JP2012150090A - Air purge type viscosity, specific gravity and liquid level gauge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose a viscosity/specific gravity/liquid level gauge for which a measuring system using air of an air purge type liquid level measuring system is diverted.SOLUTION: A viscosity/specific gravity meter for which air components such as an air purge type liquid level measuring air tube, air pump or solenoid valve are diverted remotely and safely measures viscosity, specific gravity and liquid level with a little modification.

Description

  The present invention relates to a measuring device for the viscosity and specific gravity of a liquid by a bubble method, and more particularly, to a measuring device that can measure the liquid level, viscosity, and specific gravity by making use of the function of a bubble type liquid level meter by adding components.

As a method of measuring the viscosity of the liquid, in addition to the capillary viscometer, falling ball viscometer, rotational viscometer in “JIS Z 8803 liquid viscosity—measurement method”, vibration type, cup type (Ford cup type, dip cup type, There are various methods such as a flow cup type). In addition, there is a method in which continuous measurement is performed using the relationship between the flow rate of Hagen-Poiseille and the differential pressure, as disclosed in Japanese Patent Application Laid-Open No. 2008-309743 (P2008-309743A).
On the other hand, the bubble-type liquid level meter is composed of an air pump that sends air to a measuring air tube with its tip immersed in the liquid, its control circuit, a pressure sensor, and a display. It is a technology with an old history.

  JP 2008-309743 JP 2010-054260 LIQUID LEVEL MEASURING DEVICE JP 2010-181389 LIQUID LEVEL MEASURING DEVICE

The cup type viscometer is a method that measures the viscosity by filling the sample in the container and measuring the time until the liquid to be measured flows out from the hole with the specified diameter at the bottom of the container. It is a simple method that can be configured with a cup with a smooth hole and a stopwatch.
In other words, it is a method that requires manual labor to pump up a sample and measure the time with a stopwatch, and there is a drawback that it cannot be used with a high-temperature liquid or a liquid that is dangerous to the human body (toxic liquid or flammable liquid).
Other disadvantages of this method include the fact that humans measure the time between two points from when the cup is full until the liquid finishes flowing. .
There are some mechanized time measurements between two points using light, such as a photo interrupter, but depending on the viscosity, it is easy to cause errors because it determines the gradually flowing down.
Capillary and drop ball viscometers need to pump out the liquid to be measured, and rotational viscometers and vibration viscometers are installed in the liquid of the liquid to be measured, such as tanks or paint agitators. There are types that can be used, but in addition to being expensive in nature, there are also maintenance costs for cleaning and explosion-proof problems.

  Therefore, in view of the above situation, the present invention makes use of the advantages of the bubble type liquid level meter that can be measured remotely with a single air tube, by adding parts to the basic bubble type liquid level meter. In addition to the liquid level of the liquid to be measured, the "bubble-based viscosity / specific gravity / liquid level measuring device" that measures viscosity and specific gravity simultaneously in real time has been roughly divided into three mounting methods.

  Embodiments of means for solving the above-described problems will be described by roughly dividing them into three.

As shown in FIG. 1, the viscosity measuring device according to claim 1 is attached to the cup up to the vicinity of the bottom of the cup 1-2 in which the liquid outflow hole 1-2A to be measured that can be exchanged according to the target viscosity is formed in the bottom. On the other hand, the air tube 1-1 is inserted in a state of being fixed vertically by the fixing portion 1-3 that is fixed. The lower end 1-1A of the air tube 1-1 may be formed obliquely in order to discharge bubbles smoothly. The other end of the air tube 1-1 is connected to the air pump 1-6 and the pressure sensor 1-7 using an air branching unit 1-4. If air flows backward from the air pump, Similarly, a check valve (not shown) may be inserted between the air branching unit 1-4 and the air pump 1-6.
The air pump 1-6 is turned ON / OFF by detecting that the switch 1-5 by a push switch or the like has been pressed by a control circuit 1-8 by a microprocessor.
The control unit 1-8 is also characterized in that the pressure of the pressure sensor 1-7 is read and the obtained viscosity and specific gravity are displayed on the display 1-9.
In addition, although the pulling bar at the time of pulling up the cup is indicated by 1-3A, the cup may be suspended with a chain-like one as long as the cup is kept vertical. The air tube can be selected from metal pipe, plastic or Teflon tube depending on the usage environment. Furthermore, workability and cleanability can be improved by applying surface treatment such as coating with good water repellency to the inner and outer surfaces of the air tube and cup.
In addition, when suspended by a chain or the like, the air tube 1-1 is placed along the chain and lifted and lowered by a winch or the like driven by the control unit, and the measurement is synchronized to make an automatic measuring instrument. I can do it.

