JP2005180240A - Liquid supply system, sensor unit, and liquid supply method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid supply system capable of suitably detecting a condition that liquid in a transfer tank gets empty with a simple structure at low cost without attaching a sensor on the transfer tank, a sensor unit which can be used for the liquid supply system, and a liquid supply method. <P>SOLUTION: This liquid supply system is provided with a replaceable one ton container 3, a supply pump 8 pumping out urethane undiluted solution 4 supplied from the one tone container 3, a pipe passage 10 connected to a lower part of the one tone container 3, communicating to the supply pump 8 and provided with a route 9 descending at a middle, an electrostatic capacity type sensor 5 arranged in the route and detecting existence of the urethane undiluted solution 4, and a control device 18 stopping the supply pump 8 when the electrostatic capacity sensor 5 detects no urethane undiluted solution 4. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a system and method for supplying a liquid material in a large-capacity liquid container used in a chemical factory or the like to a pump.

  Conventionally, drums have been used as tanks for transporting liquid raw materials used in chemical factories and the like. While the drum can is easy to transport and install, it becomes an industrial waste after use, which is not preferable in terms of environmental protection. In addition, it has been pointed out as a practical problem that it is necessary to wash at the time of disposal and that the liquid raw material cannot be used up to the end and a residual liquid is generated. Thus, in recent years, large-capacity liquid transfer tanks such as 1-ton containers tend to be used as liquid raw material transfer tanks.

  Further, when the liquid raw material in the transfer tank is supplied to a manufacturing facility or the like, naturally the liquid raw material is reduced, so that it is necessary to replace the transfer tank or to replenish the liquid raw material. Therefore, in order to grasp the decrease in the liquid material in the transfer tank, the liquid level in the transfer tank has been monitored. As the method, a level sensor is generally inserted from the upper surface of the transfer tank to manage the upper and lower limits of the liquid level.

  However, it is not appropriate to employ a method of attaching a sensor to a transfer tank in a large-capacity liquid transfer tank such as a 1-ton container because a complicated operation needs to be performed each time the tank is replaced. Accordingly, the following has been proposed as a method for grasping the decrease in the liquid raw material in the transfer tank without attaching a sensor such as a level sensor to the transfer tank.

For example, there has been proposed an electric pump that stops pumping when the liquid raw material in the tank runs out by detecting the negative pressure of the liquid raw material in the tank and the pipe interposed between the electric pump that pumps the liquid raw material ( See Patent Document 1 below). In addition, a sealed liquid tank is installed between the tank containing the liquid raw material and the pump for pumping out the liquid raw material, and the liquid tank is provided with venting means equipped with a control valve, and the pipe line An apparatus has been proposed in which a sensor for detecting gas and liquid is provided, and the opening and closing of a control valve is controlled based on the sensor (see Patent Document 2 below).
Japanese Patent Laid-Open No. 10-37861 (second page, FIG. 1) JP-A-9-138237 (second page, FIG. 3)

  However, since the system according to Patent Document 1 is applied to the pumping of the liquid raw material from the transfer tank, the liquid raw material in the transfer tank cannot be used up to the end, and there is a risk that residual liquid is generated. There is. In addition, when the supply operation of the liquid material is continued or the detection of the empty state is delayed when the transfer tank is empty, air is improperly bitten into the liquid supply system, and the temperature of the liquid material is decreased. There is a risk of adverse effects. Therefore, it is inappropriate when it is desired to grasp the state in which the liquid material in the transfer tank is completely emptied. In the device according to Patent Document 2, a sealed liquid tank, a control valve, a lid sensor, and the like are combined in a complicated manner, and there are problems in terms of management, maintenance, cost, installation space, and the like.

  Accordingly, an object of the present invention is to provide a liquid supply system that can suitably detect a state in which the liquid in the transfer tank is emptied with a simple configuration and at a low cost without attaching a sensor to the transfer tank, An object of the present invention is to provide a sensor unit and a liquid supply method that can be used in a liquid supply system.

