the metal shell, and the other end is connected to a vacuum pump when evacuating the vacuum.

[0022] Furthermore, the upper end surface of the metal shell is connected to the bottleneck, the bottleneck is in a connected tube shape, the inner wall of the bottleneck is smooth, and cooperates with the thermometer well to form a vacuum closed interface. The upper end surface of the metal shell and the bottleneck can be integrally formed.

[0023] Furthermore, the upper section of the outer wall of the thermometer well is designed with a vacuum sealing interface for vacuum sealing with the bottleneck, and the vacuum sealing interface has multiple grooves for placing O-type vacuum sealing rubber rings. The upper section of the inner wall of the thermometer well mouth has an internal thread for connecting the pull rod of the special operator when vacuuming.

[0024] Furthermore, the outer wall of the thermometer well is designed with a variable diameter, and is divided into three sections: the upper section, the middle upper section, and the lower section. The upper outer wall of the thermometer well and the upper section of the inner wall of the bottleneck form a vacuum-sealed interface. The outer wall of the upper section of the thermometer well is close to the well mouth, and the well has the largest outer diameter, which is the location of the vacuum-sealed interface. The outer diameter of the lower section of the thermometer well is slightly smaller, and the diameter is smaller than the minimum aperture of the bottleneck and the bottleneck cover. The middle upper section of the thermometer well has the smallest outer diameter while meeting the pressure resistance requirements. Below the lower transition cone surface of the vacuum-sealed interface of the upper section of the outer wall, a transition section is provided, and the outer diameter is the same as that of the lower section of the outer wall.

[0025] When the thermometer well is completely pulled out and the narrow diameter is located at the vacuum sealing interface of the upper section of the inner wall of the bottleneck, the vacuum is opened; when the upper outer wall of the thermometer well and the vacuum sealing interface of the upper section of the inner wall of the bottleneck are attached, the vacuum is closed.

[0026] Furthermore, conical surfaces are respectively provided at the upper and lower transitions of the vacuum sealing interface of the outer wall of the thermometer well, and the conical surface is larger near the vacuum sealing interface and smaller away from the vacuum sealing interface. The lower section of the inner wall of the bottleneck is provided with a conical surface corresponding to the upper conical surface of the vacuum sealing interface of the thermometer well, and the lower part of the through-hole wall of the bottleneck cover is provided with a conical surface corresponding to the lower conical surface of the vacuum sealing interface. During assembly, a water-proof sealing ring with the same conical surface shape is placed between the conical surface of the lower section of the inner wall of the bottleneck and the lower conical surface at the vacuum sealing interface of the thermometer well. After assembly, the above conical surfaces form a limit for the thermometer well, fix the thermometer well, and ensure coaxiality with the metal shell of the water triple point bottle. The water-proof sealing ring has the same shape as the lower transition conical surface at the vacuum sealing interface of the thermometer well, but has a slightly smaller inner diameter, and can be installed on the transition section of the thermometer well close to the lower conical surface of the vacuum sealing interface without falling off.

[0027] As an optimization, the thermometer well can be formed into a barrel-shaped body with a closed bottom by integrated molding.

[0028] Furthermore, the bottle neck cover has a through hole in the axial direction for inserting a thermometer. The bottle neck cover and the bottle neck have inner and outer threads respectively, and can be screwed together and fixed.

[0029] As an optimization, the metal shell can be made into a cup-shaped container by an integrated molding method.

[0030] Furthermore, an asymmetric U-shaped tube is installed on the metal wall at the upper end of the metal shell, the long tube of the asymmetric U-shaped tube is connected to the upper end sealing wall and communicated with the inner cavity of the metal shell, and the short tube of the asymmetric U-shaped tube is closed with a glass window.

[0031] Furthermore, the metal walls of the metal shell, thermometer well, bottleneck and plugging cap, asymmetric U-shaped tube, glass window and other components that are in contact with ultrapure water and vacuum in the closed cavity are covered with a high-purity water-resistant material coating to prevent ions in the metal from penetrating into the pure water.

[0032] The O-type vacuum sealing rubber ring is made of vacuum sealing rubber and together with the thermometer well, bottleneck, upper plugging cap and bottleneck cover, forms a vacuum sealing interface.

[0033] As an alternative, an independent vacuum sealing valve can be used to replace the above vacuum sealing interface. In this case, the thermometer well and the upper end surface of the metal shell no longer use the vacuum sealing interface, but are fixedly connected or integrally formed. When vacuuming and vacuum sealing, a matching operator is used.

[0034] As an alternative, a separate high vacuum baffle valve or other valve can be used to replace the above vacuum sealing interface. In this case, the thermometer well and the upper end surface of the metal shell no longer use the vacuum sealing interface, but are fixedly connected or integrally formed. When evacuating and vacuum sealing, the valve can be directly opened and closed.

[0035] It is also equipped with a special operator, which is made of the same type of metal as the metal shell and consists of a hand wheel, a pull rod, an operator cover, a seat body, a sealing O-ring, a bottom cover, a side pipe, a triple point bottle connection port, and a vacuum pump connection port.

[0036] The seat body is cylindrical, with an axial variable diameter through hole inside. The upper inner wall of the through hole has multiple grooves for placing sealing O-rings, forming a vacuum sealing interface with the assembled pull rod and upper cover.

[0037] The side surface of the middle part of the seat body is fixedly connected to the side pipe by welding or other methods, and the top end of the side pipe is a vacuum pump connection port.

[0038] The pull rod is a smooth-surfaced variable diameter cylinder, with a hand wheel connected to the top and an external thread at the bottom that matches the thread on the inner wall of the thermometer well. The hand wheel can be rotated to drive the pull rod to rotate, so that the bottom thread and the inner wall thread of the thermometer well are screwed together.

[0039] The side wall of the through hole at the bottom of the seat body has multiple grooves for placing sealing rubber rings. During the vacuum operation, the three-phase point bottle connection port at the bottom of the seat body is put on the bottleneck, and the bottom cover of the operator is tightened to form a vacuum sealing interface.

