JP2010139266A - Device for detecting abnormal flow of fluid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact device for detecting an abnormal flow capable of directly detecting the abnormal flow, without detecting the abnormal flow, by indirectly determining a flow rate from a pressure, thereby enhancing the accuracy of detection and preventing malfunction of detection by enlarging the ratio of a moving amount of a float to a flow rate change without enlarging the whole device. <P>SOLUTION: The device includes: an area type flow rate means wherein a large diameter pipe having a larger sectional area than a small diameter pipe and communicated with the small diameter pipe is extended on an upper part of the small diameter pipe having a straight-pipe shaped channel for a fluid, and the float having a larger specific gravity than the fluid is floated vertically movably inside the small diameter pipe while the float is held by a guide part provided inside the small diameter pipe, and the flow rate is measured by a moving position of the float; the float on which a magnetized permanent magnet is mounted; and a detection means having a magnetic switch disposed outside the large diameter pipe or the small diameter pipe. An abnormality of the pipe inside flow rate is detected by the float position. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is an apparatus for detecting an abnormal flow rate of a fluid, and is used mainly for a domestic septic tank. A domestic septic tank in which oxygen supply (air) at a constant flow rate is a legal requirement depending on the individual septic tank. The present invention relates to an abnormality detection device for periodically confirming a flow rate supplied to a battery.

  The purpose of the household septic tank is to supply oxygen (air) at a constant flow rate from an air pump into the septic tank, to propagate aerobic microorganisms, eat filth, and decompose them. A measure of the amount of oxygen (air) required for aerobic microorganisms to decompose sewage is expressed as biochemical oxygen demand (BOD), and the mg / l (milligram per liter) value is determined by the capacity of the septic tank. Since this BOD value is a measure of whether filth is properly decomposed and purified, it is extremely important to know the flow rate supplied from the air pump to the septic tank. It needs to be detected.

  As an abnormality detection device for an air pump according to the prior art, there is a pressure detection method of Patent Document 1 (see FIG. 11). In this method, a pressure receiving chamber 101 provided in a hollow container 100, a fluid vent h provided at one end of the pressure receiving chamber 101, and an airtight movable part provided at the other end of the pressure receiving chamber 101 are provided. 102, one end of a spring 103 is fixed to one surface of the movable part, the other end of the spring 103 is held by a fixed plate 104, and the movable part 102 is abnormal due to a change in the back pressure in the pressure receiving chamber 101. In the detecting means 105 for detecting the magnetic switch, the support 106 through which the spring 103 is inserted is provided in the movable portion 102, the permanent magnet 107 is attached to the end of the support 106, and the magnetic switch is provided apart from the permanent magnet 107. 108 is an abnormality warning device for detecting means.

  However, in the abnormality alarm device having pressure detection described in the above-mentioned Patent Document 1, when the clogging of the piping from the air pump to the inside of the septic tank or the diffusing pipe of the septic tank occurs, or air leakage from the piping occurs. Ventilation resistance increases and decreases, causing pressure fluctuations. At this time, it is a mechanism that deviates from the set pressure range, the distance between the magnetic switch and the permanent magnet becomes large, the magnetic switch is activated, an abnormality is notified by a lamp or the like, and the air pump is stopped. With this method, it is impossible to directly check (visually) the flow rate of the air pump supplied to the septic tank, and the normal pressure range should be within the normal flow rate range after the characteristics of the flow rate and pressure of the air pump have already been grasped in advance. However, even if a normal flow rate is initially supplied in the septic tank within the normal pressure range, for example, clogging of the diffuser pipe and leakage from the piping may occur. Even when the back pressure for pressure detection is within the normal pressure range, the flow rate supplied to the septic tank is actually decreasing. In this case, the apparatus of Patent Document 1 has a problem that it cannot be directly confirmed whether or not an appropriate constant flow rate is supplied.