As shown in FIG. 2, the viscosity measuring device according to claim 2 is a fixed portion 2 fixed to a tank (a tank, an oil tank, etc.) 2-11 containing a liquid to be measured. -3 Insert the two air tubes 2-1 and 2-2, which are inserted in a vertically fixed state with the distance between both ends appropriately separated, and connect the two air tubes 2-1 and 2-2. The other end is connected to the air branching device 2-5 through electromagnetic valves 2-4A and 2-4B, respectively.
The diameter of the air tubes 2-1 and 2-2 needs to be selected according to the target viscosity.
In addition, the tip of the air tube 2-2 can be replaced with a different diameter to adjust the speed at which bubbles are generated. Shall.
The air branch 2-5 is connected to the pressure sensor 2-7 and the air pump 2-6 by an air tube. When air flows back from the air pump 2-6, a check valve (not shown) ) May be inserted between the air branching device 2-5 and the air pump 2-6.
The pressure sensor 2-7, the solenoid valves 2-4A, 2-4B and the pump 2-6 are connected to a control circuit 2-8 by a microprocessor, and the control unit 2-8 is connected to the pressure sensor 2-7. It is characterized by reading the pressure and displaying the obtained viscosity, specific gravity, and liquid level on the display 2-9.

  As shown in FIG. 3, the measuring device according to claim 3 connects the third air tube 3-12 and the electromagnetic valve 3-4C to the air branch device 3-5 in FIG. By setting the tip 3-12A of the 3-12 so that it is above the liquid level of the non-measuring liquid, it is possible to measure the viscosity, specific gravity, and liquid level even when the tank has a lid and is sealed and has internal pressure. It is a feature.

As shown in FIG. 4, the viscosity measuring device according to claim 4 is fixed vertically by a fixing rod 4-3B fixed to a tank 4-11 containing a liquid to be measured, and the upper surface is closed by a lid 4-3C. There is a cup 4-3 having a hole 4-3A that can be changed to a different diameter depending on the target viscosity, and one end is attached to the lid 4-3C of the cup 4-3 and the other end is electromagnetic. Inserted into the cup 4-3 through the air tube 4-1 connected to the valve 4-4 and the lid 4-3C of the cup 4-3, the tip 4-2A is cut obliquely, and the other end is air branched It has an air tube 4-2 connected to the vessel 4-5.
The other end of the electromagnetic valve 4-4 is open to the atmosphere. The air branching device 4-5 is connected to the pressure sensor 4-7 and the air pump 4-6 by an air tube. As in the first aspect, when air flows backward from the air pump 4-6, a check valve (not shown) may be inserted between the air branch device 4-5 and the air pump 4-6. .
The pressure sensor 4-7, the solenoid valve 4-4 and the pump 4-6 are connected to a control circuit 4-8 by a microprocessor, and the control unit 4-8 reads the pressure of the pressure sensor 4-7 and displays it. It is characterized by displaying the viscosity, specific gravity and liquid level obtained in 4-9.

Viscosity cups such as Ford cups and Zaan cups are prone to error because the time until the liquid in the cup stops flowing is measured with a stopwatch or the like. In addition, there is a disadvantage that it cannot be used with high-temperature liquids or liquids that are dangerous to the human body (toxic liquids or flammable liquids). Capillary and drop ball viscometers need to pump and measure the liquid to be measured, and rotational viscometers and vibration viscometers can be installed in the liquid tank to be measured, but are expensive. There are also problems with cleaning and maintenance costs and explosion protection.
According to the present invention, in addition to the liquid level in the tank, the viscosity and specific gravity can be simultaneously measured remotely in real time just by adding parts to the existing bubble level gauge with a microprocessor, indicator and air pump. A measuring device can be constructed, and the merit (explosion proof, remote control, etc.) of the bubble type liquid level meter can be utilized, and the total cost can be reduced.