  The above object can be achieved by the present invention as described below. That is, the liquid supply system of the present invention includes a replaceable large-capacity liquid container, a pump that pumps out the liquid supplied from the large-capacity liquid container, a lower part of the large-capacity liquid container, and the pump. A first sensor for detecting the presence or absence of liquid in the pipeline at a location where the pipeline is provided, a pipeline having a pathway that is lowered in the middle, a route that is lowered in the middle of the pipeline, and the first sensor; Includes a control device that stops the pump when it is detected that there is no liquid.

  According to such a liquid supply system, the first sensor detects that the large-capacity liquid container is in an empty state in the path descending in the middle of the pipeline, and the control device quickly stops the pump. It is possible to prevent air from getting into the supply system. Moreover, since the first sensor is not attached to the large-capacity liquid container, no complicated work is required when replacing the container. Further, since the liquid supply system has a simple configuration, it is useful in terms of management, maintenance, cost, installation space, and the like. Furthermore, since the pipe line is connected to the lower part of the large-capacity liquid container, the liquid in the container can be used up to the end, and the generation of residual liquid can be suppressed. Here, the lower part of the large-capacity liquid container refers to the vicinity of the bottom surface of the container, and is preferably the bottom surface of the container, but may be a side surface near the bottom surface.

  Further, another liquid supply system of the present invention is installed at a lower level than the bottom level of the large-capacity liquid container, a replaceable large-capacity liquid container, a pump for pumping out the liquid supplied from the large-capacity liquid container, and A residual liquid tank, a unit connected to a lower part of the large-capacity liquid container and connected to the pump, and a unit including the residual liquid tank on the way, and a unit extending upwardly in communication with the upper surface of the residual liquid tank A main body, a first sensor that is installed at a bottom surface level of the large-capacity liquid container in the unit main body and detects the presence or absence of liquid in the unit main body at the installation location, and the first sensor And a control device that stops the pump when it is detected that there is not.

  According to such a liquid supply system, the first sensor for detecting the presence or absence of the liquid is not installed in the large-capacity liquid container but in the unit main body connected in the middle of the pipeline. No complicated work is required. Further, the liquid level in the unit main body is at the same level as the liquid level in the large-capacity container, and descends as the liquid in the container decreases. Since the first sensor is installed at the bottom surface level of the large-capacity liquid container in the unit main body, it can quickly detect that the container is empty. Then, by detecting the empty state by the first sensor, the control device can stop the pump and prevent the air from getting into the system. In addition, by installing the residual liquid tank, it is possible to absorb the return of the liquid downstream from the residual liquid tank when the pump is stopped, and to prevent the back flow of the liquid upstream from the residual liquid tank. Since such a liquid supply system has a simple configuration, it is useful in terms of management, maintenance, cost, installation space, and the like. Furthermore, since the pipe line is connected to the lower part of the large-capacity liquid container, the liquid in the container can be used up to the end, and the generation of residual liquid can be suppressed.

  In the above, it is preferable that the unit main body is formed higher than the liquid level in the large-capacity liquid container before supplying the liquid and provided with the liquid level measuring means.

  As a result, the liquid level in the large-capacity liquid container can be easily managed, and the timing of grasping the liquid amount of the container and replacing the container becomes clear.

  In the above, a second sensor for detecting the presence or absence of liquid is further installed above the installation position of the first sensor, and an alarm sounds when the second sensor detects that there is no liquid. Is preferred.

  Before the large-capacity liquid container is emptied, an alarm is generated by the second sensor, so that the timing of grasping the liquid amount of the container and the replacement of the container becomes clearer and can be handled with a margin. .

  In the above, it is preferable that each of the sensors is mounted on the upper surface at an inclination angle of 45 to 60 ° with respect to the horizontal plane.