  Moreover, the area type | formula flowmeter shown by patent document 2 is used as a flowmeter which measures the flow volume of a fluid. As shown in FIG. 12, this flow meter floats a float 110 in a vertically arranged taper tube 109 and measures the flow rate according to the position. The flow meter is magnetized in the float 110 in the vertical direction. A permanent magnet 111 is used, and a plurality of magnetoresistive elements 112 are arranged in parallel with the taper tube 109.

Utility Model Registration No. 3137999 JP-A-6-180242

  An area type flow meter using such a tapered tube is generally large and cannot be accommodated in a pump. Furthermore, in order to reduce the size, it is necessary to tighten the slope of the taper tube. In this case, as shown in the graph Ta shown in FIG. 14, the float of the float with respect to the flow rate (air) change (Q1 to Q2) is required. The rate of movement (position) (Pa1 to Pa2) is low. Therefore, when the sensor is used as a sensor for detecting an abnormality in the flow rate at the position of the float moving in the taper tube in order to detect a change in the flow rate, malfunction is likely to occur and accuracy is deteriorated. That is, when the flow rate is changed from a normal flow rate to an abnormal flow rate, the float position change (Pa2 to Pa1) is small. Therefore, if the magnetic sensor is not accurately installed, malfunctions are likely to occur and errors are likely to occur. In addition, the float is not completely stationary and sways, so the magnetic sensor reacts and malfunctions due to the change in the position of the float caused by the sway of the float, even though there is no change in the flow rate. There is a possibility.

  In addition, when using a taper tube as a sensor as described above, the distance between the position of the float at the normal flow rate and the position of the float to be detected as an abnormal flow rate becomes narrow, so accuracy is required for installation of the magnetic sensor, It becomes difficult to adjust the position of the magnetic sensor.

  Furthermore, if the interval between the float position at the normal flow rate and the float position to be detected as an abnormal flow rate is widened, that is, the ratio of the float movement amount to the flow rate change is increased, the graph Tb in FIG. As shown, there is a problem that the tapered tube becomes long and cannot be downsized.

  Therefore, in view of the above problems, it is possible to detect the flow rate indirectly from the pressure and not detect the flow rate abnormality, but directly detect the flow rate abnormality and increase the flow rate without enlarging the entire apparatus. An object of the present invention is to provide a flow rate abnormality detection device that is small in size, increases detection accuracy, and prevents detection malfunction by increasing the ratio of the amount of movement of the float to the change.

  According to the flow rate abnormality detecting device of the present invention, a large-diameter pipe having a larger cross-sectional area than the small-diameter pipe is extended to the upper part of the small-diameter pipe whose fluid flow path is a straight tube. An area-type flow rate means for measuring a flow rate according to a position where the float has been moved; A detecting means in which a magnetic switch is disposed outside the large-diameter pipe or the small-diameter pipe, and the flow rate in the pipe is detected at the position of the float. It is characterized by.

  Further, the flow rate abnormality detection device of the present invention is connected to the small-diameter pipe on the upper part of the small-diameter pipe whose fluid flow path is a straight tube, and extends a large-diameter pipe having a larger cross-sectional area than the small-diameter pipe. A medium-diameter pipe that is larger than the small-diameter pipe and has a smaller cross-sectional area than the large-diameter pipe is extended to the upper part of the large-diameter pipe. An area formula that measures the flow rate according to the position where the float moves by holding the float with a guide part provided inside the small diameter pipe and moving it up and down. Flow rate means, the float equipped with a magnetized permanent magnet, and a detection means in which a magnetic switch is disposed either outside or each of the small-diameter pipe, medium-diameter pipe or large-diameter pipe, An abnormality in the flow rate in the tube is detected at the position of the float.

