JPH0431339B2 - - Google Patents
Info
- Publication number
- JPH0431339B2 JPH0431339B2 JP60148804A JP14880485A JPH0431339B2 JP H0431339 B2 JPH0431339 B2 JP H0431339B2 JP 60148804 A JP60148804 A JP 60148804A JP 14880485 A JP14880485 A JP 14880485A JP H0431339 B2 JPH0431339 B2 JP H0431339B2
- Authority
- JP
- Japan
- Prior art keywords
- liquefied gas
- liquid level
- heating
- low
- temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000010438 heat treatment Methods 0.000 claims description 74
- 239000007788 liquid Substances 0.000 claims description 55
- 238000001514 detection method Methods 0.000 claims description 16
- 238000006073 displacement reaction Methods 0.000 claims description 3
- 239000007789 gas Substances 0.000 description 43
- 239000007791 liquid phase Substances 0.000 description 10
- 238000010586 diagram Methods 0.000 description 5
- 239000012071 phase Substances 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 239000012808 vapor phase Substances 0.000 description 2
- 238000009529 body temperature measurement Methods 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
Description
【発明の詳細な説明】
〔産業上の利用分野〕
この発明は、例えば液体ヘリウム、液体窒素な
どの低温液化ガスの液面を検知する液面検出セン
サに関するものである。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a liquid level detection sensor that detects the liquid level of a low-temperature liquefied gas such as liquid helium or liquid nitrogen.
第３図は例えば特開昭59−46515号公報に示さ
れた従来の低温液化ガス液面検出センサを示す構
成図であり、第４図は第３図の低温液化ガス液面
検出センサを低温液化ガス貯槽に取り付けた状
態、また第５図は熱電対の液面高さに対する発生
電圧特性を示すものである。図において、１は加
熱源で例えば電源、２は低温液化ガスの液面を検
出するための発熱体、例えば発熱抵抗体で、電源
１により発熱する。３は発熱抵抗体２の温度を測
定する温度センサとしての熱電対測温接点、４は
熱電対測温接点３に接続された電圧計、５は低温
液化ガス貯槽、６は支持材、７は低温液化ガスの
気相、８は低温液化ガスの液面の状態、９は低
温液化ガスの液面の状態、１１は熱電対の基準
接点、１２は低温液化ガスの液相部、１３は低温
液化ガスの気相部、１４は熱電対の発生電圧特性
曲線、発生電圧特性曲線上の点ｃは丁度発熱抵抗
体２の位置に液面がある場合である。
FIG. 3 is a configuration diagram showing a conventional low-temperature liquefied gas level detection sensor disclosed in, for example, Japanese Unexamined Patent Publication No. 59-46515, and FIG. 4 is a block diagram showing the low-temperature liquefied gas level detection sensor of FIG. FIG. 5 shows the thermocouple when it is attached to a liquefied gas storage tank, and shows the generated voltage characteristics with respect to the liquid level height of the thermocouple. In the figure, 1 is a heating source, such as a power supply, and 2 is a heating element, such as a heating resistor, for detecting the liquid level of low-temperature liquefied gas, and the power supply 1 generates heat. 3 is a thermocouple temperature measuring junction as a temperature sensor for measuring the temperature of the heating resistor 2; 4 is a voltmeter connected to the thermocouple temperature measuring junction 3; 5 is a low temperature liquefied gas storage tank; 6 is a support material; 7 is a 8 is the liquid level state of the low temperature liquefied gas, 9 is the liquid level state of the low temperature liquefied gas, 11 is the reference junction of the thermocouple, 12 is the liquid phase part of the low temperature liquefied gas, 13 is the low temperature The gas phase portion of the liquefied gas, 14, is a generated voltage characteristic curve of a thermocouple, and point c on the generated voltage characteristic curve is when the liquid level is exactly at the position of the heating resistor 2.
