JPH09304262A - Fall sphere type viscometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a viscometer capable of accurately and rapidly measuring the viscosity of freezing machine oil coexisting with a liquid cooling medium. SOLUTION: A liquid cooling medium and freezing machine oil are sealed in a measuring pipe composed of a transparent pressure-resistant cylinder arranged in an inclined state to be allowed to stand, and a fall sphere 14 composed of a ferromagnetic material is attracted by a permanent magnet 16 to be held at the upstream initial position of an freezing machine oil phase 10 in such a state that a liquid cooling medium phase 12 and the freezing machine oil phase 10 are separated in an equibrium state, and a permanent magnet support rod 18 is attracted by an electromagnet 19 to separate the permanent magnet 16 from the outer wall of a measuring pipe 13 to demagnetize the same and the attraction and holding of the fall sphere 14 is released to allow the sphere 14 to fall. The passing speed of the fall sphere 14 is measured by a passage sensor 15 arranged on the downstream side of the freezing machine oil 10 and the viscosity of the freezing machine oil is measured on the basis of the correlation of the passing speed with viscosity. Since viscosity is measured in such a state that the liquid cooling medium phase 12 and the freezing machine oil phase 10 are separated and allowed to stand, an equilibrium state is not disturbed and an accurate viscosity value is obtained. When viscosity is measured in a thermostatic tank 24, the above mentioned demagnetizing operation can be performed without opening the door of the tank 24.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a falling ball viscometer for measuring the viscosity of a refrigerant machine oil phase coexisting with a liquid refrigerant phase.

[0002]

2. Description of the Related Art A conventional viscometer will be described below with reference to the drawings. One of the means for measuring the viscosity of refrigerating machine oil in which a refrigerant is dissolved in a refrigerant atmosphere is disclosed in JP-A-3-481.
It was disclosed in Japanese Patent Laid-Open No. 34-34, and was measured using the viscometer disclosed therein and a viscometer similar thereto.

FIG. 6 is a side sectional view showing a schematic structure of the above-mentioned conventional viscometer for measuring the viscosity of refrigerating machine oil in which a refrigerant is melted in a refrigerant atmosphere. In the figure, 1 is a transparent pressure-resistant container, 2 is a lower lid, 3 is an upper lid, 4 is a refrigerant inlet / outlet, 5 is a needle, 6 is a viscometer support tube, 7 is a viscometer sandwiched, 8 is a capillary viscometer, 9
Indicates an upper oil sump, 10 indicates a refrigerator oil phase, and 11 indicates a gas refrigerant phase.

A measuring method using the viscometer having the above structure will be described. A required amount of refrigerating machine oil is put in a transparent pressure-resistant container 1, and the peripheral edge portion of the opening is sandwiched between a lower lid 2 and an upper lid 3 and fixed with a screw, and a viscometer indicating tube 6 is attached to the upper lid 3. Next, the pressure-resistant container 1 is evacuated from the refrigerant inlet / outlet 4 with a vacuum pump, and the refrigerant is introduced from the refrigerant inlet / outlet 4. Next, the pressure-resistant container 1 is installed in a constant temperature bath maintained at a constant temperature, and when the temperature reaches a predetermined temperature, the pressure-resistant container 1 is tilted by 90 degrees, and the refrigerating machine oil in which the refrigerant is dissolved is stored in the thin-tube viscometer 8. Upper oil sump 9
When the refrigerating machine oil in which the refrigerant is dissolved is filled, the pressure vessel 1 is vertically installed.

Refrigerating machine oil in which the refrigerant is dissolved in the capillary viscometer 8 passes through the upper oil sump 9 and the time taken for the liquid level to pass through the capillary of the capillary viscometer 8 is visually measured to determine the transit time. The viscosity of the refrigerating machine oil in which the refrigerant is dissolved is measured from the correlation between the viscosity and the viscosity.

[0006]

However, such a conventional viscometer has a problem that the viscosity of refrigerating machine oil in the coexistence of a liquid refrigerant cannot be accurately measured.

In the refrigerating cycle, when the temperature of the evaporator portion becomes low, the liquid refrigerant and the refrigerating machine oil are separated into a three-phase state of the liquid refrigerant phase, the refrigerating machine oil phase and the gas refrigerant phase. The refrigerating machine oil phase has high viscosity at low temperature, but is agitated by the flow of the refrigerant, dissolves a certain amount of the refrigerant, and is in an equilibrium state with the liquid refrigerant phase and the gas refrigerant phase.