  Also, the flow rate abnormality detection device of the present invention is arranged vertically inside the bottomed large-diameter outer tube, and the fluid flow path is a straight tube and the upper part is opened, and the large-diameter outer tube is opened through the opening. A small-diameter pipe communicating with the small-diameter pipe, and a float having a specific gravity greater than that of the fluid is held inside the small-diameter pipe by the guide portion provided inside the small-diameter pipe. An area-type flow rate means for measuring the flow rate according to the position, a floating means equipped with a magnetized permanent magnet, and a detection means in which a magnetic switch is arranged at the position of the opposed large-diameter outer tube, An abnormality is detected at the position of the float.

  Further, the flow rate abnormality detection device of the present invention is provided with a small-diameter pipe having a straight pipe in which the fluid flow path vertically placed inside the bottomed large-diameter outer pipe has a specific gravity higher than that of the fluid. An area-type flow rate means for measuring the flow rate according to the position where the float is moved by holding the float in a guide section in which a large float is provided inside a small-diameter pipe and moving the float upward and downward, and a magnetized permanent magnet The above-described floating element is provided with detection means in which a magnetic switch is disposed on the large-diameter outer tube or the small-diameter tube, and the small-diameter tube and the large-diameter outer tube have the same length, and the small-diameter A plurality of openings are provided in the side surface on the upper end side of the pipe, and an abnormality is detected in the pipe flow rate at the position of the float.

  Moreover, it is preferable that an upper cover is provided on the upper part of the large-diameter outer tube, large-diameter tube, small-diameter tube or medium-diameter circular tube, and a part or all of the upper cover is made of a transparent material.

  In addition, an electromagnetic air pump according to the present invention includes the flow rate abnormality detection device.

  According to the present invention, since the large-diameter pipe having a larger cross-sectional area than the small-diameter pipe is extended above the small-diameter pipe provided with the straight tubular flow path, the position of the float with respect to the change in flow rate is abrupt. By creating a magnetic switch in the region where the position of the float changes rapidly, the malfunction can be prevented due to the fluctuation of the float despite the normal flow rate. .

  In addition, the amount of movement of the float from the normal flow rate to the flow rate at which an abnormality is detected is changed abruptly, and the entire device is downsized by changing the amount of movement of the float gently in other flow regions. This can reduce the cost.

  In addition, the position of the magnetic switch can be easily adjusted and installed by rapidly changing the amount of movement of the float until it changes from a normal flow rate to a flow rate for detecting an abnormality.

  Moreover, even if the flow rate to be detected changes, the same apparatus can be used except for the float by simply changing the float.

  In addition, because the structure of the circular tube and guide part is short, the operation of the float with respect to the inclination angle is smooth, and a compact design is possible.

  Hereinafter, a flow rate abnormality detection device of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an example of the connection of the flow rate abnormality detection device of the present invention, FIG. 2 is a diagram showing an embodiment of the flow rate abnormality detection device of the present invention, and FIGS. 3 and 4 are diagrams of the present invention. It is a figure which shows one Embodiment of the float used for a flow volume abnormality detection apparatus, FIG. 5 is a figure which shows one Embodiment of the guide part used for the flow volume abnormality detection apparatus of this invention, FIG. 6 is this invention. FIG. 7 is a diagram showing another embodiment of the flow rate abnormality detecting device of the present invention, and FIG. 10 is a flow rate of the present invention. It is a figure which shows the pump with which the abnormality detection apparatus was incorporated, and FIG. 13 is a graph which shows the relationship between the flow volume-float position of the flow volume abnormality detection apparatus of this invention.

