SU968708A1 - Device for determining fat permeability of materials - Google Patents

Description

(5t) DEVICE FOR DETERMINATION OF FATTERES OF MATERIA) SE

one

The invention relates to instrumentation engineering and may find application in the food industry for assessing the quality of polymeric packaging materials, in the chemical industry for assessing the quality of workwear and other sectors of the national economy.

A device for detecting water infiltration is known, which contains a sensor in the form of rod electrodes and a reading device, the reading device being made with a pulse circuit, the control circuit of which includes electrodes with less than one perforated one, and between the electrodes there is a hygroscopic gasket f 1.

The disadvantage of this device is the impossibility of examining 2o materials with non-conductive liquids.

A device is known for determining the permeability of materials with eganic solvents, a meaningful device for attaching a sample to a dielectric base with two electrodes mounted on its upper suit, included in the measuring circuit of an electrode time relay, with both electrodes located under the test sample and isolated from each other soluble polymer strap, and the top electrode is made in the form of a metal grid, and the bottom - in the form of a set of spring-loaded metal rods, with f2J package

However, this device cannot be used to determine the moment of penetration of fats and oils through polymeric materials, since the mentioned media have high dielectric indices and their penetration also does not produce an electrical circuit between the electrodes.

3968

The closest to the proposed technical entity is a device for determining the permeability of tissues with non-conductive liquids, containing a medium supply chamber, a measuring chamber and two electrodes of a capacitive sensor, in which the medium feed chamber is made in the form of a funnel through which the sample liquid is applied to the sample in the form of drops. As the fluid passes through the tissue, the droplet enters the measuring chamber between the electrodes of the sensor and changes the capacitance of the sensor. The moment of change in the capacitance is registered, the permeability time is determined.

However, the known device does not provide the required accuracy of measurement, since the sensor signal is delayed by the time required for the drop to drop from the sample.

The aim of the invention is to improve the accuracy of determination. .

The goal is achieved by the fact that in the device for determining the lipid permeability of polymeric materials, containing a medium supply chamber, a measuring chamber and two electrodes of a capacitive sensor, the first electrode is placed inside the measuring chamber, pressed to the side surface to its walls and spring loaded, and the second electrode is placed in the wall of the measuring chamber.

The drawing shows the proposed device.

The device consists of a metal chamber t in which the medium 2 under test is located. Test sample 3 is fixed between the metal chamber 1 and the measuring chamber k with fastening screws 5. The test medium 2 is brought to the test sample 3 through the hole b of the metal chamber 1 closed with a cap 6. Between the metal chamber 1 VI test specimen 3, a rubber gasket 7 is installed. Inside the measuring chamber (on the metal spring 8, the first measuring electrode 9 is fixed on the metal spring, the first measuring electrode adjoining sample 3, and the opposite end to the wall of the measuring chamber k. In the upper cavity of the measuring chamber k parallel to the test sample 3 is mounted on the guides 10 a rod 11 of

a dielectric material with a second spring 12 located thereon, which fixes its position relative to the measuring chamber due to a latch 13 present on the rod 11. The second measuring electrode I, having a length equal to the length of the first measuring electrode 9, is installed in the wall of chamber A parallel to the test sample 3 and the first measuring electrode 9 with the second measuring electrode k is shifted relative to the first measuring electrode 9, with non-deformed first metal spring 8, to the floor fault length towards the top of the cavity k measuring chamber. A measurement circuit is connected to the second measuring electrode 1 and to the end of the first metal spring 8. As a measuring circuit, a capacitance meter (e.g., E8-3, B-C, etc.) can be used in combination with a digital printing device.

The device works as follows.

In the absence of the test medium 2 in chamber 1, the rod 11 is loaded. The latter then goes down into the measuring chamber k and moves the first measuring electrode 9 downward. The load applied to the rod 11 gradually decreases, and the rod It rises to its original position. Electrode 9 also rises as long as the forces acting on it do not mutually amplify. It is acted upon by a vertically directed upward force of elasticity of the spring 8-F of a body of gravity, directed vertically downwards.

where m is the mass of the electrode 9

g - acceleration of free fall. Friction force, also directed vertically down.