  When liquid adheres to the tip of the sensor, the sensor may detect that there is liquid due to the liquid attached to the tip even if there is no liquid in the detection region. Therefore, the sensor is attached to the upper part while being inclined with respect to the horizontal plane so that the liquid adhering to the tip of the sensor is dripped, whereby the sensor can accurately detect the inside of the pipe line. Here, the upper mounting means that the sensor is mounted with the front end facing downward. The inclination angle is preferably 45 to 60 °. If the angle is less than 45 °, the liquid adhering to the tip hardly drops, and if it exceeds 60 °, the attachment becomes difficult and the sensitivity of the sensor fluctuates.

  In the above, each of the sensors is preferably a capacitive sensor.

  The capacitance type sensor is cheaper and easier to handle than a general level sensor, and can be easily installed in a pipeline. Although there is a means for grasping the decrease in the liquid in the large-capacity liquid container with a weighing machine, there are problems in terms of cost and installation space.

  In the above, it is preferable that the installation portion of each sensor is formed of a transparent material, and each sensor is an optical sensor.

  The optical sensor is cheaper and easier to handle than a general level sensor, and can be easily installed in a pipeline.

  The sensor unit of the present invention is a sensor unit configured to be connectable in the middle of a pipe line leading from the lower part of the large-capacity liquid container to the pump, and the residual liquid installed below the bottom level of the large-capacity liquid container A tank, a unit main body that communicates with an upper surface of the residual liquid tank, and extends upward; in the unit main body, the liquid in the unit main body is installed at the bottom surface level of the large-capacity liquid container; A first sensor that detects the presence or absence of the liquid, and a control device that stops the pump and / or an alarm that sounds an alarm when the first sensor detects that there is no liquid.

  By connecting the sensor unit in the middle of the pipeline, the above-described effects can be suitably achieved.

  In the above, it is preferable that the unit main body is formed higher than the liquid level in the large-capacity liquid container before supplying the liquid and provided with the liquid level measuring means.

  As a result, the liquid level in the large-capacity liquid container can be easily managed, and the timing of grasping the liquid amount of the container and replacing the container becomes clear.

  In the above, a second sensor for detecting the presence or absence of liquid in the unit main body is further installed above the position where the first sensor is installed, and when the second sensor detects that there is no liquid, an alarm is issued. It is preferable to be configured to sound.

  Before the large-capacity liquid container is emptied, an alarm is generated by the second sensor, so that the timing of grasping the liquid amount of the container and the replacement of the container becomes clearer and can be handled with a margin. .

  The liquid supply method of the present invention is a liquid supply method for supplying a liquid from a large-capacity liquid container to a pump via a conduit, and the step of sending the liquid in the large-capacity liquid container to the pump via the conduit And a first sensor that detects the presence or absence of liquid in the pipeline at the installation location, which is installed in a path that descends in the middle of the pipeline. And a step of causing the control device to stop the pump and / or sound an alarm when the first sensor detects that there is no liquid.

  The effects produced by the above method are as described above.

  According to another aspect of the present invention, there is provided a liquid supply method for supplying a liquid from a large-capacity liquid container to a pump via a conduit, and the liquid in the large-capacity liquid container is supplied to the pump via the conduit. In the unit main body connected in the middle of the pipe line, the step of sending to the pump and the fact that the inside of the large-capacity liquid container is emptied is installed at the bottom surface level of the large-capacity liquid container. A step of detecting by the first sensor that detects the presence or absence of liquid in the unit main body, and a step of the control device stopping the pump and / or an alarm when the first sensor detects that there is no liquid A process.

  The effects produced by the above method are as described above.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall view showing an example of a liquid supply system of the present invention, and FIG. 2 is an enlarged view of a pipe line connected to a lower part of a 1-ton container.