  As shown in FIG. 1, a flow rate abnormality detection device 1 according to the present invention is provided, for example, between a pump Pu and a supply pipe S for supplying air to a septic tank D, and the flow rate of air sent from the pump Pu is Whether or not the flow rate is normal is detected. For example, when the flow rate is insufficient, it is detected that the flow rate is abnormal. The air supplied from the pump Pu passes through the flow rate abnormality detection device 1, passes through the supply pipe S, and is released from the diffuser pipe AD into the septic tank D. The flow rate abnormality detection device 1 detects an abnormality when there is an abnormality, such as when the air flow rate is too low when there is an abnormality in the pump Pu, and the abnormality is detected by a known display means such as a lamp. It functions as a notifying sensor, and after detecting an abnormality, an alarm can be issued by a known alarm means. Further, when there is an abnormality in the flow rate, the flow rate can be adjusted by operating the handle H. FIG. 1 is one embodiment of the present invention, and it goes without saying that it can be used as a flow rate abnormality detection device for purposes other than the septic tank. Also, the fluid is not limited to air, and can be applied to fluids other than air.

  As shown in FIGS. 2 to 4, the flow rate abnormality detection device 1 of the present invention has a small-diameter pipe 2 whose fluid flow path is a straight tube, and an upper portion of the small-diameter pipe 2 that communicates with the small-diameter pipe 2. A large-diameter pipe 3 having a larger cross-sectional area than the pipe 2 is extended. Outside the small-diameter pipe 2 or the large-diameter pipe 3, a magnetic switch 9 that reacts by magnetism such as a reed switch for detecting an abnormality depending on the position of the float 4 is provided. If the magnetic switch 9 mentioned later is a material which can react to the permanent magnet 4c accommodated in the float 4, it will not specifically limit, A synthetic resin, glass, etc. can be employ | adopted. The small-diameter pipe 2 and the large-diameter pipe 3 may be a circular pipe or a square pipe, and are not particularly limited as long as the cross-sectional area does not change over the top and bottom of the pipe.

  Inside the small-diameter pipe 2, a float 4 having a specific gravity larger than that of the fluid flowing in the small-diameter pipe 2 is fixed vertically between the bottom 2 a of the small-diameter pipe 2 and the upper lid 5 provided on the large-diameter pipe 3. The guide portion 6 is provided so as to be movable up and down. The upper lid 5 may be integrated with the large-diameter tube 3 or may be separate from the upper lid 5 so that dust or dirt can be visually recognized in the apparatus from above or the position of the float 4 can be visually confirmed. It is also possible to form the lid 5 from a transparent material. As the transparent material, for example, glass, acrylic and the like are preferable.

  As shown in FIG. 3, the shape of the float 4 is composed of a cylindrical portion 4a and a tapered portion 4b. The cylindrical portion 4a houses permanent magnets 4c whose upper and lower sides are different from each other. A hole penetrating in the vertical direction is provided. The material of the float 4 is not particularly limited as long as it has magnetic permeability, but a synthetic resin or the like is preferably used.

  Moreover, as shown in FIG. 4, it may be a cylindrical float 4 in which a permanent magnet 4c is accommodated. The shape of the float 4 is not limited to the shape shown in FIGS. 3 and 4, and a known float such as a spherical shape can also be used.

  As shown in FIGS. 2 and 5, the float 4 is guided by the guide portion 6 so as to be movable in the vertical direction in the small-diameter pipe 2. The guide portion 6 may be a single guide portion penetrating the center of the float 4 as shown in FIG. 5 (a), and the inner side of the small diameter tube 2 as shown in FIG. 5 (b). In this case, the float 4 is guided so as to be movable up and down by providing a corresponding recess so that the float 4 can be moved up and down along the guide portion 6. Moreover, the structure of the guide part 6 will not be restricted to the shape of Fig.5 (a) and FIG.5 (b), and especially the structure will be limited if the float 4 can be guided so that a vertical movement is possible. There is nothing.

