Ultra-micro liquid extraction device and method of use

Abstract

The invention discloses an ultra-micro liquid taking device and a use method, belonging to the technical field of ultra-micro sampling devices, comprising a plug cover sealed with a container, characterized in that a three-way pipe and a liquid taking main pipe are plugged into the plug cover in a vertical direction, a surface tension hole is provided in the liquid taking main pipe, and the surface tension hole is a small channel provided in the titration main pipe; a liquid outlet is provided on one side above the surface tension hole, and the liquid outlet is connected to the liquid taking pipe, a liquid taking pipe switch and a liquid taking head. The beneficial effect of the invention is that: with the help of microscopic forces, a state in which the liquid in the liquid taking main pipe above the surface tension hole is suspended is first obtained, and under the combined action of the surface tension of the liquid taking main pipe wall and gravity, each drop of liquid coming out of the liquid taking head is equal, which can effectively solve the problems that traditional micro liquid taking devices cannot accurately take micro liquids and cannot ensure the consistency of the volume and weight of the droplets generated each time.

Description

Technical field:

[0002] The present invention belongs to the technical field of ultra-micro sampling devices, and more particularly relates to an ultra-micro liquid sampling device and a use method thereof. Background technology:

[0004] When taking ultra-trace amounts of liquids in daily experiments, two new problems arise when using traditional micro-pipette dispensers: one is the inability to accurately take trace amounts of liquids.

[0005] Taking the hydrosilylation reaction as an example, the hydrosilylation reaction often requires the selection of chloroplatinic acid as a catalyst, but the amount of chloroplatinic acid used is only one hundred thousandth of the total experimental amount.

[0006] Another issue is the inability to guarantee consistent droplet volume and weight each time. In halo experiments, precise micro-amounts of liquid must be dispensed to maintain a consistent halo droplet volume and thus assess the experimental results. Therefore, a device capable of precisely dispensing micro-amounts of liquid at a relatively constant temperature is required. Summary of the invention:

[0008] To solve the above problems and overcome the shortcomings of the existing technology, the present invention provides an ultra-micro liquid collection device and a method of use, which can effectively solve the problems that traditional micro liquid collection devices cannot accurately collect micro liquids and cannot ensure the consistency of the volume and weight of the droplets produced each time.

[0009] The specific technical solution of the present invention to solve the above technical problems is: an ultra-micro liquid taking device, comprising a plug cover sealed with a container, characterized in that the plug cover is plugged with a three-way pipe and a liquid taking main pipe,

[0010] One end of the three-way pipe is inserted into the plug cover, one end of the three-way pipe is connected to the pressurizing structure through the vent pipe, and one end of the three-way pipe is connected to the vent regulating valve;

[0011] The liquid extraction main pipe is inserted into the plug cover in the vertical direction.

[0012] The liquid taking main pipe is provided with a surface tension hole, which is a small channel provided in the liquid taking main pipe;

[0013] A liquid outlet is provided on one side above the surface tension hole, and the liquid outlet is connected to a liquid collection pipe, a liquid collection pipe switch and a liquid collection head.

[0014] Furthermore, the inner diameter of the liquid extraction main pipe is D1 = 0.8-1.2 mm, and the inner diameter of the small channel is D2 = 0.08-0.12 mm.

[0015] Furthermore, a reflux pipe opening is provided on one side below the surface tension hole, the reflux pipe opening is connected to an air pressure connecting pipe, and an upper end of the air pressure connecting pipe is connected to a funnel.

[0016] Furthermore, the pressurizing structure is a piston-type syringe.

[0017] Furthermore, the liquid taking main pipe is provided with a funnel and the port height of the liquid taking main pipe is higher than the inner end surface of the funnel.

[0018] Furthermore, the inner diameter of the liquid outlet is D3, the diameter of the reflux pipe port is D4, and the inner diameter of the air pressure connecting pipe is D5;

[0019] Furthermore, the ratio of D3:D4:D5 is (1.5-3):1:(5-7), D5<((32000*v^2) / g)^(1 / 3); g is the local acceleration of gravity, determined by g=9.7803(1+0.0053024sin²ψ-0.000005sin²2ψ), ψ is the geographical latitude of the object; υ is the kinematic viscosity of the liquid in the bottle.