Example according to claim 1 Example according to claim 2 Example according to claim 3 Example according to claim 4 (A) Example of measured value of viscosity VS pressure according to claim 1 (B) Example of measured value of outlet diameter VS pressure according to claim 1 (C) Example of viscosity VS time according to claim 1 (A) Pressure and PNM demodulated waveform of the embodiment according to claim 2 (B) Pressure and PNM demodulated waveform of the embodiment of different diameters according to claim 2 The measured waveform of the outlet diameter VS pressure of the embodiment according to claim 4

<First Embodiment>
This will be described with reference to FIG. When the cup 1-2 is submerged and pumped into the liquid to be measured, the liquid to be measured is poured from the hole 1-2A at the bottom of the cup immediately after being poured from above the cup 1-2 to fill the liquid to be measured. Begins to flow and the liquid to be measured in the cup 1-2 begins to decrease.
Immediately after filling up or while filling up, the air is supplied through the air tube 1-1 by an air pump to expel the liquid to be measured in the air tube 1-1, and the switch 1- The pressure value (P0) in the air tube 1-1 at the time of stopping the pump by 5 is the pressure from the upper end of the cup to 1-1A at the tip of the air tube 1-1, and the pressure sensor 1-7 It can be measured. (This is the principle of the bubble level gauge.)
If the distance from the upper end of the cup 1-2 to the air tube tip 1-1A is H and the specific gravity of the liquid to be measured is ρ,
Pressure value P0 = ρ x g x H (1)
Since g is a gravitational acceleration and H is known, the specific gravity ρ can be calculated.
Similarly, a change in pressure when the liquid to be measured in the cup 1-2 gradually decreases can be continuously measured by the pressure sensor 1-7 through the air tube 1-1.
The conventional method for measuring viscosity is to measure the time from the full state of the cup 1-2 to the empty state with a stopwatch to obtain the viscosity, which involves an error.
In this example, a highly accurate viscosity measurement method is realized by utilizing the fact that the pressure can be continuously changed as described above.
Specifically, the time from full to a predetermined height, that is, a predetermined pressure, is obtained by the microprocessor 1-8 and compared with the time obtained in advance with a known viscosity standard sample. The viscosity of the liquid to be measured can be known.
Alternatively, it is not necessary to determine the full point of time by comparing the measured pressure drop curve and the curve determined in advance with a known viscosity standard sample at the time of two pressure points. Improvement in accuracy can be expected.
FIG. 5A shows a measurement example of the glycerin concentration vs. outflow time measured by changing the glycerin concentration in an aqueous solution containing glycerin. From FIG. 5A, it can be seen that the higher the concentration of glycerin, the longer the time required for outflow.
FIG. 5B shows an example of measurement of the outflow hole diameter and the outflow time. As can be seen from the figure, the larger the aperture, the shorter the time required for outflow.
FIG. 5C shows a plot of the viscosity VS outflow time by using this phenomenon and changing the diameter to φ1.8 mm and φ1.4 mm.
It can be seen from FIG. 5C that the viscosity and the outflow time can be measured in a linear relationship.

Second Embodiment
This will be described with reference to FIG. The difference in level between the tip 2-1A of the air tube 2-1 and the tip 2-2A that can be exchanged to a different diameter depending on the target viscosity of the air tube 2-2 immersed in the liquid to be measured in the tank 2-11. The distance (depth) between 2-2A and the liquid level 2-10 of the liquid to be measured is h.
First, the solenoid valve 2-4A is turned off (closed), the solenoid valve 2-4B is turned on (opened), the pump 2-6 is turned on, and the liquid to be measured is ejected from the air tube 2-2. Thus, the pressure P2 in the air tube 2-2 becomes a pressure corresponding to the liquid level of the liquid to be measured and the depth of the tip 2-2B. Here, when the specific gravity of the liquid to be measured is ρ,
P2 = ρ × g × (h−d) …………………… (1)
It becomes.
Next, the solenoid valve 2-4B is turned off (closed) while the pump 2-6 is turned on, the solenoid valve 2-4A is turned on (opened), and the liquid to be measured is ejected from the air tube 2-1. Thus, the pressure P1 in the air tube 2-1 becomes a pressure corresponding to the liquid level of the liquid to be measured and the depth h of the tip 2-2A.
P1 = ρ × g × h …………………………… (2)
From equations (1) and (2)
Specific gravity ρ = (P1−P2) / (g × d) (3)
At this time, the specific gravity ρ of the liquid to be measured is obtained, and at the same time, the accurate h (liquid level) can be obtained when ρ can be calculated.
Thereafter, the pump 2-6 is turned off (closed), the solenoid valve 2-4B is turned on (opened), and the two air tubes 2-1 and 2-2 are directly connected. The pressure in the air tubes 2-1 and 2-2 becomes the pressure P2 of the air tube 2-2.
Thereafter, the liquid to be measured begins to gradually enter the air tube 2-1, and bubble discharge starts from the tip of the air tube 2-2.
A subtle change in pressure when the bubbles pop out can be observed in the form of pulses when continuously observed by the pressure sensor 2-7. The pulse interval gradually increases as the liquid to be measured rises, and the liquid to be measured rises to the position of the air tube tip 2-2A and stops in the air tube 2-1.
Viscosity can be obtained by comparing the time when the bubbles are generated and the time previously obtained with a known viscosity. However, the change in pulse generation interval from dense to sparse is regarded as pulse density modulation. It is also possible to further increase the accuracy by obtaining a density reduction curve using a demodulator.
Further, the output of the pressure sensor can be directly processed by the microprocessor control unit 2-8 to obtain the pulse interval. FIG. 6 shows how the pressure changes due to this series of operations.
6A shows the case where the diameter of the air tube tip 2-1A in FIG. 2 is 2.5 mm. The pressure change is indicated by 6-1, and a mono multivibrator generated by using a pulse at the time of bubble generation as a trigger. Is shown by 6-2.
It can be seen that the density of the pulse of 6-1 is changed by changing the density of the pulse of 6-1.
By smoothing the output of this mono multivibrator with a low-pass filter, the amount of liquid to be measured rising in the air tube 2-1 can be determined.
FIG. 6B shows the case where the diameter of the air tube tip 2-1A is set to 3.0 mmφ, and the pulse generation of the waveforms 6-3 and 6-4 is shorter than that in FIG. 6A. You can see that