  Next, the movement of the float according to the flow rate of the flow rate abnormality detection device 1 of the present invention will be described with reference to FIG. In the flow rate abnormality detecting device 1 of the present invention, the fluid flowing in from the fluid inlet 7 provided in the small diameter pipe 2 shown in FIG. 2 passes through the small diameter pipe 2, passes between the small diameter pipe 2 and the float 4, and is large. It flows through the diameter pipe 3 and flows through the fluid outlet 8 provided in the large diameter pipe 3. The float 4 in the small diameter pipe 2 is pushed upward by the flow rate, and the float 4 with the mass Wf is stationary in a state where the float 4 floats at a differential pressure (P1−P2) = Wf / Af when the maximum diameter area Af of the float 4 is Q. To do. P1 is the lower pressure of the float 4 and P2 is the upper pressure of the float 4. Here, Q = cA√ (2gh / ρ0) (c is the outflow coefficient, A is the flow area, g is the gravitational acceleration, h is the differential pressure above and below the float, and ρ0 is the fluid density), and the flow rate is from Q1 When changed to Q2, since the inside of the small-diameter pipe 2 is a straight tube, c, A, g, and ρ0 are constant, and only the differential pressure h changes.

  According to the present invention, for example, only the weight of the float 4 is changed, and other parts (small diameter pipe 2 and large diameter pipe 3) other than the float 4 are used as an abnormality detecting device with different flow rates using the same one. (You can verify it below).

  That is, assuming that there is a flow rate abnormality detecting device in which the float 4 is stationary when the flow rate is 40 according to the present invention, and assuming that the mass Wf = 10 g of the float 4 and the maximum diameter area Af = 2 of the float 4, the differential pressure h = 5. Therefore, for example, when only the mass Wf of the float 4 is set to 12.5 g and the other conditions are exactly the same, the differential pressure h = 6.25, and the float 4 comes to rest when the flow rate Q = 60. The flow rate abnormality detecting device for the flow rate 60 can be used only by changing the mass Wf of the float 4. Furthermore, if only the mass Wf of the float 4 is 62.5 g and the other conditions are exactly the same, the pressure difference becomes h = 31.25, and the float stops at the flow rate Q = 100. It can be used as a flow rate abnormality detection device for a flow rate of 100 simply by changing the mass.

  Further, by changing not only the mass Wf of the float 4 but also the maximum diameter area Af, it can be used as an abnormality detecting device for other flow rates without changing the components other than the float 4, and the mass Wf and the maximum diameter area Af can be used. By changing both, it can be used as an abnormality detection device for other flow rates without changing components other than the float 4. Thus, according to the present invention, it can be used as an abnormality detection device with different flow rates by changing the condition of the float 4 and without changing the conditions of other parts other than the float 4.

  In the present invention, the relationship between the flow rate Q and the float position is as shown in the graph of FIG. 13 by opening the upper portion of the small diameter tube 2 and extending the large diameter tube 3 having a larger cross-sectional area than the small diameter tube 2 to the upper portion. become. In the present invention, by providing the large-diameter pipe 3 extending to the small-diameter pipe 2, by creating a place where the flow path suddenly changes, a place where the position of the float changes suddenly with respect to the flow rate change as shown in the graph. By making it, the position of the float will fluctuate greatly at the abnormal flow rate, and it is easy to detect the abnormality. In addition, the amount of movement of the float 4 from the normal flow rate to the flow rate at which an abnormality is detected is changed abruptly. In other flow regions, the amount of movement of the float 4 is gradually changed as shown in FIG. By doing so, the entire apparatus can be reduced in size, and the cost can be reduced. In addition, the position of the magnetic switch can be easily adjusted and installed by rapidly changing the amount of movement of the float until it changes from a normal flow rate to a flow rate for detecting an abnormality.

  FIG. 6 (a) shows the position of the float 4 at a normal flow rate. By adjusting the weight of the float 4 and the distance between the small diameter tube 2 and the float 4, the height of the cylindrical portion 4a of the float 4 can be adjusted. The vicinity of the center is set to coincide with the upper end of the small diameter pipe 2.

  When the flow rate in the flow path is reduced due to an abnormality such as a pump (for example, the flow rate Q1 in FIG. 13), the float 4 is lowered downward as shown in FIG. A magnetic switch 9 is provided at a position where an abnormality can be detected at the position b).

