A specific gravity measuring instrument suitable for volatile liquids

Abstract

The invention relates to a specific gravity measuring instrument suitable for volatile liquids, which includes: a measuring cylinder; a first end cover and a second end cover, which are respectively covered at both ends of the measuring cylinder; a sheath, which is inserted in the first end cover, and the sheath can selectively allow its top or bottom to be fixed in the first end cover, and a receiving cavity is arranged in the middle of the sheath; a fixed block, which is screwed to the top of the sheath through a thread and can move up and down; a specific gravity meter, the top of which can be stuck in the fixed block; when the top of the sheath is fixed in the first end cover and the specific gravity meter is inserted in the receiving cavity and its top is stuck in the fixed block, the fixed block is at the low point of the moving stroke, and when the fixed block moves upward from the low point, the specific gravity meter will not move under the restriction of the receiving cavity, and the fixed block will be separated from the specific gravity meter. In the present invention, the specific gravity meter is placed in the measuring cylinder in advance, so when measuring the specific gravity value, it is not necessary to open the end cover to put in the specific gravity meter, so the situation that the liquid evaporates and affects the personnel and the environment can be avoided.

Description

Technical Field

[0001] The invention relates to the field of measuring instruments, and in particular to a specific gravity measuring instrument suitable for volatile liquids. Background Art

[0002] In the chemical industry, it is often necessary to measure the specific gravity of a liquid. The current measurement method is to add a certain amount of the liquid to be tested to a measuring cylinder, and then put a hydrometer in the measuring cylinder to observe the specific gravity value. However, if the measured liquid is volatile and has the characteristics of toxicity, corrosiveness or irritation, the liquid will evaporate from the measuring cylinder, affecting the operator and the surrounding environment. For example, in the production process of hydrochloric acid prepared by absorbing hydrogen chloride gas with water, it is usually necessary to detect the absorption concentration. The commonly used method is sampling detection, that is, a certain amount of the liquid to be tested is collected with a measuring cylinder, and then a hydrometer is placed in the measuring cylinder to observe the specific gravity value, and then the specific gravity value is converted into a percentage concentration. However, since the sampled liquid to be tested is concentrated hydrochloric acid, which is volatile, corrosive and has a pungent odor, when measuring the specific gravity value, hydrochloric acid will evaporate from the measuring cylinder, affecting the physical and mental health of the measuring personnel and the surrounding environment.

[0003] In this regard, it is necessary to improve the existing specific gravity measuring device and provide a specific gravity value measuring instrument suitable for volatile liquids to avoid the occurrence of the above situation. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a specific gravity value measuring instrument suitable for volatile liquids, so as to avoid the influence of the volatilization of the liquid on the measuring personnel and the surrounding environment when measuring the specific gravity value.

[0005] In order to solve the above problems, the present invention provides a specific gravity measuring instrument suitable for volatile liquids, which includes a measuring cylinder, a first end cover, a second end cover, a sheath, a fixing block and a specific gravity meter;

[0006] Both ends of the measuring cylinder are open;

[0007] The first end cover is detachably mounted on one end of the measuring cylinder; and the first end cover is provided with an axially penetrating through hole;

[0008] The second end cover is detachably mounted on the other end of the measuring cylinder;

[0009] The sleeve is inserted into the through hole of the first end cover, and the two ends of the sleeve are respectively a first end and a second end. The sleeve can selectively fix the first end in the through hole or the second end in the through hole. When the first end of the sleeve is fixed in the through hole, the second end of the sleeve is located in the inner cavity of the measuring cylinder. When the second end of the sleeve is fixed in the through hole, the first end of the sleeve is located outside the measuring cylinder. At the same time, a receiving cavity for accommodating the hydrometer is provided in the middle of the sleeve, and the cavity shape of the receiving cavity matches the outer contour of the hydrometer. In addition, a sinking hole connected to the receiving cavity is provided on the end surface of the first end of the sleeve, and a first internal thread is provided in the sinking hole.

[0010] The fixing block is inserted into the sinking hole of the sheath, and the lower part of the fixing block is connected to the first internal thread of the sinking hole through the first external thread, and the number of thread turns of the first internal thread is greater than the number of thread turns of the first external thread, and the first external thread cannot be separated from the first internal thread; at the same time, the fixing block is also provided with a slot hole for accommodating the upper end of the hydrometer to be inserted therein, and a card slot is provided in the slot hole;

[0011] The upper end of the hydrometer is provided with a snap ring matching the snap groove;

[0012] When the hydrometer is inserted into the accommodating cavity of the sheath and the clamping ring is inserted into the slot and clamped in the clamping groove, the fixing block is located at a side of the sinking hole close to the second end of the sheath; when the fixing block moves from a side close to the second end to a side away from the second end under the cooperation of the first external thread and the first internal thread, the hydrometer cannot move with the fixing block under the restriction of the accommodating cavity, and the clamping groove will be separated from the clamping ring;

[0013] Wherein, when the hydrometer is fully inserted into the accommodating cavity, there is a gap between the inner wall of the accommodating cavity and the outer wall of the hydrometer; when the upper end of the hydrometer is inserted into the slot, there is a gap between the inner wall of the slot and the outer wall of the hydrometer;

[0014] Wherein, the sinking hole includes a neck hole located on the upper side and a limiting hole located on the lower side, wherein the neck hole and the limiting hole are connected to each other and the aperture of the neck hole is smaller than the aperture of the limiting hole, the bottom of the limiting hole is connected to the top of the accommodating cavity, and the first internal thread is arranged in the limiting hole; a convex column is formed on the lower part of the fixed block, and the convex column includes a neck and a limiting part, wherein the neck is inserted into the neck hole and the outer diameter is smaller than the inner diameter of the neck hole, the limiting part is located in the limiting hole and the diameter of the limiting part is larger than the aperture of the neck hole, and the first external thread is arranged on the circumferential surface of the limiting part; when the limiting part rotates in the limiting hole, the limiting part can move up and down in the limiting hole.