[0040] The assembly method of the special manipulator of the present invention:

[0041] Material pretreatment: Clean and degas at high temperature all components of the operator, including the handwheel, pull rod, upper cover, valve body, vacuum port, and bottom cover of the operator.

[0042] Sealing assembly: Apply an appropriate amount of vacuum silicone grease to the inner and outer walls of the sealing cavity and the sealing O-ring, and assemble according to the vacuum sealing requirements.

[0043] Leak detection and sealing: Perform helium mass spectrometry leak detection on the operator. If there is a leak, perform vacuum leak sealing and repair to make the leakage rate meet the requirements.

[0044] The manufacturing method of the metal shell water triple point bottle of the present invention is as follows:

[0045] All parts of the metal-shell water triple-point bottle are pre-treated by cleaning, heating and exhausting;

[0046] The metal shell, thermometer well, end face and bottleneck, asymmetric U-shaped tube, glass window and other components and the metal wall surface in contact with ultrapure water and vacuum in the closed cavity are coated with high-purity water-resistant material coating by coating or other methods.

[0047] Assemble the metal shell water triple point bottle according to the vacuum sealing requirements. When assembling the vacuum sealing interface, apply an appropriate amount of vacuum silicone grease to the sealing structure. Do not apply vacuum silicone grease to the water-proof sealing ring and the corresponding conical surface.

[0048] Perform vacuum leak detection and repair any leaks found.

[0049] Take out the thermometer well with sealing parts, clean the inner cavity of the bottle, the thermometer well and the pipeline, discharge the waste water after cleaning, and dry the water triple point bottle.

[0050] Pour ultrapure water into the bottle, and use high-frequency induction heating or other external heating methods to heat the bottle so that the water in the bottle is heated to a specified temperature and maintained for a period of time to expel the air dissolved in the water.

[0051] The water triple point bottle is frozen by freezing, and an auxiliary semi-enclosed metal tube is used to assist heating with an electric heating rod, so that the water in the triple point bottle retains an overflow channel when freezing, thereby reducing the air and impurities dissolved in the water.

[0052] Use intermittent vacuuming. First, estimate the total vacuuming time based on the water loss per unit time at the current room temperature. Then use the method of vacuuming - closing the vacuum sealing valve - taking a break for a while - continuing vacuuming. Repeat multiple cycles to achieve a better vacuuming effect and adjust the water retention in the bottle to the predetermined amount. The cold trap can be maintained during the intervals of intermittent vacuuming.

[0053] The amount of water discharged in the water triple point bottle during the above-mentioned heating, freezing, vacuuming and other steps is controlled by weighing, and the water retention in the bottle is adjusted to a predetermined amount.

[0054] The specific production process is as follows:

[0055] 1. Material pretreatment: Clean and degas all components of the water triple point bottle at high temperature.

[0056] 2. Coating treatment: The metal wall surface of the bottle body that is in contact with the ultrapure water and vacuum is coated with a high-purity, permeation-resistant coating by coating or other methods.

[0057] 3. Assembly: Metal shell water triple point bottle according to vacuum sealing requirements. When assembling the vacuum sealing interface, apply a proper amount of vacuum silicone grease to the vacuum sealing interface, and do not apply vacuum silicone grease to the water-proof sealing ring and the corresponding cone surface.

[0058] 4. Leak detection and sealing: Check the bottle for leaks. If there is any leakage, perform vacuum sealing to make the leakage rate meet the specified requirements.

[0059] 5. Cleaning: Take out the thermometer well with sealing parts, remove the vacuum silicone grease from the bottleneck and clean it, repeatedly use ultrapure water to clean the inner cavity of the bottle, the thermometer well and the pipeline, discharge the waste water after cleaning, and dry the water triple point bottle.

[0060] 6. Filling ultrapure water and weighing: Weigh the dried water triple point bottle, the mass is m w1Grams; fill the bottle with ultrapure water until it is full, use an electronic scale or other instrument to weigh the water triple point bottle filled with water, the mass is m w2 Grams, calculate or experiment to obtain the volume of the part below the thermometer well limiting cone surface and convert it into mass m w3 grams; calculate the water filling mass m w =m w2 -m w1 -m w3 , calculate the expected discharge volume m according to a certain ratio e =m w *Specified ratio.

[0061] 7. Heating pipe connection: refer to Figure 5 Connect the previously cleaned pipe to the neck of the water triple point bottle, and place a wastewater container below the outlet at the end of the pipe. Place an induction heating coil or use other heating devices to heat the bottle from the bottom.

[0062] 8. Exhaust by heating: Turn on the heating device and heat the bottom of the bottle to heat up all the water in the bottle. Heat until the water is slightly boiling, adjust the heating power to keep the water close to boiling, and at this time, a small amount of steam will be discharged from the exhaust pipe. After exhausting for a specified time, turn off the heating device and cool the bottle to room temperature. Remove the pipeline and weigh the bottle again. The mass is m h2 . Calculate the heating exhaust water loss m h =m w2 -m h2 , should be close to 0.

[0063] 9. Freezing method to exhaust and remove impurities: Figure 6 Connect the pipelines, place the metal shell water triple point bottle in the low temperature tank body of the low temperature constant temperature tank device, the neck of the water triple point bottle is connected to the drainage pipe, and a waste water container is provided below the drainage pipe. Put a small cleaned hollow bottom closed metal tube into the thermometer well position through the neck of the bottle to the bottom of the bottle, place the thermometer probe and the heating rod in the metal tube, and electrically connect the thermometer host and the adjustable DC power supply respectively.

[0064] Set the low-temperature thermostat to freezing temperature and pass low-power electric heating to the heater. At this time, the water triple point bottle will gradually enter the freezing state, and ice will appear after the temperature drops to the freezing point. At this time, water will be discharged from the pipeline. As the further freezing is completed, the freezing of the whole bottle of water will be completed. At this time, no water will be discharged from the pipeline, and when the temperature of the monitoring thermometer well drops below the freezing point, the freezing of the whole bottle of water will be completed. Take out the water triple point bottle and place it at room temperature. Remove the pipeline, dry the surface of the bottle body, and re-weigh the water-containing bottle body. The mass is m f2 . Calculate the freezing loss m f =m h2 -m f2, the freezing water loss should be approximately the total water mass m w About 1 / 11 of.

