KR100570525B1 - Density Measuring Device of Powder Sample - Google Patents

Abstract

Powder sample density measuring apparatus of the present invention was developed by applying Boyle's law that a certain amount of gas is inversely proportional to pressure and volume at a constant temperature, and can accurately measure the volume of powders.

Powder sample density measuring apparatus of the present invention is composed of a sample container containing a powder sample, an expansion container for generating a pressure change, a vacuum system for vacuum of the expansion container, a high-precision pressure gauge, a thermometer, a valve set for adjusting the pressure gauge.

Through the present invention, the basis for the basic research and experiment of density measurement of powder sample using gas pressure conversion was secured, and finally, the basis for establishing the measurement level of powder sample density to 1 × 10 ^-3 or less You can make

Powder sample, density measurement, pressure conversion, sample container, expansion container, valve set, pressure system, vacuum system, flushing system

Description

Establishment of powder density measurement             

1 is a perspective view showing the basic configuration of a density measuring apparatus according to the present invention

Figure 2 is a front view showing an example of use of the density measuring device according to the present invention

3 is a plan view of FIG.

Figure 4a, 4b is a cross-sectional view showing the structure of a large-capacity sample container in the density measuring device according to the present invention

 Figure 5 is a schematic diagram showing the process of measuring the volume of the sample container and expansion container in the density measuring device according to the present invention

6 is a schematic view showing a process of measuring the volume of the powder sample in the density measuring device according to the present invention

<Explanation of symbols for main parts of drawing>

10a, 10b, 10c, 10d, 10e, 10f, 10g, 10h, 10i: valve

11: sample container 12: large capacity sample container

13a, 13b, 13c, 13d, 13e: expansion container 14: intermediate container

15: vacuum system 16: pressure system

17: flushing system 18: main body

19: drain cock 20: relief valve

21: dead volume 22: switchgear

100: volume reference (standard weight) 110: powder sample

The present invention relates to an apparatus for measuring the density of a powder sample, and more particularly, a device including a sample container, an expansion container, a vacuum unit, a pressure and temperature measuring unit, a control valve, a data collection program, and a sample container and an expansion container. The density of the powder sample can be measured precisely by measuring the density of the powder sample using the method of measuring the pressure change and the equilibrium state. It relates to a measuring device.

In general, as the demand for density measurement for high-precision powder samples increases, the research and development of powder sample density measuring apparatus for establishing a density standard for powder samples is urgently needed.

Recently, as the added value of BT, microtechnology, and ET related products has increased, protein composites, thin film materials, activated carbon for filters, environmentally friendly detergents, biotechnology, etc. The demand for density measurement on powdered materials, such as toothpaste, cosmetics, foodstuffs, chemical synthetics, and automobile noise suppressors, is increasing rapidly.

However, it is impossible to accurately measure the density of powder and microporous materials and pores in view of the state of the art.

This is because the solid density measurement can be carried out by static fluid mass spectrometry, in which a sample is placed in a liquid density reference and the buoyancy is measured using a precision balance, because the powder sample is suspended or absorbed in the liquid. If the material is less dense than the reference material, the sample will float, making it impossible to measure the density.

On the other hand, in case of foreign countries, there are some powder characterization equipment that can measure the density of powder sample by using He, N ₂ gas, but the measurement level of powder sample density is very low, so that the reliability of the product is almost You can't expect it.

Therefore, the present invention has been made in view of the above points, the sample container for putting powder samples, the expansion container for generating a pressure change, the vacuum system for the vacuum of the expansion container, the high-precision pressure gauge and thermometer, the pressure control Density measurement including a method for measuring pressure change and equilibrium between a sample vessel and an expansion vessel while applying Boyle's law that a certain amount of gas is inversely proportional in pressure and volume at a constant temperature. By providing the device, it is possible to precisely measure the volume of the powders, and ultimately to establish the density measurement level of the powder sample up to 1 × 10 ^-3 or less, and furthermore, powder samples using gas pressure conversion. The purpose is to provide a basis for conducting basic research and experiments in density measurement.

Density measurement device of the present invention for achieving the above object has a drain cock for the composition and blocking of atmospheric pressure therein, and an openable sample container for the injection of powder samples, and a plurality of expansion containers for creating a vacuum therein A plurality of valves for intermittent between the intermediate container and the container is disposed between the sample container and the expansion container, and connected to one side of the sample container, the pressure of the sample container and the whole of the sample container and the expansion container when the valve is opened A pressure system for measuring pressure, a vacuum system connected to one side of the sample container via a valve to create a vacuum inside the expansion container, and a main body having a control panel and a program for controlling while supporting them. Characterized in that it comprises a.