[0015] Further, the sinking hole includes a neck hole located on the upper side and a limiting hole located on the lower side, wherein the neck hole and the limiting hole are connected to each other and the diameter of the neck hole is smaller than the diameter of the limiting hole; the first internal thread is arranged in the limiting hole;

[0016] A boss is formed at the lower part of the fixing block, and the boss includes a neck and a limiting portion, wherein the neck is inserted into the neck hole and has an outer diameter smaller than an inner diameter of the neck hole, and the limiting portion is located in the limiting hole and has a diameter larger than the aperture of the neck hole; and the first external thread is arranged on the peripheral surface of the limiting portion.

[0017] Furthermore, a first sealing ring is arranged in the neck hole to seal the gap between the neck hole and the neck.

[0018] Furthermore, a second sealing ring is provided in the through hole of the first end cover to seal the gap between the through hole and the sheath.

[0019] Furthermore, the upper side of the through hole is provided with a second internal thread, and the lower side of the through hole is provided with a third internal thread;

[0020] The circumferential surface of the first end of the sleeve is provided with a second external thread matching the second internal thread, and the circumferential surface of the second end of the sleeve is provided with a third external thread matching the third internal thread; the sleeve can selectively tighten the second external thread with the second internal thread of the through hole, or tighten the third external thread with the third internal thread of the through hole, so as to achieve the above-mentioned sleeve can selectively fix the first end in the through hole or the second end in the through hole.

[0021] Furthermore, the specific gravity meter also includes a locking mechanism, which is used to limit the sleeve so that it cannot rotate freely around the central axis of the through hole in the through hole.

[0022] Further, the first end cover is provided with a first receiving hole and a second receiving hole which are connected to each other, the axis lines of the first receiving hole and the second receiving hole are colinear and both extend along the radial direction of the first end cover, and at the same time, the outer side of the first receiving hole forms an opening on the side wall of the first end cover, and the inner side of the second receiving hole is connected to the through hole;

[0023] The locking mechanism includes a pressing member, a latch, a first spring and a second spring;

[0024] The pressing member is arranged in the first accommodating hole, and an axial hole concave in the axial direction is arranged at one end of the pressing member facing inward, and a magnet is arranged in the axial hole;

[0025] The latch is arranged in the first receiving hole and the second receiving hole at the same time, and the outward end of the latch is inserted into the shaft hole of the pressing member; and the latch is made of ferromagnetic material;

[0026] The first spring is arranged in the first receiving hole, and the first spring applies a force to the pressing member to move outward;

[0027] The second spring is arranged in the second receiving hole, and the second spring exerts a force on the latch to move inward;

[0028] The side wall of the first end of the sheath is provided with a first slot for accommodating the inner end of the bolt to be inserted therein, and the side wall of the second end is also provided with a second slot for accommodating the inner end of the bolt to be inserted therein;

[0029] Wherein, when the first slot or the second slot is aligned with the second receiving hole, at this time, the locking mechanism has two states, locked and unlocked, and in the natural state, the locking mechanism is in the locked state, and when the pressing piece moves from the outside to the inside, the locking mechanism will gradually switch from the locked state to the unlocked state; wherein, in the locked state, there is a distance between the outer end of the latch and the magnet, and the two are not adsorbed together, and the force applied by the first spring to the pressing piece drives the outer end of the pressing piece to protrude relative to the side wall of the first end cover, and the force applied by the second spring to the latch drives the inner end of the latch to be inserted into the first slot or the second slot; in the unlocked state, the outer end of the latch is adsorbed together with the magnet, and the protrusion degree of the outer end of the pressing piece relative to the side wall of the first end cover is smaller than that in the locked state, and the latch is not inserted into the first slot or the second slot.

[0030] Furthermore, a filter screen is provided on one side of the measuring cylinder close to the second end cover, and the four sides of the filter screen are fixed to the inner wall of the measuring cylinder.

[0031] The beneficial effects of the present invention are as follows: after the liquid to be measured is loaded into the measuring cylinder, when measuring the specific gravity value, the first end cover does not need to be opened, and the fixing block is rotated upward, and the card slot of the fixing block is first disengaged from the card ring of the hydrometer, so that the hydrometer loses its fixation and slides down from the accommodating cavity and floats in the liquid to be measured, and then the locking mechanism is unlocked, and then the fixing block is continued to be rotated, so that the fixing block drives the sheath to rotate together, so that the second external thread is disengaged from the second internal thread, and then the fixing block is lifted upward until the sheath moves to the point where the third external thread contacts the third internal thread, and then the fixing block is rotated again to screw the third external thread into the third internal thread, so that the second end of the sheath is fixed In the through hole, the sheath will be completely separated from the hydrometer and will no longer contact the hydrometer. Therefore, the hydrometer will stably float in the liquid to be tested and will not contact other objects. Therefore, by observing the liquid surface of the liquid to be tested corresponding to the value on the scale paper of the hydrometer, the specific gravity of the liquid can be determined, and then the density and concentration of the liquid can also be obtained. It can be seen that during the entire measurement process, since the hydrometer is placed in the measuring cylinder in advance, the first end cover does not need to be opened during measurement. Therefore, the measuring cylinder is always closed during the measurement process, and the liquid to be tested will not evaporate, so the evaporation of the liquid to be tested can be avoided to affect the physical and mental health of the measuring personnel and the surrounding environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a structural state diagram of Example 1 before use;

[0033] Figure 2 yes Figure 1 Enlarged view within the middle dashed line range;

[0034] Figure 3 This is a schematic diagram of Example 1 when measuring specific gravity value, the second end cover is removed and the measuring cylinder is inverted and loaded with the liquid to be measured;

[0035] Figure 4 is Figure 3 A schematic diagram of the measuring cylinder being turned back after the second end cover is closed on the basis of FIG.

[0036] Figure 5 is Figure 4 Schematic diagram of screwing the fixing block upward to the highest point on the basis;

[0037] Figure 6 is Figure 5 A schematic diagram of a method of unlocking the locking mechanism and continuing to twist the fixing block to separate the second external thread of the sheath from the second internal thread of the through hole;

[0038] Figure 7 is Figure 6 A schematic diagram of a case where the third external thread of the sheath is screwed together with the third internal thread of the through hole on the basis of the present invention;

[0039] Figure 8 yes Figure 7 Enlarged view within the middle dashed line range;

[0040] Fig. 9 The structure of the second end cover in Example 2 is shown. DETAILED DESCRIPTION

[0041] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0042] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and therefore the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0043] Embodiment 1:

[0044] See also Figure 1 and Figure 2 This embodiment provides a specific gravity measuring instrument suitable for volatile liquids, which includes a measuring cylinder 1, a first end cover 2, a second end cover 3, a sheath 4, a fixing block 5 and a specific gravity meter 6.