However, in order to reproduce this state and measure the viscosity of the refrigerating machine oil, the refrigerant is dissolved in the refrigerating machine oil by stirring well and then allowed to stand for a long period of time to maintain equilibrium while maintaining the liquid refrigerant phase. And it is necessary to separate the refrigerator oil phase. this is,
This is because the densities of the liquid refrigerant phase and the refrigerator oil are close to each other, and the viscosity of the refrigerator oil phase is high at a low temperature.

Therefore, in the conventional viscometer, since each phase is moved immediately before the measurement, the equilibrium is disturbed, and the viscosity of the refrigerating machine oil in the coexistence of the liquid refrigerant cannot be accurately measured.
In addition, since the viscosity of refrigerating machine oil increases significantly at low temperatures, even when a tilted pressure-resistant container is installed vertically, the refrigerating machine oil drops very slowly, and the refrigerating machine oil remains around the capillary viscometer. However, it becomes impossible to read that the liquid level of the refrigerating machine oil passes through the thin tube portion of the thin tube viscometer.

The present invention solves the above problems, and an object of the present invention is to provide a falling ball viscometer capable of accurately measuring the viscosity of refrigerating machine oil coexisting with a liquid refrigerant.

[0011]

A viscometer of the present invention is a state in which a liquid refrigerant and a refrigerating machine oil are enclosed in a slanting circular tube and allowed to stand, and the liquid refrigerant phase and the refrigerating machine oil phase are separated. In the above, it is a falling ball viscometer in which a falling ball is made to fall in the oil phase of the refrigerator and the viscosity is measured by the speed thereof.

Since the viscosity is measured while the refrigerating machine oil phase and the liquid refrigerant phase in the measuring tube are allowed to stand still, the equilibrium viscosity can be measured accurately. In addition, a falling ball is dropped using a demagnetizing device and the passage time is measured by a passage sensor, so it is possible to measure only the measurement pipe part at low temperature, and a low temperature and high viscosity where the passage time is long. Can also be easily measured.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A measuring tube is made of a transparent pressure-resistant circular tube so that the states of a liquid refrigerant and a refrigerating machine oil therein, for example, turbidity and separation state can be observed. The measuring pipe is installed so as to be inclined, and the liquid refrigerant and the refrigerating machine oil are enclosed and left standing therein. The falling ball is made of a magnetic material, and is adsorbed and held by a permanent magnet at a predetermined position on the upstream side in the refrigerator oil phase separated in the measuring tube, and the holding of the falling ball is released by demagnetizing the permanent magnet. And start falling. The permanent magnet is installed below the outer wall of the measuring tube. The demagnetization device means a device for releasing the fallen ball holding of the permanent magnet, and in the embodiment, it is demagnetized by moving the permanent magnet away from the fallen ball, and a permanent magnet support rod to which the permanent magnet is fixed is attached. It is attracted by an electromagnet and moved away, but it is not limited to this. Further, a passage sensor by an optical detector is installed at a predetermined distance below the outer wall of the downstream side of the measuring pipe, and the passing speed of the falling ball is measured by the passage time between them, but the optical detector is limited to the optical detector. Alternatively, a magnetic detector can be used.

Hereinafter, embodiments will be described.

[0015]

【Example】

(Example 1) Hereinafter, Example 1 of the falling ball type viscometer of the present invention
Will be described with reference to the drawings. This embodiment relates to claim 1.

FIG. 1 is a partially cutaway side view showing the structure of this embodiment. In the figure, 10 is a refrigerating machine oil phase, 11 is a gas refrigerant phase, 12 is a liquid refrigerant phase, 13 is a measuring tube made of a pressure-resistant glass circular tube, 14 is an iron falling ball, and 15 is an optical detector. A passage sensor, 16 is a permanent magnet for holding the falling ball 14, 17 is a spring that supports the permanent magnet 16, 18
Is an H-shaped iron permanent magnet support rod around which a spring 17 is wound, 19 is an electromagnet for attracting the permanent magnet support rod 18, 20 is a measuring stand, 21 is a refrigerant inlet / outlet, 22 is a valve,
Reference numeral 23 is a power source for energizing the electromagnet 19, and reference numeral 24 is a constant temperature bath provided with a glass window.