[0020] Furthermore, the height difference between the surface tension hole and the return pipe opening is H1, and the ratio of D1 to H1 is 1.5-3:1.

[0021] The method for using the ultra-micro liquid collection device adopts the ultra-micro liquid collection device, comprising:

[0022] 1. Close the liquid pipe switch and the ventilation regulating valve, and seal the plug cap with the container filled with liquid.

[0023] 2. Use the pressure structure to pressurize the container and use the pressure to press the liquid in the container into the liquid collection pipe.

[0024] 3. Under the action of pressure, the liquid level rises to the liquid outlet through the surface tension hole, the liquid pipe switch is opened, the air in the liquid pipe and the liquid head is discharged, and the liquid pipe switch is closed;

[0025] 4. Continue to pressurize the container using the pressurizing structure, and the liquid level rises to the funnel and overflows;

[0026] 5. Open the vent control valve and control the volume flow rate to λ[(π*g*D5^4) / (128*υ)], where λ is 1.1-1.5; π is the circumference of the circle; g is the local acceleration of gravity, determined by g=9.7803(1+0.0053024sin²ψ-0.000005sin²2ψ), ψ is the geographic latitude of the object; and υ is the kinematic viscosity of the liquid in the bottle. At this point, due to the combined effects of gravity and surface tension, the liquid in the pressure connecting pipe will flow back into the container through the reflux nozzle, and the liquid main pipe will maintain the preset liquid level.

[0027] 6. Due to the effect of the surface tension hole, a supporting force is generated at the lower end surface of the surface tension hole, which keeps the liquid level of the liquid main pipe at a preset height. The liquid in the liquid main pipe below the reflux pipe mouth flows back into the container, while the liquid in the liquid main pipe above the surface tension hole is suspended in the air.

[0028] 7. Turn on the liquid collection pipe switch. Under the combined action of the surface tension of the liquid collection pipe wall and gravity, each drop of liquid coming out of the liquid collection head is equal.

[0029] The beneficial effects of the present invention are:

[0030] The ultra-micro liquid collection device and usage method creatively prepared by the present invention utilizes microscopic forces to first achieve a state in which the liquid in the liquid collection main pipe located above the surface tension hole is suspended. Under the combined action of the surface tension of the liquid collection main pipe wall and gravity, each drop of liquid coming out of the liquid collection head is of equal amount, which can effectively solve the problems of traditional micro-liquid collection devices that cannot accurately collect micro-liquids and cannot ensure the consistency of the volume and weight of the droplets produced each time. Description of the drawings:

[0032] Attachment Figure 1 It is a schematic diagram of the present invention;

[0033] Attachment Figure 2 This is a schematic diagram of the first state of the present invention;

[0034] Attachment Figure 3 is a schematic diagram of the second state of the present invention;

[0035] Attachment Figure 4 is a schematic diagram of the third state of the present invention;

[0036] Attachment Figure 5 is a schematic diagram of the fourth state of the present invention;

[0037] Attachment Figure 6 is a schematic diagram of the fifth state of the present invention;

[0038] Attachment Figure 7 is a schematic diagram of the sixth state of the present invention;

[0039] Attachment Figure 8 7 is a schematic diagram of the seventh state of the present invention;

[0040] Attachment Figure 9 This is a schematic diagram of the eighth state of the present invention;

[0041] Attachment Figure 10 This is a schematic diagram of the ninth state of the present invention;

[0042] Attachment Figure 11 This is a schematic diagram of the liquid taking state of the present invention;

[0043] Attachment Figure 12 Schematic diagram of Comparative Example 1 of the present invention;

[0044] Attachment Figure 13 Schematic diagram of Comparative Example 2 of the present invention; in the accompanying drawings:

[0045] 1. Pressurized structure, 2. Vent pipe, 3. Tee, 4. Vent regulating valve, 5. Plug, 6. Container, 7. Liquid dispensing main pipe, 8. Bracket, 9. Dispensing head, 10. Liquid dispensing pipe, 11. Surface tension hole, 12. Air pressure connecting pipe, 13. Funnel, 14. Reflux pipe port, 15. Liquid dispensing pipe switch. Specific implementation method:

[0047] In the description of the present invention, specific details are provided solely to facilitate a thorough understanding of the embodiments of the present invention. However, those skilled in the art will appreciate that the present invention is not limited to these details. Furthermore, well-known structures and functions have not been described or illustrated in detail to avoid obscuring the key points of the embodiments of the present invention. Those skilled in the art will appreciate the specific meanings of the above terms as used in the present invention.