[0045] The top and bottom of the measuring cylinder 1 are both open.

[0046] The first end cap 2 is threadedly connected to cover the top of the measuring cylinder 1. The first end cap 2 is provided with a first sealing gasket 23. When the first end cap 2 is screwed on the top of the measuring cylinder 1, the first sealing gasket 23 can prevent the liquid in the measuring cylinder 1 from leaking out from the gap between the first end cap 2 and the measuring cylinder 1. In addition, an axial through hole 21 is provided in the middle of the first end cap 2.

[0047] The second end cap 3 is threadedly connected to cover the bottom of the measuring cylinder 1. The second end cap 3 is provided with a second sealing gasket 31. When the second end cap 3 is screwed onto the bottom of the measuring cylinder 1, the second sealing gasket 31 can prevent the liquid in the measuring cylinder 1 from leaking out from the gap between the second end cap 3 and the measuring cylinder 1.

[0048] The sheath 4 is inserted into the through hole 21 of the first end cover 2. The outer diameter of the sheath 4 is slightly smaller than the inner diameter of the through hole 21. The two ends of the sheath 4 are respectively a first end 41 and a second end 42. The sheath 4 can selectively fix the first end 41 in the through hole 21 or fix the second end 42 in the through hole 21. When the first end 41 of the sheath 4 is fixed in the through hole 21, the second end 42 of the sheath 4 is located in the inner cavity of the measuring cylinder 1 (see Figure 1), when the second end 42 of the sheath 4 is fixed in the through hole 21, the first end 41 of the sheath 4 is located outside the measuring cylinder 1 (see Figure 7 ). At the same time, a receiving cavity 43 for receiving the hydrometer 6 is provided in the middle of the sheath 4. The cavity shape of the receiving cavity 43 matches the outer contour of the hydrometer 6. The receiving cavity 43 can cover the lower half of the hydrometer 6, but cannot completely wrap the hydrometer 6 therein, and the size of the receiving cavity 43 is slightly about the size of the hydrometer 6, that is, when the hydrometer 6 is fully inserted into the receiving cavity 43, there is a small gap between the inner wall of the receiving cavity 43 and the outer wall of the hydrometer 6. Once the hydrometer 6 loses its fixation, the hydrometer 6 will slide out of the receiving cavity 43 under the action of gravity. In addition, a sinking hole 44 communicating with the receiving cavity 43 is provided on the end surface of the first end 41 of the sheath 4, and a first internal thread 44a is provided in the sinking hole 44.

[0049] The fixing block 5 is inserted into the sink hole 44 of the sheath 4, and the lower part of the fixing block 5 is connected to the first internal thread 44a of the sink hole 44 through the first external thread 5a, and the number of threads of the first internal thread 44a is greater than the number of threads of the first external thread 5a, and the first external thread 5a cannot be separated from the first internal thread 44a. At the same time, the interior of the fixing block 5 is also provided with a slot 51 for accommodating the upper end of the hydrometer 6 to be inserted therein, and an annular groove 511 is provided in the slot 51. At the same time, when the upper end of the hydrometer 6 is inserted into the slot 51, there is a gap between the inner wall of the slot 51 and the outer wall of the hydrometer 6, so when the hydrometer 6 is not fixed, the hydrometer 6 will slide out of the slot 51 under the action of gravity.

[0050] The hydrometer 6 is basically consistent with the common hydrometer 6 on the market, except that the hydrometer 6 of this embodiment is provided with a ring 61 on its upper end to match the clamping groove 511. The hydrometer 6 is a sealed glass tube, the upper part of which is uniform in thickness and provided with a graduated paper inside, and the lower part is slightly expanded to be a bubble-like body, in which small lead particles or mercury are filled, so that the glass tube can be vertically immersed in the liquid to be tested to a sufficient depth and stably float in the liquid to be tested. When the hydrometer 6 stably floats in the liquid, the buoyancy it receives is equal to its own gravity. Therefore, according to the Archimedean principle, when the density of the liquid is greater, the depth of the hydrometer 6 immersed in the liquid is smaller, and vice versa, the depth of immersion is greater. Therefore, when the hydrometer 6 floats in the liquid, the density of the liquid can be judged according to the immersion depth, that is, the density of the liquid (or the specific gravity value, concentration of the liquid) can be judged according to the value of the liquid surface corresponding to the graduated paper.

[0051] The accommodating cavity 43 can not only wrap the upper part of the hydrometer 6, but also wrap a part of the lower part of the bubble of the hydrometer 6. Figure 1 .

[0052] When the hydrometer 6 is inserted into the accommodating cavity 43 of the sheath 4 and the snap ring 61 is inserted into the slot 51 and clamped in the clamping groove 511, at this time, the fixing block 5 is located at a side of the sinking hole 44 close to the second end 42 of the sheath 4, that is, at this time, the fixing block 5 is located at a low point and can move upward relative to the sinking hole 44, see Figure 2 When the fixing block 5 is screwed to move from the side close to the second end 42 to the side away from the second end 42 by means of the cooperation between the first external thread 5a and the first internal thread 44a (i.e., Figure 2 In this process, since the sheath 4 is stationary, the fixing block 5 will move upward relative to the sheath 4. At the same time, since the shape of the accommodating cavity 43 matches the outer contour of the hydrometer 6, and the hydrometer 6 is a structure with a small top and a large bottom, the hydrometer 6 cannot move with the fixing block 5 under the restriction of the accommodating cavity 43, so the clamping groove 511 will be separated from the clamping ring 61 (see Figure 5 ), after separation, the hydrometer 6 loses its fixation and falls from the accommodating chamber 43 under the action of gravity.