In addition, it is characterized in that it further comprises a large-capacity sample container that is connected through the valve and the sample container can accommodate a large volume of the sample.

In addition, the large-capacity sample container is fixed on the main body and the lower case for placing the sample, and is supported by the lifting device of the post-block standing on the main body is combined in the upper portion of the lower case, a predetermined closed space therein It is characterized in that it comprises a plurality of clamping device to maintain the closed state while being disposed along the circumference of the upper case and the upper and lower cases.

In addition, the elevating device is arranged in parallel with the post block and the top and bottom end is supported by a rotatable structure, a handle coupled to the upper end of the screw bar, and one side is screwed to the screw bar at the same time guided by the guide block The other side is horizontally extended and is characterized in that it comprises an arm that is fastened to the center of the upper surface of the upper case.

In addition, the sample container and the large-capacity sample container is characterized in that it includes a dead volume that can vary the internal volume to match the powder sample of various volumes therein.

In addition, the plurality of expansion vessel is characterized in that consisting of at least three kinds of containers having different volumes.

In addition, the plurality of expansion vessel is characterized by maintaining the same distance from the intermediate vessel while being disposed radially around the intermediate vessel.

In addition, the sample container is characterized in that it further comprises a helium probe system that can be connected through a relief valve to perform a leak test inside the container.

In addition, the valve for determining the volume limit region between the vessel is characterized in that the diaphragm valve is a volume change is small and can be automatically opened and closed by pneumatic.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

It is important to configure and design the density measurement apparatus of the powder sample provided by the present invention as an optimal mechanism that can express Boyle's law under ideal gas behavior.

In order to ensure the standard traceability of the density measuring device provided by the present invention, since the 1 Kg standard weight is used as the standard volume and the sample volume, the sample container and the expansion container should be designed to have the best volumetric accuracy.

The sample container shall have a minimum volume close to the volume of the powder sample while freely inserting and removing the powder sample to be measured.

This is to ensure the accuracy of the volumetric measurement of the sample container.

Of course, it should be designed to minimize damage to the surface of the standard weight.

In particular, in order to experimentally determine the expansion volume that can obtain the highest volumetric accuracy, it is preferable to combine several containers corresponding to the drainage of the sample container. Can be.

The vacuum degree of the sample container and the expansion container provided in the present invention is designed to be maintained at 1 × 10 ^-5 mmHg or less.

Density measuring device manufactured according to the above design requirements are shown in FIGS.

As shown in Figures 1 to 3, the density measuring device has a drain cock (19) for the composition and blocking of atmospheric pressure therein, the sample container 11 for opening and closing the powder sample, the vacuum inside the A plurality of expansion containers (13a to 13e) for the composition, the intermediate container 14 is disposed between the sample container 11 and the expansion containers (13a to 13e) for connecting between the containers, for intermittent intermittent A plurality of valves (10a to 10f), connected to one side of the sample container 11, including the sample container 11 and the intermediate container 14 when the pressure of the sample container 11 and the valve 10f is opened. Pressure system 16 for measuring the total pressure of any one or more expansion vessels, connected to one side of the sample vessel 11 through the valve 10i to create a vacuum in the expansion vessels (13a to 13e) Vacuum system 15, which serves as a control panel for supporting and controlling these And it comprises a body 18 having a control program.

Here, the sample container 11 has a structure in which two cylindrical cups are assembled to allow access of standard weights or powder samples, and the one-touch opening and closing device is not a general bolting in order to minimize volume change in the assembly part. (22) is equipped.

In addition, the dead volume 21, which is a kind of cup-shaped heavy material, may be inserted into the sample container 11, and the dead volume 21 serves to vary the internal volume in accordance with various volumes of powder samples, for example. In the case of a small powder sample, the dead volume is inserted to serve to close the volume of the sample container 11 and the volume of the powder sample, and in the case of the bulk powder sample, the dead volume can be omitted.

The expansion vessels (13a to 13e) is a hollow cylinder is treated by the "V" groove welding from the inside during the upper and lower lid welding in order to minimize the gap inside the cylinder.

A ball valve type valve is attached to the upper portion of each of the expansion vessels 13a to 13e, so that the inside of the container can be flushed before and after use by operating it.

