Device and method for measuring apparent density of low-density powder

Abstract

The invention belongs to the technical field of density detection devices, and relates to a device and method for measuring the apparent density of low-density powder, the device comprises a bottle body, a cover body, a buoy and a connecting assembly, the cover body is arranged at a bottle opening, the cover body is detachably connected with the bottle body, and the cover body is used for sealing the bottle opening; the cover body is made of a glass sheet which is in smooth contact with the bottle opening, and the connector of the glass sheet and the bottle opening has good air tightness. The buoy is a shell, and scales are arranged on the side face of the buoy. The connecting assembly is arranged between the buoy and the bottle body and comprises a linear connecting piece, the first end of the connecting piece is connected with the buoy, and the other end of the connecting piece is used for being connected with the bottom face of the bottle body. The bottle body is used for containing the solvent and the low-density powder, the bottle body is inversely placed in water, the buoy is connected with the bottle body through the connecting piece, the buoy is used for measuring the buoyancy of the bottle body, the volume of the low-density powder is determined according to the buoyancy, the apparent density of the low-density powder can be measured by directly using water or kerosene as the solvent, and the device is simple in material taking, economical and convenient.

Description

Technical Field

[0001] The invention belongs to the technical field of density detection devices, and in particular relates to a device and a method for measuring the apparent density of low-density powder. Background Art

[0002] The Levitra flask, also known as the density bottle, is a precision glass instrument used to measure the density of liquids or solids. When measuring the density of powdered materials (such as cement, etc.) in the laboratory, the Levitra flask method or the volumetric flask method is mostly used.

[0003] like Figure 4 As shown, the principle of the Lewes flask determination or volumetric flask determination method is to use the difference V2-V1 between the Lewes flask scale readings before and after the addition of the powder as the absolute volume of the powder (without considering water absorption), and then convert its mass and temperature to obtain the density at this temperature.

[0004] The density of high-density powder is greater than that of solvent, while the density of low-density powder is lower than that of solvent. Kerosene is commonly used as solvent in Levitra flask, but the traditional Levitra flask determination or volumetric flask determination can only determine the density of high-density powder with a density greater than that of kerosene. Once the density is lower than that of kerosene, the low-density powder will float above the kerosene. Figure 5 As shown, the volume of the low-density powder cannot be obtained by reading the difference between the scales, and thus the apparent density of the low-density powder cannot be determined. Summary of the invention

[0005] In view of this, the present invention provides a device and method for measuring the apparent density of low-density powder, which can measure the volume of low-density powder, thereby determining the apparent density of the low-density powder.

[0006] The technical solution of the present invention is:

[0007] The device for measuring the apparent density of low-density powder provided by the present invention comprises a bottle body and a cover body, wherein the bottle body is used to contain a solvent and the low-density powder, the cover body is detachably connected to the bottle body, and the cover body is used to close the bottle mouth of the bottle body, and further comprises:

[0008] The buoy is a shell, and the buoyancy of the buoy in water is greater than the total gravity of the bottle body and the water filled in the bottle body;

[0009] A connecting component is arranged between the buoy and the bottle body, and the connecting component comprises a linear connecting piece, a first end of the connecting piece is connected to the buoy, and the other end is used to connect to the bottom surface of the bottle body.

[0010] Preferably, the connecting assembly also includes a first ring, a second ring, and a hook, the first ring is connected to the center position of the bottom surface of the bottle body, the second ring is connected to the buoy, and both ends of the connecting member are connected with hooks, and the hooks are respectively used to connect the first ring and the second ring.

[0011] Preferably, a groove is arranged outside the bottom surface of the bottle body, and the first ring is arranged in the groove.

[0012] Preferably, the buoy comprises a closed hollow shell, the shell is cylindrical, and the volume V of the buoy is 浮 The range is:

[0013] ρ 水 V 浮 >m 总 g,

[0014] Among them, ρ 水 is the density of water, g is the gravitational acceleration constant, m 总 is the total weight of the bottle and the water filled in it.

[0015] Preferably, the buoy is provided with a scale, the scale is a height value, and the zero scale line of the buoy is arranged on a side close to the connecting piece.

