JP2000266585A - Illuminance type level gage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illuminance difference detection type level gage which enables relatively easier and direct measurement of the liquid surface within a storage tank difficult in direct measurement. SOLUTION: In this illuminance type level gage, an optical fiber 3a for illumination and an optical fiber 3b for reception are inserted into a storage tank together with a stainless wire 7 and lowered toward the surface of a liquid stored. Light irradiated from the side of the lower end of the optical fiber 3a for illumination is received as scattered reflected light from the liquid surface from the side of the lower end of the optical fiber 3b for reception. The scattered reflected light is trapped by a photocell 5 on the side of the upper ends of the optical fiber 3b for reception therethrough to monitor changes in the illuminance with an illuminance gauge 6. The light irradiation end as the lower end side of the optical fiber 3a for illumination is determined to reach the liquid surface by detecting the changes in the illuminance. Thus, the position of the liquid surface is calculated from the graduation in the stainless wire 7 at this point and the drawing of a storage tank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminance type liquid level gauge capable of relatively directly measuring a liquid level in a storage tank which is difficult to measure directly.

[0002]

2. Description of the Related Art For example, calibration of a liquid level gauge installed in a storage tank for an ultra-low temperature liquid or the like is performed by using a portable level gauge because there is no portable liquid level gauge capable of directly measuring the liquid level of the stored liquid. In various indirect ways depending on the situation. It is difficult to directly measure the liquid level of the stored liquid, for example, because liquid nitrogen has a boiling point of -194 ° C, the wall surface of the storage tank is made of a thick material, and has a double structure for heat insulation. ing. For this reason, the liquid level cannot be seen from the outside of the storage tank. In addition, since the liquid itself is colorless and transparent, even if the scale is immersed in the liquid, it is unknown which part of the scale the liquid level has reached, even if the scale is taken out and no trace remains Because.

[0003]

However, since the indirect measurement method involves a predetermined mediating element, a measurement error is generated accordingly. The present invention has been proposed in view of the above background, and provides an illuminance type liquid level gauge that can relatively directly directly measure the liquid level in a storage tank that is difficult to measure directly. The purpose is to do.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a liquid level gauge for measuring a liquid level in a container which is not directly visible, wherein a plurality of graduated long members are provided. An optical fiber is fixed, and the long member is lowered together with the optical fiber toward the liquid surface in the container. The optical fiber transmits light from the light emitting means and has an end near the liquid surface. A light irradiating optical fiber configured to irradiate the light toward the liquid surface, and receiving irregularly reflected light from the liquid surface from an end portion close to the liquid surface, and receiving the received irregularly reflected light from a light receiver. The light receiving optical fiber is designed to be transmitted to the optical fiber, and the long member is moved downward together with the optical fiber while irradiating light from the end of the optical fiber for light irradiation close to the liquid surface toward the liquid surface in the container. The diffused light received by the receiving optical fiber The illuminance of the light irradiation optical fiber is monitored, and the end of the optical fiber for light irradiation that is close to the liquid surface reaches the liquid surface, and the position of the liquid surface is determined based on the scale on the long member. I tried to figure out.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an illuminance type liquid level meter according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an illuminance type liquid level meter 1,
The illuminance type liquid level meter 1 is for measuring the liquid level of an ultra-low temperature liquid (liquid nitrogen or the like) stored in a storage tank (not shown), for example. That is, the illuminance type liquid level meter 1 has a light transmitting / receiving optical fiber 3 having a light irradiating end and a light incident end on the lower end while a light transmitting / receiving section 2 for measuring light is mounted on the upper end. The light receiving optical fiber 3 is fixed to a long member (described later) provided with a scale. The transmitting / receiving optical fiber 3 is a light emitting device (described later) in the optical transmitting / receiving unit 2.
Irradiating optical fiber 3a that allows light from the light source to pass through the interior from the upper end and radiate outward from the lower end side
A light receiving optical fiber for receiving irregularly reflected light of light emitted from the light emitting optical fiber 3a from the lower end and transmitting the light to a light receiver (described later) in the optical transmitting and receiving unit 2 attached to the upper end side. 3b.