<Third Embodiment>
This will be described with reference to FIG. In the second embodiment, an additional air tube 3-12 and a solenoid valve 3-4C are added to a sealed tank with a lid 3-3 attached to the tank of FIG. 2 and connected to an air branch device 3-5.
The air tubes 3-1, 3-2 and 3-12 are fixed to the lid, and the tip of the air tube 3-12 is installed above the liquid level of the ratio measuring liquid in the tank 3-11. The internal pressure in -11 can be measured. Thus, the viscosity, specific gravity, and liquid level can be measured even when an internal pressure exists in the closed tank.

<Fourth embodiment>
This will be described with reference to FIG. From the level 4-10 of the liquid to be measured in the tank 4-11 to the hole 4-3A provided at the bottom of the viscosity measuring device 4-3 of this embodiment, which can be changed to a different diameter depending on the target viscosity. The depth is h, and the distance from 4-3A to the tip 4-2A of the air tube 4-2 is d. The specific gravity of the liquid to be measured is ρ.
First, when the electromagnetic valve 4-4 is turned on (opened) and left to stand, the liquid to be measured in the tank 4-11 enters the liquid level of the liquid to be measured in the viscosity measuring device 4-3 of this embodiment. It rises to 4-10 and is in equilibrium.
In this state, when the air pump 4-6 is first turned on, air flows through the air tube 4-2, and the liquid to be measured in the air tube 4-2 is expelled and discharged from the air tube tip 4-2A as bubbles.
When the pressure at this time is P1, P1 = ρ × g × hd) (1)
Next, when the solenoid valve 4-4 is turned OFF (closed), the air from the air pump 4-6 further pushes out the liquid to be measured in the viscosity measuring device 4-3, and finally the bottom of the viscosity measuring device 4-3. Begin to discharge air bubbles from hole 4-3A.
The pressure P2 at this time is
P2 = ρ × g × h ………………………… (2)
It becomes. From the equations (1) and (2), the specific gravity ρ is
ρ = (P2−P1) / (g × d) (3)
As well as the liquid level h.
Next, when the solenoid valve 4-4 is turned on again, the liquid to be measured starts to flow from the hole 4-3A.
In the microprocessor, the time measurement is started from the time when the electromagnetic valve 4-4 is turned on until the liquid to be measured flows into the air tube tip 4-2A from the hole 4-3A and rises. Measure time.
The viscosity can be determined by comparing this measured time with the time previously determined with a known viscosity.
However, in this example, the measured time varies depending on the distance h from the liquid level of the viscosity measuring device 4-3.
For example, when h is large, the pressure applied to the hole 4-3A at the bottom of the viscosity measuring device 4-3 is large, and the inflow speed of the liquid to be measured is also increased. It is necessary to prepare a table including the case where the depth h is changed.
In order to explain a series of operations in FIG. 4, FIG. 7 shows an actually measured waveform of the pressure VS time when the diameter of the hole 4-3A is used as a parameter.
The position 7-1 in FIG. 7 is when the air pressure in the viscosity measuring device 4-3 is P2.
Next, immediately after the solenoid valve 4-4 is turned ON, the pressure in the viscosity measuring device 4-3 becomes 0 (atmospheric pressure), but then the liquid to be measured rises in the viscosity measuring device 4-3. Then, it reaches the air tube tip 4-2A and further rises.
The pressure in the air tube 4-2 begins to rise from the time when the liquid to be measured reaches the air tube tip 4-2A. The rising start time depends on the diameter of the hole 4-3A as shown in FIG.
Therefore, if the time from when the solenoid valve 4-4 is turned on to the pressure rise point is measured with the pressure sensor 4-7 connected to the microprocessor 4-8, the diameter can be measured, and the diameter should be kept constant as well. The viscosity can be measured.