  The liquid supply system of FIG. 1 includes a 1-ton container 3 (corresponding to the large-capacity liquid container), a supply pump 8, a machine tank 22 of a foaming machine, and pipelines 10 and 20 that sequentially connect them. Prepare. The urethane stock solution 4 is contained in the 1-ton container 3, and when it is emptied by supply to the machine tank 22, it is replaced with another 1-ton container containing the urethane stock solution. Moreover, it is preferable that the 1-ton container 3 is installed in a place higher than the floor level in consideration of the arrangement of the pipelines 10 and 20 described later and movement by a forklift.

  The 1-ton container 3 and the supply pump 8 are connected by a pipe line 10, and the supply pump 8 and the machine tank 22 are connected by a pipe line 20. The urethane stock solution 4 is sent to the supply pump 8 through the pipe line 10, then pumped out by the supply pump 8, and sent to the machine tank 22 through the pipe line 20. In addition, the supply pump 8 is arrange | positioned in the position lower than the installation level of the sensor 5 mentioned later.

  The pipe line 10 is connected via a joint member 15 to an outlet 14 extending from the bottom center of the 1-ton container 3. As the joint member 15, it is preferable to use an easily detachable member such as a cam lock or a ferrule. This is because the replacement work of the 1-ton container 3 is simplified. The pipe line 10 extending from the outlet 14 has a path 9 that descends halfway. In the path 9, a metal cheese 12 is provided in the pipe line 10. A capacitive sensor 5 (corresponding to the first sensor) is installed at the joint where the cheese 12 is branched, and the presence or absence of the urethane stock solution 4 in the pipeline at the installation location can be detected.

  As shown in FIG. 2, the sensor 5 is mounted on the upper surface at an inclination angle θ of 45 to 60 ° with respect to the horizontal plane, and is held by a holding member 13 such as a nipple and a reducer made of vinyl chloride resin. Thereby, it can prevent detecting the urethane stock solution 4 adhering to the front-end | tip of the sensor 5 with the urethane stock solution 4 which passes the inside of the pipe line 10 accidentally. Moreover, it can be used even if the sensor 5 is not a shield type by setting it as the arrangement | positioning which the sensor 5 does not contact with the metal cheese 12. FIG. The sensor 5 is preferably a three-wire type sensor as a noise countermeasure.

  The controller 18 controls the supply pump 8 to stop when the sensor 5 detects that the urethane stock solution 4 is not present. The pipe 10 is provided with a ball valve 11 before the path 9, and the pipe 20 is provided with a check valve 19 and a ball valve 21.

  Next, a liquid supply method according to the present invention will be described with reference to the drawings. According to the liquid supply system of FIGS. 1 and 2, the urethane stock solution 4 in the 1-ton container 3 passes through the pipe line 10 and is supplied to the machine tank 22 by the supply pump 8. When the urethane stock solution 4 in the 1-ton container 3 decreases with supply and finally becomes empty, the urethane stock solution 4 in the pipe line between the outlet 14 and the ball valve 11 becomes empty, and then In the path 9, the liquid level descends. When the liquid level passes the detection position of the sensor 5, the sensor 5 detects that the urethane stock solution 4 is not present in the detection region, and the control device 18 stops the supply pump 8 to supply the urethane stock solution 4 to the machine tank 22. Interrupt.

  In this state, after removing the joint member 15 from the pipe line 10, the 1-ton container 3 is replaced with one containing the urethane stock solution 4, and the joint member 15 is connected to the pipe line 10 again. As described above, the supply of the urethane stock solution can be resumed without causing the supply pump 8 to bite air.

  FIG. 3 shows another type of liquid supply system according to the present invention. Except for providing the sensor unit 30 between the 1-ton container 3 and the supply pump 4 and the shape of the pipe line 10, the configuration is the same as that of the liquid supply system of FIG. That is, in the liquid supply system of FIG. 3, the sensor unit 30 including the unit main body 35, the residual liquid tank 36, and the electrostatic capacity type sensor 5 (corresponding to the first sensor) includes the pipe line 10a and the pipe line 10b. It is installed between. The pipe line 10a connected to the outlet 14 via the joint member 15 is connected to the lower side surface of the unit main body 35 without having the path 9 as shown in FIG. The pipe line 10 b communicating with the supply pump 8 is connected to the side surface of the residual liquid tank 36, and the supply pump 8 and the pipe line 10 b are disposed at a position lower than the bottom surface level LB of the 1 ton container 3.

