JPS58196423A - Liquid level control for low temperature liquefied gas - Google Patents

Abstract

PURPOSE:To prevent brittleness and damage by using particular plastic and elastomer materials on the surface layer of a float and float guide rod in a float switch that consists of a float to which a lead switch and magnet are fixed. CONSTITUTION:As particular plastics and elastomers, unsaturated polyester resin, epoxy resin, melamine resin, phenol resin, urethane elastomer (urethane resin), silicone rubber (silicone resin), fluorinated elastomer (fluorinated rubber), long chain polyamide, polyimide, polycarbonate, furan resin, polysulfon, butadiene-acryl nitryl group synthetic rubber and their modified compounds or mixtures obtained by blending them are employed. For manufacturing float guide rods, it is desirable to use those materials in the form of a composite material such as carbon fiber reinforced plastic (CFRP) and fiber reinforced plastic (FRP).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low-temperature liquefied gas level detection control method, a low-temperature liquefied gas level detection device, and a low-temperature liquefied gas handling device.

Recently, cooling technology using low-temperature liquefied gases such as liquefied nitrogen, liquefied oxygen, liquefied air, liquefied argon, or liquefied natural gas (LNG) has been developed, and it is now possible to store biological specimens, biological cells, biological tissues, vaccines, etc. at low temperatures. Transportation, etc. are becoming popular. Cooling preservation using low-temperature liquefied gas is generally carried out for objects that are sensitive to temperature conditions, so in order to keep the temperature conditions in the handling container constant, low-temperature liquefied gas lost through evaporation must be replenished to maintain the liquid level. Careful handling is often required to maintain the low temperature precisely, such as by keeping it constant or by placing it in such a way that it emits water when the liquid level reaches a certain level.

Therefore, when handling low-temperature liquefied gas, it is often necessary to detect and control the liquid level, but for low-temperature liquefied gas, the liquid level must be controlled at extremely low temperatures, such as the boiling point of -196°C in the case of liquefied nitrogen. Since it requires
The reality is that even if detection and control technology in the low-temperature region is applied as is, reliable operation cannot be expected. Many commercially available liquid level detectors at low temperatures detect the temperature difference between the liquid phase and gas phase to detect the liquid level, but the container containing the liquefied gas has poor insulation performance. The higher the quality of the detector, the smaller the temperature difference between the liquid and gas phases, making it difficult to detect that temperature difference, which can lead to problems such as insufficient sensitivity of the detector or malfunction. .

Sensors that detect changes in the electrical resistance of electrical resistors that come into contact with liquid become unstable when used at extremely low temperatures, making it difficult to use them continuously for long periods of time. However, in this method, the amount of heating not only causes evaporation loss of the low-temperature liquid and impairs the insulation performance of the container itself, reducing the cooling effect of the low-temperature liquefied gas, but also requires heating and cooling to be performed alternately. This is accompanied by undesirable phenomena such as disturbance of temperature distribution.

Ultrasonic, photoelectric, and capacitive liquid level sensors can avoid loss of cooling performance due to heat generation, but moisture in the air that enters when opening and closing the container can cause frost on the sensor surface and cause malfunction. unsuitable for open containers.

On the other hand, float switches consisting of a combination of a reed switch and a float to which a magnet is fixed to operate the switch have been commercially available for liquid level detection and control, but these commercially available ready-made products generally have low temperatures. It is assumed that it will be used in a temperature range up to about 50 degrees Celsius, and we will try to use these commercially available ready-made products as they are to detect and control the liquid level of liquefied gases in the ultra-low temperature range, such as liquefied nitrogen and LNG. However, floats are susceptible to embrittlement and damage, and if the float guide frame has a pointed tip or thin wall, the middle of the guide rod may become deformed, and metal floats and guide rods are susceptible to frost. It was acknowledged that accurate and reliable detection and control over a long period of time could not be expected as it would easily interfere with normal operation. Therefore, the inventors of the present invention have conducted intensive research into a method for accurately detecting and controlling the liquid level of liquefied gas in an ultra-low temperature region by solving these difficulties. By making improvements for suitable use in detection, we have completed the invention of the liquid level control method of the present invention, a liquid level control device using the same, and a low-temperature liquefied gas handling device.