The valves 10a to 10i that determine the volume limit region between the sample vessel 11 and the expansion vessels 13a to 13e are diaphragm valves which have a small volume change and can be automatically controlled by pneumatic pressure.

The vacuum system 15 of the vessel is composed of a vacuum pump (Diapharm pump, Varian, MD-10) and a vacuum gauge (Thermocouple gage and Ion gage, Varian) having a performance of 10 ^-10 torr, and the front end of the sample vessel (11). It is installed at and is operated with expansion vessels 13a-13e.

Meanwhile, in the present invention, a helium probe system capable of performing a leak test on a valve and a container, a connection part of a measuring sensor, a lid coupling part of a sample container, an exhaust part of an expansion container, and various welding parts in order to improve the degree of vacuum. (17; Helium detector), wherein the helium probe system 17 is connected to one side of the sample container 11 through the relief valve (20).

The pressure system 16 has a measurement range of 0 to 1189 mmHg and an accuracy of 80 ppm, and includes a sensor series 2000 and a display device Model 735.

The pressure system 16, ie, the pressure gauge, plays the most important role in measuring the volume of the sample vessel 11, the expansion vessels 13a to 13e, and the powder sample.

The pressure gauge (Paroscientific, Inc) is connected to one side of the sample container 11 is able to measure the pressure of the sample container 11 and the expanded container together.

In addition, since the pressure gauge may be damaged when pressurized above the maximum pressure, it is desirable to have a pressure regulator and a safety valve.

In addition, the valves 10a to 10i, which determine the volume limit region of the sample container 11 and the expansion containers 13a to 13e, are diaphragm valves having a small volume change and capable of automatically opening and closing by pneumatic pressure, thereby measuring the volume of the container. It is possible to minimize the change in the volume of the valve body in the pipeline between the two vessels.

The movable body 18 includes a control means, which controls the operating elements such as valves and vacuum systems, reads the values detected from the pressure system, calculates or stores them, and displays them on the display device. Play a role.

For example, a control panel is provided at the front of the main body 18 and a data collection program is embedded therein. The data collection program is a part for setting the RS-232C port to enable communication between the pressure sensor and the PC. To read the pressure and temperature from the overpressure sensor, to display the read data in a graph, to determine the safety of the pressure, to display the pressure at this time, to display the data at this time, and to store the data. It consists of.

The pressure continues to change over a very small range, and this small change has a big impact on the volumetric measurement.

Therefore, in order to reduce such an influence, it is determined that the pressure has reached an equilibrium state when the standard deviation of the pressure data of about 10 or less has become a predetermined value, and the average value at this time can be used as the measurement pressure.

The display device displays the measured pressure and sensor temperature on the front panel (not shown) and can be connected to an external device such as a PC using the RS-232C port.

There are two ways to read data using RS-232C port.

One method is to send data to the PC at regular intervals in the display device, and the other method is to send data at the request of the PC.

In the present invention, the latter method is used.

In particular, the density measuring device provided by the present invention includes a plurality of expansion vessels 10a to 10e having different volumes as a method for securing an optimum measurement condition for one sample to be measured.

These expansion vessels 10a to 10e are connected to the sample vessel 11 side including the valves 10a to 10e via the intermediate vessel 14, and the intermediate vessel 14 and the sample vessel ( 11 is connected with being interrupted by the valve 10f.

Such expansion containers (10a to 10e) can be arranged in a number of forms, for example, can be installed in a parallel arrangement or a parallel arrangement structure in a line, in view of the loss of the pipeline, etc. As shown in 3, it is preferable to maintain the same distance from the intermediate container 14 while being disposed radially around the intermediate container 14.

At this time, the expansion vessel (10a ~ 10e) is a container having a different volume or at least three different volumes to be able to perform a test under various conditions for the sample.

In addition, the density measuring apparatus of the present invention includes a helium probe system 17 that is connected through the sample container 11 and the relief valve 20 to perform the leak test in the container.

The use of such a helium probe system, ie a helium probe, enables leak testing throughout the density measurement device.

In addition, the density measuring device provided in the present invention includes a large-capacity sample container 12 that enables the density measurement for a large-capacity sample.

As shown in Figure 4a and 4b, the large-capacity sample container 12 is fixed to the main body 18 on one side of the sample container 11, the lower case 12a, the body 18 to place the sample The upper case 12d, which is supported by the elevating device 12c of the post block 12b standing on the top, is combined with the upper part of the lower case 12a to form a predetermined sealed space therein, and the upper and lower cases ( 12a) and 12d are arranged along the circumference of the clamping device 12e to maintain a closed state.