  The unit main body 35 is provided above the residual liquid tank 36 in communication with the upper surface of the residual liquid tank 36, and is formed higher than the liquid level LT in the 1-ton container 3 before supply. A ventilation portion 32 is provided on the upper surface of the unit main body portion 35, and the upper portion of the ventilation portion 32 and the 1-ton container 3 is communicated by a communication member 33. The communication member 33 is not limited in material and size as long as a communication state that allows air to pass therethrough is used, but in the present embodiment, the communication member 33 is a rubber tube. The unit main body 35 includes a magnet float type liquid level gauge 39 (corresponding to the liquid level measuring means) inside, and a side gauge 38 on the side surface along the height direction. The side gauge 38 is configured to display the liquid level in accordance with the elevation of 39. By providing the side gauge 38, the liquid level can be suitably visually observed even in the case of a stock solution with many bubbles.

  The residual liquid tank 36 is installed at a position lower than the bottom surface level LB of the 1-ton container 3, and the capacity is preferably 30 to 50 liters. In order to prevent the sensor unit 30 from overturning, it is preferable to fix the residual liquid tank 36 with an anchor 37.

  The sensor 5 is attached to the side surface of the unit main body 35 at an inclination angle θ of 45 to 60 ° with respect to the horizontal plane so that the detection unit is at the bottom surface level LB of the 1-ton container 3. The control device 18 controls the supply pump 8 to stop when the sensor 5 detects that the urethane stock solution 4 is not present in the detection region. In addition, an electrostatic capacity type sensor 6 (corresponding to the second sensor) is mounted on the upper part of the sensor 5 at an inclination angle θ of 45 to 60 ° with respect to the horizontal plane. When the absence of the urethane stock solution 4 is detected, an alarm is sounded.

  Next, another embodiment of the liquid supply method according to the present invention will be described with reference to the drawings. According to the liquid supply system of FIG. 3, the urethane stock solution 4 in the one-ton container 3 passes through the pipe line 10a, the unit main body 35, the residual liquid tank 36, and the pipe line 10b, and is supplied to the machine tank 22 by the supply pump 8. The At this time, the air in the unit main body 35 is discharged from the ventilation portion 32 to the outside of the unit main body 35, and the urethane stock solution 4 is injected into the unit main body 35. The liquid level LU in the unit main body 35 is the same level as the liquid level LT of the urethane stock solution 4 in the 1-ton container 3, and the liquid level LU can be visually observed by the side gauge 38.

  As the urethane stock solution 4 in the 1-ton container 3 decreases with the supply to the machine tank 22, the liquid level LU of the unit main body portion 35 is lowered. When the liquid level of the unit main body 35 passes the detection position of the sensor 6, the sensor 6 detects that the urethane stock solution 4 is not present in the detection region and sounds an alarm to confirm that the 1-ton container 3 is approaching an empty state. Inform the worker. Subsequently, when the inside of the 1-ton container 3 becomes empty, the liquid level LU of the unit main body portion 35 is lowered to the bottom surface level LB of the 1-ton container 3 and passes the detection position of the sensor 5. Thereby, the sensor 5 detects that the urethane stock solution 4 is not present in the detection region, and the control device 18 stops the supply pump 8 and interrupts the supply of the urethane stock solution 4 to the machine tank 22.

  Even when the 1-ton container 3 is empty in a state where the supply pump 8 is stopped, the predetermined amount of the urethane stock solution 4 remains in the residual liquid tank 36, so that it is possible to reliably prevent air from being bitten. it can. Further, even if the urethane stock solution 4 existing between the supply pump 8 and the check valve 19 flows backward, it is absorbed by the residual liquid tank 36 and the backflow up to the joint member 15 is prevented. Can be removed from the conduit 10a.