次に動作について説明する。発熱抵抗体２は外
部の電源１により電流が供給されジユール発熱に
より温度が上昇している。測温接点３は発熱抵抗
体２と熱的に接触しており、温度変化つまり低温
液化ガス液相部高さの変化によつて第５図の１４
のような発生電圧曲線を持つている。このような
装置を例えば低温液化ガス貯槽に取り付けた場
合、液面の状態では、発熱抵抗体２が低温液化
ガスの気相部に位置することから発熱抵抗体２か
ら周囲への放熱量が自然対流伝熱により支配され
るため少ない。従つて、発熱抵抗体２の温度は上
昇し、温度t2（この時の液面高さはh1）であり、
この場合、熱電対は温度t2と低温液化ガス液相部
の温度との差に応じた電圧を発生し、それが電圧
計４ではV3として検出される。また、発熱抵抗
体２の位置に液面がある場合（この時の液面高さ
h2）では、発熱抵抗体２から周囲への放熱量が核
沸騰伝熱により支配されるため多く、この結果発
熱抵抗体２の温度が下がり、ほとんど液相温度t1
に等しくなり、基準接点１１との温度差がないた
め起電力は生じず、従つて、発生電圧はほとんど
零である。液面の状態でも同様である。 Next, the operation will be explained. Current is supplied to the heating resistor 2 by the external power source 1, and the temperature rises due to Joule heat generation. The temperature measuring junction 3 is in thermal contact with the heating resistor 2, and due to temperature changes, that is, changes in the height of the liquid phase of the low-temperature liquefied gas, the temperature at 14 in FIG.
It has a generated voltage curve like this. For example, when such a device is installed in a low-temperature liquefied gas storage tank, the heat generating resistor 2 is located in the gas phase of the low-temperature liquefied gas at the liquid level, so the amount of heat radiated from the heating resistor 2 to the surroundings is natural. It is small because it is dominated by convective heat transfer. Therefore, the temperature of the heating resistor 2 rises to a temperature t 2 (the liquid level height at this time is h 1 ),
In this case, the thermocouple generates a voltage corresponding to the difference between the temperature t 2 and the temperature of the low-temperature liquefied gas liquid phase, which is detected by the voltmeter 4 as V 3 . Also, if there is a liquid level at the position of the heating resistor 2 (the liquid level height at this time
h 2 ), the amount of heat radiated from the heating resistor 2 to the surroundings is dominated by nucleate boiling heat transfer, and as a result, the temperature of the heating resistor 2 decreases, almost reaching the liquidus temperature t 1
Since there is no temperature difference with reference junction 11, no electromotive force is generated, and therefore, the generated voltage is almost zero. The same applies to the state of the liquid level.
このように、発熱抵抗体２が気相部に置かれた
場合は或る大きさの電圧を発生し、液相部に置れ
た場合は電圧を発生しないことになり、液体中に
ない場合はON、ある場はOFFというようなデジ
タル的信号が得られ、液面が発熱抵抗体２の上に
あるか下にあるかを明確に判定できる。 In this way, if the heating resistor 2 is placed in the gas phase, it will generate a certain amount of voltage, if it is placed in the liquid phase, it will not generate any voltage, and if it is not in the liquid, it will generate a certain amount of voltage. A digital signal such as ON for some fields and OFF for some fields can be obtained, and it can be clearly determined whether the liquid level is above or below the heating resistor 2.
しかしながら、従来の装置では以上のように構
成されているので、低温液化ガス液面検出センサ
を低温液化ガス貯槽５内に支持材６によつて取付
けることかつ熱電対の基準接点１１は絶えず液中
に置く必要から低温液化ガス貯槽５内の最下端に
位置させねばならないことなどの理由のため、主
として固定式となつている。従つてあらかじめ配
設した位置に液面が在るか否かの判定をする場合
に供すもので、任意の液面位置における液面有無
の判定には不都合という欠点があつた。仮りに上
下自由な可動式にしようとすれば、測温接点３と
支準接点６とを継ぐ熱電対線の遊びを長く取ると
いう処置が必要となりこの場合、低温液化ガス液
面検出センサを動かすことに因り、断線の危険性
が伴い、またこの危険性を避けようとすれば、か
なり複雑な構造となるという問題点があつた。
However, since the conventional device is configured as described above, the low-temperature liquefied gas liquid level detection sensor is mounted in the low-temperature liquefied gas storage tank 5 by the support member 6, and the reference junction 11 of the thermocouple is constantly submerged in the liquid. It is mainly a fixed type because it has to be located at the lowest end in the low temperature liquefied gas storage tank 5. Therefore, it is used for determining whether a liquid level is present at a predetermined position, and has the disadvantage that it is inconvenient for determining the presence or absence of a liquid level at an arbitrary liquid level position. If you try to make it movable up and down, it will be necessary to take a long play in the thermocouple wire connecting the temperature measurement contact 3 and the support contact 6, and in this case, move the low temperature liquefied gas liquid level detection sensor. As a result, there is a risk of wire breakage, and if this risk is to be avoided, the structure becomes quite complicated.
