CN115435867A - Glass plate liquid level meter and liquid level measuring method - Google Patents

Abstract

The invention discloses a glass plate liquid level meter and a liquid level measuring method. The glass plate liquid level meter is provided with a front glass plate (1), a rear glass plate (2), a front gland (7), a rear gland (10), a front clamping frame (6) and a rear clamping frame (11), wherein the front gland is provided with a sight guiding hole (12), and the rear gland is provided with an observation hole (3). The front glass plate, the rear glass plate, the front clamping frame and the rear clamping frame enclose a measuring cavity (5), and the measuring cavity is trapezoidal in shape on a horizontal section plane. The intersection line of the front glass plate emergent surface (15) and the rear glass plate incident surface (16) with the horizontal section plane is two trapezoidal waists, and the intersection line of the front clamping frame inner surface (8) and the rear clamping frame inner surface (9) with the horizontal section plane is two trapezoidal bottom edges. The invention discloses a method for measuring liquid level by using the glass plate liquid level meter. The invention can be used for measuring the liquid level of colorless and colored transparent liquid in various industries such as petrochemical industry, metallurgy, electric power, food, medicine and the like.

Description

Glass plate liquid level meter and liquid level measuring method

Technical Field

The invention belongs to the technical field of liquid level measurement, and relates to a glass plate liquid level meter and a liquid level measurement method.

Background

In equipment in the petrochemical refinery plant area, a glass plate liquid level meter is required to display the liquid level, and a light-transmitting glass plate liquid level meter is the most commonly used one. When the medium to be detected is transparent liquid and light penetrates through the liquid column, the light is reflected, refracted or absorbed, and the light intensity penetrating through the liquid column is weaker than the light intensity penetrating through a gas phase above the liquid column; depending on the difference in light intensity across the liquid column and the gas phase, the operator can distinguish the liquid level. When the distance is slightly far away, or the light is dark in cloudy days and at night, the light intensity difference is not large, and the liquid level is difficult to judge. When the glass plate liquid level meter is used for a long time, the inner wall of the glass plate is dirty, the light transmission intensity is weakened, and the liquid level is not easy to distinguish. Sometimes, the operator even needs to close the foot valve in front of the glass plate liquid level meter to ensure that the liquid level can be seen clearly after the liquid level fluctuates obviously.

The improvement of the visual sensitivity of the glass plate liquid level meter is a solution, and a common method is to use red-green bicolor color difference to distinguish the liquid level; by utilizing the total reflection principle and the different refractive indexes of the liquid column and the gas phase medium above the liquid column relative to the glass, the liquid column and the gas phase respectively display the red and green colors of the glass optical filter in the background. But this method is only applicable to strong light backgrounds; when the background light is dark or weak, the red and green colors are not striking under the dark background, and the light intensity is reduced more by the absorption of the light filter. The observation effect is not good in cloudy days or at night.

The glass plate liquid level meter also adopts a special external light source to forcibly increase the background light intensity (especially a boiler water level meter), does not depend on natural light and factory lighting light, and thus has large volume. The rear part of the glass plate is added with an explosion-proof lamp and a shell of the lamp is arranged, so the manufacturing cost is higher. Explosion prevention needs to be considered for introducing 220V alternating current; and the cable pulling is also needed, so that the construction quantity is large. The service life of the explosion-proof lamp is limited, the lamp is always turned on for 24 hours all day, so that the failure rate is high, and the lamp is frequently required to be maintained; explosion-proof shells also present a potential safety hazard.

Disclosure of Invention

The invention aims to provide a glass plate liquid level meter and a liquid level measuring method, which are used for solving the problems that the liquid level of the existing glass plate liquid level meter is not easy to see clearly, a special external light source is required to be adopted and the like.

