JPH10300555A - Tubeless throwing pressure-type liquid level gage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure a liquid level precisely without being affected by atmospheric pressure, by a method wherein a pressure sensing part which senses a liquid pressure and a pressure sensing part which senses only atmospheric pressure are installed separately, and electric signals of both sensing parts are computed. SOLUTION: A pressure which is applied to a liquid-pressure sensing part 1 is a pressure in which a head pressure and atmospheric pressure are added. A pressure which is applied to an atmospheric-pressure sensing part 2 in only atmospheric pressure. From both pressure sensing parts, electric signals according to their pressures are sent to an electric-signal computing device 3 by a signal cable. When the value of the latter is subtracted from that of the former, a head pressure can be computed by the electric-signal computing device 3. In addition, when the head pressure is divided by the density of a liquid, a liquid level can be computed. By making use of this action, the liquid level can be measured without being affected by atmospheric pressure even when an air tube is not installed between the liquid-pressure sensing part 1 and the air. In addition, since an air tube is not contained in the signal cable from the liquid-pressure sensing part 1, the signal cable can be manufactured easily, and it can be executed easily when a liquid level gage is installed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring a liquid level in service water, clean water, sewage, a chemical plant facility or the like without causing an error due to a change in atmospheric pressure.

[0002]

2. Description of the Related Art For example, when it is desired to know the water level of a water tank, there is a proportional relationship between the water level and the water pressure at the bottom of the water tank. Therefore, the water level can be known by measuring the water pressure at the bottom. However, at this time, since the atmospheric pressure is added to the measured water pressure, if the atmospheric pressure changes, the correct water level cannot be known.

[0003] In order to know the correct water level even when the atmospheric pressure changes, the atmospheric pressure is introduced to the back of the pressure sensing unit by an air pipe, and only the water pressure to which the atmospheric pressure is not added is applied to the pressure sensing unit. .

[0004]

In order to introduce atmospheric pressure, an air pipe must be laid to the pressure sensor. Air pipes are difficult to connect, and must be constructed so that the pipes do not block and water and dust do not enter.
Furthermore, a cable combining an electric signal line and an air tube is a special product, so that it is expensive.

The present invention has been made in view of the above points, and has as its object to provide a liquid level measuring apparatus which is not affected by changes in the atmospheric pressure and does not require an air pipe.

[0006]

SUMMARY OF THE INVENTION The gist of the present invention is to provide a pressure sensor for sensing the pressure in the liquid and a pressure sensor for sensing only the atmospheric pressure. Is to measure the correct liquid level which is not affected by the atmospheric pressure.

Next, the operation of the present invention will be described. The pressure exerted on the liquid in a pressure sensing unit (1) in FIG. 1 are those obtained by adding the head pressure P and atmospheric pressure P _o. Pressure applied to the atmospheric pressure sensing unit (2) is only atmospheric pressure P _o. From the pressure sensing unit, an electric signal corresponding to each pressure is sent to the electric signal calculation device (3) by a signal cable. The head pressure can be calculated by subtracting the latter value from the former value with the electric signal operation device (3). Further, the liquid level can be calculated by dividing the head pressure by the liquid density.

By utilizing this function, the liquid level can be measured without being affected by fluctuations in the atmospheric pressure without installing an air pipe between the submerged pressure sensing unit and the atmosphere.

[0008]

Since the present invention has the above-described configuration and operation, the signal cable from the submerged pressure sensing unit does not include an air tube, so that the signal cable can be easily manufactured and installed. It is.

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[Procedure amendment]

[Submission date] July 15, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of the drawing

[Correction method] Added

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of the entire apparatus.

[Description of Signs] 1 Underwater pressure sensor 2 Atmospheric pressure sensor 3 Electric signal operation device

Claims (1)

[Claims] 1. An apparatus for measuring a liquid level in a liquid level measurement, wherein the pressure in the liquid and the atmospheric pressure are taken out as electric signals by separate pressure sensing units, and the difference between the two is calculated by an electric signal operation device.