この発明は従来のものの問題点を解消するため
なされたもので、簡単な構造で、任意の位置にお
ける液面の有無を判定できる低温液化ガス液面検
出センサを提供することを目的としている。 The present invention was made to solve the problems of the conventional sensor, and an object of the present invention is to provide a low temperature liquefied gas liquid level detection sensor that has a simple structure and can determine the presence or absence of a liquid level at any position.
〔問題点を解決するための手段〕
この発明に係る低温液化ガス液面検出センサ
は、加熱源、この加熱源によつて発熱する第１発
熱体、加熱源によつて発熱し、第１発熱体より低
温液化ガスの液面の変位方向に離れて並設した第
２発熱体、及び第１、第２発熱体のそれぞれの温
度を計測し起電力を発生する熱電対を備え、第
１、第２発熱体間の温度差により低温液化ガスの
液面位置を検知するようにしたものである。[Means for Solving the Problems] The low-temperature liquefied gas liquid level detection sensor according to the present invention includes a heating source, a first heating element that generates heat by the heating source, and a first heating element that generates heat by the heating source. a thermocouple that measures the temperature of each of the first and second heating elements and generates an electromotive force; The liquid level position of the low temperature liquefied gas is detected based on the temperature difference between the second heating elements.
この発明における低温液化ガス液面検出センサ
においては、液面の変位方向に各々配設された第
１、第２発熱体のうち、例えば第１発熱体の温度
を基準として、第２発熱体の温度を検出し（第
１、第２発熱体の関係を反対にしても良い）、第
１、第２発熱体間に液面が位置するか否かの判定
を行うものである。
In the low-temperature liquefied gas liquid level detection sensor of the present invention, of the first and second heating elements disposed in the direction of displacement of the liquid level, for example, the temperature of the second heating element is set as a reference. The temperature is detected (the relationship between the first and second heating elements may be reversed), and it is determined whether the liquid level is located between the first and second heating elements.
以下、この発明の一実施を図について説明す
る。第１図において１〜１３までの構成要素は従
来例と同様であり、２ａ，２ｂは第１、第２発熱
体、例えば第１、第２発熱抵抗体で、液面の変位
方向、例えば上下方向に数mmから１cm程度離れ
て、支持材６に固定されている。３ａ，３ｂはそ
れぞれ第１、第２発熱抵抗体の温度を測定するた
めの熱電対の第１、第２測温接点であり、電圧計
４と接続されている。また、第２図において１５
は第１図の如き構成された場合の電圧計４で検知
される発生電圧特性曲線であり、液面高さに対す
る電圧を示すものである。，，はそれぞれ
第１図における液面位置に相当している。
Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the constituent elements 1 to 13 are the same as those of the conventional example, and 2a and 2b are first and second heating elements, for example, first and second heating resistors, and the liquid level is displaced in the direction of displacement, for example up and down. It is fixed to the support member 6 at a distance of about several mm to 1 cm in the direction. 3a and 3b are first and second temperature measuring contacts of a thermocouple for measuring the temperatures of the first and second heating resistors, respectively, and are connected to the voltmeter 4. Also, in Figure 2, 15
is a generated voltage characteristic curve detected by the voltmeter 4 when configured as shown in FIG. 1, and shows the voltage with respect to the liquid level height. , , respectively correspond to the liquid level position in FIG.