In order to solve the problems, the invention adopts the technical scheme that: the utility model provides a glass plate level gauge, be equipped with preceding glass plate, back glass plate, preceding gland, back gland, preceding clamping frame, back clamping frame, be equipped with the pilot hole on the preceding gland, be equipped with the inspection hole on the back gland, the pilot hole is relative with preceding glass plate incident surface, the inspection hole is relative with back glass plate ejection surface, preceding glass plate, back glass plate, preceding clamping frame encloses out with back clamping frame and measures the chamber, preceding glass plate is preceding glass plate ejection surface with the adjacent surface in measurement chamber, back glass plate is back glass plate incident surface with the adjacent surface in measurement chamber, preceding clamping frame is preceding clamping frame internal surface with the adjacent surface in measurement chamber, back clamping frame is back clamping frame internal surface with the adjacent surface in measurement chamber, its characterized in that: the measuring cavity is trapezoidal in shape on the horizontal cutting plane, the intersection line of the emergent surface of the front glass plate, the incident surface of the rear glass plate and the horizontal cutting plane is two trapezoidal waists, the intersection line of the inner surface of the front clamping frame, the inner surface of the rear clamping frame and the horizontal cutting plane is two trapezoidal bottom edges, and the length of the intersection line of the inner surface of the rear clamping frame and the horizontal cutting plane is larger than that of the intersection line of the inner surface of the front clamping frame and the horizontal cutting plane.

The method for measuring the liquid level by using the glass plate liquid level meter is characterized by comprising the following steps: light outside the glass plate liquid level meter is emitted to a front glass plate incidence surface through the guide hole, enters the front glass plate and passes through the front glass plate, then is emitted from a front glass plate emergence surface and enters the measurement cavity, the lower part of the measurement cavity is a liquid column, the upper part of the measurement cavity is a gas phase, the light forms a first path of light when entering the liquid column, a second path of light is formed when entering the gas phase, the first path of light passes through the liquid column, the second path of light passes through the gas phase above the liquid column, then the two paths of light respectively enter the rear glass plate from the rear glass plate incidence surface and pass through the rear glass plate, and then are emitted from different positions on the rear glass plate emergence surface, the first path of light passes through the observation hole, at an outlet of the observation hole, a human eye can observe a vertical light column formed by the first path of light facing the incoming light direction of the first path of light, cannot see the second path of light, and the liquid level of the liquid column in the measurement cavity is measured according to the vertical light column.

The invention has the following beneficial effects: 1. the vertical light column formed by the first path of light seen by human eyes is brighter, and a dark background is arranged above the vertical light column, so that the vertical light column is distinguished obviously. The level of the liquid column in the measuring chamber and thus in the process equipment can thus be easily measured. 2. The invention can use natural light and factory lighting light, does not need special additional explosion-proof light source, and is safe and energy-saving. 3. The glass plate liquid level meter is simple in structure and easy to manufacture. The required effects and functions are realized by means of light path calculation. 4. The invention uses natural light and factory lighting light without adding optical filter, and does not weaken the light, and keeps original light intensity to the maximum. 5. The invention has low requirement on the intensity of light. The higher the intensity, the clearer the resolution. When the light intensity is low, the liquid level is easy to identify because the light intensity difference between the vertical light column formed by the first path of light and the dark background above the vertical light column is obvious. 6. The glass plate liquid level meter can be designed into a symmetrical structure for bidirectional observation. 7. The glass plate level gauge of the present invention is not critical to manufacturing. The larger the width of the guide hole is, the stronger the fault tolerance of the guide angle is, and the use function of the glass plate liquid level meter is not influenced.

The invention can be used for measuring the liquid level of the transparent liquid in various industries such as petrochemical industry, metallurgy, electric power, food, medicine and the like. The transparent liquid may be a colorless and colored transparent liquid.

The present invention will be described in further detail with reference to the drawings, embodiments and examples. The drawings, detailed description and examples do not limit the scope of the invention as claimed.

Drawings

FIG. 1 is a cross-sectional view of a glass plate level gauge of the present invention through a measurement chamber in a vertical direction.

Fig. 2 is a cross-sectional view (partial) taken at T-T in fig. 1.

FIG. 3 is an optical schematic diagram of liquid level measurement using the glass plate level gauge of the present invention.

Fig. 4 is a partial schematic view of a vertical light column formed by a first ray of light and a dark background above the vertical light column viewed by human eyes.