IT .. where (y, is the force of the normal pressure acting on the ends of electrode 9, on the end face adjacent to the test sample 3 and on the end face adjacent to the wall of the measuring chamber C

K - coefficient of friction of the end face of the electrode 9 about the material of the test sample 3; k is the friction coefficient of the end face of the electrode 9 about the material of the stack of the measuring chamber k. Thus, the electrode 9 will rise up as long as F nig + h- (К h-К). (1) Gun - 4 i Measuring electrodes 9 and which are parallel and partially overlap each other, are a capacitor with flat parallel plates, having an electrical capacitance Cd, which will remain constant until difference (O, t. the first measuring electrode 9 does not shift relative to the second measuring electrode 15, which follows from the expression (-. idi-S l i where tp is the dielectric induced vacuum, g is the dielectric constant of the material (in this case, the dielectric Mat The range from which the measuring chamber is made); d is the distance between the plates {between the electrodes E and H); $ is the area of the capacitor plate if they are equal (the area of the electrode is And, which overlaps the electrode 9. After that, in the metaplastic chamber 1 brings the test medium 2 (vegetable and animal fats and oils), the measuring electrode 9 will be at rest until the medium 2 penetrates the test sample 3 to its surface. As soon as a test medium 2 (vegetable or animal fats and oils) between test sample 3 and the end of electro-gud 9 adjacent to it, the coefficient of friction K changes immediately (decreases to due to lubricant between rubbing surfaces) at the same time, equality (1) is violated, and this leads to the fact that m. large td + Pc (), since K | 7K, and the measuring electrode 9 under the action of the elastic force of the spring B moves upwards, while the forces acting on the measuring electrode 9 are mutually are not compensated. npm Vvig-KF CK + Kj. 86 When moving the measuring electrode 9, the capacitance of the electric capacitor formed by the electrodes 9 changes and, since the area of the electrode I changes, the electrode area 9 overlaps and becomes equal to S, and S S, i.e. the electrical capacitance between electrodes 9 and I will increase and become equal to C (C C (,). Thus, at the moment of penetration of the test medium 2 through the test sample 3 (polymer sample), the electrical capacitance between the measuring electrodes 9 and 14 will increase from the value of Sool As a measurement circuit, it is possible to use (instruments that allow fixing the moment of deviation of the capacitance values from the nominal capacitance meter value. / U1 of the measuring electrodes 9 and T "depends on the spring stiffness B and force yes Rts determined by the tension of screws 5. In the case of testing samples 3 in the form of thin films in the metal chamber 1, adjacent to the test sample 3, is installed (mounted in the metal chamber 1) a meta-grid grid or a metal plate with perforations in order to under the force of the normal pressure Rc, there was no deformation of the test sample 3 (not pokezan). For TOR9, for the sensitivity of this device to be maximum, it is necessary that the coefficient of friction K be as low as possible. This device by the fact that the end of the measuring electrode 9, adjacent to the wall of the measuring chamber, is lubricated with grease or other lubricant. The ends of the measuring electrode 9 have a high purity of processing, as well as the walls of the measuring chamber 4, according to. The measuring electrode 9 slides out. Since the surface of the test sample 3 may have irregularities, the edges of the electrode 9, which connect to the test sample 3, are slightly rounded (not shown). An embodiment of the proposed device may be a device in which the second measuring electrode is located in the end wall of the measuring chamber.

Claims (1)

Claim A device for determining the fat permeability of materials, comprising an ⁸ chamber for feeding the test medium, a measuring chamber and two electrodes of a capacitive sensor, characterized in that, in order to increase the accuracy of determination, the first electrode is placed inside the measuring chamber, adjoined by its side surface to its walls and spring-loaded, and the second electrode is placed in the wall * 0 of the measuring chamber.