[0016] The present invention also provides a method for measuring the apparent density of low-density powder, the method comprising the following steps:

[0017] Fill a portion of the solvent into the bottle;

[0018] Fill the bottle with low-density powder until it is flush with the bottle mouth, and shake the bottle until the bubbles in the low-density powder are removed;

[0019] Seal the bottle mouth with a cover, put the bottle upside down in a water tank, then remove the cover to allow the bottle to sink to the bottom of the water tank while pressing the low-density powder;

[0020] Using a buoy to measure the buoyancy force exerted on the bottle and the solvent and low-density powder inside the bottle;

[0021] Determine the buoyancy of low-density powders in water based on the resultant buoyancy force;

[0022] determining the volume of the low-density powder according to the buoyancy of the low-density powder in water;

[0023] The apparent density of the low-density powder is determined according to the volume of the low-density powder and the mass of the low-density powder.

[0024] Preferably, the buoyancy force F acting on the bottle and the solvent and low-density powder inside the bottle is measured by using a buoy 合 The method comprises the following steps:

[0025] The radius r of the measuring buoy;

[0026] Use the connector to connect the buoy and the bottle, keep them balanced, and read the scale h on the buoy;

[0027] Determine the buoyancy force F on the bottle and the solvent and low-density powder inside according to the following formula: 合 :

[0028] F 合 =ρ 水 ghπr 2 ,

[0029] Among them, ρ 水 is the density of water; g is the gravitational acceleration constant; h is the buoy reading; r is the buoy radius.

[0030] Preferably, the method for determining the buoyancy of a low-density powder in water comprises the following steps:

[0031] Measure the volume of the bottle and record it as V 瓶 ;

[0032] Fill the bottle with some solvent, cover it with the lid, and record the mass m1 at this time;

[0033] Fill the bottle with low-density powder until it is flush with the bottle mouth, remove the bubbles in the low-density powder, and record the mass m2 at this time;

[0034] The buoyancy F of low-density powders is determined according to the following formula 粉末 :

[0035] GF 粉末 -F 瓶体+溶剂 =F 合 ,

[0036] Where G is the total gravity of the bottle, the solvent in the bottle, and the powder in the bottle, G = m2g; F 瓶体+溶剂 is the buoyancy of the bottle and the solvent in the bottle, F 瓶体+溶剂 =ρ 水 V 瓶 .

[0037] Preferably, the volume V of the low-density powder is determined according to the following formula: 粉 :

[0038] F 粉末 =ρ 水 V 粉 ,

[0039] Among them, F 粉末 is the buoyancy of low-density powder in water, ρ 水is the density of water at the test temperature, and g is the gravitational acceleration constant.

[0040] Preferably, the apparent density of the low-density powder is determined according to the following formula: 粉 :

[0041] ρ 粉 =m / V 粉 ,

[0042] Wherein, m is the mass of low-density powder, m=m2-m1, m2 is the total mass of solvent and powder in the bottle, and m1 is the mass of the bottle and the solvent in it; V 粉 is the volume of low-density powder.

[0043] Compared with the prior art, the device and method for measuring the apparent density of low-density powder provided by the present invention have the following beneficial effects:

[0044] The cover body is detachably connected to the bottle mouth of the bottle body, and a buoy is connected to the bottom of the bottle body. When in use, the solvent and low-density powder are placed in the bottle body, and the bottle body is inverted in the solvent. The buoy is connected to the bottom of the bottle body, so that the buoyancy of the bottle body and the solvent and low-density powder inside it can be measured, and the volume of the low-density powder is determined according to the buoyancy, and then the apparent density of the low-density powder is determined. The device has low cost and simple operation. There is no need to find a special solution with extremely low apparent density as a solvent. Water or kerosene can be directly used as a solvent to measure the apparent density of the low-density powder. It only needs the solute to be insoluble in the solvent. The material is simple to obtain, and it is economical and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0046] Figure 2 It is a schematic diagram of the zero scale line of the buoy of the present invention.

[0047] Figure 3 It is a schematic diagram of the method for determining the apparent density of low-density powder according to the present invention.

[0048] Figure 4 This is a test diagram of the relative density of high-density powder measured by the prior art Leigh flask method.