[0053] In the above structure, the fixed block 5 plays the following roles: on the one hand, the fixed block 5 enables the hydrometer 6 to be placed in the inner cavity of the measuring cylinder 1 in advance, so that when measuring the specific gravity value later, it is no longer necessary to open the end cover to put in the hydrometer 6, thereby preventing the volatile liquid from volatilizing from the measuring cylinder 1; on the other hand, since the hydrometer 6 is fixed in the measuring cylinder 1 by the fixed block 5, when the measuring cylinder 1 shakes, the hydrometer will not collide with the inner wall of the measuring cylinder 1, thereby preventing the hydrometer 6 from being damaged. The sheath 4 plays the following roles: on the one hand, the sheath 4 wraps the hydrometer 6 therein, thereby preventing the hydrometer 6 from being broken when strong shaking occurs; on the other hand, when the fixed block 5 is to be separated from the hydrometer 6, the sheath 4 also serves to limit the hydrometer 6 so that it cannot move with the fixed block 5, so that the fixed block 5 can be smoothly separated from the hydrometer 6.

[0054] In this embodiment, regarding the connection between the fixing block 5 and the sheath 4 and the connection between the fixing block 5 and the hydrometer 6, the more specific structure is as follows:

[0055] See also Figure 2 The sinking hole 44 includes a neck hole 441 located on the upper side and a limiting hole 442 located on the lower side, wherein the neck hole 441 and the limiting hole 442 are connected to each other and the aperture of the neck hole 441 is smaller than the aperture of the limiting hole 442, and the bottom of the limiting hole 442 is connected to the top of the accommodating cavity 43; the first internal thread 44a is arranged in the limiting hole 442;

[0056] A boss 52 is formed at the lower part of the fixing block 5, and the boss 52 includes a neck 521 and a limiting portion 522, wherein the neck 521 is inserted into the neck hole 441 and has an outer diameter smaller than the inner diameter of the neck hole 441, the limiting portion 522 is located in the limiting hole 442 and has a diameter larger than the aperture of the neck hole 441, and a thickness of the limiting portion 522 is approximately half of the height of the limiting hole 442, and the first external thread 5a is provided on the circumferential surface of the limiting portion 522, thereby, when the limiting portion 522 rotates in the limiting hole 442, it can move up and down in the limiting hole 442; the slot 51 extends upward in the axial direction from the lower surface of the boss 52;

[0057] When the hydrometer 6 is inserted into the accommodating cavity 43 of the sheath 4 and the clamping ring 61 is clamped in the clamping groove 511, at this time, the limiting portion 522 is in the lower part area of ​​the limiting hole 442, and the limiting portion 522 has space to move upward, see Figure 2 That is, if the fixing block 5 is twisted to move upward relative to the sinking hole 44, the clamping groove 511 will be separated from the clamping ring 61, the limiting portion 522 will move to the upper part of the limiting hole 422, and the hydrometer 6 will lose its fixation. Figure 5 Subsequently, since the limiting portion 522 has moved to the highest point in the limiting hole 442, if the fixing block 5 continues to be twisted, the fixing block 5 will exert a force on the sheath 4, rotating with the sheath 4, thereby gradually disengaging the second external thread 4a from the second internal thread 21a.

[0058] Among them, the above-mentioned snap ring 61 and the slot 511 belong to a common structure of connection and cooperation in the prior art. When the two components respectively provided with the snap ring and the slot are pushed toward each other, the snap ring will be stuck in the slot to achieve the connection between the two. When the two components respectively provided with the snap ring and the slot are pulled away from each other, the snap ring will be separated from the slot to achieve the separation between the two.

[0059] Furthermore, a first sealing ring 45 is disposed in the neck hole 441 to seal the gap between the neck hole 441 and the neck 521 to prevent the liquid in the measuring cylinder 1 from leaking out of the gap.

[0060] Similarly, since the outer diameter of the sheath 4 is smaller than the inner diameter of the through hole 21 and there is a gap between the two, a second sealing ring 22 is further provided in the through hole 21 in this embodiment to seal the gap between the through hole 21 and the sheath 4 to prevent the liquid in the measuring cylinder 1 from leaking out of the gap.

[0061] In this embodiment, the first end 41 or the second end 42 of the sheath 4 is fixed to the through hole 21 by the following structure:

[0062] See also Figure 2 , a second internal thread 21a is provided on the upper side of the through hole 21, and a third internal thread 21b is provided on the lower side; and there is a non-threaded area between the second internal thread 21a and the third internal thread 21b, and the second sealing ring 22 is provided in this area;

[0063] See also Figure 2 The circumferential surface of the first end 41 of the sheath 4 is provided with a second external thread 4a matching the second internal thread 21a; see Figure 1 The circumferential surface of the second end 42 of the sheath 4 is provided with a third external thread 4b matching the third internal thread 21b;

[0064] The sheath 4 can selectively tighten the second external thread 4a with the second internal thread 21a of the through hole 21 or tighten the third external thread 4b with the third internal thread 21b of the through hole 21, so as to achieve the above-mentioned that the sheath 4 can selectively fix the first end 41 in the through hole 21 or fix the second end 42 in the through hole 21; that is, when the second external thread 4a is tightened in the second internal thread 21a (see Figure 2 ), at this time, the sleeve 4 can be rotated to rotate the second external thread 4a out from above the second internal thread 21a, so that the sleeve 4 is no longer fixed to the through hole 21, and then the sleeve 4 is lifted up until the third external thread 4b contacts the third internal thread 21b, and then the sleeve 4 is continued to be rotated, so that the third external thread 4b can be screwed into the third internal thread 21b, until the third external thread 4b is tightened in the third internal thread 21b; similarly, when the third external thread 4b is tightened in the third internal thread 21b (see Figure 8 ), at this time, the sleeve 4 can be rotated in the opposite direction to rotate the third external thread 4b out from under the third internal thread 21b, so that the sleeve 4 is no longer fixed to the through hole 21, and then the sleeve 4 is pushed downward until the second external thread 4a contacts the second internal thread 21a, and then the sleeve 4 is continued to be rotated, so that the second external thread 4a can be screwed into the second internal thread 21a, until the second external thread 4a is tightened in the second internal thread 21a.