  After removing the joint member 15 from the pipe line 10a, the 1-ton container 3 is replaced with one containing the urethane stock solution 4, and the joint member 15 is connected to the pipe line 10a again. As described above, the supply of the urethane stock solution can be resumed without causing the supply pump 8 to bite air.

[Other Embodiments]
(1) In the embodiment shown in FIGS. 1 and 2, the example in which the path 9 descending in the middle of the pipeline 10 descends at an angle of about 90 ° with respect to the ground is shown. However, the pipeline according to the present invention 10 is not limited to such a shape. For example, it may fall at an angle of 45 ° with respect to the ground.

  (2) In the embodiment shown in FIG. 1 and FIG. 2, an example in which only the sensor 5 is installed in the path 9 is shown. However, in the present invention, an alarm is given when it is detected that there is no urethane stock solution 4 in the detection region. A capacitance type sensor (corresponding to the second sensor) that sounds can be provided on the upper part of the sensor 5. As a result, before the 1-ton container 3 becomes empty, the remaining liquid amount and the replacement timing of the 1-ton container 3 become clearer, and it is possible to cope with it with a margin. In addition, in the sensor to be added, similarly to the sensor 5, it is preferable that the sensor is mounted at an upper portion with an inclination angle θ of 45 to 60 ° with respect to the horizontal plane.

  (3) In the embodiment of FIG. 3, an example in which the magnet float type liquid level gauge 39 is used is shown, but the present invention is not limited to this, and other liquid level measuring means may be used. For example, the unit main body 35 may be formed to be transparent so that the liquid level can be visually observed, and the liquid level may be measured with a scale or the like. Further, the gauge for displaying the liquid level LU in the unit main body 35 is not limited to the one provided along the height direction of the unit main body 35 as in the embodiment, and may be a dial gauge or the like.

  (4) In the embodiment of FIG. 3, an example in which the sensor 6 sounds an alarm before the one-ton container 3 becomes empty, but in the present invention, even if the liquid level gauge 39 has an alarm function, Good. That is, by adding an alarm contact to the liquid level gauge 39, an alarm can be sounded when the liquid level LU falls to a predetermined height.

  (5) In the embodiment of FIG. 3, the example in which the upper surface of the unit main body 35 and the upper part of the 1-ton container 3 communicate with each other by the rubber tube 33 is shown. However, in the present invention, the 1-ton container 3 is sealed. If the liquid level LU of the unit main body 35 is at the same level as the liquid level LT of the 1 ton container 3, it is only provided with the ventilation part 32, and the communication member 33 such as a rubber tube is provided. It does n’t matter.

  (6) In the above-described embodiment, the example in which the capacitive sensor 5 is installed in the pipe line 10 has been shown. However, in the present invention, the installation part of the sensor 5 (the path 9 in FIG. 1 and FIG. In the third example, the unit main body portion 35) may be formed of a transparent material, and the presence or absence of liquid may be detected by an optical sensor through the transparent portion. Further, the sensor is not limited to the exemplified sensor as long as it detects the presence or absence of liquid.

  (7) In the above-described embodiment, the control device 18 stops the supply pump 8 when the sensor 5 detects that there is no liquid in the detection region. However, in the present invention, the control device 18 supplies the liquid. An alarm may be sounded at the same time as the pump 8 is stopped. Thereby, an operator can be notified that supply pump 8 stopped.

