SU1434332A1 - Apparatus for measuring surface tension of a liquid - Google Patents

Abstract

The invention relates to measuring devices for the surface tension of liquids at the interface with air according to the Wilhelmy plate method and can be used for research in laboratory conditions in order to determine the optimal composition of solutions. The purpose of the invention is to improve measurement accuracy by automating the process of production. The device consists of a power supply unit, torsion weights, a differential amplifier, a stabilized power source, two reversing engines, a lifting table with a vessel for the test liquid, a balancer, an automatic control unit and an electronic memory unit. The device makes it possible to investigate the temporal dependence of the surface tension of surfactant solutions. The output of the differential amplifier can be connected to either the self- | a recording instrument, or an analog-to-digital converter with a digital display board. 2 Il. .

Description

The invention relates to a control-Io-measuring technique, in particular to measuring devices of the physiological parameters of solutions of surfactants, and can be used to determine the surface tension of liquids at the interface with air under laboratory conditions. x

I The purpose of the invention is to improve the accuracy by eliminating errors caused by the uncertainty of the moment of contact of the Wilhelmi plate with liquid,

I Fig. 1 shows a block diagram (of the device; Fig. 2 is an electrical circuit of the control unit.

A device for determining the surface tension of liquids consists of a lifting table 1 with a vessel 2 for the test liquid, torsion weights 3 with a Wilhelmi platinum plate 4 suspended above the vessel 2, control unit 5, functionally connected to the torzionngh electric contact: the balance 3 and containing the first control circuit 6 and the third 7 relay 20, then the engine 7 and the lifting table 1 together with the vessel 2 with the liquid under investigation are lowered until the end switch is activated. Suspended properly prepared die plate 4 to the rocker torsion bar in the balance 3 and turn on the toggle switch 17, Since the left contact 39 of the torsion balance 3 is closed, peiie 23, which turns on the engine 6 on the uoffbeM of the platinum plate 4, turns on. platinum plate 4 reaches the position of balancing, contact 39 is set to the middle position and the engine 6 stops, the relay 25 turns on with some delay and its contact OUT5Sh10CHIT unit 12 input. As a result, the output of block 12 vits voltage corresponding to the equilibrium position of torsion weights. Then the toggle switch 18 is turned on. As a result, the relay 23 is turned on, which will turn on the reversing motor 7 to lift the table 1. As soon as the liquid contacts the lower end of plate 4 as a result of its retraction

Versatile motors and com- munication either down, the left-handed elements turn on again, the power supply unit 8 of the entire device with the toggle switch of the stabilized power supply 9 of the reochord 10 weights and constant resistance 11. The shaft of the first engine 6 is connected the shaft of the second motor 7 is with the mechanism for moving the lift table 1. The device also contains an electronic unit 12 for storing the signal size, a differential Amplifier 13, the output of which is connected to a registering device 14. The reochord 10 scales electrically connected to the inputs of the differential amplifier 13 through the switching elements of the relay of the control unit 5 and through the electronic storage unit 12.

The electrical circuit of the control unit 5 (Figo 2) contains ISIS toggle switches, relays 20-26, button 27, light bulbs 28-30, limit switches 31-34, windings 35-38 for controlling reversible motors and electrical contact 39 for torsion weights 3.

The device works as follows;

Toggle switches 15, 16 and 19 are turned on, button 27 is pressed, and

35

40

45

50

 55

cycle 39, then relays 22 and 24. As a result, relay 23 will de-energize and de-energize the winding 36 of the engine 7. The lifting of the table will instantly stop. At the same time, the reversing motor 7 is switched on to raise the platinum plate 4 to the state of the previous equilibrium. As soon as this state is reached, relay 22 will be disconnected, including relay 26, and with its contacts it connects the inputs of differential amplifier 13 to the output of block 12 and to the output voltage of a 10-row rail,

As a result, at the output of the amplifier 13 a wits signal proportional to the magnitude of the surface tension. This signal arrives at the input of the registering device 14, on a scale of which, calibrated in units of surface tension, the surface tension is read, the surface tension of the test liquid is read.

Claims (1)

Claim The device for detecting the surface tension of the liquid, nor down, will turn on the left end 35 40 45 50 55 cycle 39, then relays 22 and 24. As a result, relay 23 will de-energize and de-energize the winding 36 of the engine 7. The lifting of the table will instantly stop. At the same time, the reversing motor 7 is switched on to raise the platinum plate 4 to the previous equilibrium state. As soon as this state is reached, relay 22 will be de-energized, relay 26 will turn on and connect the inputs of differential amplifier 13 to the output of block 12 and to the output voltage of the resistance rowcord 10, As a result, at the output of the amplifier 13 a wits signal proportional to the magnitude of the surface tension. This signal arrives at the input of the registering device 14, on a scale of which, calibrated in units of surface tension, the surface tension is read, the surface tension of the test liquid is read. Claim A device for detecting the surface tension of a fluid containing a torsion balance, with a Wilhelm plate suspended from the rocker arm, a lifting table with a vessel for the test fluid located under the Wilhelmy plate, the first reversing motor, which is connected to the axis of the torsion balance, block control functionally associated with the electrical contact of the torsion weights, and the winding of the reversing motor, and the recording device associated with the torsion-balancer reohord is different in that, in order to increase the Nost by eliminating errors caused by the uncertainty of the moment soprikosnove A Wilhelmi liquid NIN plate, the device additionally contains a second reversing motor, the shaft of which is rigidly connected with the lifting table movement mechanism, the control circuit of the second reversing motor, included in the control unit, differential, 1st amplifier, connected to the chain between the torsion weights and a recording device through the switching elements of the control unit, with one of the inputs of the differential amplifier connected to the balancer through the electronic memory storing unit Igna.  Pue.f  / L ct i9 e.g.