In fig. 1 to 4, the same reference numerals denote the same technical features. The reference numerals denote: 1-front glass plate; 2-rear glass plate; 3-observation hole; 4-bolt and nut; 5-a measuring cavity; 6, a front clamping frame; 7-front gland; 8-inner surface of front clamping frame; 9-inner surface of rear clamping frame; 10-rear gland; 11-rear clamping frame; 12-a sight guiding hole; 13-front glass plate incident surface; 14-a gasket; 15-the emitting surface of the front glass plate; 16-rear glass plate incident surface; 17-the ejection face of the rear glass plate; 18-liquid column; 19-the first path of light; 20-the second path of light; 21-normal; 22-a vertical light column formed by the first light ray 19; 23 — a dark background above the vertical column 22 formed by the first ray 19.

A is the incident angle of light outside the glass plate liquid level meter to the front glass plate incident surface 13; b-angle of refraction of light entering the front glass sheet 1 from the front glass sheet entrance face 13; c is the included angle between the emergent surface 15 of the front glass plate and the incident surface 16 of the rear glass plate; d is the exit angle of the first light ray 19 from the exit surface 15 of the front glass plate into the liquid column 18 in the measuring chamber 5; e-the angle of incidence of the second path of light 20 from the gas phase above the liquid column 18 in the measurement cavity 5 onto the rear glass plate entrance face 16; f is the refraction angle of the second path of light 20 from the incident surface 16 of the rear glass plate to the rear glass plate 2; g-the difference in exit angle between the exit angle of the second path of light 20 from the rear glass plate exit surface 17 and the exit angle of the first path of light 19 from the rear glass plate exit surface 17; h is an included angle between the second path of light 20 and the emitting surface 15 of the front glass plate when entering the gas phase above the liquid column 18 in the measuring cavity 5 from the emitting surface 15 of the front glass plate; k is the viewing angle of the viewing aperture 12; p-optional one external incident ray calculation position; r-the observation position of the vertical light column 22 formed by the first light ray 19 at the outlet of the observation hole 3.

Detailed Description

Referring to fig. 1 and 2, the glass plate liquid level gauge of the present invention is provided with a front glass plate 1, a rear glass plate 2, a front gland 7, a rear gland 10, and a body provided with a front clamping frame 6 and a rear clamping frame 11. The front glass plate 1, the rear glass plate 2, the front gland 7, the rear gland 10, the front clamping frame 6 and the rear clamping frame 11 are all vertically arranged. The front gland 7 and the rear gland 10 are connected by bolt and nut 4. One vertical side sealing part of the front glass plate 1 is clamped between the front gland 7 and the front clamping frame 6, and the other vertical side sealing part of the front glass plate 1 is clamped between the front gland 7 and the rear clamping frame 11; one vertical side sealing part of the rear glass plate 2 is clamped between the rear gland 10 and the front clamping frame 6, and the other vertical side sealing part of the rear glass plate 2 is clamped between the rear gland 10 and the rear clamping frame 11; a sealing gasket 14 is provided at each clamping point.

The front gland 7 is provided with a sight guiding hole 12, and the rear gland 10 is provided with an observation hole 3. The viewing port 12 faces the front glass plate incident surface 13, and the observation port 3 faces the rear glass plate exit surface 17. The sight guiding hole 12 and the observation hole 3 are both vertical strip-shaped holes and are arranged in a plurality. The sight-guiding holes 12 are aligned in a row in the vertical direction, and the observation holes 3 are aligned in a row in the vertical direction. Each of the sight-guiding holes 12 and the sight holes 3 has two side faces, a top face and a bottom face; the side is vertical, and the top surface and the bottom surface are horizontal. Both side surfaces of the sight-guiding hole 12 are parallel to each other, and both side surfaces of the observation hole 3 are parallel to each other.