[0048] Specific implementation of the present invention:

[0049] In order to better understand the present invention, a specific embodiment is used for illustration. It is worth emphasizing that the effects of this embodiment are not substantially different from those of various embodiments within the scope of protection of the present invention, including the respective reagents and the content ratios of the reagents. All of them can achieve the effects described in the present invention and solve the above-mentioned problems. Other combinations are not described here.

[0050] The ultra-micro liquid extraction device comprises a plug cover 5 sealed with a container 6, wherein the plug cover 5 is provided with a three-way pipe 3 and a liquid extraction main pipe 7.

[0051] One end of the three-way pipe 3 is inserted into the plug cover 5, one end of the three-way pipe 3 is connected to the pressurizing structure 1 through the vent pipe 2, and one end of the three-way pipe 3 is connected to the vent regulating valve 4;

[0052] The liquid extraction main pipe 7 is inserted into the plug cover 5 in the vertical direction.

[0053] The liquid taking main pipe 7 is provided with a surface tension hole 11, the surface tension hole 11 is provided in the liquid taking main pipe 7 of the small channel;

[0054] A liquid outlet is provided on one side above the surface tension hole 11 , and the liquid outlet is connected to the liquid collection pipe 10 , the liquid collection pipe switch 15 and the liquid collection head 9 .

[0055] Furthermore, the inner diameter of the liquid extraction main pipe 7 is D1 = 0.8-1.2 mm, and the inner diameter of the small channel is D2 = 0.08-0.12 mm.

[0056] Furthermore, a reflux pipe opening 14 is provided on one side below the surface tension hole 11 . The reflux pipe opening 14 is connected to the air pressure connecting pipe 12 , and the upper end of the air pressure connecting pipe 12 is connected to the funnel 13 .

[0057] Furthermore, the pressurizing structure 1 is a piston-type syringe.

[0058] Furthermore, the liquid-intake main pipe 7 is penetrated by a funnel 13 and a port height of the liquid-intake main pipe 7 is higher than an inner end surface of the funnel 13 .

[0059] Furthermore, the inner diameter of the liquid outlet is D3, the diameter of the reflux pipe port 14 is D4, and the inner diameter of the air pressure connecting pipe 12 is D5;

[0060] Furthermore, the ratio of D3:D4:D5 is 1.5-3:1:5-7, D5<32000*v^2 / g^1 / 3; g is the local acceleration of gravity, determined by g=9.7803(1+0.0053024sin²ψ-0.000005sin²2ψ), ψ is the geographical latitude of the object; υ is the kinematic viscosity of the liquid in the bottle.

[0061] Furthermore, a height difference between the surface tension hole 11 and the return pipe opening 14 is H1, and a ratio of D1 to H1 is 1.5-3:1.

[0062] The method for using the ultra-micro liquid collection device adopts the ultra-micro liquid collection device, comprising:

[0063] 1. Close the liquid pipe switch 15 and the ventilation regulating valve 4, and seal the plug cover 5 with the container 6 filled with liquid.

[0064] 2. Use the pressurizing structure 1 to pressurize the container 6, and use the pressure to press the liquid in the container 6 into the liquid extraction main pipe 7.

[0065] 3. Under the action of pressure, the liquid level rises to the liquid outlet through the surface tension hole 11, the liquid pipe switch 15 is opened, the air in the liquid pipe 10 and the liquid head 9 is discharged, and the liquid pipe switch 15 is closed;

[0066] 4. Continue to pressurize the container 6 using the pressurizing structure 1, and the liquid level rises to the funnel 13 and overflows;

[0067] 5. Open the vent control valve 4 and control the volume flow rate to λ[(π*g*D5^4) / (128*υ)], where λ is 1.1-1.5; π is the circumference of ...

[0068] 6. Due to the action of the surface tension holes 11, a supporting force is generated at the lower end surface of the surface tension holes 11, which keeps the liquid level of the liquid main pipe 7 at a preset height. The liquid in the liquid main pipe 7 below the reflux pipe opening 14 flows back into the container 6, while the liquid in the liquid main pipe 7 above the surface tension holes 11 is suspended in the air.

