SU815509A2 - Device for metering liquids - Google Patents

Description

Union of Soviet

Socialist

Republics

(72) Author of the invention (71) Applicant (n) 815509

DESCRIPTION

Inventions

TO AUTHOR CERTIFICATE (61) Additional to the author's certificate B 479953 (22) Announced on 03.20.79 (21) 2770819 / 18-10 with the addition of application No. (23) Priority Published 2 LC 3.81. Bulletin N9 11

Date of publication of the description 23.03.81 (51) M. Cl. ³

G01 F 13/00 (53) UDC681.26 (088.8)

P.S. Skvortsov

Mari Pulp and Paper Mill (54) DEVICE FOR DISPENSING LIQUID The invention relates to devices for dispensing liquid from measuring tanks.

and also in the measuring device, with the help of hydraulic level gauges - differential pressure gauges and can find application in the chemical and other industries.

According to the main author. St. No. 479953 a device is known comprising a measuring vessel connected in the lower and upper parts with a differential pressure gauge, valves on the drain line from the measuring device and on the line connecting the upper part of the measuring device with its lower part parallel to the pressure gauge, controlled by the output of the logic unit connected to the output of the pressure gauge 11].

Such a device does not provide high accuracy of dosing of individual doses due to the appearance of an additional error in the measurement of the differential pressure differential pressure gauge, which determines the volume of a single dose of liquid. This error is due to the fact that during dosing with an unchanged volume of liquid in the positive chamber of the pressure gauge connected to the upper part of the meter, due to the elastic deformation of the sensitive element of the pressure gauge, an example of a membrane changes by · 30, the volume of the positive chamber changes and, as a result, the column height fluid in the line connected to the positive chamber.

So, for example, draining the liquid from the measuring device during the dosing process causes the sensor to deform towards an increase in the positive chamber volume of the differential pressure gauge and, as a result, a decrease in the liquid column in the line connected to the positive chamber.

In differential pressure gauges with mercury aggregate, this error is due to the flow of mercury from the positive chamber to the negative chamber and, as a result, a decrease in the liquid column above the mercury in the positive chamber. At the same time, the display of the manometer is underestimated.

The purpose of the invention is improving the accuracy of dosing.

This goal is achieved by the fact that a pneumatic repeater is introduced into the pipeline, the inlet chamber of which is connected to the upper part of the measuring vessel and to the equalizing valve, and the outlet - to the positive chamber of the differential pressure gauge.

The drawing schematically shows the proposed device.

The device comprises a measuring vessel 1, a drain valve 2, a pneumatic repeater 3, valve 4 for equalizing the pressure in the chambers of the differential pressure gauge 5.

The logical unit consists of pneumatic elements b and 7 comparing the power amplifier 8 and the pneumatic button 9.

The scheme works as follows.

In the initial position, valve 2 is closed, valve 4 is open, in the inlet chamber A of the pneumatic repeater 3 and in the negative chamber of the pressure gauge 5, the pressure is the same, and the pressure drop across the gauge is zero. fifteen

When you press the pneumatic button 9, the pneumatic signal enters the chamber B and C of the comparison elements b and 7. In this case, a pneumatic signal appears at the output of the comparison element 7 and then at the output 20 of the power amplifier 8, which opens the valve 2 on the drain line from the meter 1 and closes the valve 4 in this case, in the chamber B of the pneumatic repeater e and, accordingly, in the positive chamber of the manometer 5, the air pressure equal to the pressure in the minus chamber of the manometer 5 is set and stored before dosing from the meter.

as the liquid is dosed on the pressure gauge, the pressure drop increases and, accordingly, the output signal of the pressure gauge. When the output pressure of the pressure gauge reaches the set value at the output of the comparison element 6. A signal appears that translates the comparison element 7 to the position at which the signal disappears at its output. In this case, the power amplifier 8, relieving pressure from valves 2 and 4, transfers them to their original position. this ends one dosing cycle.

In the proposed device, the pneumatic repeater eliminates the dependence of the pressure in the positive chamber of the differential pressure gauge on the change in its volume due to the elastic deformation of the sensitive element of the pressure gauge, for example, the membrane, when the pressure drop changes during dosing, since the pressure in the chamber is the pneumatic repeater and, accordingly, in the positive chamber of the differential the pressure gauge does not depend on the change in the volume of the positive chamber of the differential pressure gauge. .