The front glass plate 1, the rear glass plate 2, the front clamping frame 6 and the rear clamping frame 11 enclose a measuring chamber 5. The surface of the front glass plate 1 adjacent to the measurement cavity 5 is a front glass plate emergent surface 15, the surface of the rear glass plate 2 adjacent to the measurement cavity 5 is a rear glass plate incident surface 16, the surface of the front clamping frame 6 adjacent to the measurement cavity 5 is a front clamping frame inner surface 8, and the surface of the rear clamping frame 11 adjacent to the measurement cavity 5 is a rear clamping frame inner surface 9. The front glass plate incident surface 13 and the front glass plate exit surface 15 are parallel to each other, and the rear glass plate incident surface 16 and the rear glass plate exit surface 17 are parallel to each other.

The measuring cavity 5 is in a sealed state, and the top and the bottom are communicated with process equipment (not shown) needing to measure liquid level through pipelines. The liquid in the process equipment enters the bottom of the measuring cavity 5 through a pipeline and rises until the liquid level in the measuring cavity 5 is the same as the liquid level in the process equipment.

According to the invention, the measuring chamber 5 is trapezoidal in shape in the horizontal section plane. The intersection lines of the front glass plate emergent surface 15 and the rear glass plate incident surface 16 with the horizontal cutting plane are two waists of a trapezoid, and the intersection lines of the front clamping frame inner surface 8 and the rear clamping frame inner surface 9 with the horizontal cutting plane are two bottom sides of the trapezoid (the intersection lines of the sealing gasket 14 and the measuring cavity 5, which are adjacent to each other, and the horizontal cutting plane are respectively counted into the two bottom sides of the trapezoid). The length of the intersection line of the inner surface 9 of the rear clamping frame and the horizontal cutting plane is larger than that of the intersection line of the inner surface 8 of the front clamping frame and the horizontal cutting plane.

According to a preferable scheme of the invention, the measuring cavity 5 is in an isosceles trapezoid shape on a horizontal section plane, and a vertical plane passing through the midpoints of two bottom edges is a symmetry plane of the glass plate liquid level meter. The space between the front glass plate 1 and the rear glass plate 2, the space between the front gland 7 and the rear gland 10, and the space between the guide hole 12 and the observation hole 3 are respectively symmetrical relative to the symmetry plane of the glass plate liquid level meter.

The angle C between the exit face 15 of the front glass plate and the entrance face 16 of the rear glass plate is generally 30 to 90. The angle between the side of the viewing guide 12 and the plane parallel to the inner surface 9 of the rear clamping frame is the viewing angle K of the viewing guide 12, which is generally 5 to 25 degrees, and the sign of "°" indicates a degree.

The optimal scheme of the invention is that the included angle C between the ejection surface 15 of the front glass plate and the incidence surface 16 of the rear glass plate, the included angle between the ejection surface 15 of the front glass plate and the inner surface 9 of the rear clamping frame and the included angle between the incidence surface 16 of the rear glass plate and the inner surface 9 of the rear clamping frame are all 60 degrees.

The width u of the sight hole 12 is generally 20 to 30 mm, the width v of the observation hole 3 is generally 20 to 30 mm, and the length of the intersection line of the inner surface 9 of the rear clamping frame and the horizontal cutting plane is generally 30 to 80 mm.

The thickness of the front glass plate 1 and the thickness of the rear glass plate 2 are both generally 15 to 30 mm, and are determined mainly by the pressure of the liquid column 18 and the gas phase in the measurement chamber 5. The thickness of the front glass pane 1 is measured between the front glass pane entry face 13 and the front glass pane exit face 15, and the thickness of the rear glass pane 2 is measured between the rear glass pane entry face 16 and the rear glass pane exit face 17.

The front clamping frame 6, the rear clamping frame 11, the front gland 7 and the rear gland 10 can be made of carbon steel or stainless steel and the like, and are determined according to the corrosivity of the liquid column 18 and the gas phase in the measuring cavity 5. The material of the gasket 14 is an elastic corrosion-resistant material.