[0069] 7. Turn on the liquid taking pipe switch 15. Under the combined effect of the surface tension of the liquid taking main pipe 7 and gravity, each drop of liquid coming out of the liquid taking head 9 is equal in amount.

[0070] In order to more intuitively demonstrate the advantages of the device and method of the present invention, the device and method of the present invention are compared with the method using equivalent replacement of the same process.

[0071] Comparative Example 1:

[0072] The preparation method is the same as that of the embodiment, except that: in the preparation process of this comparative example, the liquid in the liquid main pipe located above the surface tension hole is not suspended in the air, and the liquid is directly discharged; Figure 12 ;

[0073] Specifically

[0074] 1. Close the liquid pipe switch and the ventilation regulating valve, and seal the plug cap with the container filled with liquid.

[0075] 2. Use the pressure structure to pressurize the container and use the pressure to press the liquid in the container into the liquid collection pipe.

[0076] 3. Under the action of pressure, the liquid level rises to the liquid outlet through the surface tension hole, the liquid pipe switch is opened, the air in the liquid pipe and the liquid head is discharged, and the liquid pipe switch is closed;

[0077] 4. Continue to use the pressurizing structure to pressurize the container. After the liquid level rises to a certain level, directly open the liquid extraction pipe switch. At this time, the liquid will be directly discharged from the liquid extraction head 9. Specifically, the liquid column in the liquid extraction main pipe 7 drops first, and then the liquid column in the air pressure connecting pipe 12 drops. The liquid column dropped by the air pressure connecting pipe 12 will cause the liquid column in the liquid extraction main pipe 7 to rise, but it shows an overall downward trend until the gas pressure in the bottle is equivalent to the height of the liquid column in the liquid extraction main pipe 7. At this time, the liquid surface of the liquid extraction main pipe 7 and the air pressure connecting pipe 12 are flush. During this process, the air pressure in the device changes complexly. The liquid column in the device is affected by the time-varying gravity, external pressure and air pressure in the bottle, so that the total force on the liquid extraction head 9 is constantly changing, and the droplets produced will not be uniform.

[0078] The present invention, however, ensures that each drop of liquid emerging from the liquid collection head is of equal volume due to the combined effects of surface tension on the liquid collection main pipe wall and gravity. This is likely due to the following: after operation of the present invention, no liquid column remains in the air pressure communication pipe 12, and the liquid column in the liquid collection main pipe 7 is suspended in mid-air. Consequently, the total force acting on the liquid collection head 9 is solely related to the suspended liquid column in the liquid collection main pipe 7. The present invention controls the liquid level of the suspended liquid column in the liquid collection main pipe 7 to change uniformly with each drop of liquid produced by the liquid collection head 9. Furthermore, since the liquid column is suspended in mid-air, it is not affected by changes in the air pressure within the bottle. In other words, the droplets at the liquid collection head 9, whether due to work done by gravity or atmospheric pressure differences, remain uniform.

[0079] Comparative Example 2:

[0080] The preparation method is the same as that of the embodiment, except that the side of the liquid main pipe is not provided with a reflux pipe port and a pressure connecting pipe. Figure 13 ;

[0081] Although surface tension holes are also provided in the liquid taking main pipe, after the ventilation regulating valve 4 is opened, the air pressure in the bottle is consistent with the air pressure at the liquid level of the liquid column in the liquid taking main pipe 7, and the liquid column falls back; after the liquid taking pipe switch is opened, the liquid flows down naturally from the liquid taking head 9.

[0082] This may be because: the comparative example cannot make the liquid column suspended in the air, so that the pressure difference between the upper and lower parts of the liquid column is consistent and falls back, and uniform dripping cannot be achieved.

[0083] Comparative Example 3:

[0084] The preparation method is the same as that of the embodiment, except that the inner diameter of the liquid taking main pipe is D1 = 10 mm;

[0085] Compared with the present invention, the comparative example cannot achieve the suspension of the liquid column, and thus cannot achieve uniform dripping.