[0065] 10. Intermittent vacuuming:

[0066] 1) Calculate the estimated net vacuum time: Weigh the water triple point bottle, the mass is m v1 . With the total water mass m w Compare and calculate the cumulative water loss m l =m w -m v1 . Compare the expected discharge volume m e , calculate the expected amount of water discharged in the vacuum step m ev =m e -m l ; According to the historical experience of the ambient temperature during vacuuming and the water loss rate v of the pipeline used l , calculate the estimated net vacuum time t e =m ev / v l If the estimated time is too short, the water triple-point bottle should be supplemented with pre-exhausted water, or the temperature of the water triple-point bottle should be lowered during vacuuming.

[0067] 2) Develop a vacuuming plan in interval mode, and set the estimated net vacuuming time t e Divide into several sections. Generally, the first and last sections can be set longer, the middle section can be set shorter, and each section can be inserted with an intermittent state. In the intermittent state, close the pipeline vacuum valve and keep the vacuum sealing valve open. The vacuum pump is not turned off to maintain the vacuum state of the pipeline and the cold trap.

[0068] As an optimization, the cold trap can be drained and maintained during the intermittent state. For example, the temperature of the cold trap is raised, and the condensed water in the cold trap is evaporated and discharged by vacuum. At the end of the intermittent state, the temperature of the cold trap is restored, and the water triple point bottle is vacuumed again.

[0069] 3) Press Figure 7 Connect the vacuum pipeline. Connect the thermometer well equipped with O-type vacuum sealing rubber ring and watertight sealing ring to the pull rod of the special operator, and draw the thermometer well into the cavity of the special operator so that the narrow diameter of the thermometer well is located at the position where the bottleneck will be connected.

[0070] Operate the special operator, insert the thermometer well from the bottleneck into the water triple point bottle, and insert the bottleneck into the connection port of the special operator triple point bottle. Tightly connect the bottleneck and tighten the lower cover of the operator to complete the installation of the operator. Check and confirm the position of the pull rod to turn on the vacuum.

[0071] Weigh the water triple point bottle with the operator installed, the mass is m p1 .

[0072] The vacuum pump connection port of the special operator is connected to the vacuum tank through a pipeline, the vacuum tank is connected to the cold trap through a pipeline vacuum valve, a vacuum gauge is installed in the pipeline between the vacuum tank and the pipeline vacuum valve, and the cold trap is connected to the vacuum pump group through a pipeline.

[0073] 4) Draw vacuum according to the vacuum plan. During the vacuum extraction, open the pipeline vacuum valve and vacuum sealing valve. During the interval, close the pipeline vacuum valve and keep the vacuum sealing valve open. After the vacuum extraction is completed, the vacuum degree should meet the requirements and close the vacuum sealing valve.

[0074] 5) Vacuum sealing

[0075] Use the hand wheel to push the rod downwards, so that the vacuum seal on the thermometer well falls into the bottleneck of the water triple point bottle and reaches the limit. Remove the pipeline and weigh the water triple point bottle with the operator installed. The mass is m p2 .

[0076] Remove the operator, install the bottle neck cover, and screw it tightly to fix the thermometer well. Install the introduction cap to complete the vacuum sealing operation.

[0077] When using the sealing valve, use the vacuum sealing valve operator to seal the sealing plug into the vacuum sealing valve according to the instructions, remove the vacuum sealing valve operator, remove the vacuum pipeline, and cover the vacuum sealing valve protection cap.

[0078] When using alternative valves such as flapper valves, close the valve diameter, remove the vacuum line, and cover the valve body interface with a protective cap.

[0079] After completing the above steps, calculate the vacuum water loss m p =m p2 -m p1 And the total accumulated water loss m a =m p +m l . Re-test the water retention capacity of the bottle, and the water retention capacity should be within the specified range.

[0080] As an optimization, an electronic scale can be used to monitor the weight of the water triple point bottle in real time. At this time, the water triple point bottle is connected to the pipeline with a hose of a certain strength, and the pipeline is kept approximately horizontal and tension-free.

[0081] The freezing and storage method of the metal shell water triple point bottle of the present invention:

[0082] The water triple point bottle made by the present invention is opaque and allows high-purity water to be completely frozen into ice without damage. Therefore, it can be frozen based on the low-temperature liquid method using the following procedure:

[0083] At a temperature lower than the freezing point of supercooled water, use a cryogenic liquid to freeze a water triple point bottle and keep it for a specified time; after all the water in the bottle is frozen, raise the cryogenic liquid to the storage temperature for warming up and keep it for a specified time; take out the water triple point bottle and perform internal and external melting at normal room temperature;

[0084] Alternatively, the water triple point bottle is placed vertically in a freezer at a set temperature for freezing. After freezing, it is warmed up in an ice-water mixture in a zero-degree freezing point device, stored and used;

[0085] Among them, the method of manually measuring the moment of inertia is used to detect the formation of ice sheath in the water triple point bottle.

[0086] The specific steps are as follows:

[0087] 1. Preparation: Place the water triple point bottle into the low temperature liquid tank. The liquid level should be higher than the well of the bottle thermometer but lower than the observation window.

[0088] 2. Supercooling freezing: The low-temperature liquid tank is set to the supercooling temperature and frozen for a specified time so that all the water in the bottle is frozen into ice.

[0089] 3. As an alternative, you can also use a freezer to freeze the water triple point bottle. Put the water triple point bottle vertically into the freezer and freeze it at a specified temperature for a specified time until all the water in the bottle is frozen into ice.

[0090] 4. Rewarming to storage state: Adjust the temperature of the low-temperature liquid tank to the storage state temperature, so that the ice in the triple point bottle can be rewarmed and maintained for the specified time.

