JPS6131947A - Automatic solidifying point measuring instrument - Google Patents

Abstract

PURPOSE:To make possible the calculation of the solidifying point of a sample liquid with high accuracy by measuring continuously the temp. change of the sample liquid while agitating the same and detecting the point of the time when the temp. change of the sample liquid attains equil. or increases as the latent heat of the solidification of the sample liquid. CONSTITUTION:A vessel 2 into whih the sample liquid 1 is injected is charged into a cooling bath 5 contg. a refrigerant 4 via an outside cylinder 3. While agitating the test liquid 1 by an agitating means 8 consisting of an agitating bar 6 and an agitating bar driver 7, the temp. of the sample liquid 1 is periodically measured by a temp. measuring means consisting of a temp. sensor 9 and a temp. measuring circuit 10. The point of the time when the temp. of the liquid 1 increases or attains the equil. state is detected as the latent heat of solidification by an arithmetic control means 12 and the operation of the means 8 is stopped. The solidification point is calculated by the means 12 and is displayed by a display means 13. The human intervention is eliminated in reading of the temp. in the above-mentioned manner and therefore the solidifying point is determined with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic freezing point measuring device used for measuring the freezing point of a liquid.

[Conventional technology]

As is well known, the method for measuring the freezing point of a liquid is based on the Standard Oil and Fat Analysis Test Method established by the Japan Oil Chemists' Association (JOC52, 3).
, 5, 1-71) and Japanese Industrial Standards (JISKOO65).
) There is a method for measuring the trowel surface point of chemical products. These methods involve manually stirring a sample liquid in a container such as a test tube, reading the temperature change of the sample liquid in the container with a thermometer, and plotting the read value on graph paper. It is used to find the freezing point.

In this method, the sample solution must be manually stirred repeatedly until the freezing point is determined, and the temperature must be read and plotted many times. Since changes, etc. are observed with the naked eye, there is a drawback that errors are likely to occur δ [Problems to be solved by the invention] This invention solves the conventional problems as described above, such as the troublesomeness of measurement and the tendency to cause errors. It is an object of the present invention to provide an automatic freezing point measuring device that can solve the problems and automatically and highly accurately measure the freezing point of a liquid with a simple configuration.

[Means for Solving the Problems] In the course of consideration to achieve the above object, the inventor discovered the following:
First, we focused on the fact that the temperature change of a liquid in a cooled state has the following specific regularity if the liquid generates latent heat of solidification.

In other words, as shown in Figure 4, the cooling state of the liquid is such that the liquid is cooled with a certain temperature gradient, and then when the liquid solidifies, the latent heat of solidification is released and the temperature rises or the equilibrium state (point a) continues. , and then the temperature drops.

Therefore, as a result of intensive studies to solve the above-mentioned conventional problems by obtaining an automatic freezing point measuring device that utilizes the regularity of temperature changes, the inventor found that while stirring the sample liquid, the temperature of the sample liquid increases. We succeeded in obtaining an automatic freezing point measurement device that continuously measures changes in temperature, detects the point at which the temperature change of the sample liquid reaches equilibrium or rises as the latent heat of solidification of the sample liquid, and calculates the freezing point from this.

That is, the above-mentioned apparatus of the present invention includes a temperature measuring means for regularly measuring the temperature of the sample liquid, and a temperature measuring means that measures the temperature of the sample liquid at a time when the temperature change reaches equilibrium or rises depending on the output from the temperature measuring means. The present invention has a simple structure by being equipped with an arithmetic control means that detects the latent heat of solidification of the sample liquid and stops the operation of the stirring means and calculates the freezing point of the sample liquid, and a display means that displays the freezing point. This method is characterized in that the freezing point of a liquid can be measured automatically and with high precision, thereby eliminating all the problems of the conventional methods.

[Embodiments of the Invention] Figure 1 is an overall configuration diagram of an automatic freezing point measuring device according to the present invention.

As shown in FIG. 1, the apparatus according to the present invention includes a sample liquid 1
A sample liquid container 2 such as a cylindrical test tube filled with
The sample liquid 1 is charged into a cooling bath 5 containing a refrigerant 4 through a holder, and while being stirred by a stirring means 8 consisting of a stirring rod 6 and a stirring rod driving device 7, a temperature sensor 9 and a temperature measuring circuit 1 are connected to the sample liquid 1. A temperature measuring means 11 consisting of a temperature measuring means 11 periodically measures the temperature of the sample liquid 1, and an arithmetic control means 12 detects the point in time when the temperature of the sample liquid 1 rises or reaches an equilibrium state as latent heat of solidification, and stirring means 8 is stopped, the calculation control means 12 calculates the freezing point, and the display means 13 displays the freezing point.

FIG. 2 is a block diagram showing a circuit configuration of an automatic freezing point measuring device based on the configuration of FIG. 1. This second
In the example shown in the figure, the configuration is such that the freezing points of two types of sample liquids can be measured.

