SU147023A1 - Device for measuring the surface tension of liquids by the method of maximum pressure - Google Patents

Description

The present invention relates to devices for measuring the surface tension of liquids by the method of maximum pressure using a heating device, communicating vessels and a capillary tube.

The proposed device differs from the known ones in that, in order to measure the level of the liquid in the tank, a cathetometer with a capillary dipped into it is used to create gas bubbles that raise the level in the tank connected by a manometric tube with a gas cylinder.

Such an embodiment of the device makes it possible to measure the surface tension by changing the level of the test liquid due to the formation of a gas bubble in it.

The drawing schematically shows the proposed device.

The device consists of a glass tank with the liquid under investigation, filled with an inert gas. In the process of heating the cylinder 1 by means of an electric furnace 2. In the left part of the device, an excess pressure AP is created, the liquid thereby moves from the position indicated by a dotted line from the tank 3 to the manometric tube 4, fills the tube 5 and rises through the tube 6. In this case excess pressure is balanced by hydrostatic pressure:

where g is the acceleration of the force of gravity; p is the density of the liquid; h is the change in its level. At the same time, the liquid is displaced from the capillary 7 and a gas bubble is formed at its end. At the maximum gas pressure in this bubble, the latter detaches from the capillary and floats up, and after this, through the capillary p 7,

L P gph,

No. 147023-2 pass through another such bubbles. This causes a decrease in pressure on the left side of the device and the process of "pushing gas through the capillary" stops. The height of the AZ, at which the first gas bubble passes through the capillary, is measured by a cathetometer and is used to determine the surface tension of the fluid by the formula

(Y ,,

where r is the radius of the tube (for narrow tubes, the pressure P due to the surface tension of the fluid takes: r - n)

To repeat the measurements after overheating of the cylinder 7, the furnace 2 is raised, the pressure in the left part of the device is reduced, the excess pressure in the tank 8 begins to move the liquid through the tubes 6, 9 and 4, through the capillary 7 and through the tube 5 to the tank 3. As soon as the level of LIQUID1 in tube 5 reaches -cap of capillary 7, gas from tank 8 will flow into tank 3, into the trap 10 n into cylinder 1, while the gas displaced by the gas will remain in the measuring part of the device. After the pressure in different parts of the device is equalized, proceed to continue the measurement at this temperature. Temperature measurement is performed to measure the surface tension of the fluid at some other temperature.

Subject invention

Claims (2)

1. A device for measuring the surface tension of liquids by the method of maximum pressure, containing a pressure source, a heating device, communicating vessels, a capillary tube, characterized in that, in order to measure the surface tension from a change in the level of the subsequent liquid due to the formation of a gas 1 bubble in it it uses a cathetometer to measure the level of a liquid in a tank, with a capillary lowered into it to create gas bubbles that raise the level in a tank connected by a pressure gauge bkoy gas bottle. 2. The device according to claim 1, except for the fact that, in order to accelerate the production of repeated measurements, it is performed with a gas trap, relieving pressure in the reservoir with the test liquid. 2a -.