41 The method of the present invention detects and controls the liquid level of low-temperature liquefied gas contained in a container using a float switch consisting of a combination of a reed switch and a float fixed with a magnet for actuating the reed switch. ■ Unsaturated polyester resin, epoxy resin,
Melamine resin, phenolic resin, polyurethane elastomer (urethane resin), silicone rubber (silicone resin), fluorinated elastomer (fluorine rubber), long chain polyamide, polyimide, polycarbonate, furan resin, polysulfone, butadiene-acrylotritrile synthetic rubber, and the like. One or two selected from the group consisting of modified products such as
(1) A space inside a guide culm provided in the container of the liquefied gas in order to move the above-mentioned float up and down according to fluctuations in the liquid level of the low-temperature liquefied gas on which it floats; A method for detecting and controlling the liquid level of a low-temperature liquefied gas, characterized by using a liquid level detection section configured to maintain the pressure equal to the pressure of the gas phase space above the low-temperature liquefied gas contained in a container.

The float switch used in this method may be of any known type, and the guide frame that allows the float to move up and down along a fixed path may be installed in any manner. good.

Specific examples of the arrangement of the float, the float guide frame, and the reed switch are shown in FIGS. 1 to 4.

The device shown in Figure 1 is a liquefied gas testing device that is equipped with a reed switch, a lead wire connected to the reed switch, and a detection section built into the float that is inserted into the guide frame of the float and a magnet that activates the reed switch. , the present invention will be explained in detail by taking this device as an example.

On the insulating lid 2 of the low temperature liquefied gas container consisting of the Dua bottle 1,
Attach the float guide frame 3 housing the reed switch 4 and the lead wire 5 connected thereto, and the liquefied gas supply pipe 11.
A disk-shaped float 6 with a donut-shaped hole in the center is fitted on the outside of the cylindrical guide frame 3 with a closed tip, and the float 6 flows along the guide frame 3 with liquefied gas. 8
The magnet 9 fixed in the float moves up and down according to the vertical displacement of the liquid level, and as the magnet 9 approaches and moves away from the reed switch, the reed switch contact part opens and closes, and the reed switch is connected to the reed switch by a lead wire. It is possible to cause a blinking operation of the saliva level detection circuit and furthermore the liquid level control circuit.

If a metal guide frame or metal float is used in this device, frost will form on the surface during use, making smooth movement of the float impossible. The float is made of wood or vinyl chloride resin,
Vinylidene chloride resin, expanded polystyrene, acrylic resin, nylon 6, natural rubber, styrene-butadiene rubber,
When plastics or elastomers such as urea resins are used, frost resistance is almost eliminated, but they become brittle and damaged during use, and cannot withstand long-term use.

If you use plastics or elastomers that can withstand relatively low temperatures, you can avoid problems caused by frost buildup on the float and guide frame, but the guide rod should be made into a tubular shape to accommodate the reed switch and lead wire, and sealed for insulation. In this case, even if a thin metal tube or the like is used as the reinforcing material 7-, deformation cannot be avoided, which obstructs the vertical movement of the float, which tends to cause problems such as erroneous or impossible detection of the liquid level.

This is because the air inside the guide frame condenses or freezes under low-temperature usage conditions, resulting in a volume reduction and a reduced pressure inside the guide frame, creating a pressure difference between the air and the outside space of the guide frame. I found out something.

Therefore, the inventors of the present invention have conducted intensive research to overcome these difficulties and solve the technical problem of smoothly and precisely detecting the liquid level in the ultra-low temperature region. These problems can only be avoided by combining the two conditions of using specific plastics and elastomer materials for the surface layer of the frame and maintaining the space inside the guide culm at the same pressure as the space above the low-temperature liquefied gas. The present inventors have discovered that the present invention can be obtained, and have completed the present invention.

Specific plastics and elastomers that satisfy the above condition (■) include unsaturated polyester resins, epoxy resins, melamine resins, phenol resins, 8-urethane elastomers (urethane resins), silicone rubbers (silicone resins), and fluorinated elastomers. (fluororubber), long chain polyamide, polyimide, polycarbonate,
Examples include furan resins, polysulfones, butadiene-acrylonitrile synthetic rubbers, modified products thereof, and mixtures thereof. Modified products include copolymers and cocondensates obtained by copolymerizing or cocondensing small amounts of comonomers,
Examples include graft copolymers. These may be used alone or in a blend of two or more, and physical properties such as softness and flexibility can be adjusted as appropriate by blending.