[0049] Figure 5 It is a schematic diagram of low-density powder floating on kerosene in the prior art.

[0050] Figure 6 Schematic diagram of a high-precision density meter in the prior art.

[0051] Description of reference numerals:

[0052] 1. Cover body, 2. Bottom surface, 3. First ring, 4. Scale, 5. Float, 6. Connecting piece, 7. Second ring. DETAILED DESCRIPTION

[0053] It should be noted that, in the description of the present invention, the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0054] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0055] In addition, it should be noted that the component connection relationships not specifically mentioned in the present invention are all assumed to adopt the existing technology. Since they do not involve the invention point and are widely used in the existing technology, the structural connection relationships are not described in detail.

[0056] The subject of the present invention is a device and method for measuring the apparent density of low-density powder. The Lieberle flask, also known as the density bottle, is a precision glass instrument used to measure the density of liquids or solids. When measuring the density of powdered materials (such as cement, etc.) in the laboratory, the Lieberle flask determination or the volumetric flask determination method is mostly used, such as Figure 4 The principle of this method is to use the difference between the scale readings of the Lieberle flask before and after the powder is added (V2-V1) as the absolute volume of the powder (without considering water absorption), and then convert its mass and temperature to obtain the density at this temperature. The commonly used solvent in the Lieberle flask is kerosene.

[0057] However, this method can only measure the density of high-density powders with a density greater than kerosene, because once the density is lower than kerosene, the powder will float above the kerosene, and its volume cannot be obtained by reading the difference in scale (such as Figure 5 ). At this time, only solvents with lower density than kerosene can be used to solve the problem. However, solutions with lower density than kerosene are rare in life and inconvenient to obtain. Low-density powders are very common in actual engineering, such as microbeads. Therefore, the traditional Lieberle flask method has great limitations - there are many scenarios for measuring low-density powders, but the test method is difficult to implement or even impossible to measure. High-precision instruments (such as Figure 6 ) Although it can measure the density of various materials very well, it has the disadvantages of high cost, easy damage and non-portability in actual engineering applications.

[0058] Based on the above reasons, the present invention provides a device and method for measuring the apparent density of low-density powder in order to solve the above-mentioned technical problems. Figures 1 to 3 The present invention is described in detail with reference to the structural schematic diagram of FIG.

[0059] Example 1

[0060] A device for measuring the apparent density of low-density powder comprises a bottle body 8 and a cover body 1. The cover body 1 is detachably connected to the bottle body 8 and is used to seal the bottle mouth of the bottle body 8. The device is characterized in that it also comprises a buoy 5 and a connecting component.

[0061] The cover body 1 can be made of a glass sheet, which is in smooth contact with the bottle mouth, and the interface between the two has good airtightness.

[0062] The float 5 is a cylindrical shell, and a scale 4 is set on the side of the float 5; the scale 4 is set to be reversed, and the reason for the reverse is to facilitate the reading of the float 5 during use. The buoyancy of the float 5 in the water is greater than the total gravity of the bottle body 8 and the water filled in the bottle body 8. The float 5 is used to measure the buoyancy of the bottle body 8 and the solvent and low-density powder in the bottle, and the volume of the low-density powder can be determined based on the buoyancy.

[0063] The connection assembly is arranged between the buoy 5 and the bottle body 8 , and the connection assembly includes a linear connection member 6 , a first end of the connection member 6 is connected to the buoy 5 , and the other end is used to connect to the bottom surface 2 of the bottle body 8 .

[0064] The bottle body 8 is used to contain solvent and low-density powder. The solvent can be water or kerosene, etc. The bottle body 8 is inverted and placed in the solvent. The connector 6 connects the buoy 5 to the bottle body 8. The buoy 5 is used to measure the buoyancy of the bottle body 8 and the low-density powder. The apparent density of the low-density powder can be determined based on the buoyancy.

[0065] In this embodiment, the float 5 includes a closed hollow shell, which is cylindrical, and the buoyancy of the float 5 is greater than the combined gravity of the bottle 8 and the solvent filled therein. The scale 4 of the float 5 is the height value, and the zero scale line of the float 5 is set on the side close to the connecting member 6.