このような装置を低温液化ガス貯槽に取り付け
た場合、液面の状態では、第１、第２発熱抵抗
体２ａ，２ｂの温度はそれぞれ低温液化ガス液相
部１２の温度に比べ上昇しているが、上昇度は互
いに同程度となつている。それ故出力電圧として
は、ほとんど零であり、第２図の左側平坦部の様
な出力特性となる。また、液面の状態では第
１、第２発熱抵抗体２ａ，２ｂは共に低温液化ガ
ス液相部１２に位置するためほぼ低温液化ガス液
相と同温度になり、やはり出力電圧としてはほと
んど零となり、第２図の右側平坦部の様な出力特
性となる。そして、液面の状態では、第１発熱
抵抵体２ａは低温液化ガス気相部１３に、第２発
熱抵抗体２ｂは低温液化ガス液相部１２にそれぞ
れ位置することになりこの場合、第１発熱抵抗体
２ａの温度は第２発熱抵抗体２ｂの温度より上昇
しているため、出力電圧としてある値が発生され
ることになる。従つて、この状態の出力電圧特性
が第２図の凸部に相当するもので、その時の出力
電圧としてV4が得られることとなる。 When such a device is installed in a low-temperature liquefied gas storage tank, at the liquid level, the temperatures of the first and second heating resistors 2a and 2b are respectively higher than the temperature of the low-temperature liquefied gas liquid phase section 12. However, the rate of increase is about the same. Therefore, the output voltage is almost zero, resulting in an output characteristic like the flat part on the left side of FIG. 2. In addition, in the liquid level state, the first and second heating resistors 2a and 2b are both located in the low temperature liquefied gas liquid phase part 12, so the temperature is almost the same as the low temperature liquefied gas liquid phase, and the output voltage is almost zero. This results in an output characteristic similar to the flat part on the right side of FIG. In the liquid level state, the first heating resistor 2a is located in the low-temperature liquefied gas vapor phase part 13, and the second heating resistor 2b is located in the low-temperature liquefied gas liquid phase part 12. Since the temperature of the first heating resistor 2a is higher than the temperature of the second heating resistor 2b, a certain value is generated as the output voltage. Therefore, the output voltage characteristic in this state corresponds to the convex portion in FIG. 2, and V4 is obtained as the output voltage at that time.
このように、第１、第２発熱抵抗体２ａ，２ｂ
が共に低温液化ガス気相部１３あるいは液相部１
２に位置する場合は電圧を発生せずに第１発熱抵
抗体２ａが低温液化ガス気相部１３に位置し、第
２発熱抵抗体２ｂが低温液化ガス液相部１２に位
置する場合、つまり第１、第２発熱抵抗体２ａ，
２ｂ間に液面がある場合のみ、或る大きさの電圧
を発生する。従つて、低温変化ガスの液面位置を
ON／OFFというデジタル的信号にて明確に判定
できることになる。 In this way, the first and second heating resistors 2a, 2b
are both low temperature liquefied gas gas phase part 13 or liquid phase part 1
2, no voltage is generated and the first heating resistor 2a is located in the low-temperature liquefied gas vapor phase section 13, and the second heating resistor 2b is located in the low-temperature liquefied gas liquid phase section 12, that is. First and second heating resistors 2a,
A voltage of a certain magnitude is generated only when there is a liquid level between 2b. Therefore, the liquid level position of the low temperature changing gas is
This means that it can be clearly determined using digital signals such as ON/OFF.
上記のように、近接した第１、第２発熱抵抗体
２ａ，２ｂによつて液面を検出するので、両者を
支持材６に固定し、支持材６を移動することによ
り、任意の液面を検出できる。第１、第２発熱抵
抗体２ａ，２ｂ間を接続する熱電対線の長さも固
定で、短かくなり、断線の危険性も低下する。 As mentioned above, since the liquid level is detected by the first and second heating resistors 2a and 2b that are close to each other, by fixing both to the support member 6 and moving the support member 6, it is possible to detect any liquid level. can be detected. The length of the thermocouple wire connecting between the first and second heating resistors 2a and 2b is also fixed and shortened, and the risk of wire breakage is also reduced.
