JP2019066377A - Level gauge and level measuring method - Google Patents

Abstract

To provide a level gauge capable of accurately performing measurement with a simple configuration, and a level measuring method.SOLUTION: A level gauge 1 comprises: a tube 2 for containing liquid inside; an opening 7 formed in the lower end of the tube 2; a lid part 3 for sealing the upper part of the tube 2; and a pressure sensor 4 provided to the upper end inside the tube. The level gauge 1 is configured to measure the liquid pressure P on the basis of a signal from the pressure sensor and to calculate the liquid level h with respect to a reference position of the tube using the following formula: h=P/ρg, in which ρ: Liquid density, g: gravity acceleration (formula 1).SELECTED DRAWING: Figure 1

Description

The present invention relates to an apparatus and method for measuring liquid level.

In the case of measuring the height of water in a pit in the ground, etc., the water surface is usually located considerably deep from the pit entrance, and it is difficult to measure the water level by direct visual observation or the like. A throw-in water gauge is used to measure such water level precisely. A pressure sensor, a measurement circuit, a power supply, etc. are provided in a cylinder at the tip, and a long electric cable or optical cable is connected to this cylinder, and information obtained by the pressure sensor can be used as an external instrument panel It is supposed to be transmitted to A cylinder containing a pressure sensor is inserted into the bottom of a drainage pit or the like, and the fluid pressure is measured. Based on the fluid pressure data, the height of the fluid level relative to the pressure sensor can be calculated, and the fluid level can be determined. The level can be measured outside the pit by transmitting pressure data or calculated level data to the instrument panel provided outside the pit via a cable. For example, the invention described in Patent Document 1 is also based on a similar throwing water level gauge.

Moreover, as a simple liquid level measuring device, there is one in which a plurality of floats are provided at different heights. Since the float above the liquid level is in a lowered state but the float in the liquid is lifted, it is possible to know the liquid level by detecting the state of the float.

Japanese Patent Application Laid-Open No. 11-37825

The throw-in type liquid level gauge used in Patent Document 1 and the like is easy to install and can perform measurement with high accuracy. However, this level gauge is expensive. On the other hand, float type level gauges can be made inexpensively, but can not grasp the speed of rise and fall of the liquid level. Since measurement can be performed only at a certain position of the float, only rough information can be obtained, and continuous liquid level information between the float and the float can not be obtained.

An object of the present invention is to provide a level gauge and a level measurement method capable of continuously performing accurate measurement while having a simple configuration.

In order to solve the above-described problems, the liquid level meter according to the present invention comprises a pipe for containing liquid therein, an opening provided at the lower end of the pipe, a lid for sealing the upper end of the pipe, and the inside of the pipe And a pressure sensor provided at the upper end. A liquid supply port provided on the upper surface of the pipe, an open / close lid for opening and closing the liquid supply port, an open / close member for opening and closing the opening at the lower end, and an open / close operation member for opening and closing the open / close member from the top of the pipe preferable. It has an arithmetic unit connected to the pressure sensor, and measures the hydraulic pressure P based on the signal of the pressure sensor, and calculates the liquid level h relative to the reference position of the pipe based on the following equation.
h = P / ρg ρ: density of liquid, g: gravitational acceleration (equation 1)
Furthermore, it is preferable to have a self-diagnosis function that generates a signal indicating that the fluid pressure P is abnormal when it is at atmospheric pressure.

According to the liquid level measuring method of the present invention, a pipe for containing the liquid therein, an opening provided at the lower end of the pipe, a lid for sealing the upper end of the pipe, and the upper end inside the pipe A pressure sensor, a liquid supply port provided on the upper surface of the pipe, an open / close lid for opening and closing the liquid supply port, an open / close member for opening and closing the opening at the lower end, and an open / close operation member for opening and closing the open / close member from the top of the pipe Using a liquid level meter equipped with a computing device connected to the pressure sensor,
Insert the lower end of the pipe into the liquid to be measured, close the opening at the lower end with the opening and closing member and open the liquid supply port, and supply the liquid from the liquid supply port into the pipe to fill the pipe,
The liquid supply port is closed by the opening and closing lid, and the opening and closing member is operated by the opening and closing operation member to open the opening,
The fluid pressure P is measured based on the signal of the pressure sensor, and the fluid level h relative to the reference position of the pipe is calculated based on the following equation.
h = P / ρg ρ: density of liquid, g: gravitational acceleration (equation 1)

The liquid level meter according to the present invention has a simple structure using an elongated pipe and a pressure sensor at the upper end as main members, and can be realized inexpensively. The tip does not contain delicate members such as sensors, and the liquid level can be measured quickly and accurately.

It is a conceptual diagram showing the outline of a level gauge. It is a conceptual diagram which shows the wearing principle of a level gauge. It is a graph which shows the example of measurement of a liquid level.

A mode for carrying out the present invention will be described based on the drawings. It is a conceptual diagram showing the outline of a level gauge.