The operation of the above configuration will be described. Put the falling ball 14 and a necessary amount of refrigerating machine oil in the measuring pipe 13.
Next, the refrigerant inlet / outlet port 21 is connected to the vacuum pump and the refrigerant cylinder, and first, the inside of the measuring tube 13 is evacuated by the vacuum pump. At this time, the air dissolved in the refrigerating machine oil is also sufficiently expelled. Next, the connection is switched to the refrigerant cylinder and the refrigerant is introduced. After sealing a required amount of the refrigerant, the valve 22 is closed, the refrigerant is well stirred so that the refrigerant is dissolved in the refrigerating machine oil, and the measuring tube 13 is attached to the measuring table 20 installed in the constant temperature bath 24 kept at a low temperature. In addition, the falling ball 14 is attached to the permanent magnet 16
Held for a long time and allowed to stand for a long time to separate into a refrigerator oil phase 10 and a liquid refrigerant phase 12.

At this time, the refrigerating machine oil phase 10 becomes turbid. This phenomenon occurs because the lower the temperature is, the smaller the amount of saturated refrigerant dissolved in the refrigerating machine oil is, the refrigerant that cannot be completely melted deposits into particles, and is dispersed in the refrigerating machine oil. If the refrigerator oil phase 10 and the liquid-refrigerant phase 12 are equilibrium-separated due to the difference in density when the mixture is left still for a long time after this, the turbidity of the refrigerator oil phase 10 disappears.

After completely separating, the demagnetizing device consisting of the spring 17, the permanent magnet supporting rod 18, and the electromagnet 19 is operated to drop the falling ball 14. The above demagnetization device demagnetizes the permanent magnet support rod 18 by pulling the switch of the power source 23 of the electromagnet on from the outside of the constant temperature bath 24 to draw the permanent magnet support rod 18 away from the falling ball 14. The falling ball 14 is designed to fall. The time taken for the fallen ball 14 to pass between the passage sensors 15 is measured, and the viscosity is obtained from the correlation between the viscosity and the passage time.
At this time, the falling ball 14 is not directly held by the electromagnet 19,
The reason for using the permanent magnet 16 is to prevent the temperature of the refrigerating machine oil phase from rising due to heat generation of the electromagnet 19. In addition, when the electromagnet 19 is turned off, the demagnetizer returns the permanent magnet 16 to the original holding position by the elasticity of the spring 17.

As described above, according to the present embodiment, the viscosity of the refrigerating machine oil coexisting with the liquid refrigerant is measured while the refrigerating machine oil phase and the liquid refrigerant phase remain stationary in the measuring pipe 13, so that the accuracy is high. Since the viscosity can be measured and the temperature of only the measurement portion can be lowered, the measurement at low temperature becomes easy. Furthermore, by holding the falling ball 14 using the permanent magnet 16, it is possible to perform temperature adjustment with higher accuracy.

Although iron balls are used for the falling balls 14 in this embodiment, any ferromagnetic material such as nickel balls may be used.
It is advisable to select a material having an optimum density according to the viscosity range to be measured. Although the optical sensor is used as the passage sensor 15 in this embodiment, a magnetic detector may be used. Also,
In the demagnetization device of this embodiment, the magnetic force of the permanent magnet 16 is reduced by increasing the distance between the falling ball 14 and the permanent magnet 16.
It is also possible to insert a member for blocking the lines of magnetic force between the falling ball 14 and the permanent magnet 16.

(Embodiment 2) Embodiment 2 of the falling ball viscometer of the present invention will be described below with reference to the drawings. This embodiment relates to claims 2 to 4.

FIG. 2 is a partially cutaway side view showing the structure of this embodiment. Note that the same components as those of the first embodiment shown in FIG.

In this embodiment, a plurality of pairs of demagnetizing devices each including a spring 17, a permanent magnet support rod 18, and an electromagnet 19 are provided, and the falling ball holding position is changed by changing the position at which the permanent magnet 16 is installed. The distance between the holding position and the passage sensor 15 is variable. The operation of this embodiment is the same as that of the first embodiment.
Is the same as

The viscosity of the refrigerating machine oil is measured by measuring the time taken for the falling balls 14 passing through the refrigerating machine oil to pass between the passage sensors 15.
The viscosity is obtained from the correlation between the passage time and the viscosity. In order to obtain the viscosity from this correlation, when the falling ball 14 passes through the passage sensor 15, the terminal velocity must be reached. When the falling ball 14 passes through the refrigerating machine oil, it falls by being accelerated by gravity, but it becomes constant at a speed commensurate with the resistance of the refrigerating machine oil, which is called a terminal speed. A high runway requires a short runway, while a low runway requires a long runway. That is, when measuring low-viscosity refrigerating machine oil, it is necessary to set a long distance between the falling ball holding position and the passage sensor 15.