[0086] This may be due to: the diameter of the liquid main pipe in this comparative example is too large, the gravity of the liquid column is too large, and there is a high possibility that the surface tension of the liquid in the small channel will be broken; the diameter of the liquid main pipe in this comparative example is much larger than the diameter of the gas connecting pipe. In step 5 of this example, after the vent valve is opened, the liquid column in the liquid main pipe is subjected to a greater gravity than the liquid column in the gas connecting pipe, and it cannot be ensured that the liquid column in the gas connecting pipe descends before the liquid column in the liquid main pipe, and it cannot be ensured that the air at the reflux pipe mouth falls before the liquid column in the liquid main pipe. As a result, the air at the reflux pipe mouth cannot enter the bottom of the small channel when the liquid column in the liquid main pipe is above the small channel, causing the liquid column to be suspended in the air.

[0087] Comparative Example 4:

[0088] The preparation method is the same as in the embodiment, except that the ratio of the inner diameter of the liquid taking main pipe D1 to H1 is 10:1;

[0089] Compared with the present invention, the suspension of the liquid column cannot be achieved, and thus uniform dripping cannot be achieved.

[0090] This may be because: compared with comparative example 3, this comparative example can make the liquid column in the gas connecting pipe descend before the liquid column in the liquid main pipe, so that the air at the reflux pipe mouth falls back before the liquid column in the liquid main pipe, so that the air at the reflux pipe mouth can enter the bottom of the small channel when the liquid column in the liquid main pipe is located above the small channel. However, since the ratio of D1 to H1 is too large, that is, the reflux pipe mouth is too far away from the small channel, when the air at the reflux pipe mouth enters the bottom of the small channel, it cannot pass through the changes of air gas at the connection between the reflux pipe mouth and the liquid main pipe - the gas enters the liquid column, experiences the generation and The collapse process of bubbles is due to the continuous gas replenishment from the reflux pipe mouth and the fluid impact when the last bit of liquid before the gas falls back. The diameter of the reflux pipe mouth is small. Based on the principle of constant flow, the fluid flow rate here is large, which produces an impact effect. The bubbles grow from small to large and fill the liquid main pipe. However, since the reflux pipe mouth is too far away from the small channel, the bubble boundary cannot touch the bottom of the small channel, and thus cannot cut off the liquid return channel in the liquid main pipe. Then the bubble is subjected to the pressure of the liquid column, and its volume increase is limited. After the critical point, it begins to collapse, causing the liquid in the liquid main pipe to continue to flow slowly.

[0091] Comparative Example 5:

[0092] The preparation method is the same as that of the embodiment, except that the diameter of the reflux pipe opening is different from D4 and is much larger than the diameter of the reflux pipe opening of the present invention; wherein the ratio of D3:D4:D5 is 1:3:3;

[0093] Compared with the present invention, the suspension of the liquid column cannot be achieved, and thus uniform dripping cannot be achieved.

[0094] This may be because: the diameter of the reflux pipe opening is increased to D4, and is larger than the diameter of the liquid main pipe, and consistent with the diameter of the gas connecting pipe; so that the liquid flow rate in the gas connecting pipe does not increase when the liquid falls back to the reflux pipe opening, and cannot provide impact force for the gas to enter the liquid main pipe; and due to the increase in the diameter of the reflux pipe opening D4 itself, the connecting area of the connection between the reflux pipe opening and the liquid main pipe is also increased, that is, when the liquid at the reflux pipe opening is completely refluxed, the exposed area of the liquid column in the liquid main pipe increases, which means that the liquid pressure faced by the gas at the reflux pipe opening when entering the liquid column in the liquid main pipe also increases; based on the above two points, the outcome of this comparative example is the same as that of comparative example 4, both of which cannot effectively cut off the liquid in the liquid main pipe, causing it to continue to flow slowly and cannot be suspended in the air.

[0095] To sum up: the ultra-micro liquid collection device and usage method creatively prepared by the present invention, with the help of microscopic forces, first obtains a state in which the liquid in the liquid collection main pipe located above the surface tension hole is suspended. Under the combined action of the surface tension of the liquid collection main pipe wall and gravity, each drop of liquid coming out of the liquid collection head is equal, which can effectively solve the problems that traditional micro-liquid collection devices cannot accurately collect micro-liquids and cannot ensure the consistency of the volume and weight of the droplets produced each time.