The level gauge 1 comprises a tube 2 for containing the liquid therein. This pipe may be of any length as long as it reaches the bottom of the container x containing the liquid to be measured, and a hard pipe such as a metal pipe or a vinyl chloride pipe is suitable, but a flexible pipe such as a hose May be. In this example, the water level in the drainage pit is measured, and a stainless steel pipe having a sufficient rigidity against oxidation and corrosion and having a relatively inexpensive price is used. For example, a stainless steel pipe having a diameter of 50 mm is particularly used. Is suitable.

The pipe 2 is used in a state of extending in the vertical direction, but there is no problem if it is inclined. And the upper part of this hollow tube needs to be sealed. Therefore, the upper end surface of the tube is closed by the sealing lid 3. A liquid supply port 5 and a cap-like open / close cover 6 for opening and closing the liquid supply port 5 are provided on the closed cover 3.

On the other hand, the lower part of the tube 2 needs to be formed with an opening 7 through which liquid can enter and exit. This opening 7 may be provided on the side surface of the lower end, but it is preferable to provide it on the bottom of the tube 2 in order to prevent foreign matter from being deposited inside. Furthermore, an opening and closing member 8 for opening and closing the opening 7 and an opening and closing operation member 9 for opening and closing the opening and closing member 8 from the upper part of the pipe 2 are provided. In this example, in order to simplify the configuration of the device, a door-like opening / closing member 8 and an opening / closing operation member 9 such as a wire or a bar connected to the door are used.

In addition, a support member 10 is provided at the lower part of the pipe 2 so as to support the opening 7 at a predetermined height away from the bottom of the drainage pit. In the case of the drainage pit, by installing the opening 7 at a position higher by about 50 to 300 mm from the bottom, it is possible to prevent the sludge accumulated in the bottom from blocking the opening 7 of the pipe 2.

Further, a hydraulic pressure sensor 4 is provided at an upper end portion of the pipe 2. Furthermore, an arithmetic unit 11 is provided outside, and the hydraulic pressure sensor 4 and the arithmetic unit 11 are connected via a line 12. This connection may be wired or wireless, or may be a combination thereof or via a communication line such as the Internet.

Next, an example of a liquid level measurement method will be described based on how to use the liquid level meter 1. First, the lower end of the pipe 2 is placed in the container x to be measured. The position of the pressure sensor 4 is fixed using the support member 10 or the like, and the opening 7 is placed in the liquid at a predetermined height.

Before starting the measurement, the open / close operation member 9 is operated to close the lower opening 7 by the open / close member 8. On the other hand, the open / close lid 6 is opened, and the same liquid as the liquid y to be measured is supplied from the liquid supply port 5 into the pipe 2. For example, in the case of drainage pit measurement, water is supplied. When the liquid is filled to the upper end of the tube 2, the open / close lid 6 is closed to seal the upper end.

Then, the opening / closing operation member 9 is operated to open the lower opening 7 by the opening / closing member 8. Thereby, the liquid y can be moved in and out through the opening 7, and the measurement of the liquid level can be started.

The operation principle of the level gauge and level measurement method of the present invention will be described. FIG. 2 is a conceptual view showing the operation principle of the level gauge. Here, only the main components are shown, and those that are not directly involved in the liquid level measurement are omitted.

The upper end of the tube 2 is placed above the maximum height of the upper surface of the liquid to be measured. That is, the liquid level is always lower than the pressure sensor at the upper end of the tube 2. Since the upper end of the pipe 2 is sealed, the hydraulic pressure at the upper end is a negative pressure lower than the atmospheric pressure. On the other hand, the pressure on the upper surface of the liquid y in the drainage pit x is atmospheric pressure. Therefore, assuming that the difference between the height of the liquid top surface and the pressure sensor 4 is h, the density of the liquid y is rho, and the gravitational acceleration is g, the pressure difference between the liquid top surface and the reference position near the pressure sensor 4 The detected pressure has the following relationship.
h = P / ρg
This gives h. Further, since the position of the pressure sensor 4 is fixed, this h is a value indicating the liquid level.

The pressure information P obtained by the pressure sensor 4 is sent to an external arithmetic unit 11, and the liquid level h may be calculated by the arithmetic unit 11, and a small processing terminal provided near the upper end of the pipe 2 (shown It may be transmitted to an external server using a communication member attached to the small-sized processing terminal after calculating the liquid level h according to the description etc. or adding processing such as time averaging and noise removal.

As described above, if the pressure sensor 4 is set higher than the maximum rise position of the liquid y of the container x, the pressure P should be a negative pressure (less than the atmospheric pressure) as long as it is normally measured. However, if the pipe 2 is punctured, the liquid level in the pipe 2 will be the same as the liquid level of the container x, and the pressure P will also be atmospheric pressure. Therefore, when the liquid level is continuously measured, it is possible to determine whether or not the pressure P is less than the atmospheric pressure by the computing device, and to determine that it is abnormal when the pressure P becomes the atmospheric pressure. In this case, the measurement data up to that point is stored in the storage device, and the subsequent measurement is stopped. Then, it is possible to display the occurrence of an abnormality on the display device 13 or the like and to display the abnormality occurrence time, or to issue an alarm by voice or the like. Thus, the liquid level gauge can be provided with a self-diagnosis function without adding special equipment.

