SU1422120A1 - Apparatus for checking liquid media - Google Patents

Description

(21) 4088235 / 31-25

(22) 05/03/86

(46) 09/07/88. Bul Number 33

(71) Azerbaijan Energy Research Institute

them. IG Yesman and the Azerbaijan Polytechnic Institute. Ch.Ildryma

(72) M.S. Kasimzade and A.A. Jafarov

(53) 543.25 (088.8)

(56) Kasimzade M..C. and others. Electro-kontichesky information converters .- M.: Energie, 1973, p. 6-9.

USSR Author's Certificate No. 828054, cl. G 01 N 27/26, 1981.

(54) DEVICE FOR THE CONTROL OF LIQUID MEDIA

(57) The invention relates to electroanalytical chemistry, namely, devices for monitoring the composition and properties, and can be used as a sensor for the purity of a liquid. The aim of the invention is to increase the accuracy of control by eliminating the influence of electrical conductivity and dielectric properties of the medium. The essence of the invention lies in the fact that the introduction of additional electrodes connected with measuring electrodes into the circuit into the RPC casing establishes an unambiguous functional

5 I g

This is the relation between the transient voltage in the external circuit of the converter and the electro-mega potential that characterizes the composition and properties of the analyzed liquid, which increases the accuracy of control. The chambers of housing 2 are filled with the analyzed fluid 1. A constant external pneumatic pressure created, for example, by an electropneumatic device with a differential output, acts alternately on the membranes 5 of the chambers, as a result of which the fluid 1 that is being analyzed makes a pulsing movement through the partition 3. On the measuring electrodes 4, a variable flow potential appears, the amplitude of which varies with the composition and properties of the analyzed liquid. By introducing into the RPC case two pairs of additional plane-parallel mesh electrodes 6, 7 connected with the main electrodes 4 to an external circuit built on the basis of operational amplifiers 8, 10 operating in the scaling mode, eliminates the influence of the physicochemical properties of the liquid on the results of the control. 1 PC.

i

(L

 to yu

to

and/

The invention relates to a measurement technique, namely, devices for monitoring the composition and properties of binary and pseudobinary fluid mixtures, and can be used as a sensor for monitoring the purity of liquids.

The aim of the invention is to improve the accuracy of control by eliminating the effects of electrical conductivity and dielectric properties of the medium,; The drawing shows a diagram of a device for controlling liquid media. . The device contains a housing 2 filled with the analyzed liquid 1, divided into two porous chambers, a partition 3 with measuring electrodes 4, located on both sides, membranes 5 mounted on the open ends of the housing 2, and a device for oscillation of the membrane (not shown ), as well as two pairs of additional voltages 6 and 7 introduced into the housing 2, one (electrode 6) of which forms a non-inverting operational amplifier 8 feedback circuit, the input of which is connected to the measuring electrodes 4, and the output through the detector 9 and the second pair of additional electrodes 7 - to the input of another - inverting op amp 10.

Device J is as follows.

The chambers of the housing 2 are filled with the analyzed fluid 1. External external pressure is constant in magnitude, for example, by an electropneumatic device with a differential output (not shown), acting alternately on the membranes 5 of the chambers, as a result of which the liquid is analyzed, 1 makes a pulsing movement through the partition 3. On the measuring electrodes 4, a varying flow potential appears, the amplitude of which varies with the composition and properties of the analyzed fluid. The output variable potential E in the conditions of operation of the converter in the operating frequency range and the movement of the membranes 5 in the limit of the linear deflection is determined by the formula

F YD d.,

where (ZR - pressure drop;

(one)

0

five

0

five

0

five

0

five

0

five

 a nl

Е - electrokinetic potential J

 - dielectric constant;

A — specific electrical conductivity; f — dynamic viscosity;

kozffi, ient, characterizing the composition and physico-chemical properties of the liquid. According to the formula (1) at a constant pressure drop of the LR, the voltage E depends on the parameters (,,; (/, Л) associated with the composition of the liquid. To establish a unique functional dependence of the output voltage of the converter on the electrokinetic potential, it is necessary to significantly reduce the effect of physicochemical parameters (, jU, Л), in particular, dielectric constant () and conductivity (E) of the analyzed liquid 1 on the output parameter (the result of the device analysis). This problem is solved by introducing device two additional pairs of plane mesh electrodes 6 and 7 included with measuring electrodes 4 to the external circuit, constructed on the basis of operational amplifiers 8 and 10, the PA botak Tsikh in zoom mode.