As described above, according to this embodiment, the distance between the falling ball holding position and the passage sensor 15 can be variably set so that the falling ball holding position and the passage sensor 15 can be used when the viscosity is low. When the viscosity is high, the distance between the falling ball holding position and the passage sensor 15 can be set short to shorten the measurement time.

In this embodiment, the distance between the falling ball holding position and the passage sensor 15 can be variably set by providing a plurality of pairs of permanent magnets and demagnetizers.
Alternatively, the passage sensor 15 may be varied by a means such as a slide plate that slides in parallel with the measuring tube 13. Needless to say, as shown in the drawing, the permanent magnet 16 that does not hold the falling ball 14 may be removed from the permanent magnet support rod 18.

(Embodiment 3) Hereinafter, Embodiment 3 of the falling ball viscometer of the present invention will be described with reference to the drawings. This embodiment relates to claim 5.

FIG. 3 is a partially cutaway side view showing the structure of this embodiment. Note that the same components as those of the first embodiment shown in FIG.

In the figure, 25 is an electromagnet, 26 is a linear motor as a moving device for moving the electromagnet 25 in parallel with the measuring tube 13 from the downstream side of the measuring tube to the upstream side of the measuring tube, and 27.
Is a power source of the electromagnet 25.

The operation of the above configuration will be described. After the operation shown in the first embodiment, in order to manually perform the operation of returning the falling ball 14 at the lower portion of the measuring tube 13 to the falling ball holding position, the door of the constant temperature bath 24 has to be opened once. The temperature of the constant temperature bath 24 is disturbed. When the temperature control of the constant temperature bath 24 is disturbed, the time during which the temperature of the constant temperature bath 24 becomes constant,
It must wait for the refrigerator oil phase 10, the gas refrigerant phase 11, and the liquid refrigerant phase 12 to equilibrate. In the present embodiment, in order to reduce this time, when the falling ball falls to the downstream side of the measuring tube, the moving device 2 such as the electromagnet 25 and the linear motor is moved.
6 is used to return the falling ball 14 to the falling ball holding position by using a falling ball conveying device including the power source 27 of the electromagnet 25.

In this falling ball conveying device, the power supply 27 is turned on and the electromagnet 25 is operated to hold the falling ball 14. Next, the moving device 2 is held while holding the falling ball 14.
6 is operated to slowly return to the falling ball holding position so as not to disturb the equilibrium between the refrigerator oil phase 10 and the liquid refrigerant phase 12. At the time of returning to the falling ball holding position, the switch of the power supply 27 is turned off, and when the falling ball 14 is released, it is held by the permanent magnet 16 and becomes ready to measure again.

As described above, according to this embodiment, by using the falling ball transporting device, the falling ball 14 can be maintained while maintaining the equilibrium between the refrigerator oil phase 10 and the liquid refrigerant phase 12 without opening the door of the constant temperature bath 24. Return to the falling ball holding device to enable continuous measurement.

(Example 4) Hereinafter, Example 4 of the falling ball type viscometer of the present invention will be described with reference to the drawings. This embodiment relates to claim 6.

FIG. 4 is a schematic diagram showing the structure of this embodiment. Note that the same components as those of the first embodiment shown in FIG. In the figure,
28 is a turbidity sensor using an optical detector.

The operation of the above configuration will be described. Stir well so that the refrigerant dissolves in the refrigerating machine oil.
Table 20 installed in a constant temperature bath 24 in which the temperature is kept low
Attach to Next, the falling ball 14 is held by the permanent magnet 16 and left standing for a long time to separate into the refrigerator oil phase 10 and the liquid refrigerant phase 12. At this time, the refrigerating machine oil phase 10 becomes turbid, but as described above, the lower the temperature, the smaller the amount of saturated refrigerant dissolved in the refrigerating machine oil becomes, and the refrigerant that cannot be completely melted deposits into particles, and This is because it is dispersed in. If left as it is for a long time, the refrigerator oil phase 10 and the liquid refrigerant phase 12 are separated due to the difference in density, and the refrigerator oil phase 10 is not turbid.