  Further, when the flow rate increases, for example, when the flow rate Q2 in FIG. 13 is reached, the position of the boundary between the cylindrical portion 4a and the tapered portion 4b of the float 4 reaches the position of FIG. Ascending to the same height as the position of the upper end of the small diameter tube 2. When the flow rate is larger than the flow rate Q2 at the position shown in FIG. 6C, the space between the float 4 and the small-diameter pipe 2 is widened, so that the position of the float 4 rises gently as shown in FIG. Will come to do. Therefore, the position of the float 4 does not rise, and the entire apparatus can be made compact.

  FIG. 7 is a diagram showing another embodiment of the present invention, in which a large-diameter tube 3 is extended above the small-diameter tube 2, and a cross-sectional area smaller than that of the large-diameter tube 3 and a small-diameter tube. A medium-diameter pipe 10 having a cross-sectional area larger than 2 is extended. Although two magnetic switches 9 are provided in FIG. 7, the number is not particularly limited.

  By providing the middle-diameter pipe 10 of the present embodiment, it is possible to detect an abnormality in the flow rate in a plurality of areas where it is desired to detect the abnormality. Further, by providing a medium-diameter pipe 10 having a larger cross-sectional area than the small-diameter pipe 2 at the upper part of the large-diameter pipe 3, when the float 4 exceeds the upper end of the large-diameter pipe 3, if the small-diameter pipe 2 is used, the float 4 rises all at once, but by making the medium diameter tube 10 larger in cross-sectional area than the small diameter tube 2, the rapid rise of the float 4 can be mitigated.

FIG. 8 is a view showing still another embodiment of the present invention, in which a small-diameter inner tube 21 is vertically placed in a large-diameter outer tube 31, and an upper portion of the small-diameter inner tube 21 is opened. In FIG. 9, the small-diameter inner tube 21 is provided with a plurality of openings 21 a on the side surface of the upper end portion of the small-diameter inner tube 21.
By creating a large-diameter outer tube 31 extending to the small-diameter inner tube 21 or an opening 21a of the small-diameter inner tube 21 communicating with the large-diameter outer tube 31, a location where the flow path changes suddenly is created. As described above, by creating a location where the position of the float changes suddenly with respect to the change in flow rate, it is possible to prevent malfunction due to the swing of the float 4 despite the normal flow rate. In addition, the amount of movement of the float 4 from the normal flow rate to the flow rate at which an abnormality is detected is changed abruptly. In other flow regions, the amount of movement of the float 4 is gradually changed as shown in FIG. By doing so, the entire apparatus can be reduced in size, and the cost can be reduced. In addition, the position of the magnetic switch can be easily adjusted and installed by rapidly changing the amount of movement of the float until it changes from a normal flow rate to a flow rate for detecting an abnormality.

  According to the present invention, since the size of the flow rate abnormality detection device 1 can be made compact, it can be built in the pump Pu as shown in FIG.

It is a figure which shows an example of the connection of the flow volume abnormality detection apparatus of this invention. It is a figure which shows one Embodiment of the flow volume abnormality detection apparatus of this invention. It is a figure which shows one Embodiment of the float used for the flow volume abnormality detection apparatus of this invention. It is a figure which shows one Embodiment of the float used for the flow volume abnormality detection apparatus of this invention. It is a figure which shows one Embodiment of the guide part used for the flow volume abnormality detection apparatus of this invention. It is a figure which shows the position of the float according to the flow volume of the flow volume abnormality detection apparatus of this invention. It is a figure which shows other embodiment of the flow volume abnormality detection apparatus of this invention. It is a figure which shows other embodiment of the flow volume abnormality detection apparatus of this invention. It is a figure which shows other embodiment of the flow volume abnormality detection apparatus of this invention. It is a figure which shows the pump with which the flow volume abnormality detection apparatus of this invention was incorporated. It is a figure which shows the conventional pump abnormality detection apparatus. It is a figure which shows the flowmeter using the conventional taper tube. It is a graph which shows the relationship between the flow volume-float position of the flow volume abnormality detection apparatus of this invention. It is a graph which shows the relationship between the flow volume-float position of the conventional flow volume abnormality detection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flow abnormality detector 2 Small diameter pipe 2a Bottom part 3 Large diameter pipe 4 Float 4a Cylindrical part 4b Tapered part 4c Permanent magnet 5 Upper lid 6 Guide member 7 Fluid inlet 8 Fluid outlet 9 Magnetic switch 10 Medium diameter pipe 21 Small diameter inner pipe 31 Large diameter outer tube AD Diffuser tube D Septic tank H Handle Pu pump Su Supply tube

