RU2811338C1 - Method for measuring volume and determining density of porous materials - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: method for measuring volumes and determining the densities of porous bodies of arbitrary shape, different moisture content, as well as fractional composition, used in all areas of research or application of porous objects. A method for measuring the volume and determining the density of porous bodies includes weighing the test body, placing it in a sample vessel, which is equipped with a pressure sensor and is connected through a valve to the mounting cross, closing the valve between the sample vessel and the mounting cross, establishing a pressure that is nonequilibrium with atmospheric pressure in the measuring vessel, equipped with a pressure sensor and connected through a valve to the mounting cross, readings from the pressure sensors, according to the invention, are carried out by changing the pressure sequentially in each of the vessels by the same amount of air volume measured and recorded by the flow meter, followed by closing the valves between the vessels and the mounting cross, measuring and recording the pressure in the vessels and calculating the volume of the body using the formula:

where V_T is the required volume of the body, V_C is the volume of each vessel, ΔP₁ is the magnitude of the pressure change in the sample vessel, ΔP₂ is the magnitude of the pressure change in the measuring vessel; the density of the porous body under study is determined by the formula:

where ρ is the density of the porous body under study, m is the weight of the porous body under study.

EFFECT: increase in the accuracy of measuring the volume and determining the density of porous bodies of arbitrary shape, different humidity and fractional composition.

1 cl, 1 dwg

Description

The invention relates to a technique for measuring volumes and determining densities of porous bodies of arbitrary shape, varying humidity, as well as fractional composition, and can be used in all areas of research or application of porous objects.

There is a known method for measuring volume and determining density, including weighing the body under study, placing it in a sample vessel, which is connected in series through valves to a measuring vessel of similar volume and a pump that creates a change in pressure simultaneously in two vessels, followed by closing the valves and sequential reverse bypass air by opening the valves first into the measuring vessel until atmospheric pressure is reached in it, with simultaneous measurement and fixation by the flow meter of the change in air volume, and then into the sample vessel, also with the measurement and fixation by the flow meter of the change in air volume, while the volume of the body is determined by the formula , Where - the required body volume, - volume of each vessel, - the magnitude of the change in air volume in the sample vessel, - the magnitude of the change in air volume in the measuring vessel; and the density of the porous body under study is determined by the formula (Patent No. 2744281 RF, IPC G01F 17/00, G01N 9/26. Method for measuring volume and determining the density of porous materials / Gainullin Ren. Kh., Tsvetkova E.M., Gainullin Rish. Kh., Fedotova A.A., Vorontsova V.V. No. 2020124266; application 07/22/2020; publ. 03/04/2021; bulletin No. 7).

The disadvantage of this method is the low measurement accuracy.

The closest in technical essence is a method for measuring the volume and determining the density of porous bodies, including weighing the test body, placing it in a sample vessel connected to the measuring vessel and a pressure sensor by a pneumatic line with a valve, closing the valve between the measuring vessel and the sample vessel, establishing the pressure non-equilibrium with atmospheric in the measuring vessel, opening the valve between the measuring vessel and the sample vessel, balancing the pressure in the vessels, taking pressure sensor readings, calculating the volume of particles, carried out by sequential three-fold air bypass, the first of which is carried out by opening the valves between the vessels with fixation of the equilibrium pressure and calculating body volume using formulas , , the second bypass of air between one of the vessels and the atmosphere is carried out until atmospheric pressure is reached in it, and the same equilibrium pressure is maintained in the other vessel, and then a second bypass between the vessels with fixation of the equilibrium pressure and calculation of the volume of the body using the formulas , , , , Where - the magnitude of the initial change in pressure in one of the vessels, And - the value of the equilibrium pressure in the vessels after the first bypass, , , , - the value of the equilibrium pressure in the vessels after the second bypass; the density of the porous body under study is determined by the formulas , , , (Patent No. 2775151 of the Russian Federation, IPC G01N 9/26. Method and device for measuring volume and determining the density of porous materials / Gainullin Ren. Kh., Gainullin Rish. Kh., Tsvetkova E.M. No. 2021130427; application 10.19.2021; Published June 28, 2021; Bulletin No. 19).

The disadvantage of this method is the low measurement accuracy.

The technical result is to increase the manufacturability of the procedure and the accuracy of measuring volume and determining the density of porous bodies of arbitrary shape, different humidity and fractional composition.

The technical result is achieved by the fact that the method of measuring volume and determining the density of porous bodies, including weighing the test body, placing it in a sample vessel, which is equipped with a pressure sensor and is connected through a valve to the mounting cross, closing the valve between the sample vessel and the mounting cross, establishing pressure nonequilibrium with atmospheric pressure in the measuring vessel, equipped with a pressure sensor and connected through a valve to the mounting cross, taking readings from the pressure sensors, according to the invention, is carried out by changing the pressure sequentially in each of the vessels by the same amount of air volume measured and recorded by the flow meter, followed by closing the valves between vessels and mounting cross, measuring and recording pressure in vessels and calculating body volume using the formula:

,

Where - the required body volume,

- volume of each vessel,

- the magnitude of the pressure change in the sample vessel,

- the magnitude of the pressure change in the measuring vessel;

The density of the porous body under study is determined by the formula:

,

Where - density of the porous body under study,

- mass of the porous body under study.