One of these materials may be stored in a container, and the material may be appropriately selected and used by considering the swelling property, solubility, and economic efficiency of the liquefied gas that comes into contact with the material.For example, liquefied nitrogen or liquefied Any material may be used for an inert substance such as argon, but relatively swellable materials such as liquefied natural gas may be used.
When handling materials with high solubility, materials with poor affinity for solvents such as furan resins with high solvent resistance, fluorinated elastomers (fluorine rubber), epoxy resins, and urethane elastomers (urethane resins) are suitable.

It is one of the essential requirements of the present invention to use these materials for at least the surface layer of the float and the float guide culm, but it is not possible to use these materials not only for the surface layer but also for the entire surface layer. It's a shame.

When making a float guide culm using these materials, carbon fibers, quartz fibers, glass fibers, metal fibers, wire mesh, perforated metal plates, ceramic materials, etc. are used to provide physical properties such as strength and rigidity. is used as a reinforcing material, such as carbon fiber reinforced plastics (CFRP) or fiber reinforced plastics (FRP).
It is desirable to use it in the form of a composite material, such as
It may be molded with fillers or other additives as appropriate, or may be coated on a support material, and the processing method is not limited in any way.

When making a float, it also functions as a float,
As long as at least the surface layer is made of these materials, the processing method may be arbitrarily selected.

For example, various forms may be used as appropriate, such as a foam molded body with built-in closed cells, an aluminum float in which helium is press-fitted and coated with plastics, or a plastics elastomer with a sealed honeycomb structure. .

Commercially available materials, such as a float material made by foaming and molding a blend of butadiene-acrylonitrile synthetic rubber and a thermoplastic resin, may be suitably processed and used. Of course, a composite material using various reinforcing fibers may also be used. In short, when a float is used floating on low-temperature liquefied gas, the external shape must not change due to cooling and the accuracy of liquid level detection must not deteriorate, so prevention of deformation is important, and the required number is Accordingly, it is preferable to fill the space inside the float with a gas that does not liquefy even at the operating temperature, such as helium.

Any means may be used to maintain the space inside the float guide culm and the gas phase space above the liquefied gas in the container at the same pressure, which is the condition (2), but the simplest method is to A hole or a slit may be provided in the upper part so that the gas in the gas phase space inside the container and the space inside the guide culm can mutually circulate. At this time, it is desirable to use a material that is difficult to resist frost to prevent frost from forming on the perforations and slits and causing blockage, but this is because the internal space has already cooled down by the time frost forms. In fact, there is little risk of the guide frame being deformed due to the pressure difference between the inside and outside, and there is no need to avoid using metal materials inside the guide culm for convenience of construction.

In this case, it is sufficient to pass the plastic tube through the perforation and internal metal part to maintain equal pressure between the space inside the float guide culm and the space inside the liquefied gas container.

As mentioned above, the method of the present invention can only be carried out by combining the conditions (1) using a specific material and (2) maintaining the internal space of the float guide culm and the internal space of the liquefied gas container at equal pressure. The method of the present invention is capable of detecting and detecting low-temperature liquefied gas liquid levels, for which no good solutions have been shown in the past.
This is a major advance in the control method, its practical value is extremely high, and the benefits it brings to low temperature science and industry are significant. In the above explanation, the float guide culm and the float fitting hole are cylindrical, but the shape of the guide frame may be changed to a prismatic shape as necessary, such as to fix the direction of the magnet. No problem.

In short, any structure may be used as long as the float fits into the float guide culm and the float floating on the liquefied gas can move up and down smoothly and sharply following the up and down fluctuations of the liquefied gas level. Although there is a method of floating a float inside a cylindrical or rectangular guide frame, it is generally better to fit the float outside the central guide frame, both in terms of functionality and reliability. It is superior in terms of ease of work, maintenance, and cost, and the drawings in this specification only illustrate the case where the float is fitted on the outside of the guide frame.

Although FIGS. 2, 3, and 4 illustrate various embodiments of the method of the present invention by changing the arrangement of reed switches, magnets, and floats, the present invention is not limited to these illustrative examples. It's not something you can do.

In Figure 2, the magnet that activates the reed switch is fixed to the float member apart from the float member floating in the liquefied gas and via a support member, and the magnet member containing this magnet responds to the vertical movement of the float. The case where the float slides on the guide culm is illustrated. In the present invention, the term float includes the magnet member that slides on the float guide culm, the float member, and the support member that connects the float and the magnet. In the case as shown in Figure 2, if frost forms on the float part, the accuracy of liquid level detection will be reduced, so it goes without saying that the method of the present invention must be applied to the entire float part including these parts. be.