Referring to fig. 3, 4 and 1 and 2, the method of level measurement using the glass plate level gauge of the present invention is: light rays outside the glass plate liquid level meter are emitted to the front glass plate incidence surface 13 through the guide hole 12, then enter the front glass plate 1 and pass through the front glass plate 1, and then are emitted from the front glass plate emission surface 15 and enter the measuring cavity 5. The lower part of the measuring chamber 5 is a liquid column 18 and the upper part is a gas phase. The light rays form a first path of light rays 19 (as shown by the thick solid lines in fig. 3) when entering the liquid column 18, and form a second path of light rays 20 (as shown by the two-dot chain lines in fig. 3) when entering the gas phase. The first path of light 19 is a main light and passes through the liquid column 18; the second ray 20 passes through the gas phase above the liquid column 18. The two light beams then enter the rear glass plate 2 from the rear glass plate incident surface 16, pass through the rear glass plate 2, and are emitted from different positions on the rear glass plate emitting surface 17. The first light ray 19 is located below the second light ray 20, the first light ray 19 is emitted through the observation hole 3, at an outlet (position R in fig. 3) of the observation hole 3, a vertical light column 22 formed by the first light ray 19 can be observed by human eyes facing the light incoming direction of the first light ray 19, the second light ray 20 cannot be observed, and the liquid level of the liquid column 18 in the measurement cavity 5 is measured according to the vertical light column 22.

The light outside the glass plate liquid level meter is natural light (generally sunlight in the daytime) and factory lighting light (lighting light at night). The liquid phase in the liquid column 18 is a transparent liquid. The transparent liquid may be colorless (e.g., water, methanol, or ethanol, etc.) or colored (e.g., gasoline, etc.). The gas phase above the liquid column 18 is air and/or gas that is volatilized from the liquid phase in the liquid column 18.

Referring to fig. 3, the light rays are refracted as they pass through the front glass plate entrance face 13, the front glass plate exit face 15, the rear glass plate entrance face 16, and the rear glass plate exit face 17. The letters indicating various angles such as an incident angle, an exit angle, and the like are referred to in the description of the figure. For various angles of incidence, angles of emergence, etc., the present invention is simply referred to as angles. The light rays pass through normal lines 21 at points on the front glass plate entrance face 13, the front glass plate exit face 15, the rear glass plate entrance face 16 and the rear glass plate exit face 17, and are indicated by dashed lines in fig. 3.

The width u and the viewing angle K of the viewing aperture 12, as well as the width v of the observation aperture 3 and the angle between its side and a plane parallel to the inner surface 9 of the rear clamping frame can be adjusted to ensure that the vertical light column 22 formed by the first light ray 19 can always be observed at the exit (position R) of the observation aperture 3. The position R corresponds to the lower part of the observation hole 3. The first light ray 19 and the second light ray 20 are both planar surfaces perpendicular to the horizontal plane, and the exit angle difference G described above is also an angle between the light surface of the first light ray 19 and the light surface of the second light ray 20, which are actually emitted from the exit surface 17 of the rear glass plate. The second light ray 20 is emitted from the rear glass plate emitting surface 17, and is generally projected onto one side surface of the observation hole 3, and is not emitted from the observation hole 3. When a small amount of the second light 20 is emitted from the observation hole 3, because of the existence of the angle G and the first light 19 is located below the second light 20, only the vertical light column 22 formed by the first light 19 can be seen when the position R is viewed in the light direction of the first light 19, and the second light 20 cannot be seen. The background of the observation hole 3 above the vertical light column 22 formed by the first light ray 19 is therefore dark, and the vertical light column 22 formed by the bright first light ray 19 is clearly contrasted with the dark background 23 and is easy to observe, see fig. 4. The top of the vertical column of light 22 is the level of the column of liquid 18.