The proposed method makes it possible to improve the manufacturability of the procedure, as well as the accuracy of volume measurement and determination of the density of porous bodies of arbitrary shape, different humidity and fractional composition.

No similar method for measuring the volume and determining the density of porous bodies has been found in the patent and scientific and technical literature.

The above method is illustrated graphically, where in FIG. 1 shows a device that implements the proposed method for measuring the volume and determining the density of porous bodies, including a mounting cross 1, to the three ends of which, through valves 2, 3, 4, a sample vessel 5 and a measuring vessel 6 of similar volume are connected, equipped with pressure sensors 7, 8, and a flow meter 9 with a pneumatic pump 10 that creates a change in pressure, and a bypass valve 11 is connected to the fourth end.

According to the proposed method, measuring the volume and determining the density of porous bodies can be carried out both in rarefaction mode and in excess pressure mode.

When the pneumatic system operates in vacuum mode, volume measurement and determination of the density of porous bodies is carried out as follows. Weigh sample 12, determining its mass m. To measure the volume of the test sample it is placed in sample vessel 5, while valves 2, 3, 4 are open, and atmospheric pressure is set in vessels 5 and 6. After this, valve 3 is closed, pneumatic pump 10 is turned on, which moves air from the sample vessel 5 into the atmosphere with a volume of , recorded by flow meter 9, and thereby creates a pressure change of , recorded by pressure sensor 7. After closing valve 2, using bypass valve 11, air is bypassed between the atmosphere and the cavity of the mounting cross. Then open valve 3, turn on the pneumatic pump 10, which moves air from the measuring vessel 6 into the atmosphere of a similar volume , recorded by flow meter 9, and thereby creates a pressure change of , recorded by pressure sensor 8. Taking into account the constant temperature of the system, its state in vessels 5 and 6 at atmospheric pressure and after removing part of the air, it can be reflected by equations that obey the Boyle-Mariotte law:

Where - the value of atmospheric pressure,

- the magnitude of the pressure change in the sample vessel,

- the magnitude of the pressure change in the measuring vessel,

- volume of each vessel,

- the required body volume,

- the volume of air moved from vessels to the atmosphere.

Simplifying expressions (1) and (2) and expressing from them , we get:

Equating the right-hand sides of equations (3), (4), and solving for the desired volume of the body , we obtain an equation for calculating the volume of the body under study 12:

Using a known volume of the vessel and measured values And you can calculate the volume of the body under study 12, in turn, the density is determined by the formula:

When the pneumatic system operates in excess pressure mode, volume measurement and determination of the density of porous bodies is carried out as follows. Weigh sample 12, determining its mass m. To measure the volume of the test sample it is placed in sample vessel 5, while valves 2, 3, 4 are open, and atmospheric pressure is set in vessels 5 and 6. After this, valve 3 is closed, pneumatic pump 10 is turned on, which moves air from the atmosphere with a volume of , recorded by flow meter 9, and thereby creates a pressure change of , recorded by pressure sensor 7. After closing valve 2, using bypass valve 11, air is bypassed between the atmosphere and the cavity of the mounting cross. Then open valve 3, turn on the pneumatic pump 10, which moves air from the atmosphere of a similar volume into the measuring vessel 6 , recorded by flow meter 9, and thereby creates a pressure change of , recorded by pressure sensor 8. Taking into account the constant temperature of the system, its state in vessels 5 and 6 at atmospheric pressure and the creation of excess pressure can be reflected by equations that obey the Boyle-Mariotte law:

Where - the value of atmospheric pressure,

- the magnitude of the pressure change in the sample vessel,

- the magnitude of the pressure change in the measuring vessel,

- volume of each vessel,

- the required body volume,

- the volume of air moved from the atmosphere into the vessels.

Simplifying expressions (7) and (8) and expressing from them , we get:

Equating the right-hand sides of equations (9), (10), and solving for the desired volume of the body , we obtain an equation for calculating the volume of the body under study 12:

Using a known volume of the vessel and measured values And you can calculate the volume of the body under study 12, in turn, the density is determined by the formula:

The use of the proposed method makes it possible to improve the manufacturability of the procedure, as well as the accuracy of measuring volume and determining the density of porous bodies of arbitrary shape, different humidity and fractional composition.

Claims (2)

A method for measuring volume and determining the density of porous materials, including weighing the test body, placing it in a sample vessel, which is equipped with a pressure sensor and is connected through a valve to the mounting cross, closing the valve between the sample vessel and the mounting cross, establishing a pressure that is nonequilibrium with atmospheric pressure in the measuring device a vessel equipped with a pressure sensor and connected through a valve to the mounting cross, taking readings from the pressure sensors, characterized in that the pressure is changed sequentially in each of the vessels by the same amount of air volume measured and recorded by the flow meter, followed by closing the valves between the vessels and the mounting cross , measuring and recording pressure in vessels and calculating body volume using the formula: , where V _T is the desired volume of the body, V _C is the volume of each vessel, ΔP ₁ is the amount of pressure change in the sample vessel, ΔP ₂ is the amount of pressure change in the measuring vessel; The density of the porous body under study is determined by the formula: , where ρ is the density of the porous body under study, m is the mass of the porous body under study.