At this time, the turbidity sensor 28 confirms that the refrigerator oil phase 10 and the liquid refrigerant phase 12 are completely separated. In this embodiment, an optical detector composed of a light emitting element and a light receiving element is used as the turbidity sensor 28, and the intensity of light passing through the refrigerating machine oil phase 10 interposed between both elements and reaching the light receiving element. The turbidity is calculated based on the signal corresponding to. Here, there is a certain relationship between the turbidity of the refrigerator oil phase 10 and the light transmittance, and as the turbidity progresses, the transmittance decreases and the amount of light reaching the light receiving element decreases. Therefore, when the refrigerating machine oil phase 10 becomes cloudy due to the deposited refrigerant, the light transmission becomes poor, and when the equilibrium state is reached, the refrigerating machine oil phase 10 becomes transparent and the light transmission rate is improved.
The equilibrium state can be automatically determined by measuring the turbidity of. Further, the turbidity of only the refrigerating machine oil is measured as a blank, and a blank value or a turbidity slightly larger than the blank value is set as a predetermined turbidity, and when the predetermined turbidity is reached, the switch of the power supply 23 is turned on. By setting as above, the measurement is automatically started. In addition,
Other operations are similar to those of the first embodiment.

As described above, according to this embodiment, by measuring the turbidity of the refrigerating machine oil with the turbidity sensor, the equilibrium state can be automatically determined, and the turbidity of the refrigerating machine oil is below a predetermined value. If so, the measurement can be started automatically.

(Embodiment 5) Embodiment 5 of the falling ball type viscometer of the present invention will be described below with reference to the drawings. This embodiment relates to claim 7.

FIG. 5 is a partially cutaway side view showing the structure of this embodiment. The same components as those of the fourth embodiment shown in FIG. 4 are assigned the same reference numerals and detailed explanations thereof will be omitted. In the figure, 29 is a control device for controlling the temperature of the constant temperature bath 24.

The operation of the above configuration will be described. When the viscosity of the refrigerating machine oil phase 10 increases at a low temperature, the settling speed of the heavy liquid refrigerant also decreases accordingly, so that the refrigerating machine oil phase 1
In order to separate into 0 and the liquid refrigerant phase 12, it has to stand still for a long time. However, since the higher temperature reaches equilibrium in a shorter time, the time to reach the equilibrium is shorter when the temperature is lowered stepwise. Therefore, in order to optimize the temperature of the constant temperature bath 24, the temperature of the constant temperature bath 24 is started to be lowered after mounting the measuring tube 13. When the turbidity of the refrigerating machine oil reaches a predetermined turbidity higher than the turbidity in the equilibrium state, the controller 29 sets the temperature of the constant temperature bath 24 to be constant at that temperature. When the turbidity reaches a temperature in an equilibrium state by standing still at that temperature, the temperature of the constant temperature bath 24 is set again by the control device 29 so as to decrease. When the turbidity of the refrigerating machine oil reaches a predetermined turbidity that is higher than the turbidity in the equilibrium state due to the temperature decrease, the controller 29 sets the temperature of the constant temperature bath 24 to be constant at that temperature. . This operation is repeated until the turbidity of equilibrium is reached at a predetermined temperature.
The other operations are the same as in the fourth embodiment.

As described above, according to this embodiment, the turbidity sensor 28 and the controller 29 for controlling the temperature of the constant temperature bath 24 are used to control the temperature of the constant temperature bath 24 step by step, whereby the constant temperature bath is controlled. It is possible to optimize the temperature of 24 and shorten the time for the refrigerator oil phase 10 to reach an equilibrium state.

[0043]

As is clear from the above description, the falling-ball viscometer of the present invention measures the viscosity while leaving the refrigerating machine oil phase and the liquid refrigerant phase in the measuring pipe stationary, so that the viscosity in the equilibrium state Can be measured accurately. Also, by using the demagnetization device to drop the falling ball and measuring the passage time with the passage sensor,
It is possible to measure only the measuring tube portion at a low temperature, and it is also possible to easily measure a low temperature and high viscosity in which the passage time is long.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view showing a configuration of Example 1 of a falling ball viscometer of the present invention.