FIG. 3 shows an example in which the reed switch is provided outside the liquefied gas container body, and only the float and the float guide culm are arranged in the liquefied gas storage section in close proximity to the reed switch. Furthermore, Fig. 4 shows an example of a configuration in which a reed switch is provided in the vacuum insulation part of the liquefied gas container, and a float and a float guide culm are arranged in the liquefied gas storage part in close proximity to the container wall. Various possible embodiments other than those illustrated are also encompassed within the present invention unless they depart from the scope of the claims of the present application. The low temperature liquefied gas level detection device of the present invention includes:
It is a device that constitutes a detection section used when carrying out the liquid level search and control method described in detail above, and the low-temperature liquefied gas handling device of the present invention is a storage tank, a storage container, a storage container equipped with the above-mentioned detection section. , transportation equipment, reactors, coolers, laboratory equipment,
This term refers to analytical instruments, etc., and all are included within the scope of the present invention.

The present invention is useful for detecting and controlling the level of liquefied gases such as liquefied nitrogen, liquefied oxygen, liquefied air, liquefied argon, or liquefied natural gas (LNG) in ultra-low temperature ranges, but at temperatures higher than this range. It is very convenient in that it can also be used to detect the level of liquid in water.

Regarding flammable liquefied gases such as LNG, explosion-proof construction is required for equipment that handles flammable liquefied gases such as LNG, but in the case of the equipment of the present invention, the terminal part of the switch is sealed with an inert gas inside a glass tube. Therefore, one of the features of the present invention is that by adopting an intrinsically safe explosion-proof structure for the lead wire portion and the detection/control circuit portion, it can be suitably used as an explosion-proof structure handling device. Since the present invention can be implemented using a small and easy-to-handle detection section, the present invention can be easily implemented regardless of whether the low-temperature liquefied gas handling equipment to which it is applied is large or small. This makes it possible to perform highly accurate detection and control economically.

Further explanation will be given below with reference to Examples.

Examples 1 to 10 and Control Examples 1 to 10 Liquefied nitrogen cryopreservation container DR-11 (product of Dia Reiki Kogyo Co., Ltd., outer diameter 260 cm, height 540■, diameter 63.5m, liquefied nitrogen capacity 11t) lid (2 in the figure, made of aluminum exterior,
Drill 18 holes in diameter in the insulation part (made of epoxy resin), and insert a liquefied nitrogen supply pipe (inner diameter 6 mm) made of glass fiber reinforced epoxy resin.
Insert a float switch guide rod (a cylindrical tube with a diameter of 9 mm with the tip closed, length 300 mm below the lid), and guide a donut-shaped float equipped with a magnet into the guide rod. It is fitted so that it can move vertically along the rod, and a reed switch with a lead wire connected is fixed inside the guide rod, and a liquefied nitrogen supply pipe that passes through the hole in the lid and the guide rod are A pipe was further wrapped around the outside and fixed to the lid using epoxy adhesive.

Inside the guide rod from the tip ■57m+, ■77w1■152
Simply, by setting a reed switch at position ■175■, the liquefied nitrogen evaporates and decreases, and when the float approaches the reed switch at ■, the reed switch is activated, detects the liquid level, and activates the solenoid valve to release liquefied nitrogen. Refill from the liquefied nitrogen supply pipe, and when the liquid level of liquefied nitrogen rises and the float approaches the reed switch number marked with ■, the reed switch operates, detects the liquid level, and closes the liquefied nitrogen replenishment solenoid valve. A test was conducted to detect and further control the liquid nitrogen level. If the replenishment of liquefied nitrogen is not carried out smoothly and the liquid level drops excessively and the float approaches the reed switch (■), the drop in the liquid level will be detected by the operation of the reed switch and an alarm will be issued. The system also detects and controls the liquid level by issuing an alarm even if the liquid level rises excessively and the float approaches the reed switch (①).

In Examples 1 to 10 of the present invention, the detection and control of the liquid level was performed smoothly and there were no problems, whereas in Comparative Examples 1 to 10,
In No. 10, accurate operation could not be maintained because the float and guide rod were damaged, deformed, or frosted.