[0065] In this embodiment, the rotation direction of all internal threads and all external threads is consistent. Further, when the sleeve 4 is fixed, the fixing block 5 is rotated counterclockwise, and the limiting portion 522 of the fixing block 5 will gradually move upward relative to the limiting hole 442; when the second external thread 4a of the sleeve 4 is tightened in the second internal thread 21a of the through hole 21, if the first end cover 2 is fixed at this time, and then the sleeve 4 is rotated counterclockwise, the second external thread 4a will gradually break away from the top of the second internal thread 21a, and the sleeve 4 will move upward relative to the first end cover 2; when the top of the third external thread 4b of the sleeve 4 contacts the bottom of the third internal thread 21b of the through hole 21, if the first end cover 2 is fixed at this time, and then the sleeve 4 is pulled upward while rotating the sleeve 4 counterclockwise, the second external thread 4a will gradually screw into the third internal thread 21b, and the sleeve 4 will gradually move upward. Among them, the counterclockwise rotation mentioned above refers to the rotation direction from the top view in the accompanying drawings.

[0066] In this embodiment, since the fixing block 5 is connected to the sink hole 44 by means of threads, and the sheath 4 is also connected to the through hole 21 by means of threads, when the fixing block 5 rotates upward from the lowest point in the sink hole 44 (i.e., from Figure 2 If the rotation of the sheath 4 is not restricted, the sheath 4 may rotate together with the fixing block 5. Therefore, in order to avoid this possibility, the present embodiment intentionally adds a locking mechanism 7 to restrict the rotation of the sheath 4. The specific mechanism is as follows:

[0067] The locking mechanism 7 is used to restrict the sheath 4 from freely rotating in the through hole 21 around the central axis of the through hole 21;

[0068] See also Figure 2 In order to install the locking mechanism 7, a first receiving hole 24 and a second receiving hole 25 are provided in the first end cover 2, which are connected to each other. The axis lines of the first receiving hole 24 and the second receiving hole 25 are colinear and extend along the radial direction of the first end cover 2. At the same time, the outer side of the first receiving hole 24 forms an opening on the side wall of the first end cover 2, and the inner side of the second receiving hole 25 is connected to the through hole 21.

[0069] See also Figure 2 , the locking mechanism 7 includes a pressing member 71, a latch 72, a first spring 73 and a second spring 74;

[0070] The pressing member 71 is arranged in the first receiving hole 24, and an axial hole 711 concave in the axial direction is provided at one end of the pressing member 71 facing inward, and a magnet 75 is provided at the bottom of the axial hole 711;

[0071] The latch 72 is arranged in both the first receiving hole 24 and the second receiving hole 25, and the outward end of the latch 72 is inserted into the shaft hole 711 of the pressing member 71; and the latch 72 is made of iron material;

[0072] The first spring 73 is arranged in the first receiving hole 24, and the first spring 73 exerts a force on the pressing member 71 to move outward (i.e. Figure 2 on the right side of the );

[0073] The second spring 74 is arranged in the second receiving hole 25, and the second spring 74 exerts a force on the latch 72 to move inward (i.e. Figure 2 on the left side of the );

[0074] In order to cooperate with the latch 72, the side wall of the first end 41 of the sheath 4 is provided with a first slot 46 for accommodating the inner end of the latch 72 to be inserted therein (see Figure 2 ), the side wall of the second end 42 is also provided with a second slot 47 for receiving the inner end of the latch 72 and inserting it therein (see Figure 8 );

[0075] When the first slot 46 or the second slot 47 is aligned with the second receiving hole 25, the locking mechanism 7 has two states: locked and unlocked. In the natural state, the locking mechanism 7 is in the locked state. When the pressing member 71 moves from outside to inside (i.e., toward Figure 2 The locking mechanism 7 will gradually switch from the locked state to the unlocked state; wherein, when in the locked state, see Figure 2 There is a gap between the outer end of the latch pin 72 and the magnet 75, and the two are not adsorbed together. The force exerted by the first spring 73 on the pressing member 71 drives the outer end of the pressing member 71 to protrude relative to the side wall of the first end cover 2, and the force exerted by the second spring 74 on the latch pin 72 drives the inner end of the latch pin 72 to be inserted into the first slot 46 or the second slot 47; when in the unlocked state, see Figure 6When the locking cam 72 is in the unlocked state, the locking cam 72 will automatically return to the locked state if the pressing member 71 loses the driving force to move inward (for example, when the finger no longer presses the pressing member 71), that is, when the locking cam 7 is in the unlocked state, the force of the first spring 73 on the pressing member 71 is greater than the adsorption force between the latch pin 72 and the magnet 75. Therefore, once the pressing member 71 loses the driving force to move inward, the first spring 73 will push the pressing member 71 to move outward, so that the magnet 75 is separated from the latch pin 72, and then the second spring 74 will also push the latch pin 72 to move inward, and finally the locking cam 7 will return to the locked state.

[0076] The first slot 46 and the second slot 47 are both strip-shaped slots that surround the outer wall of the sheath 4 and span a certain angle. For example, the first slot 46 and the second slot 47 are both arc-shaped slots with corresponding central angles of 60 degrees, and have a certain inclination similar to a thread. After being designed as strip-shaped slots, the sheath 4 does not need to be rotated to a certain position before the pin 72 can be inserted into the slots 46 and 47, but only needs to be rotated within a certain range before the pin 72 can be inserted into the slots 46 and 47. Compared with a slot with a hole structure, it is more conducive to the smooth insertion of the pin 72 into the slot.

[0077] For further information, see Figure 2 The outer wall of the pressing member 71 is provided with a first convex ring 712 with an enlarged diameter, and the first receiving hole 24 is provided with a first annular groove 241 with an enlarged diameter. The first convex ring 712 is located in the first annular groove 241, and the first convex ring 712 can move back and forth in the first annular groove 241. One end of the first spring 73 abuts against the inner end surface of the pressing member 71, and the other end abuts against the inner end surface of the first receiving hole 24. In a natural state, the force applied by the first spring 73 to the pressing member 71 will drive the first convex ring 712 of the pressing member 71 to be close to the outer end of the first annular groove 241. At the same time, at this time, the outer end of the pressing member 71 is raised relative to the side wall of the first end cover 2 (the raised height is preferably 2mm to 5mm). Figure 2 At this time, if the outer end of the pressing member 71 is pressed by hand, the pressing member 71 will move inward and compress the first spring 73 until the pressing member 71 moves to the inner end of the first convex ring 712 close to the first ring groove 241, and the pressing member 71 can no longer move inward. Figure 6 ;