The angles C and D can be adjusted. When the measuring chamber 5 is shaped as an isosceles trapezoid in a horizontal cross-sectional plane, and the angle D is in a fixed relationship with the angle C, i.e., "angle D =90 ° - (180 ° -angle C)/2 = angle C/2", the first ray 19 passes through the portion of the liquid column 18 in the measuring chamber 5 and is parallel to the rear clamping frame inner surface 9. At the moment, the space between the front glass plate 1 and the rear glass plate 2, the space between the front gland 7 and the rear gland 10, and the space between the guide hole 12 and the observation hole 3 of the glass plate liquid level meter are respectively symmetrical relative to the symmetry plane of the glass plate liquid level meter; the light path of the light rays which penetrate and pass through the front glass plate 1 and the light path of the first light ray 19 which penetrates through the rear glass plate 2 and is emitted from the emitting surface 17 of the rear glass plate are symmetrical relative to the symmetry plane of the glass plate liquid level meter, the first light ray 19 penetrates through the liquid column 18, two parts positioned on two sides of the symmetry plane of the glass plate liquid level meter are symmetrical relative to the symmetry plane of the glass plate liquid level meter, and the numerical value of the emitting angle of the first light ray 19 emitted from the emitting surface 17 of the rear glass plate is the same as the value of the angle A. According to the principle of reversible light path, the sight guiding hole 12 and the observation hole 3 can be used interchangeably, namely the sight guiding hole 12 is used as the observation hole 3, and the observation hole 3 is used as the sight guiding hole 12; thus, when observation at one location is inconvenient, observation at another location is possible. Under the above conditions, the correspondence between the angle C, the guide angle K, and the exit angle difference G can be calculated, see table 1. Other calculation conditions for the data in table 1 are: the liquid column 18 at the lower part of the measuring cavity 5 is a water column, the measuring cavity 5 above the liquid column 18 is filled with air, and the front glass plate 1 and the rear glass plate 2 are made of quartz glass. The data in table 1 can be calculated by reference to the method described in the examples of the present invention.

As can be seen from Table 1, the larger the angle C, the larger the angle G. As angle C decreases, angle G decreases. When the angle C is 0 °, the visual effect of the conventional transparent glass plate level gauge appears, which is not required in the present invention.

In the case where the light outside the glass plate level gauge is white light, it is composed of a plurality of colored lights of different wavelengths. The glass plate, the liquid column, and the like have different refractive indexes for light of different wavelengths, and the emission positions of light of different wavelengths are different. When light passes through the liquid column 18 at the lower part of the measuring chamber 5, the white light will be dispersed if there is a colorless transparent liquid medium in the liquid column 18. The vertical column of light 22 formed by the first ray 19 observed at the exit of the inspection hole 3 will have an iridescent edge, which is red, orange, yellow, green, bluish purple. Human eyes are very sensitive to rainbow color light, and the rainbow color light is extremely striking and easy to observe and distinguish from a long distance because the original light intensity is kept to the maximum extent without using a filter and compared with a dark background 23. The more transparent the liquid column 18, the larger the angle C, and the more pronounced the rainbow effect. When the medium of the liquid column 18 is a colored transparent liquid, the vertical light column 22 will not form the iridescent edges described above. The vertical light column 22 formed by the first light ray 19 is still bright and clearly distinguished from the dark background 23 above the vertical light column, and is still easy to observe.

The angle of view K and the difference G of the angle of departure can be calculated according to the refractive index of the gas phase in the measurement chamber 5, the refractive index of the liquid medium in the liquid column 18, the refractive indices of the glass materials in the front glass plate 1 and the rear glass plate 2, the refractive index of air and the selected angle C, so as to achieve the best effect of distinguishing the liquid level. The angle C is preferably chosen to be 60 deg., in which case the dispersion effect is good, as well as other effects (e.g. symmetry of the glass plate level gauge).

Examples

The glass plate level gauge of the present invention was used for liquid level measurement, see fig. 1 to 4. The measurement is carried out in daytime, and the light outside the glass plate liquid level meter is natural light. The liquid column 18 at the lower part of the measuring cavity 5 is a water column, and the refractive index of the water is 1.333; the measurement cavity 5 above the liquid column 18 is filled with air, and the refractive index of the air is 1.00029. The refractive indices mentioned in the present invention are all relative to the refractive index of vacuum. The front glass plate 1 and the rear glass plate 2 are made of quartz glass and have a refractive index of 1.55. The measuring cavity 5 is in an isosceles trapezoid shape on a horizontal section plane, and is respectively symmetrical relative to the symmetry plane of the glass plate liquid level meter between the front glass plate 1 and the rear glass plate 2, between the front gland 7 and the rear gland 10, and between the guide hole 12 and the observation hole 3. The included angle C between the ejection surface 15 of the front glass plate and the incident surface 16 of the rear glass plate, the included angle between the ejection surface 15 of the front glass plate and the inner surface 9 of the rear clamping frame and the included angle between the incident surface 16 of the rear glass plate and the inner surface 9 of the rear clamping frame are all 60 degrees.