また、構造が簡単で扱い易いため、低温液化ガ
ス貯槽への出し入れ作業が容易となり、従つて判
定に要する操作が非常に容易となる。 In addition, since the structure is simple and easy to handle, it is easy to put it in and take it out of the low temperature liquefied gas storage tank, and therefore the operation required for determination is very easy.
上記実施例では、発熱体として発熱抵抗体を用
い、加熱源として電源を用いた場合について説明
したが、他の例として発熱体として受光発熱体を
用い、加熱源として光源を用いた場合にも、上記
実施例と同様の効果を奏する。また、これに限ら
ずある操作により発熱する構造体であれば良い。 In the above embodiment, a case has been described in which a heating resistor is used as a heating element and a power source is used as a heating source. However, as another example, a case in which a light-receiving heating element is used as a heating element and a light source is used as a heating source is also applicable. , the same effect as the above embodiment is achieved. Further, the present invention is not limited to this, and any structure that generates heat due to a certain operation may be used.
第１、第２発熱体間の距離は、上記実施例に限
るものではないが、あまり離れると液面検出精度
が悪くなり、近すぎると、互いに温度の影響を受
けるため、両者の温度差による出力電圧が得られ
なくなる。また、第１、第２発熱体は液面に垂直
でなくても、多少ななめに配置してもよい。 The distance between the first and second heating elements is not limited to the above example, but if they are too far apart, the liquid level detection accuracy will deteriorate, and if they are too close, they will be influenced by each other's temperature, so Output voltage cannot be obtained. Furthermore, the first and second heating elements do not have to be perpendicular to the liquid surface, but may be arranged somewhat diagonally.
以上述べたように、この発明によれば、加熱
源、この加熱源によつて発熱する第１発熱体、加
熱源によつて発熱し、第１発熱体より低温液化ガ
スの液面の変位方向に離れて並設した第２発熱
体、及び第１、第２発熱体のそれぞれの温度を計
測し起電力を発生する熱電対を備え、第１、第２
発熱体間の温度差により低温液化ガスの液面位置
を検知するようにしたことにより、簡単な構造
で、任意の位置における液面の有無を検出できる
低温液化ガス液面検出センサが得られる効果があ
る。
As described above, according to the present invention, there is a heating source, a first heating element that generates heat by the heating source, and a direction in which the liquid level of the liquefied gas that generates heat by the heating source and is lower than the first heating element is displaced. and a thermocouple that measures the temperature of each of the first and second heating elements and generates an electromotive force;
By detecting the liquid level position of low-temperature liquefied gas based on the temperature difference between the heating elements, it is possible to obtain a low-temperature liquefied gas liquid level detection sensor that can detect the presence or absence of a liquid level at any position with a simple structure. There is.
第１図は、この発明の一実施例による低温液化
ガス液面検出センサを示す構成図、第２図は第１
図のセンサによる液面高さに対する発生電圧特性
曲線を示す特性図、第３図は従来の低温液化ガス
液面検出センサを示す構成図、第４図は、第３図
のセンサを取付けた低温液化ガス貯槽の断面図、
第５図は第３図のセンサによる液面高さに対する
発生電圧特性曲線を示す特性図である。
１……加熱源、２ａ……第１発熱体、２ｂ……
第２発熱体、３ａ……第１熱電対測温接点、３ｂ
……第２熱電対測温接点、２……液面。なお、図
中、同一符号は同一、又は相当部分を示す。
FIG. 1 is a configuration diagram showing a low-temperature liquefied gas level detection sensor according to an embodiment of the present invention, and FIG.
Figure 3 is a configuration diagram showing a conventional low-temperature liquefied gas liquid level detection sensor; Figure 4 is a low-temperature sensor equipped with the sensor shown in Figure 3. Cross-sectional view of liquefied gas storage tank,
FIG. 5 is a characteristic diagram showing a voltage characteristic curve generated by the sensor of FIG. 3 with respect to the liquid level height. 1... Heat source, 2a... First heating element, 2b...
Second heating element, 3a...First thermocouple temperature measuring junction, 3b
...Second thermocouple temperature measuring junction, 2...Liquid level. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.
