JPS5942810B2 - Liquid level indicator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid level gauge that can measure the height of a liquid level in a container, particularly in a vacuum.

Conventionally, there has been a differential pressure gauge type liquid level gauge shown in FIG. 1 as a liquid level gauge.

In the figure, 1 is a differential pressure gauge, which measures the liquid level in a container 7 (hereinafter referred to as tank). The diaphragm 1-1 is displaced due to the pressure difference between the left diaphragm chamber 1-2 and the right diaphragm chamber 1-3, which changes in accordance with the height of the liquid level of the liquid 6 to be treated.
the displacement is guided to the extraction detection part 1-5 by the lever 1-4,
The detection unit 1-5 detects the signal using electrical, pneumatic, etc. methods and outputs it as an analog value. Reference numeral 2 denotes a diaphragm partition provided in the tank 7 to prevent the liquid from directly entering the chamber 1-2 and becoming contaminated and causing functional deterioration when the liquid 6 is not clear. A liquid 3-1 such as silicone oil is sealed inside the partition wall 2 and led to the left diaphragm chamber 1-2 through a pipe 3.

The pressure at the bottom of the tank 7 is based on the height of the liquid column of the liquid 6 in the tank T, and the pressure received by the diaphragm partition 2 is transferred to the diaphragm 1-1 via the liquid 3-1 in the pipe 3. The signal is transmitted and becomes the output of the differential pressure gauge 1. When the tank is sealed as shown in the figure and there is a possibility that the pressure inside the tank 7 may fluctuate, the internal pressure is led from the upper space of the tank 7 to the right diaphragm chamber 1-3 of the differential pressure gauge 1 and the liquid column is Only pressure is taken out from the differential pressure gauge 1. In this case as well, to prevent foreign matter from entering the right diaphragm chamber 1-3 and causing a decline in the function of the differential pressure gauge, a diaphragm partition wall 4 is provided as in the case of liquid pressure detection at the bottom of the tank T described above, and silicone oil etc. liquid 5-1 is enclosed,
The pipe 5 leads to the diaphragm chamber 1-3.Even when the pressure inside the tank 7 fluctuates, the diaphragm 1-1 displaces in accordance with the height of the liquid level, so the differential pressure gauge 1 shows the height of the liquid level. An analog value output corresponding to the height is obtained and the height of the liquid level is measured. When the cal tank 7 is in a vacuum state, the pressure sealed inside the diaphragm partitions 2 and 4, that is, the space between the diaphragm partition 2 and the diaphragm 1-1, and the space between the diaphragm partition 4 and the diaphragm 1-1, respectively. Since the transmission liquid 3-15-1 is exposed to a low pressure state, the gas contained in the liquid foams and becomes bubbles, so that the diaphragm partition wall 2
, the pressure on the four surfaces is no longer properly transmitted to the diaphragm chambers 1-2, 1-3, and the measured values begin to include errors.

The pipes 3, 5, diaphragm chamber 1-2,
Although it is possible to some extent to enclose it within 1-3, etc.
It is technically difficult to achieve perfection, and the condition may gradually deteriorate over time, so it is impossible to eradicate the trouble of not being able to use it under vacuum as described above. This invention was made to eliminate these conventional drawbacks, and it provides a liquid level gauge that can measure accurately even under vacuum by constantly applying a pressure higher than a predetermined level to the liquid for pressure transmission. The purpose is to provide.

An embodiment of the present invention shown in FIG. 2 will be described below.

In FIG. 2, the difference from FIG. 1 is that a diaphragm partition 4 for introducing pressure into the tank 7 is arranged near the diaphragm partition 2 which is disposed several tens of cIn below the bottom surface of the tank 7, and the diaphragm partition 4 A small container 11 is provided above the container 11 so that a high-boiling point component liquid 13 such as silicone oil can be placed at a height of several tens of centimeters. Case 2- of container 11 and diaphragm partition 2
The diaphragm partition walls 2 and 4 are mounted as close as possible or in close contact with each other and then covered with a heat insulating material 14, so that the diaphragm partition walls 2 and 4 are kept at the same temperature. Next, the operation will be explained.

A constant pressure is applied to the diaphragm partition 4 by the liquid 13 located at the upper part of the diaphragm partition 4 arranged in the small container 11 . This pressure is approximately the height of the liquid column (m) x specific gravity/
It becomes 10. For this reason, even if the upper part of the tank 7 becomes a vacuum state and the pressure reaches such a level that bubbles are generated in the liquid inside the pipe 5, the pressure from the liquid 13 above the diaphragm partition wall 4 is added to the diaphragm partition wall 4. Therefore, the pressure transmitting liquid under the pipe 5 and the diaphragm partition wall 4 does not foam. The liquid 3-1 sealed inside the diaphragm partition wall 2, that is, in the space between the diaphragm partition wall 2 and the diaphragm 1-1, has the diaphragm partition wall 2 installed lower than the bottom of the tank 7, so that a constant amount of the liquid to be measured is always 6. Besides, l
Due to this presence, a constant pressure is applied to the surface of the diaphragm partition wall 2, and the liquid 3-1 does not foam inside the pipe 3 or the like.

Therefore, the diaphragm 1-1 is under vacuum (even if the liquid 6 is
It is displaced according to the height of the liquid level, and the height of the liquid level can be measured accurately. The height of the liquid 13 above the diaphragm partition wall 4,
The distance from the bottom of the tank 7 to which the tie ram bulkhead 2 is attached is determined from the following relationship.

Assuming that the pressure a (?/d) at which bubbles begin to be generated from the liquids 3-1 and 5-1 in the pipe 35 is the lowest pressure b (Kfl/CTl) that the space above the tank 7 reaches, then the pressure at the top of the diaphragm is This is the height of the liquid column.

As described above (according to the present invention), the diaphragm partition wall is configured so that a pressure higher than a predetermined level is always applied to the diaphragm partition, so the pressure-transmitting liquid does not bubble even under a vacuum, and the liquid level height can be accurately determined even under a vacuum. Can be measured well.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional liquid level gauge, and FIG. 2 is a block diagram showing an embodiment of the present invention. (Here, 1... Differential pressure gauge, 2, 4... Diaphragm partition, 3, 5, 12... Pipe, 3-1, 5-1
．． ．． ．． Liquid for pressure transmission, 11... Small container, 13.
...Liquid, 14...Insulating material.

Claims (1)

[Scope of Claims] 1. A device for guiding the pressures in the lower and upper spaces of the liquid container to a differential pressure gauge through a diaphragm partition and the liquid, respectively, and measuring the height of the liquid level in the liquid container from the above pressure, A liquid level gauge characterized in that a means is provided to always apply a predetermined pressure or more to a diaphragm partition that transmits pressure in the upper space. 2. The liquid level gauge according to claim 1, wherein a certain amount of high boiling point liquid is held in the upper part of the diaphragm partition as means for applying the pressure.