Claims

1. An ultra-micro liquid extraction device, comprising a plug cover (5) sealed with a container (6), characterized in that The plug cover (5) is provided with a three-way pipe (3) and a liquid extraction main pipe (7). One end of the three-way pipe (3) is inserted into the plug cover (5), one end of the three-way pipe (3) is connected to the pressurizing structure (1) through the vent pipe (2), and one end of the three-way pipe (3) is connected to the vent regulating valve (4); The liquid extraction main pipe (7) is inserted into the plug cover (5) in a vertical direction. The liquid taking main pipe (7) is provided with a surface tension hole (11), wherein the surface tension hole (11) is a small channel provided in the liquid taking main pipe (7); A liquid outlet is provided on one side above the surface tension hole (11), and the liquid outlet is connected to a liquid collection pipe (10), a liquid collection pipe switch (15), and a liquid collection head (9); A reflux pipe opening (14) is provided on one side below the surface tension hole (11), the reflux pipe opening (14) is connected to the air pressure connecting pipe (12), and the upper end of the air pressure connecting pipe (12) is connected to the funnel (13).

2. The ultra-micro liquid extraction device according to claim 1, characterized in that The inner diameter of the liquid extraction main pipe (7) is D1 = 0.8-1.2 mm, and the inner diameter of the small channel is D2 = 0.08-0.12 mm.

3. The ultra-micro liquid extraction device according to claim 1, characterized in that The pressurizing structure (1) is a piston-type syringe.

4. The ultra-micro liquid extraction device according to claim 1, characterized in that The liquid taking main pipe (7) is penetrated by a funnel (13), and the height of the port of the liquid taking main pipe (7) is higher than the inner end surface of the funnel (13).

5. The ultra-micro liquid extraction device according to claim 1, characterized in that The inner diameter of the liquid outlet is D3, the diameter of the reflux pipe opening (14) is D4, and the inner diameter of the air pressure connecting pipe (12) is D5.

6. The ultra-micro liquid dispensing device according to claim 5, characterized in that the ratio of D3:D4:D5 is (1.5-3):1:(5-7), D5<((32000*v^2) / g)^(1 / 3); g is the local acceleration of gravity, determined by g=9.7803(1+0.0053024sin²ψ-0.000005sin²2ψ), ψ is the geographical latitude of the object; υ is the kinematic viscosity of the liquid in the bottle.

7. The ultra-micro liquid extraction device according to claim 2, characterized in that The height difference between the surface tension hole (11) and the return pipe opening (14) is H1, and the ratio of D1 to H1 is (1.5-3):

1.

8. A method for using an ultra-micro liquid extraction device, comprising: using the ultra-micro liquid extraction device according to any one of claims 1 to 7, characterized in that include: Step 1: Close the liquid pipe switch (15) and the ventilation regulating valve (4), and seal the plug cover (5) and the container (6) filled with liquid. Step 2: Use the pressurizing structure (1) to pressurize the container (6), and use the pressure to press the liquid in the container (6) into the liquid extraction main pipe (7). Step 3: Under the action of pressure, the liquid level rises to the liquid outlet through the surface tension hole (11), the liquid collection pipe switch (15) is opened, the air in the liquid collection pipe (10) and the liquid collection head (9) is discharged, and the liquid collection pipe switch (15) is closed; Step 4: Continue to pressurize the container (6) using the pressurizing structure (1), and the liquid level rises to the funnel (13) and overflows; Step 5. Open the ventilation regulating valve (4) and control the volume flow rate to λ[(π*g*D5^4) / (128*υ)], where λ is 1.1~1.5; π is the pi; g is the local acceleration of gravity, determined by g=9.7803(1+0.0053024sin²ψ-0.000005sin²2ψ), ψ is the geographical latitude of the object; υ is the kinematic viscosity of the liquid in the bottle; At this time, due to the combined effects of gravity and the surface tension holes (11), the liquid in the air pressure connecting pipe (12) will flow back into the container (6) through the reflux pipe opening (14), and the liquid main pipe (7) will maintain the liquid level at a preset height; Step 6: Due to the action of the surface tension hole (11), a supporting force is generated at the lower end surface of the surface tension hole (11), so that the liquid level of the liquid main pipe (7) is maintained at a preset height. The liquid in the liquid main pipe (7) below the reflux pipe opening (14) flows back into the container (6), and the liquid in the liquid main pipe (7) above the surface tension hole (11) is suspended in the air. Step 7: Open the liquid taking pipe switch (15). Under the combined effect of the surface tension of the liquid taking main pipe (7) and gravity, each drop of liquid coming out of the liquid taking head (9) is equal in amount.

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