[0078] For further information, see Figure 2The outer wall of the latch 72 is provided with a second convex ring 721 with an enlarged diameter. The second receiving hole 25 is divided into two sections, the inner section has a smaller diameter (slightly larger than the outer diameter of the latch 72), and the outer section has a larger diameter. The second convex ring 721 is located in the outer section of the second receiving hole 25. The second convex ring 721 can move back and forth in the outer section of the second receiving hole 25. One end of the second spring 74 abuts against the outer end surface of the second convex ring 721, and the other end abuts against the outer end surface of the second receiving hole 25. In the natural state, the force exerted by the second spring 74 on the second convex ring 721 drives the second convex ring 721 to be located at the innermost side of the moving stroke. At the same time, at this time, the inner end of the latch 72 extends from the second accommodating hole 25 and is inserted into the first slot 46 or the second slot 47, and the outer end of the latch 72 is inserted into the axial hole 711 of the pressing member 71 and is spaced from the magnet 75. That is, at this time, the magnet 75 has no adsorption force on the latch 72 or the adsorption force of the magnet 75 on the latch 72 is smaller than the force exerted by the second spring 74 on the second convex ring 721. Figure 2 At this time, if the pressing piece 71 moves inward, the distance between the magnet 75 and the latch 72 will become smaller and smaller. When the distance is small to a certain extent, the adsorption force of the magnet 75 on the latch 72 will be greater than the force of the second spring 74 on the second convex ring 721 at this time. Therefore, the latch 72 will quickly move to the side close to the magnet 75 and be adsorbed on the magnet 75, so that the inner end of the latch 72 leaves the first slot 46 or the second slot 47, allowing the sheath 4 to be unlocked.

[0079] In addition, in this embodiment, a filter screen 8 is provided on one side of the measuring cylinder 1 close to the second end cover 3, and the filter screen 8 is fixed to the inner wall of the measuring cylinder 1 on all sides.

[0080] Before use, the specific gravity measuring instrument of this embodiment has a structural state as follows: Figure 1 and Figure 2 As shown:

[0081] The first end cap 2 is screwed on the top of the measuring cylinder 1, and the second end cap 3 is screwed on the bottom of the measuring cylinder 1. The first end 41 of the sheath 4 is screwed on the through hole 21 of the first end cap 2 by the cooperation of the second external thread 4a and the second internal thread 21a. The limiting portion 522 of the fixing block 5 is screwed on the bottom position of the limiting hole 442. The hydrometer 6 is inserted into the accommodating cavity 43 of the sheath 4. At the same time, the upper end of the hydrometer 6 is inserted into the slot 51 of the fixing block 5 and the snap ring 61 of the hydrometer 6 is inserted into the snap groove 511 of the fixing block 5, that is, the hydrometer 6 is suspended and fixed in the measuring cylinder 1, and the locking mechanism 7 is in a locked state, that is, at this time, the outer end of the pressing member 71 protrudes relative to the side wall of the first end cap 2, and the inner end of the latch 72 is inserted into the first slot 46 of the sheath 4, and the outer end is spaced apart from the magnet 75.

[0082] When using the specific gravity measuring instrument of this embodiment to measure the specific gravity value of the liquid to be measured, the steps are as follows:

[0083] First, unscrew the second end cap 3, and then invert the entire device, and then inject the liquid to be tested 9 into the measuring cylinder 1. During the injection, the liquid to be tested may contain impurities, which will be blocked by the filter 8 and cannot fall. When the measuring cylinder 1 is turned over, the impurities will be blocked under the filter 8, thereby preventing the impurities from floating in the measuring cylinder 1 and affecting the measurement of the specific gravity value. The state diagram after injecting the liquid to be tested 9 is as follows: Figure 3 As shown;

[0084] After that, screw the second end cap 3 back, then turn the whole device over and place it on a flat surface, such as Figure 4 As shown;

[0085] Then, the specific gravity value of the liquid to be measured 9 is measured. During the measurement process, the fixation of the hydrometer 6 needs to be released first, so that the hydrometer 6 floats in the liquid to be measured, and then the sheath 4 is removed to prevent the hydrometer 6 from contacting the sheath 4 and affecting the free floating of the hydrometer 6 in the liquid to be measured 9, and finally the specific gravity value is observed;

[0086] When releasing the fixation of the hydrometer 6, the specific steps are as follows: hold the outer wall of the measuring cylinder 1 with one hand, and pinch the top of the fixing block 5 with the other hand and then rotate it counterclockwise. During this process, since the sheath 4 is restricted by the locking mechanism 7 and cannot rotate freely, the limiting portion 522 of the fixing block 5 will gradually move upward in the limiting hole 422, and the hydrometer 6 cannot move upward with the fixing block 5 due to the restriction of the sheath 4 accommodating cavity 43. Therefore, the card groove 511 will eventually be separated from the clamping ring 61, the hydrometer 6 will lose its fixation and then slide down from the accommodating cavity 43 and float in the liquid 9 to be measured, and the limiting portion 522 will move to the highest point in the limiting hole 422, see Figure 5 ;

[0087] Afterwards, when removing the sheath 4, the specific steps are as follows: press the outer end of the pressing piece 71 with the thumb and keep it still to move the pressing piece 71 inward, so that the locking mechanism 7 is switched to the unlocked state (that is, the outer end of the latch 72 is attracted to the magnet 75, and the inner end leaves the first slot 46), and then continue to rotate the fixing block 5 counterclockwise. At this time, since the limiting portion 522 of the fixing block 5 has moved to the highest point in the limiting hole 422, the limiting portion 522 cannot continue to move upward in the limiting hole 422. At the same time, the sheath 4 is unlocked and can rotate in the through hole 21, so the rotation of the fixing block 5 will drive the sheath 4 to rotate together, so the second external thread 4a of the sheath 4 will rotate out from above the second internal thread 21a of the through hole 21 until the second external thread 4a completely leaves the second internal thread 21a, see Figure 6; Afterwards, since the second external thread 4a completely leaves the second internal thread 21a, the sleeve 4 and the through hole 21 lose their mutually fixed relationship. At this time, continue to press the outer end of the pressing piece 71, and then lift the fixing block 5 upward to move the sleeve 4 upward. When the third external thread 4b of the sleeve 4 contacts the third internal thread 21b of the through hole 21, then pull the fixing block 5 upward while rotating it counterclockwise. During this process, the third external thread 4b will gradually screw into the third internal thread 21b until the two are completely tightened, and the second slot 47 will align with the latch pin 72. At this time, release the thumb and no longer press the pressing piece 71, the locking mechanism 7 will automatically return to the locked state, and the inner end of the latch pin 72 will be inserted into the second slot 47, so that the sleeve 4 is locked and cannot rotate freely. See Figure 7 and Figure 8 ;

