JPS60220823A - Liquid level transmitter - Google Patents

Abstract

PURPOSE:To measure the level of fluid to be measured accurately by providing a temperature detecting element which detects the temperature of the objective fluid and an arithmetic unit which calculating the extent of variation in the volume of the objective fluid with temperature and corrects a pressure detected value. CONSTITUTION:When the pressure P1 of the objective fluid 2 and the internal pressure P2 in a tank 3 are applied, the pressure sensor of a detector body 9 is displaced according to the pressure difference between P1 and P2 and the extent of this displacement is led out electrically as the pressure detected value of the objective fluid 2. At this time, the arithmetic unit 17 calculates the extent of variation in the volume of the objective fluid 2 with temperature and corrects the pressure detected value. This electric signal is amplified by an amplifier and displayed as the liquid level of the objective fluid 2. The arithmetic unit 17 calculates the variation in volume with the temperature of the objective fluid 2, i.e. with specific gravity corresponding to each temperature and corrects the pressure detected value of the objective fluid 2 which is detected by the detector body 9. Consequently, the liquid level is measured accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a liquid level transmitter equipped with a pressure extraction flange.

[Prior art]

Conventionally, this type of liquid level transmitter has a pressure sensor and is installed in a container such as a tank or a vessel via a mounting flange. Then, assuming that the specific gravity of the fluid to be measured remains unchanged, the pressure of the fluid to be measured in the container P1 and the internal pressure of the container P
! The liquid level is measured by electrically extracting the differential pressure amount.

For this reason, the conventional liquid level transmitter has the disadvantage that when a temperature change occurs in the fluid to be measured, its specific gravity changes and accurate liquid level measurement cannot be performed.

[Summary of the invention]

The present invention was made in view of the above circumstances, and includes a temperature detection element that detects the temperature of the fluid to be measured, and an arithmetic device that calculates the amount of volume change due to temperature change of the fluid to be measured and corrects the detected pressure value. With the extremely simple configuration of preparing
The present invention provides a liquid level transmitter that can prevent measurement errors caused by temperature changes. Hereinafter, the configuration and the like will be explained in detail with reference to embodiments shown in the drawings.

〔Example〕

The figure is a sectional view showing a liquid level transmitter according to the present invention. In the figure, the reference numeral 1 indicates a pressure extraction flange for a liquid level transmitter, which is fixed to a transmitter mounting flange 4 of a tank 3 containing a fluid to be measured 2 with a through bolt 6 via a gasket 5. has been done. This pressure release larange l
A barrier diaphragm 7 facing the fluid to be measured 2 is provided at the open end of the barrier diaphragm 7, and an inner chamber 8 of the barrier diaphragm 7 is connected to one inner chamber of a detector body 9 having a pressure sensor (not shown) therein. It communicates with a chamber (not shown) via a capillary tube 10.

The detector body 9 is located in the other inner chamber (not shown).
The fluid pressure to be measured in the tank 3 transmitted through the pressure transmission fluid 11 such as silicone is detected based on the ratio of the internal pressure of the tank 3 introduced into the tank 3, and an electrical signal is output in accordance with this detected pressure. It is configured. Reference numeral 12 denotes a temperature detection element such as a thermocouple or thermistor for detecting the temperature of the fluid 2 to be measured, and is connected to a terminal 16 of a transmissor housed in a housing 15 by a lead wire 14 inserted through an armored tube 13. There is. Note that this transmitter has a function of receiving the output signal of the temperature detection element 12. Reference numeral 17 denotes a calculation device connected to the terminal 16 and the detector body 9, which stores information representing a specific gravity value corresponding to the temperature of the fluid 2 to be measured.
It is stored inside. Then, this calculation device 17 calculates the amount of volume change due to the temperature change of the fluid 2 to be measured, that is, the change in the specific gravity value corresponding to each temperature, and calculates the amount of volume change due to the change in the specific gravity value corresponding to each temperature, and
The pressure detection value of the fluid to be measured 2 detected by the pressure detection value can be corrected.

Therefore, by applying the pressure P1 of the fluid 2 to be measured and the internal pressure P of the tank 3, the pressure sensor of the detector body 9 is displaced according to the differential pressure (P+Pg) between the pressures P+ and Pg, and the amount of this displacement is is electrically extracted as a pressure detection value of the fluid 2 to be measured. At this time, the volume change amount due to the temperature change of the fluid 2 to be measured is calculated by the calculation bag W17, and the pressure detection value is corrected. After this electrical signal is amplified by an amplifier (not shown), it is displayed on a meter (not shown) as the liquid level height of the fluid 2 to be measured.