The light transmitting and receiving unit 2 includes a light emitting device 4 (for example, a light emitting diode 4) attached to an upper end of a light irradiating optical fiber 3a and a light receiving device 5 (for example, photo) attached to an upper end of a light receiving optical fiber 3b. Cell 5). An illuminometer 6 is connected to the photocell 5. The lower ends of the light irradiation optical fiber 3a and the light receiving optical fiber 3b are penetrated and held by a weight 8 attached to a lower end of a long member 7 (for example, a stainless steel wire 7). The light irradiation optical fiber 3a and the light receiving optical fiber 3b are fixed to the stainless steel wire 7 along the stainless steel wire 7, but are separately illustrated in this figure.

With the above-described configuration, the optical fiber for light irradiation 3a and the optical fiber for light reception 3b, together with the stainless steel wire 7, are inserted into the inside of the storage tank through, for example, the communication port provided at the top of the storage tank, and the surface of the liquid to be stored is inserted. It is going to descend toward. At this time, the light irradiation optical fiber 3a
The light irradiated from the lower end of the optical fiber 3b is received from the lower end of the light receiving optical fiber 3b as irregularly reflected light from the liquid surface, and the irregularly reflected light is captured by the upper end photocell 5 via the light receiving optical fiber 3b. By monitoring the variation of the illuminance of the irregularly reflected light with the illuminometer 6 and detecting the variation of the illuminance, it is determined that the light irradiation end, which is the lower end side of the light irradiation optical fiber 3a, has reached the liquid level, At this time, the position of the liquid level is calculated from the scale of the stainless steel wire 7 and the drawing of the storage tank.

In the illuminance type liquid level meter 1 constructed as described above, the stainless steel wire 7 is inserted into the inside of the storage tank by the weight 8 together with the light irradiation optical fiber 3a and the light reception optical fiber 3b from the communication port at the top of the storage tank. Then, it is lowered toward the liquid surface to be stored. The light emitted from the light emitting diode 4 on the upper end side of the light irradiation optical fiber 3a in the light transmitting and receiving unit 2 passes through the light irradiation optical fiber 3a and is irradiated from the lower end toward the liquid surface. The irradiation light passes through the atmosphere at the place, is irregularly reflected on the liquid surface, and reaches the photocell 5 on the upper end side from the lower end side of the optical fiber 3b through the optical fiber 3b. At this time, a change in illuminance can be monitored by the illuminometer 6 from the reflected light captured by the photocell 5 on the upper end side of the light receiving optical fiber 3b. That is, when the light irradiation end, which is the lower end side of the light irradiation optical fiber 3a, reaches the liquid level, the illuminance fluctuates. Assuming that the light irradiation end has reached the liquid level, the scale of the stainless wire 7 at this time is read, and the position of the liquid level can be calculated with reference to the drawing of the storage tank.

[0009]

According to the present invention, the liquid level in the storage tank, which is difficult to measure directly, can be measured relatively easily, and highly accurate measurement can be performed.

[0011]

[Brief description of the drawings]

FIG. 1 is a schematic structural explanatory view showing an example of an illuminance type liquid level meter according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Illumination type liquid level meter 2 Optical transmission / reception part 3 Optical fiber for transmission / reception 3a Optical fiber for light irradiation 3b Optical fiber for light reception 4 Light emitting diode 5 Photocell 6 Illuminance meter 7 Stainless steel wire 8 Weight

Claims (1)

[Claims] 1. A liquid level gauge for capturing a liquid level in a container which is not directly visible, wherein an optical fiber is fixed to a long member provided with a scale, and the liquid in the container is fixed to the long member together with the optical fiber. A light irradiating optical fiber for transmitting light from a light emitting means and irradiating the light toward the liquid surface from an end portion close to the liquid surface. And a light-receiving optical fiber configured to receive irregularly reflected light from the liquid surface from an end portion close to the liquid surface and to transmit the received irregularly reflected light to a light receiver. Monitors the illuminance of the irregularly reflected light received by the light receiving optical fiber when descending while irradiating light from the end of the light irradiating optical fiber close to the liquid surface along with the optical fiber toward the liquid surface in the container. By detecting the change in the illuminance, the light for light irradiation is detected. An illuminance type liquid level meter characterized in that the position of the liquid level is grasped based on the scale of the long member, assuming that the end of the fiber close to the liquid level has reached the liquid level.