[0088] Afterwards, since the entire sheath 4 has been completely moved to the top of the measuring cylinder 1, the accommodating cavity 43 is completely separated from the hydrometer 6, and the sheath 4 does not contact the hydrometer 6, so the hydrometer 6 will stably float in the liquid to be tested 9 and will not contact other objects. Therefore, the density of the liquid (or the specific gravity value, concentration of the liquid) can be known by directly observing the value on the scale paper of the hydrometer 6 corresponding to the liquid surface of the liquid to be tested 9;

[0089] In the above process, only Figure 3 When the liquid 9 to be tested is injected into the measuring cylinder 1, there may be a situation where the liquid evaporates. However, in the process of measuring the specific gravity value later, since the hydrometer 6 is placed in the measuring cylinder 1 in advance, there is no need to open the end cover to put in the hydrometer 6 during measurement. During the measurement process, the measuring cylinder 1 is always closed, so the liquid 9 to be tested will not evaporate, so the situation that the evaporation of the liquid 9 to be tested affects the physical and mental health of the measuring personnel and the surrounding environment can be avoided. In the existing measurement method, since the top of the measuring cylinder is always open, the volatile liquid to be tested will evaporate from the measuring cylinder. If the liquid to be tested is also toxic, corrosive or irritating, it is bound to affect the physical and mental health of the measuring personnel and the surrounding environment.

[0090] In addition, in the chemical industry, after collecting the liquid to be measured with the measuring cylinder 1, it may be limited by space and environment, and the measurement cannot be performed immediately. It is necessary to cover the end cap and leave the collection point to go to the laboratory or workbench to measure. Therefore, under the existing measurement method, after the measuring cylinder 1 is transferred to the laboratory or workbench, the end cap must be opened and the hydrometer 6 must be placed before measurement, so the liquid to be measured will evaporate in the process. After adopting the measuring device of this embodiment, after the measuring cylinder 1 is transferred to the laboratory or workbench, the end cap does not need to be opened again, the hydrometer 6 is placed in the measuring cylinder 1 in advance, and the measuring cylinder 1 is closed during the measurement process, so the liquid will not evaporate.

[0091] In this embodiment, the fixing block 5 mainly plays the role of fixing the hydrometer 6, so that the hydrometer 6 can be placed in the inner cavity of the measuring cylinder 1 in advance, and the subsequent measurement can be carried out when the measuring cylinder 1 is closed, and there is no need to open the end cover to put in the hydrometer 6, thereby avoiding the evaporation of the liquid to be measured. The sheath 4 plays the role of wrapping the hydrometer 6 to avoid the hydrometer 6 from being broken when it is shaken strongly. At the same time, when the fixing block 5 is to be separated from the hydrometer 6, the sheath 4 also plays the role of limiting the hydrometer 6 so that it cannot move with the fixing block 5, so that the fixing block 5 can be smoothly separated from the hydrometer 6, and the hydrometer 6 is no longer fixed, so that the hydrometer 6 falls into the liquid 9 to be measured to measure the specific gravity value of the liquid 9 to be measured.

[0092] Embodiment 2:

[0093] The difference between this embodiment and embodiment 1 is that: Fig. 9 A liquid guide tube 32 is arranged inside the second end cover 3, one end of the liquid guide tube 32 is connected to the inner cavity of the measuring cylinder 1, and the other end extends from the side wall of the second end cover 3 and forms a port 33, which is sealed by a detachable sealing cap 34.

[0094] When the liquid 9 to be tested needs to be injected into the measuring cylinder 1, the second end cover 3 does not need to be opened. The sealing cap 34 only needs to be removed, and then a tube is connected to the port 33 to inject the liquid 9 to be tested into the measuring cylinder 1. After the injection, the sealing cap 34 is covered.

[0095] The advantage of this embodiment over the first embodiment is that the injection of the liquid 9 to be tested is carried out in a closed state without opening the second end cover 3, so that the liquid can be prevented from volatilizing as much as possible during the injection process. Therefore, whether when injecting the liquid 9 to be tested or when measuring the specific gravity value, the measuring cylinder 1 is closed, so the influence of the volatilization of the liquid on the measuring personnel and the surrounding environment can be avoided as much as possible.