[0091] 5. Internal and external melting: Take out the water triple point bottle, place it at room temperature, and rinse the outer wall of the water triple point bottle and the thermometer well with water slightly higher than 0.01°C to melt the ice layer near the outer wall and the thermometer well;

[0092] 6. Check the rotational inertia: Pick up the water triple point bottle by hand, keep it vertical, and gently rotate it around the axis of the water triple point bottle. When you feel that the rotational inertia becomes significantly smaller, and you can still feel the internal ice cover rotating after stopping the rotation, the ice cover is completed;

[0093] 7. Storage and use: Set the low-temperature liquid tank to the specified storage temperature and put the water triple point bottle in for storage and use.

[0094] 8. As an alternative, a zero-degree freezing point device or a simple ice-water mixture device can be used instead of a low-temperature liquid tank for rewarming, storage and use.

[0095] 9. As an alternative, the water triple point bottle made by the present invention can also be frozen and preserved using an automatic freezing and preservation device based on the low temperature liquid method.

[0096] Compared with the prior art, the metal shell water triple point bottle and its manufacturing method and freezing storage method of the present invention have at least the following beneficial effects:

[0097] (1) In terms of design and production, compared with the water triple point bottle made of glass, the water triple point bottle shell of the present invention is made of corrosion-resistant metal, and the inner cavity is coated with an anti-ion penetration coating, so the durability of the bottle body is greatly improved.

[0098] (2) In terms of use, since the metal shell triple point of water bottle is not afraid of the stress caused by freezing, it can enter the "full ice" state during freezing. At the same time, the "ice bridge" formed during the freezing process will not damage the bottle body. The professional requirements for use are relatively low and the technical process is simple.

[0099] (3) Engineering manufacturing: Standard parts can be used to make water triple point bottles, which improves product quality and interchangeability and reduces manufacturing costs.

[0100] (4) Cost of use: It can be frozen and stored in a high-precision low-temperature liquid thermostatic bath or even in a simple freezer, which has low cost and good usability. It has good maintainability. After the vacuum degree drops or the vacuum is lost, it can be refilled and vacuumed. If the parts are damaged, they can be replaced, which has low cost of use.

[0101] The present invention has the following effects in this field:

[0102] First, it can provide a new technical route for improving the water triple point bottle. In addition to the technical route of glass shell, a new technical route based on metal shell is provided. This technical route has further development space in terms of vacuum maintenance, pure water anti-ion pollution, freezing method, application environment requirements, etc.

[0103] Secondly, due to the lower manufacturing and use costs, good durability, ease of use and maintainability, it is more conducive to the use and promotion of the water triple point bottle.

[0104] Third, the metal-water triple point bottle has strong environmental adaptability and can be extended to the field of industrial measurement to improve the overall accuracy of industrial temperature measurement and realize on-site and in-situ measurement.

[0105] Fourth, based on this solution, the water triple point bottle and the control device can be further miniaturized and intelligentized, the cost can be reduced, the method of use can be simplified, and the scope of application can be further expanded.

[0106] The metal shell water triple point bottle and its manufacturing method and freezing storage method of the present invention are further described below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0107] Figure 1 It is a schematic diagram of the structure of a water triple point bottle in the prior art;

[0108] Figure 2 It is a schematic structural diagram of a water triple point bottle based on a metal container of the present invention;

[0109] Figure 3 Schematic diagram of vacuum sealing interface cross section

[0110] Figure 4 Schematic diagram of the cross-section of the vacuum sealing interface assembly;

[0111] Figure 5 Configuration diagram for high temperature heating;

[0112] Figure 6 Configuration diagram for low temperature freezing;

[0113] Figure 7 A diagram of the configuration for vacuuming;

[0114] Figure 8 Exploded cross-sectional view of the dedicated vacuum operator;

[0115] Fig. 9 A cross-sectional diagram of the position of the operator's lever during vacuuming;

[0116] Fig.10 Schematic cross-section of the operator lever positions when the vacuum is closed.

[0117] Wherein, 101-glass container, 102-glass thermometer trap, 103-vacuum, 104-pure water;

[0118] 1-metal shell, 2-thermometer trap, 3-ultrapure water, 4-neck, 5-asymmetric U-shaped tube, 6-upper end sealing wall, 7-glass window, 8-neck cover, 9-introduction cap, 10-vacuum sealing interface, 11-upper plugging cap, 12-O-type sealing rubber ring, 13-waterproof sealing ring;

[0119] 50-hand wheel, 51-pull rod, 52-upper cover, 53-seat body, 54-sealing O-ring, 55-bottom cover, 56-side pipe, 57-triple point bottle connection port, 58-vacuum pump connection port;

[0120] 110-metal shell water triple point bottle, 111-neck opening, 112-drainage pipeline, 113-waste water container, 114-high frequency induction heating coil, 115-insulating heat insulation board, 116-electromagnetic shielding iron plate, 117-main unit of high frequency induction heating device, 118-connecting wire;

[0121] 120- low temperature tank body, 121- low temperature constant temperature tank device, 122- semi-enclosed metal tube, 123- thermometer probe, 124- heating rod, 125- adjustable DC power supply, 126- thermometer host, 127- three-way pipe, 128- dust plug;

[0122] 131-metal shell water triple point bottle, 132-special operator (connected with thermometer trap with O-ring), 133-vacuum tank, 134-pipeline vacuum valve, 135-cold trap, 136-vacuum gauge, 137-vacuum pump set, 138-vacuum pipeline. DETAILED DESCRIPTION

[0123] The technical scheme of the present invention is further specifically described below by way of examples and in conjunction with the accompanying drawings. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0124] The main English abbreviations involved are as follows:

[0125] 1. ITS-90: International Temperature Scale of 1990;

[0126] 2. PVDF: polyvinylidene fluoride.