Table 1 19-20 - Examples 11 to 17 External dimensions Height: 939 m, Width: 876 cm, Depth: 952 cm Inside a square stainless steel outer cage, Inner dimensions: Depth: 648 m,
A cylindrical Dua bottle with an inner diameter of 787 m and consisting of an inner wall made of glass fiber reinforced epoxy resin and an outer wall made of steel was placed.
A liquefied nitrogen type ultra-low temperature storage container with a stainless steel exterior and a freely opening/closing lid with a foamed urethane resin insulation cover (surface polyamide coating) installed on the outside and inside. The guide rod of the float switch was attached with a support clip to a stainless steel liquefied nitrogen supply pipe that descended along the inner wall surface of the main body of the storage container and opened near the bottom of the Dua bottle.

The guide culm is a cylindrical tube with a closed tip as shown in Table 2, with a diameter of 9 mm and a length of 600 m.
57 from the bottom of the bottle [■-・77■■, 152 defacement, 175
The reed switch was fixed at the position of ■■, and the lead wire connected to the reed switch was pulled out from the upper part of the guide culm and connected to an electronic circuit for detection control provided outside the container along the liquefied nitrogen supply pipe. The lead wire outlet of the guide rod was narrowed and sealed with epoxy resin, and a small circular hole with a diameter of 1 square inch was opened at a position 250 mm from the bottom end of the guide rod, which communicated with the space inside the guide culm. A donut-shaped float with a magnet attached was fitted into the guide rod, and the float was configured to move according to the rise and fall of the liquid level. This is the structure created by placing liquefied nitrogen in this ultra-low-temperature storage container, causing the liquid level to drop and rise by natural evaporation and replenishment of the liquefied nitrogen, and when the liquid level drops and the float approaches the reed switch ■, liquefied nitrogen is replenished. The switch operates so that the device works, and when the float approaches the reed switch ■, the switch operates so that the liquefied nitrogen supply device stops.
In addition, an electronic circuit was installed as a system that would sound an alarm if the liquid level dropped excessively and the float approached the reed switch (2), or if the liquid level rose too much and the float approached the reed switch (2). The float and its guide rod had the specifications shown in Table 2.

After filling the container with liquefied nitrogen and closing the container, the electronic circuit for liquid level detection control was started. When replenishment of liquefied nitrogen was performed, the date and time and amount of replenishment were recorded on an automatic recorder, and the lid was opened once every two days to observe the inside.

In all of the examples shown in Table 2, a control mechanism operated to detect a decrease in liquefied nitrogen due to natural vaporization every few days and to compensate for this, replenishing liquefied nitrogen. Moisture contained in the atmosphere entered the upper part of the container when the lid was opened and closed and condensed, gradually increasing the amount of frost that could build up.However, the liquid level detection and liquid volume control devices were working normally and the liquid nitrogen The evaporation and replenishment operations were repeated, and no alarms were sounded during the Mikizuki test, and no problems occurred.

23- Table 2 24 - Examples 18 to 23 A glass fiber-reinforced epoxy resin dual-bottle was placed inside an aluminum cylindrical case with a total external height of 813 mm, an outer diameter of 445 m, an inner diameter of 356 mm, and a liquefied nitrogen capacity of 46.61 cm. A circular hole with a diameter of 18 cm was inserted into the lid of the liquefied nitrogen cryogenic storage container (manufactured by Union Carbide, USA, model number LR-40) (made of aluminum exterior and foamed polyurethane insulation material covered with polyamide resin). was opened, a liquefied nitrogen supply pipe (made of stainless steel 5US316) was attached, and a lead wire was passed through a small gap between the supply pipe and the hole, and the remaining gap was completely sealed with epoxy resin.

A cylindrical float guide frame having a diameter of 9 mm and a length of 300 mm and having a closed tip was attached to the liquefied nitrogen supply pipe using a support clip. Inside this float guide frame, there is a dual
57W ■, 77 ■■, 152 tone ■, 175 from the inner bottom of the bottle
A reed switch was fixed at the position of ■■, and a lead wire was connected along the above-mentioned liquefied nitrogen supply pipe, and the other end of the lead wire was connected to an electronic circuit for detection and control provided outside the container.

A donut-shaped float with a magnet attached to activate the reed switch was fitted into the guide rod, and the float moved according to the rise and fall of the liquid level.

The specifications of the float and float guide frame are as shown in Table 3.