Here, the upper and lower case 12a, 12d may be installed at a slight distance from the upper surface of the main body 18 by the clamping (12e), the rubber ring (12k) for the airtight portion in contact with each other It is fitted together.

In addition, one side of the lower case 12a is provided with a connector 12l extending from the inside to the outside, and the pipe extending from the sample container 11 side can be connected thereto.

In addition, the post block 12b is composed of two block combinations, and has a structure that can be separated or reassembled by removing and fastening the knob 12j on one side.

The elevating device 12c for opening and closing the upper case 12d is arranged to be parallel to the post block 12b and is rotatable by supporting the upper and lower ends together with the bearing by using up and down brackets extending horizontally from the post block 12b. The screw bar 12f is installed as a handle, a handle 12g integrally coupled to the upper end of the screw bar 12f, and one side is screw-coupled to the screw bar 12f, and a guide block which is in contact with the wall surface of the post block 12b ( 12h) is guided by the other side is horizontally extended and consists of an arm (12i) is fastened to the center of the upper surface of the upper case (12d).

Accordingly, when the handle 12g is turned after the clamping device 12e is released, one end of the arm 12i, which is integrally coupled to the upper case 12d, is screw-transferred with the screw bar 12f. Opening and closing is possible.

The large-capacity sample container 12 also has a dead volume 21, which is a hollow material in the form of a hollow ring, can be inserted therein, and is connected to the sample container 11 side through a valve 10g, so that the sample container 11 can be inserted therein. It can optionally be used under the same conditions as.

The measuring principle of the density measuring device provided by the present invention is the application of Boyle's law that the pressure and volume of a certain amount of gas in a certain container are inversely proportional.

The ideal gas law can be used in relation to pressure and volume, since even in readily available air in the atmosphere, the pressure expands below 1 atm.

At room temperature, gases such as oxygen, nitrogen, helium, and pores follow the ideal gas law, which is about 0.1% below 1 atm, so air can also be applied near atmospheric pressure.

First, in order to measure the volume of the container, as shown in FIG. 5, one or two of the two sample containers 11 or 12 and the expansion containers 13a to 13e divided about the valves 10a to 10f. Vacuum).

Since the vacuum at this time is applied to the expansion container side through the sample container, the sample container also becomes a vacuum state, but this is not a problem.

Subsequently, the valve is closed to maintain the vacuum of the expansion container, and the sample container is sealed after opening to atmospheric pressure, and then the pressure of the two containers is measured.

Subsequently, the valve is opened to expand the gas in the sample container into the expansion container, and the pressure in the containers passing through each other at this time is measured.

Again, the sample container is opened and the volume reference 100 (Volume CRM), for example, 1Kg standard weight of known volume is closed and closed again.

Of course, the expansion vessel at this time is a vacuum state.

Subsequently, the pressure of the two vessels is measured, the valve is opened, the gas of the sample vessel is expanded to the expansion vessel, and the pressure in the vessels passing through each other at this time is measured.

After two pressure measurements, the pressure value is obtained, and the following equations (1) and (2) are established by PV = C, and the volume of the sample container and the volume of the expansion container are obtained from equation (3). .

Equation (1): P _i ^e V _i ^e + P _f ^e V _f = P _t ^e (V _i ^e + V _f )

Equation (2): P _i ^s V _i ^s + P _f ^s V _f = P _t ^s (V _i ^s + V _f )

Equation (3): V _i ^s = V _i ^e -V _c

Where P _i ^e : pressure of the sample container (atmospheric pressure)

P _f ^e : Pressure of expansion vessel (vacuum)

P _i ^s : Pressure of sample container (standard weight in)

P _t ^e : Pressure of sample container + expansion container

P _t ^s : Pressure of sample container + expansion container (standard weight in)

V _i ^e : Volume of sample container (atmospheric pressure)

V _f : Volume of expansion vessel

V _i ^s : Volume of sample chamber (standard weight in)

V _c : Volume of standard weight

After calculating the volumes for these two containers, the volume of the powder sample to be measured can also be obtained in the same way.

As shown in FIG. 6, the powder sample 110 is placed in the sample container instead of the standard weight.