Overall view showing an example of a liquid supply system of the present invention Enlarged view of the pipe connected to the bottom of the 1-ton container in FIG. Overall view showing an example of a liquid supply system of the present invention

Explanation of symbols

3 1 ton container 5, 6 Capacitance type sensor 8 Supply pump 10 Pipe line 18 between outlet and supply pump 18 Controller 20 Pipe line 30 between supply pump and machine tank Sensor unit 35 Unit main body 36 Residual liquid tank

Claims (12)

A replaceable high-capacity liquid container;
A pump for pumping the liquid supplied from the large-capacity liquid container;
A pipe line connected to the lower part of the large-capacity liquid container and connected to the pump, and having a path that descends halfway;
A first sensor that is installed in a path that descends in the middle of the pipeline and detects the presence or absence of liquid in the pipeline at the installation location;
A liquid supply system comprising: a control device that stops the pump when the first sensor detects that there is no liquid. A replaceable high-capacity liquid container;
A pump for pumping the liquid supplied from the large-capacity liquid container;
A residual liquid tank installed below the bottom level of the large-capacity liquid container;
A pipe connected to the lower part of the large-capacity liquid container and connected to the pump, and provided with the residual liquid tank in the middle;
A unit main body that communicates with the upper surface of the residual liquid tank and extends upward;
A first sensor that is installed at the bottom surface level of the large-capacity liquid container in the unit main body, and detects the presence or absence of liquid in the unit main body at the installation location;
A liquid supply system comprising: a control device that stops the pump when the first sensor detects that there is no liquid. The liquid supply system according to claim 2, wherein the unit main body is formed higher than a liquid level in the large-capacity liquid container before supplying the liquid, and further includes a liquid level measuring unit. A second sensor for detecting the presence or absence of liquid is further installed above the installation position of the first sensor, and an alarm sounds when the second sensor detects that there is no liquid. The liquid supply system in any one of 1-3. 5. The liquid supply system according to claim 1, wherein each of the sensors is mounted at an upper portion with an inclination angle of 45 to 60 ° with respect to a horizontal plane. The liquid supply system according to claim 1, wherein each of the sensors is a capacitive sensor. The liquid supply system according to any one of claims 1 to 4, wherein an installation portion of each sensor is formed of a transparent material, and each sensor is an optical sensor. A sensor unit configured to be connectable in the middle of a pipe line leading to a pump from a lower part of a large-capacity liquid container,
A residual liquid tank installed below the bottom level of the large-capacity liquid container;
A unit main body that communicates with the upper surface of the residual liquid tank and extends upward;
A first sensor that is installed at the bottom surface level of the large-capacity liquid container in the unit main body, and detects the presence or absence of liquid in the unit main body at the installation location;
A sensor unit comprising: a control device that stops the pump and / or an alarm that sounds an alarm when the first sensor detects that there is no liquid. The sensor unit according to claim 8, wherein the unit main body is formed higher than a liquid level in the large-capacity liquid container before liquid supply, and further includes a liquid level measuring unit. A second sensor for detecting the presence or absence of liquid in the unit main body is further installed above the position where the first sensor is installed, and an alarm sounds when the second sensor detects that there is no liquid. The sensor unit according to claim 8 or 9, wherein the sensor unit is configured as follows. In a liquid supply method for supplying a liquid from a large-capacity liquid container to a pump via a pipeline,
Sending the liquid in the large-capacity liquid container to the pump via the conduit;
A step of detecting that the inside of the large-capacity liquid container is emptied by a first sensor that is installed in a path that descends in the middle of the pipeline and detects the presence or absence of liquid in the pipeline at the installation location; ,
When the first sensor detects that there is no liquid, the control device includes a step of stopping the pump and / or a step of sounding an alarm. In a liquid supply method for supplying a liquid from a large-capacity liquid container to a pump via a pipeline,
Sending the liquid in the large-capacity liquid container to the pump via the conduit;
In the unit main body connected in the middle of the conduit, the fact that the inside of the large-capacity liquid container is empty is installed at the bottom surface level of the large-capacity liquid container, and the liquid in the unit main body at the installation location A step of detecting by a first sensor for detecting the presence or absence of
When the first sensor detects that there is no liquid, the control device includes a step of stopping the pump and / or a step of sounding an alarm.

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