Claims (1)
源によつて発熱する第１発熱体、上記低温液化ガ
ス中に設けられ上記加熱源によつて発熱し、第１
発熱体より上記低温液化ガスの液面の変位方向に
離れて並設した第２発熱体、及び第１、第２発熱
体の温度差により起電力を発生するように配設し
た熱電対を備え、第１、第２発熱体間に液面があ
る時の温度差による起電力を検出することによ
り、上記低温液化ガスの液面位置を検知するよう
にした低温液化ガス液面検出センサ。 ２ 第１発熱体と第２発熱体を数mmから１cm程度
離れて並設した特許請求の範囲第１項記載の低温
液化ガス液面検出センサ。 ３ 加熱源は電源であり、発熱体は発熱抵抗体で
ある特許請求の範囲第１項又は第２項記載の低温
液化ガス液面検出センサ。 ４ 加熱源は光源であり、発熱体は受光発熱体で
ある特許請求の範囲第１項又は第２項記載の低温
液化ガス液面検出センサ。[Scope of Claims] 1. A heating source, a first heating element provided in the low-temperature liquefied gas and generating heat by the heating source, a first heating element provided in the low-temperature liquefied gas and generating heat by the heating source;
A second heating element arranged in parallel apart from the heating element in the direction of displacement of the liquid surface of the low-temperature liquefied gas, and a thermocouple arranged so as to generate an electromotive force due to a temperature difference between the first and second heating elements. A low temperature liquefied gas liquid level detection sensor configured to detect the liquid level position of the low temperature liquefied gas by detecting an electromotive force due to a temperature difference when there is a liquid level between the first and second heating elements. 2. The low-temperature liquefied gas liquid level detection sensor according to claim 1, wherein the first heating element and the second heating element are arranged side by side at a distance of about several mm to 1 cm. 3. The low temperature liquefied gas liquid level detection sensor according to claim 1 or 2, wherein the heating source is a power source and the heating element is a heating resistor. 4. The low temperature liquefied gas liquid level detection sensor according to claim 1 or 2, wherein the heating source is a light source and the heating element is a light-receiving heating element.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14880485A JPS628019A (en) | 1985-07-04 | 1985-07-04 | Sensor for detecting liquid level of low temperature liquefied gas |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14880485A JPS628019A (en) | 1985-07-04 | 1985-07-04 | Sensor for detecting liquid level of low temperature liquefied gas |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS628019A JPS628019A (en) | 1987-01-16 |
| JPH0431339B2 true JPH0431339B2 (en) | 1992-05-26 |
Family
ID=15461079
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14880485A Granted JPS628019A (en) | 1985-07-04 | 1985-07-04 | Sensor for detecting liquid level of low temperature liquefied gas |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS628019A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5782131A (en) * | 1996-06-28 | 1998-07-21 | Lord; Richard G. | Flooded cooler with liquid level sensor |
| NL2003849C2 (en) * | 2009-11-23 | 2011-05-24 | Stichting Energie | LEVEL SENSOR IN AN EVAPORATOR. |
| US8438919B2 (en) * | 2010-07-23 | 2013-05-14 | Rosemount Aerospace Inc. | Systems and methods for liquid level sensing having a differentiating output |
| DE102011052775B4 (en) * | 2011-08-17 | 2013-09-05 | Thermofin Gmbh | Arrangement and method for refrigerant level monitoring and control in refrigeration systems |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54118330A (en) * | 1978-03-08 | 1979-09-13 | Hitachi Ltd | Detection of surface position of molten metal |
| JPS5544923A (en) * | 1978-09-27 | 1980-03-29 | Japan Atom Energy Res Inst | Heater surface temperature measuring type level gage |
-
1985
- 1985-07-04 JP JP14880485A patent/JPS628019A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54118330A (en) * | 1978-03-08 | 1979-09-13 | Hitachi Ltd | Detection of surface position of molten metal |
| JPS5544923A (en) * | 1978-09-27 | 1980-03-29 | Japan Atom Energy Res Inst | Heater surface temperature measuring type level gage |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS628019A (en) | 1987-01-16 |
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