In this embodiment, an example is shown in which the arithmetic unit 17 stores information representing the specific gravity value corresponding to the temperature of one type of fluid 2 to be measured. Of course, information representing each specific gravity value corresponding to the temperature of the fluid to be measured can be stored.

〔Effect of the invention〕

As explained above, according to the present invention, the present invention includes a temperature detection element that detects the temperature of the fluid to be measured, and an arithmetic device that calculates the volume change amount due to the temperature change of the fluid to be measured and corrects the detected pressure value. , the liquid level can be measured accurately. Furthermore, the structure is extremely simple, making it easy to handle on site.

[Brief explanation of the drawing]

The figure is a sectional view showing a liquid level transmitter according to the present invention. DESCRIPTION OF SYMBOLS 1... Pressure extraction flange, 2... Fluid to be measured, 7... Barrier diaphragm, 9... Detector body, 12... Temperature detection element, 17... Computing device. Patent Applicant: Yamatake Honeywell Co., Ltd. Agent Masaki Yamakawa (2 persons) Procedural Amendment (Saba) Date: June 4, 1989 Mr. Commissioner of the Japan Patent Office 1. Indication of the Case 1980 Patent Application No. 76617 2. Name of the invention Liquid level transmitter 3. Relationship with the case of the person making the amendment Patent Applicant name (name) (666) Yamatake Honeywell Co., Ltd. 5.
The figure 1 on page 2, lines 19 to 20 of the ill specification that is subject to correction is...
FIG. ' shall be corrected as follows. ``Figure 1 is a sectional view showing a liquid level transmitter according to the present invention, and Figure 2 is a diagram for explaining an example of calculation for liquid level measurement performed using the same liquid level transmitter.'' ( 2) Same book, page 4, lines 17-20
It is displayed in the [and...] line. " Next, an example of calculation for liquid level measurement will be explained using FIG. 2. In the same figure, static pressure PO in tank 3 + liquid level. Specific gravity rt of measured fluid 2 at temperature t + pressure transmission liquid 1
1 specific gravity T, distance HH between flange 1 and transmitter A, distance HL between flange 1a and transmitter A + distance H between flanges l and la, pressure P applied to the pressure sensor on the H side.
M is (po +rth+γHH), and the pressure PL applied to the pressure sensor on the L side is (po +rHL). Therefore, the detected pressure value ΔP of the fluid to be measured 2 is (PHpt=γ
th+γ(H□−HL)=γth−rH). Rearranging this, h=(ΔP+γH)/γ. Here, since the specific gravity γ of the pressure transmission fluid 11 hardly changes even if the temperature changes, and (HL-H,)=H is constant, γH may be a constant value. Then, the amount of change in volume of the fluid to be measured 2 corresponding to the temperature t, that is, the specific gravity value γ, is calculated, and the level of the fluid to be measured 2 can be accurately detected. ” is inserted. (3) On page 5, lines 1 to 6 of the same book, after "Of course...", the following "Also, according to the present invention, in the arithmetic unit 17, γ, = γ. (l + αt). It is also possible to calculate rt based on an arithmetic expression. Here, γ is the specific gravity value of the fluid 2 to be measured at 0° C., and α is the coefficient of thermal expansion." is inserted. (4) "The figure is a sectional view" on page 5, lines 16 and 17 of the same book is corrected as follows. [FIG. 1 is a sectional view showing a liquid level transmitter according to the present invention, and FIG. 2 is the same (7 diagrams for explaining an example of calculation of liquid level measurement performed using the liquid level transmitter). ” (5) Correct Figure 1 as shown in the attached drawings and add Figure 2.

Claims (1)

[Claims] A diaphragm provided at the open end of the pressure extraction flange, a detector body that communicates with the inside of the diaphragm and has a pressure sensor therein, and a temperature sensor built in the pressure extraction flange to detect the temperature of the fluid to be measured. A liquid level transmitter comprising: an element; and an arithmetic device connected to the temperature detecting element and the detector body, which calculates the amount of volume change due to temperature change of the fluid to be measured and corrects the detected pressure value. .