JPH04166724A - Buoyancy-type liquid level gage of liquid tank - Google Patents

Abstract

PURPOSE:To display the liquid level in the storage tank by providing a float in the liquid tank, and providing an electric scale which detects the weight of the float and detects the change in buoyancy for the volume of the submerged float caused by the change in height of the liquid surface as the weight. CONSTITUTION:A columnar float 1 is so provided in detecting liquid that the upper end is extruding from the highest liquid surface. Guide tools 3 are so provided at a bottom surface 2 of a tank that the float is not abnormally moved by waving and the like of the liquid as required. A weight 4 is so put in the float 1 that the attitude is stable and the center of gravity is located at the lower side when buoyancy acts. Thus, the weight of the float 1 is so set that the adequate gravity is obtained even at the time of the highest liquid surface. An electric scale 5 for detecting the weight is provided at the upper part of the float and connected to the float 1 through a metal fitting 6. Thus, the liquid level in the tank can be accurately measured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a liquid level gauge for detecting the liquid level in a liquid storage tank.

A liquid level gauge is indispensable for liquid storage tanks.
They are widely used in everything from relatively small tanks such as household water tanks and kerosene fuel tanks to large tanks at chemical factories and oil terminals.

There are also a wide variety of types, including glass tube type, differential pressure type, capacitance type, radiation type, ultrasonic type, and buoyancy type. The present invention is related to the buoyant surface type, and aims to provide a product with higher precision and reliability at a lower cost.

The upper end is made to protrude above the liquid level, and the amount of displacement of the float due to changes in the buoyant force acting on the float due to changes in the immersed volume of the float due to changes in the height of the liquid is converted into a small amount of displacement by a spring called a torque tube. The torque tube method detects the liquid level using the torque tube method, and the force balance method detects the liquid level by suspending a float from the tip of the force rod of a pneumatic differential pressure transmitter and balancing the force generated in the feedback bellows via a fulcrum diaphragm. A buoyant liquid surface type, such as the formula, is used.

These conventional buoyancy type liquid level type torque tube type detectors are mechanical mechanisms, so they must be installed with great care. Therefore, there are problems such as the installation position of the indicator part is limited, the scale part of the indicator cannot be divided very tightly, and therefore the liquid level cannot be read very precisely. Although the force balance type can achieve relatively high detection accuracy, it requires a relatively expensive detection device called a differential pressure transmitter, which poses problems in terms of initial cost, and since it is a precision device, it requires maintenance and installation. There were problems such as the above precautions.

Means, Embodiments, and Operations for Solving the Problems The present invention seeks to improve these problems of the prior art.

be.

The present invention will be explained based on the drawings. First, a columnar float (1) having an equal cross-sectional area is placed in a detection liquid so that one upper end thereof protrudes above the highest liquid level. In order to detect the weight, the float is installed so that it does not touch the bottom of the storage tank (2), and the guide tool (3) is placed on the bottom of the storage tank (3) as necessary to prevent the float from moving abnormally due to undulation of the liquid. 2) Attach.

The float (1) has a weight (4
), and it is best to use one that is selected with cross-sectional area and weight in mind so that an appropriate amount of gravity remains even when the maximum buoyancy is applied at the highest liquid level.

A fitting A (6) is provided on the top of the float to connect an electric scale (5) for weight detection. ).

A hanging electric scale is used, and its type and model number are determined by taking into account the atmosphere of the installation location depending on the properties of the liquid to be detected, the required accuracy of liquid level detection, etc.
In order to detect in 5 mm increments at a maximum liquid level of 5 m, an overall accuracy of about 1/1000 is required, but with the current technology, it is impossible to do this with an electric scale. too,
This is an accuracy that is relatively easy to achieve.

The detection electric scale (5) is attached to the nozzle (8) attached to the roof (7) above the storage tank using a metal fitting B (9).

If the atmosphere inside the storage tank is not suitable for installing an electric detection scale (5), use a fully enclosed electric scale or install a sensor between the inside of the storage tank and the detection chamber (10). It is also possible to install a partition wall bellows (11) or the like for blocking the atmosphere to block the atmosphere inside the storage tank and install the detection electric scale (5). In this case, it is possible to accurately detect the liquid level by taking into account the spring constant of the bellows and correcting it by adjusting the span of the internal electric circuit of the indicator (12), which will be described later. It is.

The electric signal detected and taken out by the electric scale is connected to an indicator (12) installed at a necessary location using a cable (13), if necessary, and converted to liquid level and displayed on the indicator. be done. Also, since the liquid level position is taken out as an electrical signal of weight, it can be output externally from the indicator and given remotely.
It is also relatively easy to enter information into a computer.

Since buoyant liquid level gauges use buoyancy to measure the liquid level, the amount of buoyant force that acts per unit volume of the float changes depending on the specific weight of the liquid being measured, so correction is necessary. With electric scales, this can be easily corrected by adjusting the span.

Furthermore, even if it is necessary to correct changes in specific gravity due to temperature changes, a temperature detection end (14) is used to detect the temperature of the liquid.
can be installed in the storage tank by detecting the temperature, capturing it as an electrical signal, and using an indicator with arithmetic functions.
Calculation correction and instructions can be given.

Effects of the Invention By using the device of the present invention, the following effects are expected.

l. Since there are no moving parts, there is no deterioration due to wear etc.

2. It has a very simple structure of simply hanging the detection float on an electric scale, and is easy to install.

3. Simple structure, less failure and easy maintenance.

4. Since it is an electric type, it can be used simply by connecting it with a cable, so there are no restrictions on where the indicator can be installed.

5. Most adjustments can be made on the indicator side, and there is no need to perform 7N adjustment in places with poor work environments such as inside the storage tank or on the roof of the storage tank. 6. Since it is an electric type, external output can be easily made.

7. High precision.

8. It is inexpensive.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional structural diagram showing the present device, and FIG. 2 is a structural cross-sectional diagram of a detection chamber provided with a partition wall bellows.

Claims (1)

[Claims] In order to detect the height of the liquid level in the liquid storage tank, a float for detecting the height of the stored liquid level in the storage tank is installed in the liquid level gauge attached to the storage tank. An electric scale is installed to detect the change in buoyancy due to the immersion volume of the float due to a change in surface height as a change in weight, and the change in weight is extracted as an electric signal, and the electric signal is used to determine the liquid level inside the storage tank. A buoyant liquid level gauge for a liquid storage tank, characterized by being equipped with an indicator that displays