Claims (6)

A large diameter pipe having a cross-sectional area larger than that of the small diameter pipe is extended to the upper part of the small diameter pipe having a fluid flow path connected to the small diameter pipe, and the specific gravity is larger than the fluid inside the small diameter pipe. The float is held vertically by a guide provided inside the small-diameter pipe, and is floated up and down. The area-type flow rate means for measuring the flow rate according to the position of the float and a magnetized permanent magnet are installed. A flow rate abnormality detecting device comprising: the floating element, and a detecting means having a magnetic switch provided outside the large diameter pipe or the small diameter pipe, and detecting an abnormal flow rate in the pipe at the position of the floating element. A fluid passage is connected to the upper portion of the small-diameter tube having a straight tubular shape, and a large-diameter tube having a cross-sectional area larger than that of the small-diameter tube is extended. The upper portion of the large-diameter tube is larger than the small-diameter tube. Extending a medium-diameter pipe having a smaller cross-sectional area than the large-diameter pipe, and further extending a large-diameter pipe having a cross-sectional area larger than that of the medium-diameter pipe above the medium-diameter pipe, which has a larger specific gravity than the fluid. An area-type flow means for measuring the flow rate according to the moved position of the float, holding the float with a guide portion provided inside a small-diameter pipe and floating up and down, and measuring the flow rate, and a magnetized permanent magnet The mounted float and the outside of each of the small diameter pipe, the medium diameter pipe or the large diameter pipe or a detecting means provided with a magnetic switch are provided, and an abnormal flow rate in the pipe is detected at the position of the float. A flow rate abnormality detection device characterized by: A small-diameter pipe that is placed vertically inside a large-diameter outer pipe with a bottom and that has a straight fluid flow path and an upper opening that communicates with the large-diameter outer pipe through the opening is provided. An area-type flow rate means for measuring the flow rate according to the position where the float moves by holding the float in the inside of the small-diameter pipe and holding the float in a guide portion provided inside the small-diameter pipe so that the float is vertically movable. And detecting means in which a magnetic switch is arranged at the position of the opposed large-diameter outer tube, and detecting an abnormal flow rate at the position of the float. An abnormal flow detection device characterized by A fluid flow path placed vertically inside the bottomed large-diameter outer tube is provided with a straight-tube small-diameter tube, and a float having a larger specific gravity than the fluid is provided inside the small-diameter tube. An area-type flow rate means for measuring the flow rate according to the position where the float moves, holding the float in the guide portion and moving up and down, the float equipped with a magnetized permanent magnet, and the large-diameter outer tube Or a detecting means having a magnetic switch disposed in a small diameter tube, the small diameter tube and the large diameter outer tube are of the same length, and a plurality of openings are formed on the side surface on the upper end side of the small diameter tube. An abnormal flow rate detecting device provided for detecting an abnormal flow rate in a pipe at the position of the float. The upper lid is provided on the upper portion of the large-diameter outer tube, large-diameter tube, small-diameter tube or medium-diameter circular tube, and a part or all of the upper lid is made of a transparent material. The abnormal flow detection device according to any one of the above. An electromagnetic air pump comprising the flow rate abnormality detection device according to any one of claims 1 to 5.

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