In the figure, reference numerals 21 and 22 indicate one temperature sensor 9. An amplifier and a constant current circuit provided correspondingly to the 2
3.24 is an amplifier and constant current circuit provided corresponding to the other temperature sensor 92, and 25 is the amplifier 2.
1.23 by periodically switching the output value from analog
This is a multiplexer for inputting to a digital converter (hereinafter referred to as an A/D converter) 26, which constitutes the temperature measuring means 11 in FIG. 27 and 28 are motor drive circuits and motors provided corresponding to one stirring rod 6, respectively, and 29 and 30 are respective stirring rods 6 on the other side.
This is a motor drive circuit and a motor provided corresponding to No. 2.

31 is a microcomputer, which has a CPU 32, a memory 33, an input circuit 34, and an output circuit 35;
U32 extracts the sample liquid 10 from the output of the A/D converter 26,
A temperature change of 1□ is detected at an interval of 30 seconds, and from this temperature change the freezing point of the sample liquid can be calculated and the motor drive circuit 2
7.29 is controlled via the output circuit 35. 36 is a display drive circuit connected to the output circuit 35, 37 is a 7-segment indicator, 38 is a printer, 39
is an alarm.

At this point, the operation of the above configuration will be explained with reference to FIGS. 2 and 3.

First, sample solutions 1□ and 12 are injected into test tubes 20 and 2□, respectively, and temperature sensors 91 and 9□ and stirring rods 61 and 6□ are set. Then, the above sample solution 11
．． Each test tube 21, 2□ is placed in a cooling bath 5 containing a refrigerant 4 approximately 15° C. lower than the expected freezing point of 1□.

When the device starts operating, each motor drive circuit 27, 29 is set to 0 by a command from the microcomputer 31.
NL (Fig. 3 processing step 1o1), each motor 28, 3
Stirring rod 6, driven at 0.

6□ stirs 11 piles of each sample solution. On the other hand, the temperature detection signals from each temperature sensor 90, 9□ are amplified by amplifiers 21 and 23, and then applied to the A/D converter 26 while being alternately switched by the multiplexer 25.
The signal is converted into a digital signal by the D converter 26 and sent to the microcomputer 31.

The CPU 32 first reads the temperature Tn after the temperature of the sample liquids II and 12 begins to fall (processing step 102 in FIG. 3), waits for 30 seconds (processing step 1O3 in FIG. 3), and then reads the temperature T ( ) is read (processing step 1o4 in FIG. 3), and the temperature difference ΔT before and after 30 seconds is calculated from the following equation (processing step 105 in FIG. 3).

ΔT=Tn-T(n→-]) However, T temperature, n...integer, ΔT/temperature difference above CP
U32 repeats the above operation until the above ΔT becomes zero or negative.

Now, assuming that ΔT of the sample liquid 11 becomes ΔT≦0,
The CPU 32 detects this at judgment step 106 in FIG.
), the motor drive circuit 27 is turned off in order to stop stirring the sample liquid 11 (processing step 1 in Fig. 3).
07). Then, wait another 30 seconds (processing step 108 in FIG. 3) and read the temperature T(n+4) again (step 3).
Figure processing step 109), and ΔT is calculated in the same manner as above (Figure 3 processing step 110). This is repeated until the above ΔT becomes positive. When the above ΔT becomes positive (determination step 111 in FIG. 3), 3 when this ΔT becomes positive
The temperature 0 seconds ago is calculated and this is displayed as the freezing point of the sample liquid 11 on the 7-segment display 37 via the display drive circuit 36.
(processing step 112 in FIG. 3). Of course, at this time, the printer 38 may be used to record or an alarm 39 such as a buzzer may be activated. For a sample liquid of 1°, the freezing point is determined in the same manner as described above, and its explanation will be omitted.

Note that by setting a recorder (none of which is shown) in the output circuit of the microcomputer 31 via a D/A converter, it is possible to automatically record the cooling curve of the sample liquid in which latent heat of solidification does not occur. .

Next, the results of measuring the freezing points of various chemical product sample solutions using the above device are displayed. For comparison, results obtained using the conventional JIS method (K 0065) are also shown. Each measured value is the average value obtained by measuring the same sample solution five times.

〔Effect of the invention〕

As is clear from the above measurement results, this invention can accurately measure the freezing point of a sample liquid, and is more efficient because it eliminates the human effort of manually stirring the sample liquid and plotting the temperature on paper. In addition to being able to perform accurate measurements, since human intervention is eliminated in temperature reading, a highly reliable automatic a-fixing point measuring device that can determine the a-fixing point with high accuracy can be obtained.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of an automatic freezing point measuring device according to the present invention, FIG. 2 is a block diagram showing a specific circuit configuration of the device in FIG. 1, FIG. 3 is a flowchart for explaining the operation of the device, and FIG. FIG. 4 is a graph showing temperature changes in the cooling state of the liquid. 1. Sample liquid, 2. Container, 5. Cooling bath, 8. Stirring means, 11. Temperature measuring means, 12. Arithmetic control means, 13. Display means.

Claims (1)

[Claims] (1) A sample liquid container filled with a sample liquid and placed in a cooling bath, a sample liquid stirring means for stirring the sample liquid, a temperature measuring means for periodically measuring the temperature of the sample liquid, and the above-mentioned Arithmetic control for detecting the point in time when the temperature change of the sample liquid reaches equilibrium or rises in response to the output from the temperature measuring means as the latent heat of solidification of the sample liquid, and stopping the operation of the stirring means and calculating the freezing point of the sample liquid. and display means for displaying the freezing point.