1-1 Air Tube 1-1A Air Tube Tip 1-2 Cup 1-2A Replaceable Cup Bottom Hole 1-3 Air Tube Fixture 1-3A For 1-4 Air Divider 1-5 Measurement Start Switch 1 -6 Air pump 1-7 Pressure sensor 1-8 Microprocessor control unit 1-9 Display 1-10 Liquid level 2-1 Air tube 2-1A Air tube tip 2-2 Air tube 2-2A Replaceable air tube Tip 2-3 Air Tube Fixture 2-4A Solenoid Valve 2-4B Solenoid Valve 2-5 Air Divider 2-6 Air Pump 2-7 Pressure Sensor 2-8 Microprocessor Control Unit 2-9 Display Unit 2-10 Liquid Surface 2-11 Tank 3-1 Air tube 3-1A Air tube tip 3-2 Air tube 3-2A Replaceable air tube tip 3-3 Container sealed 3-4A Solenoid valve 3-4B Solenoid valve 3-4C Solenoid valve 3-5 Air branching unit 3-6 Air pump 3-7 Pressure sensor 3-8 Microprocessor control unit 3-9 Display unit 3-10 Liquid level 3 11 Tank 3-12 Air tube 4-1 Air tube 4-2 Air tube 4-2A Air tube tip 4-3A Replaceable cup bottom hole 4-3B Cup fixing device 4-3C Cup lid 4-4 Solenoid valve 4 -5 Air divider 4-6 Air pump 4-7 Pressure sensor 4-8 Microprocessor control unit 4-9 Display 4-10 Liquid level 4-11 Tank

Claims (4)

  The hole diameter of the bottom of the viscosity measuring cup can be exchanged, one end is connected to the air tube fixed to the viscosity measuring cup, the air branch connected to the other end of the air tube, and the air branch Viscosity / specific gravity, which consists of an air pump and pressure sensor, a controller that drives the air pump, a microprocessor that takes in the output of the pressure sensor, and a display that displays the viscosity, specific gravity, and liquid level processed by the controller Liquid level measuring instrument. One end is composed of two air tubes, immersed in the liquid to be measured for viscosity, has a step at the tip, and has a structure that allows the diameter of the shallow tube to be exchanged, and is fixed to the container containing the liquid to be measured The two air tubes and electromagnetic valves connected to the other ends of the two air tubes are provided, and the two electromagnetic valves are further connected to an air pump and a pressure sensor through an air branching device.
The air pump and the pressure sensor are connected to a microprocessor control unit, and the microprocessor control unit is connected to an indicator for displaying the measured viscosity, specific gravity, and liquid level.   A third air tube having a tip above the liquid level of the liquid to be measured and a solenoid valve are added to the fourth aspect of the invention to provide a viscosity, specific gravity and liquid level measuring device for a sealed liquid container to be measured.   The hole diameter of the bottom of the viscosity measuring cup can be exchanged, one end is fixed to the viscosity measuring cup lid and the other end is connected to the solenoid valve, and one end penetrates the viscosity measuring cup lid and the inside of the cup There is another air tube that is inserted and fixed at a specified position from the bottom and whose other end is connected to an air branch, and an air pump and a pressure sensor are connected to the branch, and the air pump and the pressure sensor Is a viscosity / specific gravity / liquid level measuring device connected to a microprocessor control unit, and an indicator for displaying the measured viscosity, specific gravity and liquid level is connected to the microprocessor control unit.

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