[0066] Specifically, the buoy 5 includes a closed hollow shell, the shell is cylindrical, and the volume V of the buoy 5 is 浮 The range is:

[0067] ρ 水 V 浮 >m 总 g,

[0068] Among them, ρ 水 is the density of water, g is the gravitational acceleration constant, m 总It is the total gravity of the bottle body 8 and the water filled in the bottle body 8.

[0069] In order to facilitate the disassembly and connection of the bottle body 8 and the buoy 5, the connection assembly further includes a first ring 3, a second ring 7, and a hook. The first ring 3 is connected to the center of the bottom surface 2 of the bottle body 8, the second ring 7 is connected to the buoy 5, and hooks are connected to both ends of the connection member 6, which are respectively used to connect the first ring 3 and the second ring 7. The volumes of the first ring 3, the second ring 7, the hook, and the connection member 6 in the connection assembly are relatively small, and the total buoyancy and total gravity of the connection assembly can be ignored.

[0070] After the buoy 5 is removed, in order to facilitate the normal placement of the bottle body 8, the bottom surface 2 of the bottle body 8 is set to be thick, and a groove is set outside the bottom surface 2 of the bottle body 8, and the first ring member 3 is set in the groove. The first ring member 3 does not exceed the plane of the bottom surface 2, ensuring that the bottle body 8 can be placed and used normally.

[0071] How to use this embodiment

[0072] By detachably connecting the cover body at the mouth of the bottle body 8 and connecting the float to the bottom of the bottle body 8, when in use, the solvent and low-density powder are placed in the bottle body 8, the bottle body 8 is inverted in the solvent, and the float is connected to the bottom surface of the bottle body 8, so that the buoyancy of the bottle body 8 and the solvent and low-density powder inside it can be measured, and the volume of the low-density powder is determined according to the buoyancy, and then the apparent density of the low-density powder is determined. The device is low in cost and simple to operate. There is no need to find a special solution with extremely low apparent density as a solvent. Water or kerosene can be directly used as a solvent to measure the apparent density of the low-density powder. It only needs the solute to be insoluble in the solvent, and the material is simple to obtain, which is economical and convenient.

[0073] Example 2

[0074] This embodiment provides a method for measuring the apparent density of low-density powder based on the device proposed in Embodiment 1, and the method comprises the following steps:

[0075] S1. Place the bottle 8 upright and fill the bottle 8 with about 4 / 5 of solvent. The solvent may be water, kerosene, etc. In this embodiment, water is used as the solvent.

[0076] S2. Low-density powder is placed in the bottle body 8 until it is flush with the bottle mouth, and the bottle body 8 is shaken until bubbles in the low-density powder are removed.

[0077] like Figure 3 As shown in (a), during the measurement process, low-density powder is filled into the bottle body 8 until it is full of powder, and then a glass sheet is moved horizontally along the bottle mouth to remove the powder that is full of powder. Next, the glass sheet is pressed tightly and the bottle body is shaken to remove bubbles in the powder, and the above operation is repeated one or two times.

[0078] S3. Seal the bottle mouth with the cover 1, put the bottle 8 upside down into the water tank, then remove the cover 1, so that the bottle 8 presses the low-density powder to sink to the bottom of the water tank.

[0079] like Figure 3 As shown in (b), specifically, the cover body 1 can use a glass sheet. During the measurement process, the glass sheet is pressed tightly, the bottle mouth is turned down in the water tank, and the glass sheet is released under water. At this time, since the apparent density of the powder is smaller than that of water, the powder will float to the bottom of the bottle above, and the buoyancy is not enough to make the bottle body 8 float on the water surface, so the bottle body 8 will press the powder to sink to the bottom of the water (such as Figure 3 shown).

[0080] S4. Use the buoy 5 to measure the combined buoyancy force on the bottle 8 and the water and low-density powder inside it.

[0081] like Figure 3 As shown in (c), the bottle body 8 is connected to the buoy 5 underwater by a hook. At this time, the buoyancy of the buoy is greater than the gravity of the bottle body, which will pull the bottle body upward. Since the hook only transmits longitudinal tension but not torque and horizontal force, the buoy will not tilt whether the powder in the bottle is evenly accumulated or not, and the buoy will always maintain its balanced vertical state.