[0127] 1. Structure of Metal Shell Water Triple Point Bottle and Vacuum Operator

[0128] (1) Metal shell water triple point bottle

[0129] like Figure 2-6 As shown, a metal shell water triple point bottle is composed of a metal shell 1, a thermometer well 2, ultrapure water 3, a bottleneck 4, an asymmetric U-shaped tube 5, a glass window 7, a bottleneck cover 8, an introduction cap 9, an upper plugging cap 11, an O-type sealing rubber ring 12, and a water-proof sealing ring 13.

[0130] The metal shell 1 is a cylindrical body with a height of 30 cm, and is made of 0Cr17Ni12Mo2 stainless steel (316 stainless steel); the upper and lower ends of the metal shell 1 are closed, and a closed cavity is formed inside, which is filled with a certain amount of ultrapure water 3, evacuated, and placed vertically when in use.

[0131] The thermometer well 2 is made of the same type of metal as the metal shell 1 and is tubular. The upper part of the thermometer well 2 is designed with a vacuum sealing interface 10 for vacuum sealing with the bottleneck 4, and the vacuum sealing interface 10 has multiple grooves for placing O-type sealing rubber rings 12. The upper part of the inner wall of the well mouth of the thermometer well 2 is provided with an internal thread for connecting the pull rod 51 of the special operator when vacuuming.

[0132] The bottleneck 4 is made of the same type of metal as the metal shell 1, and is tubular, and is fixedly connected to the opening in the center of the upper plugging cap 11 through the central axis. The upper and middle parts of the bottleneck through hole are smooth cylindrical structures, and cooperate with the thermometer well 2 to form a vacuum closed interface.

[0133] The thermometer well 2 is inserted into the bottle body through the bottleneck 4. The lower end of the thermometer well 2 is closed with a plug, and the distance from the bottom plug cap or plug is slightly smaller than the radius of the metal shell 1. The upper end of the thermometer well 2 is open for inserting the thermometer to be tested.

[0134] The outer wall of the thermometer well 2 is designed with variable diameter, and the upper part near the well mouth has the largest outer diameter, which is the vacuum sealing interface position. The lower part of the outer wall of the thermometer well has a slightly smaller outer diameter, which is smaller than the minimum aperture of the bottleneck 6 and the bottleneck cover 8. The outer diameter of the upper part of the outer wall of the thermometer well is the smallest.

[0135] Conical surfaces are respectively provided at the upper and lower transitions of the vacuum sealing interface of the thermometer well 2, and the conical surface is larger near the vacuum sealing interface and smaller away from the vacuum sealing interface. A conical surface corresponding to the upper conical surface of the vacuum sealing interface of the thermometer well 2 is provided at the lower portion of the inner wall of the bottleneck 4, and a conical surface corresponding to the lower conical surface of the vacuum sealing interface is provided at the lower portion of the through hole of the bottleneck cover 8. During assembly, a water-proof sealing ring 13 made of PVDF material with the same conical surface shape is placed between the conical surface of the lower portion of the inner wall of the bottleneck 4 and the conical surface at the lower transition of the vacuum sealing interface of the thermometer well 2. After assembly, the above conical surfaces form a limit for the thermometer well 2, which can fix the thermometer well 2 and ensure coaxiality with the metal shell 1 of the water triple point bottle.

[0136] The bottle neck cover 8 has a through hole in the axial direction, which allows the thermometer to be inserted. The bottle neck cover 8 and the bottle neck 4 have inner and outer threads respectively, which can be screwed together and fixed.

[0137] The upper plugging cap 11 is one of the specific forms of the upper end surface sealing wall 6, which is made of the same type of metal as the metal shell 1, and is equipped with an asymmetric U-shaped tube 5, which is connected to the interior of the metal shell 1; the short tube of the symmetric U-shaped tube 5 is closed by a glass window 7.

[0138] The introduction cap 9 is made of plastic materials such as polytetrafluoroethylene, and has an axial through hole, which is larger at the top and smaller at the bottom. The lower through hole connects the thermometer well / sealing cap and the well mouth of the thermometer well to facilitate the insertion of the guiding thermometer.

[0139] The metal walls of the metal shell 1, the thermometer well 2, the bottleneck 4 and the upper plugging cap 11, the asymmetric U-shaped tube 5, the glass window 7 and other components that are in contact with the ultrapure water and vacuum in the closed cavity are coated with a high-purity water-resistant material PVDF coating by coating or other means.

[0140] The O-type vacuum sealing rubber ring 12 is made of fluororubber, and together with the thermometer well 2 , the bottleneck 2 , the upper plugging cap 6 , and the bottleneck cover 8 , constitutes one of the specific implementation forms of the vacuum sealing interface 10 . Figure 6 and Figure 7 They are respectively the decomposition and assembly schematics of the vacuum sealing interface.

[0141] As an alternative, a separate vacuum sealing valve or a high vacuum baffle valve or the like may be used to replace the vacuum sealing interface 10 .

[0142] (ii) Special operator

[0143] The dedicated operator is made of the same type of metal as the metal housing 1, and is composed of a hand wheel 50, a pull rod 51, an upper cover 52, a seat 53, a sealing O-ring 54, a bottom cover 55, a side pipe 56, a triple point bottle connection port 57, and a vacuum pump connection port 58. Figure 8 .

[0144] The seat body 53 is cylindrical, with an axial variable diameter through hole inside. The upper inner wall of the through hole has multiple grooves for placing sealing O-type rubber rings 54, forming a vacuum sealing interface with the assembled pull rod 51 and the upper cover 52 of the operator.

[0145] The side surface of the middle part of the seat body is fixedly connected to the side tube 56 by welding or the like, and the top end of the side tube 56 is a vacuum pump connection port 58 .

[0146] The pull rod 51 is a variable diameter cylinder with a smooth surface, the top of which is connected to a hand wheel 50, and the bottom of which is provided with an external thread matching the inner wall thread of the thermometer well 2. The hand wheel 50 can be rotated to drive the pull rod to rotate, so that the bottom thread and the inner wall thread of the thermometer well 2 are screwed together.