SinA/SinB =1.55/1.00029, sind/SinB =1.55/1.333. The angle D is angle C/2 and the first ray 19 passes through the portion of the liquid column 18 in the measurement chamber 5 parallel to the rear holder inner surface 9. The light path of the light rays which penetrate and pass through the front glass plate 1 and the light path of the first light ray 19 which penetrates through the rear glass plate 2 and is emitted from the emitting surface 17 of the rear glass plate are symmetrical relative to the symmetry plane of the glass plate liquid level meter, and the first light ray 19 penetrates through the liquid column 18 and is symmetrical relative to the symmetry plane of the glass plate liquid level meter at two parts on two sides of the symmetry plane of the glass plate liquid level meter. In this case, the first light ray 19 is emitted from the rear glass plate emission surface 17 at an emission angle equal in value to the angle a.

The exit angle of the second path of light 20 entering the gas phase in the measuring cavity 5 from the exit surface 15 of the front glass plate is equal to the angle A, and the included angle H =90 ° -angle A. Angle E =90 ° - (180 ° -angle C-angle H), sinE/SinF =1.55/1.00029. The second path of light 20 emerges from the rear glass plate exit surface 17 at an exit angle that is the same value as angle E.

When the angle C is 60 ° and the angle D is 30 °, the angle a =41.8 ° and the angle E =18.2 ° are calculated by the above method. The difference in the angles of emergence G = angle a-angle E =23.6 °. An incident ray emanating from position P passes through the sight guiding aperture 12 at an angle K = angle a-angle D = angle a-angle C/2=11.8 °.

As can be seen from the above calculation and by referring to fig. 3, after the external natural light in the same vertical direction enters the viewing port 12 and passes through the front glass plate 1, the liquid column 18 and the gas phase in the measurement cavity 5, and the rear glass plate 2, the included angle G (i.e., the exit angle difference G) between the light surface of the first path of light 19 emitted from the exit surface 17 of the rear glass plate and the light surface of the second path of light 20 is relatively large, and the second path of light 20 is greatly deflected with respect to the first path of light 19. At the position R, the vertical light beam 22 formed by the first light ray 19 can be clearly observed, and the second light ray 20 cannot be observed, and a dark background 23 is above the vertical light beam 22.

TABLE 1

Angle C, unit: degree (degree)	Angle K, unit: degree (C)	Angle G, unit: degree (C)
			0	0	0
10.0	1.7	3.3
			20.0	3.4	6.8
30.0	5.2	10.4
			40.0	7.1	14.2
50.0	9.3	18.6
			60.0	11.8	23.6
70.0	14.9	29.7
			80.0	18.9	37.9
90.0	25.4	50.9
			97.2	39.8	79.6

Claims (10)

1. The utility model provides a glass board level gauge, be equipped with preceding glass board (1), back glass board (2), preceding gland (7), back gland (10), preceding clamping frame (6), back clamping frame (11), be equipped with on preceding gland (7) and lead sight hole (12), be equipped with observation hole (3) on back gland (10), it is relative with preceding glass board incident surface (13) to lead sight hole (12), observation hole (3) are relative with back glass board emergent surface (17), preceding glass board (1), back glass board (2), preceding clamping frame (6) and back clamping frame (11) enclose and measure chamber (5), preceding glass board (1) is preceding glass board emergent surface (15) with the adjacent surface in measurement chamber (5), back glass board (2) are back glass board incident surface (16) with the adjacent surface in measurement chamber (5), preceding clamping frame (6) are preceding clamping frame internal surface (8) with the adjacent surface in measurement chamber (5), back clamping frame (11) are its characterized in that internal surface (9) are pressed from both sides after with the adjacent in measurement chamber (5), its characterized in that: the shape of the measuring cavity (5) on the horizontal cutting plane is trapezoidal, the intersection line of the emergent surface (15) of the front glass plate and the incident surface (16) of the rear glass plate with the horizontal cutting plane is two waists of the trapezoid, the intersection line of the inner surface (8) of the front clamping frame and the inner surface (9) of the rear clamping frame with the horizontal cutting plane is two bottom sides of the trapezoid, and the length of the intersection line of the inner surface (9) of the rear clamping frame with the horizontal cutting plane is larger than that of the intersection line of the inner surface (8) of the front clamping frame with the horizontal cutting plane.