[0082] Measure the radius of the cylindrical buoy and record it as r;

[0083] Use a connector to connect the buoy and the bottle 8, and after keeping them balanced, read the scale h on the buoy;

[0084] According to Archimedes' principle, the buoyancy force F acting on the bottle 8 and the water and low-density powder inside it is determined by the following formula: 合 :

[0085] F 合 =ρ 水 ghπr 2 ,

[0086] Among them, ρ 水 is the density of water; g is the gravitational acceleration constant; h is the buoy reading; r is the buoy radius.

[0087] S5. Determine the buoyancy of the low-density powder in water according to the resultant buoyancy force. Specifically, the process includes the following steps:

[0088] Measure the volume of the bottle and record it as V 瓶 ;

[0089] Fill the bottle 8 with water, cover it with the cover 1, and record the mass m1 at this time;

[0090] Fill the bottle 8 with low-density powder until it is flush with the bottle mouth, remove the bubbles in the low-density powder, and record the mass m2 at this time; Figure 3In (a), the bottom of the bottle 8 is an electronic scale.

[0091] According to the principle of resultant force:

[0092] Gravity of low-density powder + gravity of bottle + gravity of water in bottle - buoyancy of low-density powder - buoyancy of bottle = combined buoyancy

[0093] The buoyancy F of low-density powders is determined according to the following formula 粉末 :

[0094] GF 粉末 -F 瓶体+水 =F 合 ,

[0095] Among them, G is the gravity of low-density powder + the gravity of the bottle + the gravity of water in the bottle, G = m2g; F 瓶体+水 is the buoyancy of the bottle 8 and the water in the bottle, F 瓶体+水 =ρ 水 V 瓶 .

[0096] Where ρ 水 is the density of water at the test temperature T (g / cm 3 ) shall be taken according to Table B-1 in Appendix B of the “Test Procedure for Aggregates for Highway Engineering” (JTGE42-2005).

[0097] S6. Determine the volume of the low-density powder based on its buoyancy in water.

[0098] The volume V of the low-density powder is determined according to the following formula: 粉 :

[0099] F 粉末 =ρ 水 V 粉 ,

[0100] Among them, F 粉末 is the buoyancy of low-density powder in water, ρ 水 is the density of water at the test temperature, and g is the gravitational acceleration constant.

[0101] S7, determining the apparent density of the low-density powder according to the volume of the low-density powder and the mass of the low-density powder. Specifically comprising the following steps:

[0102] The mass m of the low-density powder is determined according to the following formula:

[0103] m=m2-m1,

[0104] Wherein, m2 is the total mass of water and powder in the bottle 8, and m1 is the mass of the bottle 8 and the water in it;

[0105] The apparent density ρ of low-density powder is determined according to the following formula粉 :

[0106] ρ 粉 =m / V 粉 ,

[0107] Where m is the mass of low-density powder, V 粉 is the volume of low-density powder.

[0108] The above disclosure is only a preferred specific embodiment of the present invention, but the embodiments of the present invention are not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A device for measuring the apparent density of a low-density powder, comprising a bottle body (8) and a cover body (1), wherein the bottle body (8) is used to contain a solvent and a low-density powder, the cover body (1) is detachably connected to the bottle body (8), and the cover body (1) is used to seal the bottle mouth of the bottle body (8), characterized in that: Also includes: The buoy (5) is a shell, and the buoyancy of the buoy (5) in water is greater than the total gravity of the bottle (8) and the water filled in the bottle (8); A connecting component is arranged between the buoy (5) and the bottle body (8), and the connecting component comprises a linear connecting member (6), a first end of the connecting member (6) is connected to the buoy (5), and the other end is used to connect to the bottom surface (2) of the bottle body (8).

2. The device for measuring the apparent density of low-density powder according to claim 1, characterized in that: The connecting assembly further comprises a first ring member (3), a second ring member (7), and two hooks, wherein the first ring member (3) is connected to the center position of the bottom surface (2) of the bottle body (8), the second ring member (7) is connected to the buoy (5), and hooks are connected to both ends of the connecting member (6), and the hooks are respectively used to connect the first ring member (3) and the second ring member (7).