[0147] like Figure 9-10 As shown, the side wall of the through hole at the bottom of the seat body 53 has multiple grooves for placing sealing O-rings 54. During the vacuum operation, the triple point bottle connection port 57 at the bottom of the seat body 53 is sleeved on the bottle neck 4, and the bottom cover 55 of the operator is tightened to form a vacuum sealing interface.

[0148] 2. Assembly process of special manipulator

[0149] 1. Material pretreatment: All components of the operator, including the hand wheel 50, the pull rod 51, the upper cover 52, the seat body 53, the vacuum pump connection port 58, and the operator bottom cover 55, are cleaned and degassed at high temperature.

[0150] 2. Sealing assembly: Assemble according to the vacuum sealing requirements. When assembling the vacuum sealing interface, apply an appropriate amount of vacuum silicone grease on the inner and outer walls of the sealing cavity and the sealing O-ring.

[0151] 4. Leak detection and sealing: Perform helium mass spectrometry leak detection on the operator. If there is a leak, perform vacuum leak sealing and repair to make the leakage rate meet the requirements.

[0152] 3. Production process of water triple point bottle

[0153] 1. Material pretreatment: Clean and degas at high temperature the stainless steel pipes, pipe caps, glass windows, valves and operators of all bottle components.

[0154] 2. Coating treatment: PVDF coating is applied to the metal wall surfaces of the bottle components that are in contact with ultrapure water and vacuum.

[0155] 3. Sealing assembly: Assemble the metal shell water triple point bottle according to the vacuum sealing requirements. When assembling the vacuum sealing interface, apply a proper amount of vacuum silicone grease on the inner and outer walls of the sealing cavity and the O-type sealing rubber ring. Do not apply vacuum silicone grease on the PVDF sealing ring and the corresponding cone surface.

[0156] 4. Leak detection and sealing: Perform helium mass spectrometry leak detection on the bottle. If there is a leak, perform vacuum sealing and repair to make the leakage rate meet the requirements.

[0157] 5. Cleaning: Take out the thermometer well 2 with the O-ring 12, remove the vacuum silicone grease from the neck of the bottle, repeatedly use ultrapure water to clean the inner cavity of the bottle, the thermometer well and the pipeline, discharge the waste water after cleaning, and dry the water triple point bottle.

[0158] 6. Filling with pure water and weighing: Weigh the dried water triple point bottle, the mass is m w1 Grams; fill the bottle with ultrapure water (such as Figure 2 ) until the bottle is full, weigh the full bottle, the mass is m w2 Grams, calculate or experiment to obtain the volume of the part below the limiting cone of the thermometer well 2 and convert it into mass m w3 grams; calculate the total water filling mass m w =m w2 -m w1 -m w3 , calculate the expected discharge water volume m e =m w *15%, target water retention m t =m w *85%.

[0159] 7. Open the vacuum structure: keep the bottleneck 4 open, the thermometer well 2, the bottleneck cover 8 and the introduction cap 9 are not installed, and the bottleneck 4 is used as a liquid discharge port.

[0160] If an independent vacuum sealing valve or other valve is used, keep the valve open before vacuuming. The exposed interface of the sealing valve is the drain port.

[0161] 8. Heating pipe connection: Use high frequency induction heating method, press Figure 5 A pre-cleaned drainage pipe 112 is connected to the bottleneck 111 of the water triple point bottle, and a wastewater container 113 is placed below the outlet of the pipe end. A high-frequency induction heating coil 114 is placed outside the middle and lower part of the bottle shell, and the coil is connected to the main unit 117 of the high-frequency induction heating device. An insulating heat insulation board 115 and an electromagnetic shielding iron plate 116 are placed below the water triple point bottle.

[0162] 9. Exhaust by heating method: Turn on the main unit 117 of the high-frequency induction heating device, add water to the bottle until it is slightly boiling, and adjust the heating power to keep the water close to boiling. At this time, a small amount of steam is discharged from the exhaust pipe 112. After exhausting for a specified time (such as 30 minutes), turn off the main unit 117 of the high-frequency induction heating device. Observe that the exhaust stops, and the exhaust by heating method is completed. Cool the bottle to room temperature, drain the liquid in the pipeline, remove the pipeline, and weigh the bottle containing water again. The mass is m h2 . Calculate the heating water loss m h =m w2 -m h2 , should be close to 0.

[0163] 10. Freezing method to exhaust and remove impurities:

[0164] according to Figure 6 Connect the pipelines, place the metal shell water triple point bottle 110 in the low temperature tank body 121 of the low temperature constant temperature tank device 121, the bottleneck 111 of the water triple point bottle is connected to the drainage pipeline 112, and a waste water container 113 is provided below the outlet of the drainage pipeline. A small cleaned hollow bottom closed metal tube 122 is placed in the thermometer well position through the bottleneck 111 to close to the bottom of the bottle, and a thermometer probe 123 and a heating rod 124 are placed in the metal tube 122, and are electrically connected to the thermometer host 126 and the adjustable DC power supply 125 respectively.

[0165] Set the low-temperature thermostat to freezing temperature and pass low-power electric heating to the heater. At this time, the water triple point bottle will gradually enter or cold state, and ice will appear after the temperature drops to the freezing point. At this time, water will be discharged from the pipeline. As the freezing continues, when no ultrapure water flows out of the pipeline and the temperature of the monitoring thermometer well drops below the freezing point, the freezing of the entire bottle of water is completed. Take out the water triple point bottle and place it at room temperature. Remove the pipeline, dry the surface of the bottle body, and re-weigh the water-containing bottle body. The mass is m f2 . Calculate the freezing loss m f =m h2 -m f2 , the freezing water loss should be approximately the total water mass m w About 1 / 11 of.

[0166] 11. Intermittent vacuuming:

[0167] 1) Calculate the estimated net vacuum time: Weigh the water triple point bottle, the mass is m v1 . With the total water mass m w Compare and calculate the cumulative water loss m l =m w -m v1 . Compare the expected discharge volume m e , calculate the expected amount of water discharged in the vacuum step m ev =me -m l ; According to the historical experience of the ambient temperature during vacuuming and the water loss rate v of the pipeline used l , calculate the estimated net vacuum time t e =m ev / v l (e.g. 10h). If the estimated time is too short, the water triple point bottle should be supplemented with exhausted water, or the temperature of the water triple point bottle should be lowered during vacuuming.