To connect the lead wire from the reed switch to the electronic circuit,
We created a system that starts replenishing liquefied nitrogen when the float approaches reed switch ■, stops replenishing liquefied nitrogen when the float approaches reed switch ■, and warns when the float approaches reed switch ■ or ■.

After filling the container with liquefied nitrogen and closing the container, the electronic circuit for liquid level detection control was started. The date and time of liquefied nitrogen replenishment and the amount of replenishment were automatically recorded, and the lid was opened once every five days to observe the inside.

In all of the examples shown in Table 3, a control mechanism was operated to detect a decrease in liquefied nitrogen due to natural vaporization every few days and to compensate for this, thereby replenishing liquefied nitrogen.

When the lid was opened and closed, moisture from the atmosphere was taken in and condensed, forming frost on the upper part of the container, but there was no frost on the float or guide rod, and there was no deformation or damage. The quantity control device repeatedly operated normally, and no alarms sounded and no problems occurred during the June test period. The device of Example 18 was applied to a liquefied nitrogen storage container for a cold trap in a high vacuum evacuation system, and a practical test was conducted, but no problems were caused during the six month test period.

Table 3

[Brief explanation of the drawing]

1 to 4 are sketches for explaining the present invention. 1. Dual bottle 2, insulation lid 3, float guide frame 4, reed switch 5, lead wire 6, float 7, small hole 8 for obtaining equal pressure, liquefied gas 9, magnet IO, support member 11, liquefied gas Supply pipe, patent applicant: Taiyo Sanso Co., Ltd. Procedural Amendment (Voluntary application [I, May 1, 2006] Case indication: 157 Patent application No. 79'?Numa No. 2, Title of invention: Low-temperature liquefied gas liquid Position detection control method 3, name of the person making the amendment■ Patent applicant 4, "Claims" column 5 of the specification to be amended, content of the amendment H1ii As per the EO, appendix Claims (1) Reed switch When detecting and controlling the liquid level of low-temperature liquefied gas contained in a container using a float switch consisting of a float switch and a float to which a magnet is fixed to operate the switch, At least the surface layer of the float that moves up and down and the guide culm of the float contains unsaturated polyester resin, epoxy resin, melamine resin, fluorine resin, polyurethane elastomer (urethane resin), silicone rubber (silicone resin), and fluorine-based resin. Elastomer (fluororubber), long chain polyamide, polyimide,
In addition to using one or a mixture of two or more selected from the group consisting of polycarbonate, furan resin, polysulfone, butadiene-acrylonitrile synthetic rubber, and modified products such as; A liquid level detection unit is provided with a structure in which a space inside a guide culm provided in a container for the liquefied gas is kept at the same pressure as a gas phase space above the liquefied gas in the container in order to move the gas up and down according to fluctuations in the liquid level. Low-temperature liquefied gas liquid level detection control method characterized by using ■ A low-temperature liquefied gas level detection device having a liquid level detection section using the above-mentioned float as a floating low-temperature liquefied gas. Detecting or further controlling the liquid level of low-temperature liquefied gas using one or more types selected from the group consisting of en-acrylonitrile-based synthetic rubber and modified products thereof. Low-temperature liquefied gas handling equipment with a mechanism to 127-

Claims (1)

[Claims] (1) In detecting and controlling the liquid level of low-temperature liquefied gas contained in a container using a float switch consisting of a combination of a reed switch and a float fixed with a magnet for actuating the reed switch, ■ Unsaturated polyester resin, epoxy resin, melamine resin, phenol resin, polyurethane elastomer (urethane resin), silicone is used at least in the surface layer of the float and the guide culm of the float, which move up and down in response to fluctuations in the liquid level of low-temperature liquefied gas. Rubber (silicone resin), fluorine-based elastomer (fluorine rubber), long-chain polyamide, polyimide,
Using one or a mixture of two or more selected from the group consisting of polycarbonate, furan resin, polysulfone, butadiene-acrylonitrile synthetic rubber, and modified products thereof, and A liquid level detection unit is provided with a structure in which a space inside a guide culm provided in a container for the liquefied gas is kept at the same pressure as a gas phase space above the liquefied gas in the container in order to move the gas up and down according to fluctuations in the liquid level. for. (2) A low-temperature liquefied gas level detection device constituting the liquid level detection section according to claim (1). (3) Claims ( 1) A low-temperature liquefied gas handling device having a mechanism for detecting or further controlling the liquid level of low-temperature liquefied gas using the liquid level detection section described above.