Two pressure measurements were made in the same manner as above to obtain a pressure value. Then, the following formula (1) and formula (2) were established by PV = C, and the volume of the powder sample 110 was obtained through formula (3). V _s )

Equation (1): P _i ^e V _i ^e + P _f ^e V _f = P _t ^e (V _i ^e + V _f )

Equation (2): P _i ^s V _i ^s + P _f ^s V _f = P _t ^s (V _i ^s + V _f )

Equation (3): V _i ^s = V _i ^e -V _s

Where P _i ^e : pressure of the sample container (atmospheric pressure)

P _f ^e : Pressure of expansion vessel (vacuum)

P _i ^s : Pressure of sample container (powder in)

P _t ^e : Pressure of sample container + expansion container

P _t ^s : Pressure of sample container + expansion container (powder sample in)

V _i ^e : Volume of sample container (atmospheric pressure)

V _f : Volume of expansion vessel

V _i ^s : Volume of sample chamber (standard weight in)

V _s : volume of powder sample

By using the density measuring device that is standardized as described above, it is possible to easily and accurately perform density measurement on a sample, especially a powder sample, and to establish density measurement standards such as porosity, powder, small objects, and powder.

As described above, the present invention comprises a sample container for putting a powder sample, an expansion container for generating a pressure change, a vacuum system for vacuum of the expansion container, a high-precision pressure gauge and thermometer, a valve set for adjusting pressure, and the like. By providing a density measuring device including a method for measuring the density of the powder sample by measuring the pressure change and equilibrium state between the sample container and the expansion container, there is an advantage that can accurately measure the volume of powders Finally, the effect of establishing the density measurement level of powder samples to 1 × 10 ^-3 or less, and further, the foundation for the basic research and experiment of powder sample density measurement using gas pressure conversion can be secured. It can be effective.

Claims (9)

A sample container 11 having a drain cock 19 for creating and blocking atmospheric pressure therein, and an openable sample container 11 for inputting a powder sample, a plurality of expansion containers 13a to 13e for forming a vacuum therein, and A plurality of valves 10a to 10f for intermittent control between the intermediate container 14 and the container disposed between the sample container 11 and the expansion containers 13a to 13e, and connected to one side of the sample container 11 Pressure vessel 16 for measuring the pressure of the sample vessel 11 and the total pressure of the sample vessel 11 and the expansion vessels 13a to 13e when the valve is opened, and the sample vessel 11 through the valve 10i. And a main body 18 having a control panel and a program for control while supporting the vacuum system 15, which is connected to one side and serves to create a vacuum inside the expansion vessels 13a to 13e. Density measuring device of the powder sample, characterized in that. The apparatus of claim 1, further comprising a large sample container (12) connected to the sample container (11) and the valve (10 g) to accommodate a large amount of sample. The method of claim 2, wherein the large-capacity sample container 12 is fixed to the main body 18, the lower case 12a for placing the sample and the lifting and lowering of the post block 12b standing on the main body 18 The upper case 12d and the upper case 12a and 12d which are supported by the apparatus 12c and combined with the upper part of the lower case 12a to form a predetermined closed space therein, are arranged along the circumference. Density measurement device of the powder sample, characterized in that it comprises a plurality of clamping device (12e) to maintain a closed state. 4. The handle of claim 3, wherein the elevating device 12c is disposed in parallel with the post block 12b and is supported by a top and bottom end rotatable structure, and a handle coupled to an upper end of the screw bar 12f. 12g and one arm 12i which is screwed to the screw bar 12f and is guided by the guide block 12h and the other extends horizontally to be fastened to the center of the upper surface of the upper case 12d. Density measurement device of the powder sample, characterized in that comprises a. The powder according to claim 1 or 2, wherein the sample container (11) and the large-capacity sample container (12) include a dead volume (21) capable of varying an internal volume in accordance with powder samples of various volumes therein. Sample density measuring device. 2. The density measurement apparatus for a powder sample according to claim 1, wherein the plurality of expansion containers (13a to 13e) are made of a container having at least three different volumes. The density of the powder sample according to claim 1 or 6, wherein the plurality of expansion containers (13a to 13e) are radially arranged around the intermediate container (14) while maintaining the same distance from the intermediate container (14). Measuring device. The density measurement of the powder sample of claim 1, wherein the sample container 11 further includes a helium probe system 17 connected through a relief valve 20 to perform a leak test inside the container. Device. The density measurement apparatus of the powder sample according to claim 1, wherein the valves (10a to 10i) for determining the volume limit region between the vessels are diaphragm valves having a small volume change and which can be opened and closed automatically by pneumatic pressure.

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