[0168] 2) Develop a vacuuming plan in interval mode, and set the estimated net vacuuming time t e Divide into several sections. Generally, the first and last sections can be set longer, and the middle section can be shorter. Interval time is inserted in the middle of each section. In the intermittent state, close the pipeline vacuum valve and keep the vacuum sealing valve open. The vacuum pump is not turned off to maintain the vacuum state of the pipeline and the cold trap. For example, 10 hours can be divided into 3-2-2-3 stages, with a 4-hour interval between each section.

[0169] During the intermittent period, the cold trap is drained and maintained. For example, the temperature of the cold trap is raised to 2°C, and the condensed water in the cold trap is evaporated and discharged by vacuum. At this time, it should be noted that the vapor pressure must not exceed the allowable water vapor pressure of the vacuum pump. When using a rotary vane pump, open the gas ballast valve. At the end of the intermittent state, close the gas ballast valve, restore the temperature of the cold trap, and then continue to evacuate.

[0170] 3) Press Figure 7 Connect the vacuum line.

[0171] Connect the thermometer well 2 equipped with O-ring 12 and watertight seal ring 13 to the pull rod 51 of the special operator 132, draw the thermometer well 2 into the cavity of the special operator, and make the narrow diameter of the thermometer well 2 located at the position where the bottleneck 4 will be connected.

[0172] Operate the special operator 132, insert the thermometer well 2 into the water triple point bottle from the bottle neck 4, and insert the bottle neck 4 into the special operator triple point bottle connection port 57. Tightly connect the bottle neck 4 and tighten the operator lower cover to complete the installation of the operator. Check and confirm the position of the pull rod 51 to turn on the vacuum.

[0173] Weigh the water triple point bottle with the operator installed, the mass is m p1 .

[0174] The vacuum pump connection port 58 of the special operator 132 is connected to the vacuum tank 133 through a pipeline 138, and the vacuum tank 133 is connected to the cold trap 135 through a pipeline vacuum valve 134. The pipeline between the vacuum tank 133 and the pipeline vacuum valve 134 is equipped with a vacuum gauge 136, and the cold trap 135 is connected to the vacuum pump group 137 through a pipeline.

[0175] 4) Draw vacuum according to the vacuuming plan. During the vacuuming period, open the vacuum sealing valve, and during the interval, close the vacuum sealing valve. After the vacuuming is completed, the vacuum degree should meet the requirements.

[0176] 5) Vacuum sealing:

[0177] Use the hand wheel 50 to push the pull rod 51 downwards, so that the vacuum seal pad on the upper part of the thermometer well 2 falls into the bottleneck of the water triple point bottle and reaches the limit. Remove the pipeline and weigh the water triple point bottle with the operator installed. The mass is m p2 .

[0178] Remove the operator, install the bottle neck cover 8, and screw it tightly to fix the thermometer well 2. Install the introduction cap 9 to complete the vacuum sealing operation.

[0179] When using the sealing valve, use the vacuum sealing valve operator to seal the sealing plug into the vacuum sealing valve according to the instructions, remove the vacuum sealing valve operator, remove the vacuum pipeline, and cover the vacuum sealing valve protection cap.

[0180] When using alternative valves such as flapper valves, close the valve diameter, remove the vacuum line, and cover the valve body interface with a protective cap.

[0181] 6) After completing the above steps, calculate the vacuum water loss m p =m p2 -m p1 And the total accumulated water loss m a =m p +m l Re-test the water retention of the bottle, and the water retention should be within the specified range (such as the total water mass m w of 82% to 86%).

[0182] 4. Freezing and Storage of Water Triple Point Bottle

[0183] The water triple point bottle made by the present invention is opaque and allows high-purity water to be completely frozen into ice without damage. Therefore, it can be frozen based on the low-temperature liquid method using the following procedure:

[0184] 1. Preparation: Place the water triple point bottle into the low temperature liquid tank, and the liquid surface must exceed the well of the bottle thermometer;

[0185] 2. Supercooling freezing: The low-temperature liquid tank is set to the supercooling freezing temperature (such as -8°C), frozen for a specified time (such as 4h), take out the water triple point bottle, shake it gently, and there should be no sound of water flowing or colliding.

[0186] 3. Storage state temperature uniformity: The low-temperature liquid tank is set to the storage state temperature (such as 0.006°C) and stored for a specified time (such as 24 hours) to allow the ice in the triple point bottle to return to a temperature close to 0.01°C.

[0187] 4. Internal melting and external melting: Take out the water triple point bottle and use water slightly higher than 0.01°C to rinse the outer wall of the bottle and the thermometer well to melt the ice layer on the outer wall of the bottleneck and the outer wall of the bottle.

[0188] 5. Check the rotational inertia: Pick up the water triple point bottle by hand, keep it vertical, and gently rotate it around the axis of the water triple point bottle. When you feel that the rotational inertia becomes significantly smaller and you can still feel the internal ice sheath rotating after stopping rotation, the preparation of the ice sheath is completed.

[0189] 6. Storage and use: Keep the low-temperature liquid tank at the storage temperature (such as 0.006°C) and put the water triple point bottle in for storage.

[0190] 7. The water triple point bottle made according to the present invention can also be frozen and preserved using an automatic freezing and preservation device based on the low temperature liquid method.