The resistance of the column of the analyzed liquid 1, enclosed between the additional electrodes 6 and 7 pairs, depending on their structural dimensions, i.e. The surface area of the flat electrodes and the distance between them, as well as the type of electrical signal (constant or variable) applied to these electrodes, may have an almost capacitive or active character. In this case, the equivalent parameter of the pair of electrodes 6 with liquid 1, connected as a capacitive element in the feedback circuit of the operational amplifier 8, is the capacitance Cp, which can be achieved under conditions of an effective choice of the frequency of the alternating voltage E applied to the input of the operating voltage amplifier 8, and the design parameters of a pair of electrodes 6.

In this case, the transmission coefficient of the rotary amplifier 8 is determined by the expression

y, E Cf

1 + Co. , С С С С

(С „С). (2) From here we find the voltage U at the output of the operational amplifier 8 taking into account formula (1)

  f; | dP

and, 5i.

And where S, d

Cg S / 1Td AIT 4S (U

(3)

respectively, the impermeable surface area of one flat electrode and the distance between the electrons of a pair of 6; K is a constant coefficient; С - capacitance of the external circuit capacitor.

As can be seen from expression (3), with a certain accuracy, the influence of the change in the dielectric constant H of the liquid on the parameter U at the output of the operational amplifier 8 is excluded.

AC voltage U after detection, i.e. converting into a constant voltage U, is fed through pairs of electrodes 7 to the input of the operational amplifier 10.

On a constant current, a vapor of an electrode 7 with a liquid 1 exhibits a purely

A device for controlling liquid media, containing a housing filled with the analyzed medium, divided into two chambers by a porous partition with measuring electrodes located on both sides of the membrane, mounted on the open ends of the coercive resistance and therefore the resistance Cd of the liquid portion bounded by plane-parallel electrodes depends on the specific Electro-35 starts, and a device for initiating the conductivity D of fluid oscillation of the membranes, characterized by the transmission coefficient of the operational amplifier 10 TC ratio

U8.M) (1 B I RO ROS

 40th

U i

RA

d / AS

This is so that, in order to increase the control accuracy by eliminating the influence of electrical conductivity and dielectric properties of the medium, two pairs of additional plane-parallel electrodes are introduced into the case, one of which forms a feedback circuit of an operational amplifier, whose input g is connected to the measuring electrodes, and the output through the detector and the second pair of additional parallel electrodes are connected to the input of another operational amplifier.

to,

where, taking into account expression (3), we determine the ratio for the output voltage and 5 (, | in the external circuit

q ,, „K2i; to,

 Ki

and

where Kj is the conversion coefficient (recr m pen) of the detector,

Kt is a constant coefficient;

RO is the resistance of the feedback circuit of the amplifier lOj

RI - resistance of the analyzed l

fluid.

ten

15 20

From (5) it follows that the output signal of the RPC does not depend on the change in the electrical conductivity of the liquid.

The device can be used to study the structural characteristics of transforming capillary-porous bodies and the electrical double layer of solid-liquid systems by measuring the potential, and also as an indicator for monitoring the purity of liquids. The device allows to increase the accuracy of monitoring of liquid media.

Claims (1)

Invention Formula A device for controlling liquid media, comprising a housing filled with the analyzed medium, divided into two chambers by a porous partition with measuring electrodes located on both sides, membranes, mounted on the open ends of the housing, and a device for exciting membrane oscillations, 40 This is so that, in order to increase the control accuracy by eliminating the influence of electrical conductivity and dielectric properties of the medium, two pairs of additional plane-parallel electrodes are introduced into the case, one of which forms a feedback circuit of an operational amplifier, whose input g is connected to the measuring electrodes, and the output through the detector and the second pair of additional parallel electrodes are connected to the input of another operational amplifier.