[0096] In the description of the present invention, the terms "connection", "installation", "fixation" and the like should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A specific gravity measuring instrument suitable for volatile liquids, characterized in that: It comprises a measuring cylinder (1), a first end cover (2), a second end cover (3), a sheath (4), a fixing block (5) and a specific gravity meter (6); Both ends of the measuring cylinder (1) are open; The first end cover (2) is detachably mounted on one end of the measuring cylinder (1); and the first end cover (2) is provided with an axially penetrating through hole (21); The second end cover (3) covers the other end of the measuring cylinder (1) and is detachable; The sheath (4) is inserted into the through hole (21) of the first end cover (2), and the two ends of the sheath (4) are respectively a first end (41) and a second end (42). The sheath (4) can selectively fix the first end (41) in the through hole (21) or fix the second end (42) in the through hole (21). When the first end (41) of the sheath (4) is fixed in the through hole (21), the second end (42) of the sheath (4) is located in the inner cavity of the measuring cylinder (1). When the second end (42) of the sheath (4) is fixed in the through hole (21), the second end (42) of the sheath (4) is located in the inner cavity of the measuring cylinder (1). ) is fixed in the through hole (21), the first end (41) of the sheath (4) is located outside the measuring cylinder (1); at the same time, a receiving cavity (43) for receiving the hydrometer (6) is provided in the middle of the sheath (4), and the cavity shape of the receiving cavity (43) matches the outer contour of the hydrometer (6); and a sinking hole (44) communicating with the receiving cavity (43) is provided on the end surface of the first end (41) of the sheath (4), and a first internal thread (44a) is provided in the sinking hole (44); The fixing block (5) is inserted into the sinking hole (44) of the sleeve (4), and the lower part of the fixing block (5) is connected to the first internal thread (44a) of the sinking hole (44) through the first external thread (5a), and the number of thread turns of the first internal thread (44a) is greater than the number of thread turns of the first external thread (5a), and the first external thread (5a) cannot be separated from the first internal thread (44a); at the same time, the fixing block (5) is also provided with a slot (51) inside which the upper end of the hydrometer (6) is inserted, and a clamping groove (511) is provided in the slot (51); The upper end of the hydrometer (6) is provided with a snap ring (61) matching the snap groove (511); When the hydrometer (6) is inserted into the accommodating cavity (43) of the sleeve (4) and the snap ring (61) is inserted into the slot (51) and is clamped in the clamping groove (511), the fixing block (5) is located at a side of the sinking hole (44) close to the second end (42) of the sleeve (4); when the fixing block (5) moves from a side close to the second end (42) to a side away from the second end (42) under the cooperation of the first external thread (5a) and the first internal thread (44a), the hydrometer (6) cannot move with the fixing block (5) under the restriction of the accommodating cavity (43), and the clamping groove (511) will be separated from the snap ring (61); When the hydrometer (6) is completely inserted into the accommodating cavity (43), a gap exists between the inner wall of the accommodating cavity (43) and the outer wall of the hydrometer (6); when the upper end of the hydrometer (6) is inserted into the slot hole (51), a gap exists between the inner wall of the slot hole (51) and the outer wall of the hydrometer (6); The sinking hole (44) comprises a neck hole (441) located on the upper side and a limiting hole (442) located on the lower side, wherein the neck hole (441) and the limiting hole (442) are connected to each other and the diameter of the neck hole (441) is smaller than the diameter of the limiting hole (442), the bottom of the limiting hole (442) is connected to the top of the accommodating cavity (43), and the first internal thread (44a) is arranged in the limiting hole (442); a boss (52) is formed on the lower part of the fixing block (5), and the boss (52) comprises a neck (5 21) and a limiting portion (522), wherein the neck (521) is inserted into the neck hole (441) and has an outer diameter smaller than an inner diameter of the neck hole (441), the limiting portion (522) is located in the limiting hole (442) and has a diameter larger than the aperture of the neck hole (441), and the first external thread (5a) is arranged on the circumferential surface of the limiting portion (522); when the limiting portion (522) rotates in the limiting hole (442), the limiting portion (522) can move up and down in the limiting hole (442).

2. A specific gravity measuring instrument suitable for volatile liquids according to claim 1, characterized in that: A first sealing ring (45) is provided in the neck hole (441) to seal the gap between the neck hole (441) and the neck (521).

3. A specific gravity measuring instrument suitable for volatile liquids according to claim 2, characterized in that: A second sealing ring (22) is provided in the through hole (21) of the first end cover (2) to seal the gap between the through hole (21) and the sheath (4).

4. A specific gravity measuring instrument suitable for volatile liquids according to claim 3, characterized in that: The upper side of the through hole (21) is provided with a second internal thread (21a), and the lower side of the through hole (21) is provided with a third internal thread (21b); The circumferential surface of the first end (41) of the sleeve (4) is provided with a second external thread (4a) matching the second internal thread (21a), and the circumferential surface of the second end (42) of the sleeve (4) is provided with a third external thread (4b) matching the third internal thread (21b).

5. A specific gravity measuring instrument for volatile liquids according to claim 1, characterized in that: The specific gravity measuring instrument further comprises a locking mechanism (7) for limiting the sheath (4) so ​​that it cannot freely rotate in the through hole (21) around the central axis of the through hole (21).

6. A specific gravity measuring instrument for volatile liquids according to claim 5, characterized in that: The first end cover (2) is provided with a first receiving hole (24) and a second receiving hole (25) which are connected to each other. The axis lines of the first receiving hole (24) and the second receiving hole (25) are collinear and both extend along the radial direction of the first end cover (2). At the same time, the outer side of the first receiving hole (24) forms an opening on the side wall of the first end cover (2), and the inner side of the second receiving hole (25) is connected to the through hole (21). The locking mechanism (7) comprises a pressing member (71), a latch (72), a first spring (73) and a second spring (74); The pressing piece (71) is arranged in the first accommodating hole (24), and an axial hole (711) which is concave in the axial direction is arranged at an inward end of the pressing piece (71), and a magnet (75) is arranged in the axial hole (711); The latch (72) is arranged in the first receiving hole (24) and the second receiving hole (25) at the same time, and the outward end of the latch (72) is inserted into the shaft hole (711) of the pressing member (71); and the latch (72) is made of ferromagnetic material; The first spring (73) is arranged in the first receiving hole (24), and the first spring (73) imparts a force to the pressing member (71) to move outward; The second spring (74) is arranged in the second receiving hole (25), and the second spring (74) exerts a force on the latch (72) to move inward; The sheath (4) is provided with a first slot (46) on the side wall of the first end (41) for accommodating the inner end of the latch pin (72) to be inserted therein, and a second slot (47) is also provided on the side wall of the second end (42) for accommodating the inner end of the latch pin (72) to be inserted therein; When the first slot (46) or the second slot (47) is aligned with the second receiving hole (25), the locking mechanism (7) has two states: locked and unlocked. In the natural state, the locking mechanism (7) is in the locked state. When the pressing member (71) moves from the outside to the inside, the locking mechanism (7) gradually switches from the locked state to the unlocked state. When in the locked state, there is a distance between the outer end of the latch (72) and the magnet (75), and the two are not adsorbed together. The first spring (73) presses the pressing member (71) to release the first spring. ) drives the outer end of the pressing member (71) to protrude relative to the side wall of the first end cover (2), and the force applied by the second spring (74) to the latch (72) drives the inner end of the latch (72) to be inserted into the first slot (46) or the second slot (47); when in the unlocked state, the outer end of the latch (72) is attracted to the magnet (75), the protrusion degree of the outer end of the pressing member (71) relative to the side wall of the first end cover (2) is smaller than that in the locked state, and the latch (72) is not inserted into the first slot (46) or the second slot (47).

7. A specific gravity measuring instrument for volatile liquids according to claim 1, characterized in that: A filter screen (8) is provided on one side of the measuring cylinder (1) close to the second end cover (3), and the four sides of the filter screen (8) are fixed to the inner wall of the measuring cylinder (1).

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