2. The glass sheet level gauge of claim 1, wherein: the measuring cavity (5) is in an isosceles trapezoid shape on a horizontal section plane, a vertical plane passing through the middle points of two bottom edges is a symmetry plane of the glass plate liquid level meter, and the symmetry plane is respectively symmetrical relative to the symmetry plane of the glass plate liquid level meter between the front glass plate (1) and the rear glass plate (2), between the front gland (7) and the rear gland (10), and between the guide hole (12) and the observation hole (3).

3. The glass sheet level gauge of claim 2, wherein: the sight guide hole (12) and the observation hole (3) are used interchangeably.

4. Glass sheet level gauge according to claim 2 or 3, characterized in that: the included angle C between the emergent surface (15) of the front glass plate and the incident surface (16) of the rear glass plate is 30-90 degrees.

5. The glass sheet level gauge of claim 4, wherein: an included angle C between the ejection surface (15) of the front glass plate and the incidence surface (16) of the rear glass plate, an included angle between the ejection surface (15) of the front glass plate and the inner surface (9) of the rear clamping frame, and an included angle between the incidence surface (16) of the rear glass plate and the inner surface (9) of the rear clamping frame are all 60 degrees.

6. Glass sheet level gauge according to claim 1 or 2, characterized in that: the width u of the sight guiding hole (12) is 20-30 mm, the width v of the observation hole (3) is 20-30 mm, and the length of the intersection line of the inner surface (9) of the rear clamping frame and the horizontal sectioning surface is 30-80 mm.

7. Glass sheet level gauge according to any of claims 1 to 6, the front glass sheet (1) and the rear glass sheet (2) being made of quartz glass, characterized in that: the thickness of the front glass plate (1) and the thickness of the back glass plate (2) are both 15-30 mm.

8. A method of level measurement using the glass sheet level gauge of claim 1, wherein: the external light of glass plate level gauge shoots at preceding glass plate incident surface (13) through guide hole (12), reentrant preceding glass plate (1) and pass through preceding glass plate (1), later shoot out from preceding glass plate emergent surface (15), get into measurement chamber (5), the lower part of measurement chamber (5) is liquid column (18), the upper portion is the gaseous phase, light forms first way light (19) when getting into liquid column (18), form second way light (20) when getting into the gaseous phase, first way light (19) are through liquid column (18), second way light (20) are through the gaseous phase of liquid column (18) top, later two way light respectively get into back glass plate (2) and pass through back glass plate (2) from back glass plate incident surface (16), shoot out from the different positions on back glass plate emergent surface (17), first way light (19) are shot out through observation hole (3), the light at observation hole (3), people's eye sees the light of first way light (19) in the incoming direction and sees the light column (19) and form, the vertical light column (22) of measuring in the liquid column (18), measure according to the liquid column (22) in the light column (18), the vertical light (22) of two ways light (22).

9. The method of claim 8, wherein: the exit angle D of the first path of light (19) entering the liquid column (18) from the exit surface (15) of the front glass plate is equal to half of the included angle C between the exit surface (15) of the front glass plate and the entrance surface (16) of the rear glass plate, and the part of the first path of light (19) passing through the liquid column (18) in the measuring cavity (5) is parallel to the inner surface (9) of the rear clamping frame.

10. The method according to claim 8 or 9, characterized in that: and calculating the angle of refraction K and the angle difference G of emergence according to the refractive index of the gas phase in the measuring cavity (5), the refractive index of the liquid phase medium in the liquid column (18), the refractive index of the glass material in the front glass plate (1) and the rear glass plate (2), the refractive index of air and the selected angle C.

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