FIG. 2 is a partially cutaway side view showing the configuration of Example 2 of the falling-ball viscometer of the present invention.

FIG. 3 is a partially cutaway side view showing the configuration of Example 3 of the falling ball viscometer of the present invention.

FIG. 4 is a partially cutaway side view showing the configuration of Example 4 of the falling ball viscometer of the present invention.

FIG. 5 is a partially cutaway side view showing the configuration of Example 5 of the falling ball viscometer of the present invention.

FIG. 6 is a side sectional view showing the configuration of a conventional viscometer.

[Explanation of symbols]

 10 Refrigerator Oil Phase 11 Gas Refrigerant Phase 12 Liquid Refrigerant Phase 13 Measuring Tube 14 Falling Ball 15 Passing Sensor 16 Permanent Magnet 17 Spring (Demagnetizing Means) 18 Permanent Magnet Support Rod (Demagnetizing Device) 19 Electromagnet (Demagnetizing Device) 20 Measurement Platform 23 Power supply (demagnetization device) 24 Constant temperature bath 25 Electromagnet (falling ball transfer device) 26 Moving device (falling ball transfer device) 27 Power supply (falling ball transfer device) 28 Turbidity sensor 29 Control device

Claims (7)

[Claims] 1. A falling ball viscometer for measuring viscosity from the speed of falling balls in refrigerating machine oil coexisting with a liquid refrigerant, comprising:
An inclined measuring tube made of a transparent pressure-resistant circular tube, a falling ball made of a ferromagnetic material, a permanent magnet installed below the outer wall of the measuring tube, a demagnetizing device for the permanent magnet, and the permanent magnet. With a passage sensor installed on the lower side of the outer wall of the measuring pipe on the downstream side of the magnet, the liquid refrigerant and the refrigerating machine oil are enclosed and settled in the inclined measuring tube, and equilibrated with the liquid refrigerant phase and the refrigerating machine oil phase. In the state in which the refrigerating machine oil phase is separated and the liquid refrigerant phase is separated into the slanting downstream side and the slanting downstream side, the permanent magnet holds the falling ball in the refrigerating machine oil phase, and the demagnetizing device. Is to reduce the magnetic force of the permanent magnet to release the holding of the falling ball, and the passage sensor measures the speed at which the falling ball passes through the refrigerating machine oil phase in accordance with its viscosity. Viscometer. 2. A plurality of sets of a permanent magnet that holds a falling ball and a demagnetizing device that demagnetizes the permanent magnet are sequentially provided along the measuring tube, and the set that holds the falling ball is selectively used. The falling ball type viscometer according to claim 1, wherein the distance between the falling ball holding position and the passage sensor can be set arbitrarily by doing so. 3. A falling ball holding position is provided with slide means for slidably holding one set of a permanent magnet holding a falling ball and a demagnetizing device for demagnetizing the permanent magnet along a measuring tube. The falling ball viscometer according to claim 1, wherein the distance to the passage sensor can be set arbitrarily. 4. The falling ball type according to claim 1, further comprising slide means for holding the passage sensor slidably along the measuring pipe so that a distance between the falling ball holding position and the passage sensor can be arbitrarily set. Viscometer. 5. A falling ball conveying device comprising an electromagnet on the outer wall of the measuring pipe capable of adsorbing a falling ball in the oil phase of a refrigerator, and a moving device for moving the electromagnet from the downstream side to the upstream side in parallel with the measuring pipe. The falling-ball viscometer according to claim 1, wherein the falling-ball viscometer is configured to convey the already-falling falling balls to the falling-ball holding position by the falling-ball conveying device. 6. The fall-down according to claim 1, further comprising a turbidity sensor for measuring the turbidity of the refrigerator oil phase in the measuring tube, and detecting the equilibrium state between the liquid refrigerant phase and the refrigerator oil phase by the turbidity. Spherical viscometer. 7. A thermostat for accommodating a measuring tube and a controller for controlling the temperature of the thermostat according to the output signal of the turbidity sensor, and when the turbidity exceeds a predetermined value larger than the equilibrium turbidity. The temperature inside the thermostatic bath is gradually changed to a desired temperature by repeating the process of holding the temperature of the thermostatic bath and changing the temperature of the thermostatic bath by a predetermined value when the turbidity falls below the predetermined value. The falling ball type viscometer according to claim 6, wherein.