The main body portion of the liquid level meter of the present invention is a simple structure having the pipe 2 and the pressure sensor 4 as main members, and can be implemented inexpensively. Therefore, it is also possible to make a level gauge into a set of three. If the values of the respective pressure sensors 4 are compared with each other and the value of the combination with the smallest difference is adopted, the reliability can be enhanced. Furthermore, when a hole is bored in one pipe, the self-diagnosis function notifies of an abnormality, and the remaining two can continue measurement and wait for exchange to a new triple.

An embodiment of the level gauge of the present invention will be described. FIG. 3 is a graph showing an example of liquid level measurement. The water tank is filled with water, drained after being full, the change in water level h during that time is measured, and the time is displayed as the horizontal axis. A water tank of 500 mm × 500 mm × 1600 mm is used as a container. As a tube, an acrylic resin having a diameter of 100 mm and a height of 1700 mm is used. A scale of 0 to 2000 mm is also vertically inserted into the water tank and used to check the water level h. A pressure sensor for measuring negative pressure is installed at the top of the tube. The pressure sensor data is recorded with a digital recorder in 0.1 second cycles.
First, let the water go up to the top of the tube, then slowly pump the water into the water tank and drain it from the water tank when it is almost full. The water level h of the water tank was calculated by the above-mentioned formula based on the pressure data detected by the pressure sensor, and was also compared with the water level measured by the scale.
The water level based on the data of the pressure sensor is displayed in FIG. The bottom of the water tank is indicated as the reference height, and the upper direction is indicated as positive. It quickly follows changes in water level, and it is possible to carry out virtually real-time measurement with high accuracy. It was confirmed that the readings of the water level and the scale had an error of about ± 1% even in consideration of the reading error, and they were almost completely in agreement.

The liquid level meter and the liquid level measuring method can be widely applied to various fields.
The water level of the river can be measured continuously at a safe place by installing it in a river and transmitting it remotely to a computing device or server. Because it is an inexpensive device, it can be installed in many places, so that the danger point can be monitored without leakage.
It can be installed in manhole pits and drainage neutralization pits to monitor the water level remotely.
The liquid level of the chemical solution tank can also be measured remotely.
It is possible to continuously measure the water level of the triangle and obtain information for calculating the total drainage volume.
In addition, it can be applied to the remote measurement of the water level of reservoirs and wells, and it can be used for the appropriate use of water resources such as water saving by accurately grasping the storage volume.
In addition, the water level of underground drainage can be applied to telemetry.
As described above, by measuring the liquid level inexpensively and reliably for various places and liquids, it can contribute to disaster prevention and response, effective use of resources, and the like.

1. Level gauge 2. Tube 3. Opening and closing lid 4. Pressure sensor
5. Supply port 6. Opening and closing lid 7. Opening 8. Opening and closing member 9. Opening and closing operation member 10. Support member 11. Arithmetic unit
12. Line
13. Display device x. Container y. liquid

Claims (6)

A level gauge comprising a pipe for containing liquid inside, an opening provided at the lower end of the pipe, a lid for sealing the upper end of the pipe, and a pressure sensor provided at the upper end inside the pipe. A bill comprising a liquid supply port provided on the upper surface of the pipe, an open / close lid for opening and closing the liquid supply port, an open / close member for opening and closing the opening at the lower end, and an open / close operation member for opening and closing the open / close member from the top of the pipe The liquid level meter according to Item 1. The hydraulic pressure P is measured based on the signal of the pressure sensor, and the liquid level h with respect to the reference position of the pipe is calculated based on the following equation. Level gauge as described in.
h = P / ρg ρ: density of liquid, g: gravitational acceleration (equation 1) The level gauge according to claim 3, further comprising a self-diagnosis function that generates a signal indicating that the fluid pressure P is at an atmospheric pressure. A tube containing liquid inside, an opening provided at the lower end of the tube, a lid for sealing the upper end of the tube, a pressure sensor provided at the upper end inside the tube, and an upper surface of the tube The liquid supply port, the opening / closing lid for opening / closing the liquid supply port, the opening / closing member for opening / closing the opening at the lower end, the opening / closing operation member for opening / closing the opening / closing member from the top of the pipe, and the calculation connected to the pressure sensor Use a liquid level meter equipped with
Insert the lower end of the pipe into the liquid to be measured, close the opening of the lower end by the opening / closing member and open the liquid supply port, and supply the liquid from the liquid supply port into the pipe to fill the pipe,
The liquid supply port is closed by the opening and closing lid, and the opening and closing member is operated by the opening and closing operation member to open the opening,
A liquid level measurement method of measuring the hydraulic pressure P based on the signal of the pressure sensor and calculating the liquid level h with respect to the reference position of the pipe based on the following equation.
h = P / ρg ρ: density of liquid, g: gravitational acceleration (equation 1) The liquid level measurement method according to claim 5, wherein a signal indicating abnormality is generated when the hydraulic pressure P is atmospheric pressure.

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