Thus, the proposed device improves the accuracy of dispensing liquids.

Claims (1)

The invention relates to devices for dispensing liquid from a measuring device as well as to a measuring device, with the help of hydraulic level gauges - diffrenational pressure gauges, and can be used by the chemical and other industries. According to the main author. St. No. 479953, a device containing a measuring vessel connected in the lower and upper parts with differential pressure gauge valves on the drain line from the measuring device and on the line, connecting the upper part of the measuring device with its lower part parallel to the pressure gauge, controlled in the course of the logic unit, is connected the output of the pressure gauge 11. Such a device does not provide a high accuracy of dosing of individual doses due to the occurrence of an additional error in measuring the differential pressure differential pressure gauge, which determines the volume of the separated ozy liquid. This error is due to the fact that in the course of dosing with a constant volume of liquid in the positive chamber of the manometer connected to the upper part of the measuring device, due to the elastic deformation of the sensitive element of the manometer, for example of the membrane, the volume of the positive chamber changes and consequently the height of the liquid column in the line connected to the plus camera. For example, draining the liquid from the measuring device during the dosing process causes the deformation of the sensing element in the direction of increasing the volume of the positive chamber of the differential pressure gauge and, consequently, a decrease in the liquid column in the line connected to the positive chamber. In differential mercury-filled nanometers, this error is due to the flow of mercury from the positive chamber to the negative chamber and, consequently, a decrease in the liquid column of mercury in the positive chamber. At the same time, the display of the manometer is underestimated. The purpose of the invention is to improve the accuracy of dosing. The goal is achieved by introducing a pneumatic repeater into the pipeline, the inlet chamber of which is connected to the upper part of the measuring vessel and to the balancing valve, and the outlet to the positive chamber of the differential pressure gauge. The drawing schematically shows the proposed device. The device contains a measuring vessel 1, a drain valve 2, a pneumatic repeater 3, a valve 4 for equalizing the pressure in the chambers of the differential pressure gauge 5. The logic unit consists of pneumatic elements b and 7 of the power amplifier 8 and pneumo-button 9 ihem works as follows. In the initial position, the valve 2 is closed, the valve 4 is open, at the entrance chamber A of the pneumatic repeater 3 and the negative chamber of the pressure gauge 5, the pressure is equal, and the pressure drop across the pressure gauge is zero. When the pneumatic button 9 is pressed, the pneumatic signal enters the chamber B and B of the elements b and 7 of the comparison. At the same time, the pneumo signal is output at the output of the comparison element 7 and further at the output of the pneumatic amplifier 8, which opens the valve 2 at the discharge line of the liquid from the measuring device 1 and It closes the control panel 4. In the chamber B, the pneumatic repeater J and, accordingly, in the plus chamber of the pressure gauge 5, air pressure is set and remembered equal to the pressure in the negative pressure chamber of the pressure gauge 5 before the metering begins. But as the metering of fluid on the gauge increases, the differential and the output signal of the gauge increase accordingly. When the output pressure of the pressure gauge reaches a predetermined value, a signal appears at the output of the element. Compared with the comparison element 7, the signal disappears at its output. In this case, the power amplifier 8 relieves pressure from the valves 2 and 4, transfers them to the initial position, with this one dosing cycle ends. In the proposed device, the pneumatic repeater eliminates the pressure in the positive chamber of the differential pressure gauge as a function of the change in its volume due to the elastic deformation of the sensitive element of the pressure gauge, for example, the membrane, when the pressure changes during the dosing process, since the pressure in the pneumatic repeater chamber and, accordingly, in the differential pressure gauge chamber does not depend on the change in volume of the positive chamber of the differential pressure gauge. . Thus, the proposed device improves the accuracy of liquid dosing. The invention of the device for dispensing a liquid on the author. St. W 479953, characterized in that, in order to improve metering accuracy, a pneumatic repeater is introduced into the pipeline, the inlet chamber of which is connected to the upper part of the measuring vessel and with the equalizing valve, and the outlet with the positive chamber of the differential pressure gauge. Sources of information taken into account in the examination 1. USSR author's certificate itt 479953, CL. G 01 F 13/00, 1973. / N