[0191] The embodiments described above are merely descriptions of preferred implementation modes of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A metal shell water triple point bottle, characterized in that: The invention comprises a metal shell (1) with a vacuum sealing interface (10), wherein a thermometer well (2) is arranged in the metal shell (1), and the internal closed cavity of the metal shell (1) is filled with ultrapure water (3) and evacuated (11); the outer wall of the thermometer well (2) is designed with a variable diameter, and is divided into three sections, namely, an upper section, a middle upper section and a lower section; the upper section of the outer wall of the thermometer well (2) is close to the well mouth and has the largest well outer diameter, and forms a vacuum sealing interface (10) with the upper section of the inner wall of the bottleneck (4); the lower section of the thermometer well (2) has a slightly smaller outer diameter, and its diameter is smaller than the minimum aperture of the lower section of the inner wall of the bottleneck (4); the middle upper section of the thermometer well (2) has the smallest outer diameter under the premise of meeting the pressure resistance requirements; A transition section is provided below the transition cone surface below the vacuum sealing interface (10) of the upper section of the outer wall of the thermometer well (2), and the outer diameter of the transition section is the same as that of the lower section of the outer wall; Conical surfaces are respectively provided at the upper and lower transitions of the vacuum sealing interface (10) of the upper outer wall of the thermometer well (2), which are larger in the middle and gradually smaller on both sides; the lower part of the through hole wall of the bottleneck cover (8) and the lower inner wall of the bottleneck (4) are respectively provided with conical surfaces corresponding to the conical surfaces at the upper and lower transitions; during assembly, a water-proof sealing ring (13) is placed between the conical surface of the lower inner wall of the bottleneck (4) and the lower transition conical surface at the vacuum sealing interface of the thermometer well (2); The water-proof sealing ring (13) has the same shape as the lower transition cone surface at the vacuum sealing interface of the thermometer well (2), but has a slightly smaller inner diameter, and can be mounted on the transition section of the thermometer well (2) close to the lower cone surface of the vacuum sealing interface without falling off; When the thermometer well (2) is completely pulled out upward or the narrow diameter is located at the vacuum sealing interface of the upper section of the inner wall of the bottleneck (4), the vacuum is opened; when the upper outer wall of the thermometer well (2) and the vacuum sealing interface of the upper section of the inner wall of the bottleneck (4) are attached, the vacuum is closed.

2. The metal shell water triple point bottle according to claim 1, characterized in that: The metal shell (1) is a cylindrical body with a height of 10 cm to 50 cm and is made of corrosion-resistant metal; both ends of the metal shell (1) are closed, and a closed cavity is formed inside.

3. The metal shell water triple point bottle according to claim 1, characterized in that: The thermometer well (2) is made of the same metal as the metal shell (1) and is in the shape of a semi-closed tube with a closed lower end and an open upper end. The thermometer well (2) passes through the bottleneck (4) on the upper end sealing wall (6) and penetrates into the cavity of the metal shell (1).

4. The metal shell water triple point bottle according to claim 1, characterized in that: The metal shell (1) is provided with a vacuum sealing interface (10), one end of which passes through the metal shell (1) and communicates with the inner cavity of the metal shell (1), and the other end of which is connected to a vacuum pump when vacuuming.

5. The metal shell water triple point bottle according to claim 1, characterized in that: An asymmetric U-shaped tube (5) is mounted on the metal wall at the upper end of the metal shell (1); the long tube of the asymmetric U-shaped tube (5) is connected to the upper end sealing wall (6) and is in communication with the inner cavity of the metal shell (1); the short tube of the asymmetric U-shaped tube (5) is sealed with a glass window (7).

6. The metal shell water triple point bottle according to claim 1, characterized in that: The metal shell (1), the thermometer well (2), the asymmetric U-shaped tube (5), and the metal wall surfaces of the glass window (7) that are in contact with ultrapure water and vacuum are all covered with a high-purity water-resistant material coating.

7. The metal shell water triple point bottle according to claim 1, characterized in that: The special operator is made of the same type of metal as the metal shell, and is composed of a hand wheel, a pull rod, an operator upper cover, a seat body, a sealing O-ring, a bottom cover, a side pipe, a triple point bottle connection port, and a vacuum pump connection port; The main body of the seat is cylindrical, with an axial variable diameter through hole inside; the upper inner wall of the through hole has multiple grooves for placing sealing O-rings, forming a vacuum sealing interface with the assembled pull rod and upper cover; The middle side of the seat body is fixedly connected to a side tube, and the top of the side tube is a vacuum pump connection port; The pull rod is a variable diameter cylinder with a smooth surface, the top of which is connected to a hand wheel, and the bottom of which is provided with an external thread matching the thread on the inner wall of the thermometer well; the pull rod can be driven to rotate by rotating the hand wheel so that the bottom thread and the thread on the inner wall of the thermometer well are screwed together; The side wall of the through hole at the bottom of the seat body has multiple grooves for placing sealing rubber rings. During the vacuum operation, the three-phase point bottle connection port at the bottom of the seat body is put on the bottleneck, and the bottom cover of the operator is tightened to form a vacuum sealing interface.

8. The method for manufacturing the metal shell water triple point bottle according to any one of claims 1 to 7, characterized in that: 1) The metal shell (1) and the sealing walls at both ends, the thermometer well (2), the asymmetric U-shaped tube (5), the glass window (7) and the metal wall surfaces in contact with ultrapure water and vacuum are covered with a high-purity water-resistant material coating; 2) For the bottle filled with ultrapure water, use external heating to heat the lower part of the bottle to heat the water in the bottle and keep it warm for a period of time; 3) freezing the water triple point bottle by low temperature liquid freezing method, and heating the metal shell (1) cavity center axis position by using an electric heating rod with a clean metal isolation cover; 4) Vacuuming is performed in multiple stages and the water content in the bottle is adjusted to a predetermined amount; 5) Use weighing method to monitor the weight change of the water triple point bottle at each step.

9. A freezing and storage method for the metal-shell water triple point bottle according to any one of claims 1 to 7, characterized in that: 1) Using refrigeration equipment, freeze a vertically placed triple point bottle of water at a temperature below the supercooling freezing point and keep it for a specified time to achieve freezing of all the water; 2) After all the water in the bottle is frozen, place the water triple point bottle in a low-temperature liquid at the storage temperature and keep it for a specified time; 3) Before use, rinse the outer wall of the bottle and the thermometer well with water above 0.01°C to melt the ice layer on the outer wall of the bottleneck and the outer wall of the bottle.

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