3. The device for measuring the apparent density of low-density powder according to claim 2, characterized in that: The bottom surface (2) of the bottle body (8) is provided with a groove on the outside, and the first ring member (3) is arranged in the groove.

4. The device for measuring the apparent density of low-density powder according to claim 1, characterized in that: The buoy (5) comprises a closed hollow shell, the shell is cylindrical, and the volume V of the buoy (5) is 浮 The range is: ρ 水 gV 浮 >m 总 g, Among them, ρ 水 is the density of water, g is the gravitational acceleration constant, m 总 is the total weight of the bottle (8) and the water filled in the bottle (8).

5. The device for measuring the apparent density of low-density powder according to claim 1, characterized in that: The buoy (5) is provided with a scale (4), the scale (4) being a height value, and the zero scale line of the buoy (5) is provided on a side close to the connecting member (6).

6. A method for determining the apparent density of low-density powder, using the device according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: A portion of solvent is placed in the bottle (8); Low-density powder is placed in the bottle body (8) until it is flush with the bottle mouth, and the bottle body (8) is shaken until bubbles in the low-density powder are removed; The bottle mouth is sealed with a cover (1), the bottle (8) is placed upside down in a water tank, and then the cover (1) is removed, so that the bottle (8) presses the low-density powder to sink to the bottom of the water tank; Using a buoy (5) to measure the combined buoyancy force exerted on the bottle (8) and the solvent and low-density powder inside the bottle; Determine the buoyancy of low-density powders in water based on the resultant buoyancy force; determining the volume of the low-density powder according to the buoyancy of the low-density powder in water; The apparent density of the low-density powder is determined according to the volume of the low-density powder and the mass of the low-density powder.

7. The method for measuring the apparent density of low-density powder according to claim 6, characterized in that: The buoy (5) is used to measure the buoyancy force F exerted on the bottle (8) and the solvent and low-density powder inside the bottle (8). 合 The method comprises the following steps: Measuring the radius r of the buoy (5); Use the connector (6) to connect the buoy (5) and the bottle (8), and after keeping them balanced, read the scale h on the buoy (5); The buoyancy force F acting on the bottle (8) and the solvent and low-density powder inside is determined by the following formula: 合 : F 合 =ρ 水 ghπr 2 , Among them, ρ 水 is the density of water; g is the gravitational acceleration constant; h is the buoy reading; r is the buoy radius.

8. The method for measuring the apparent density of low-density powder according to claim 7, characterized in that: The method for determining the buoyancy of a low-density powder in water comprises the following steps: Measure the volume of the bottle (8) and record it as V 瓶 ; A portion of the solvent is placed in the bottle (8), and the cover (1) is closed. The mass m1 at this time is recorded; Fill the bottle (8) with low-density powder until it is flush with the bottle mouth, remove the bubbles in the low-density powder, and record the mass m2 at this time; The buoyancy F of low-density powders is determined according to the following formula 粉末 : G-F 粉末 -F 瓶体+溶剂 =F 合 , Wherein, G is the total gravity of the bottle body (8), the solvent in the bottle, and the powder in the bottle, G = m2g; F 瓶体+溶剂 is the buoyancy of the bottle (8) and the solvent in the bottle, F 瓶体+溶剂 =ρ 水 V 瓶 .

9. The method for measuring the apparent density of low-density powder according to claim 8, characterized in that: The volume V of the low-density powder is determined according to the following formula: 粉 : F 粉末 =ρ 水 gV 粉 , Among them, F 粉末 is the buoyancy of low-density powder in water, ρ 水 is the density of water at the test temperature, and g is the gravitational acceleration constant.

10. The method for measuring the apparent density of low-density powder according to claim 9, characterized in that: The apparent density ρ of low-density powder is determined according to the following formula 粉 : r 粉 =m / V 粉 , Wherein, m is the mass of the low-density powder, m=m2-m1, m2 is the total mass of the solvent and the powder in the bottle (8), and m1 is the mass of the bottle (8) and the solvent therein; V 粉 is the volume of low-density powder.

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