Blaine viscometer calibration method

Abstract

The invention belongs to the technical field of viscosity measurement and calibration, and discloses a Blaine viscometer calibration method, which is used for calibrating the temperature indication error, fluctuation and uniformity of a Blaine viscometer thermostatic bath by the following steps of: setting the measurement temperature of the Blaine viscometer thermostatic bath at 60 DEG C, placing a platinum resistance thermometer in a working plane which is 1 / 2 of the liquid height in the thermostatic bath, and after the temperature of the thermostatic bath is stable, reading the temperature indicating value at a uniform interval of one time per minute for at least 10 minutes to obtain 11 measurement values, and calculating the temperature indicating value error and the temperature fluctuation. The method is simple to operate and time-saving.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of viscosity measurement calibration, and particularly relates to a Brookfield viscometer calibration method. BACKGROUND

[0002] Brookfield viscosity refers to the viscosity value converted from the time taken by 100ml gelatin solution flowing through a standard capillary at 60 DEG C. The working principle of the Brookfield viscometer is based on Poiseuille's Law, which describes the characteristics of fluid flow in a capillary. According to Poiseuille's Law, the flow rate of fluid through the capillary is related to the pressure difference, the size of the capillary and the viscosity of the fluid. By measuring the time taken by the fluid to pass through the capillary, the kinematic viscosity can be calculated. Then, the Brookfield viscosity is automatically converted from the input fluid density value.

[0003] According to the above working principle, the Brookfield viscometer can accurately measure the viscosity of a liquid and is widely used in measuring the Brookfield viscosity performance of industrial gelatin, edible gelatin, medicinal gelatin, etc. It is widely used in the scientific research and production laboratories of the national defense industry, especially in the production enterprises of explosives and propellants, petroleum and chemical industry, pharmaceutical industry, food industry, etc. It is mainly used for measuring the Brookfield viscosity of gelatin, and further studying and controlling the vulcanization characteristics of gelatin. It is an important experimental equipment for measuring the viscosity of fluids in the laboratories of enterprises such as explosives and propellants, petroleum and chemical industry, pharmaceutical industry, food industry, etc.

[0004] Through investigation, it is found that there is no Brookfield viscometer calibration device in the domestic and foreign industries or other industries at present. The commonly used calibration method is to refer to the requirements of the enterprise technical manual, and to measure the viscosity value of 40% and 60% sucrose solution at (60±0.1) DEG C to calculate the constant of the capillary viscometer. The problem of this method is that the sucrose solution preparation time is relatively long, and the calibration error is large. The viscosity values of 40% and 60% sucrose solution at 60 DEG C are 2 mPa•s and 10 mPa•s, respectively, which cannot cover the measurement range of (0~999.99) mPa•s of the instrument viscosity measurement. SUMMARY

[0005] The technical problem to be solved by the present application is how to calibrate the Brookfield viscometer.

[0006] To solve the above technical problems, the specific technical scheme of the present application is as follows: A Brookfield viscometer calibration method, the temperature indication error, fluctuation, uniformity of the Brookfield viscometer constant temperature tank are calibrated as follows: Set the temperature of the constant temperature bath of the Blaine viscometer to 60℃. Place a platinum resistance thermometer in the working plane at 1 / 2 of the liquid height in the constant temperature bath. After the temperature of the constant temperature bath stabilizes, read the temperature reading at a uniform interval of once per minute for at least 10 minutes to obtain 11 measurement values. Calculate the temperature reading error and temperature fluctuation. The temperature uniformity test was conducted at 60℃. A standard platinum resistance thermometer was used as a fixed thermometer, inserted halfway into the working area and fixed at the center of the working area. Another thermometer was used as a movable thermometer, inserted into four points evenly distributed on the upper horizontal plane and four points evenly distributed on the lower horizontal plane of the working area. After the constant temperature bath reached 60℃ and stabilized for at least 10 minutes, the temperature readings were taken and recorded. The temperature uniformity was then calculated. The viscosity tube constant calibration is as follows: The viscosity tube of the Blaine viscometer to be tested is repeatedly rinsed with distilled water at a temperature above 70°C, then cleaned with alcohol or petroleum ether and dried. After that, the viscosity tube is placed in the working area of ​​the constant temperature bath. The lower end of the viscosity tube was sealed, and 110 mL of the first standard viscosity oil was added to the tube using a metering peristaltic pump. The temperature was kept constant for 10 minutes. After the temperature stabilized, the seal at the lower end of the tube was opened, and the measurement began. The time taken for the viscosity oil to pass through the photoelectric timer was obtained. kinematic viscosity of standard viscosity oil and dynamic viscosity A second filling of 110 mL was performed using a peristaltic pump, and the average of the two measurements was taken to obtain the timing, kinematic viscosity, and dynamic viscosity of the oil with the first viscosity. , , ; After cleaning and drying the viscosity tube, the above method was repeated twice using another standard viscosity liquid to obtain the time taken for the second standard viscosity oil to pass through the photoelectric timer, as well as the kinematic viscosity and dynamic viscosity values ​​of the standard viscosity oil. , , ; Based on the measurement results of the two viscosity oils, the Blaine viscosity constants A and B values ​​of the tested oil and the Blaine viscosity of the two standard viscosity oils were calculated. , ; The Blaine viscometer reading error calibration is as follows: Install the viscosity tube onto the Blaine viscometer being tested, re-enter the constant value of the viscosity tube and the density value of the viscosity oil, and measure the Blaine viscosity of the two standard viscosity oils to obtain the Blaine viscosity values ​​of the two standard viscosity liquids. , The viscosity indication error is calculated using the following formula: , In the formula: —Relative error in viscosity measurement by the viscometer, % —The Blaine viscosity value measured by the Blaine viscometer for the i-th time, in mPa·s; —The Blaine viscosity value measured by the viscosity tube constant calibration device for the i-th time, in mPa•s; Two standard viscosity liquids were selected, and the one with the larger absolute value of the Blaine viscosity measurement error was taken as the viscosity indication error of the viscometer being tested.

[0007] The present invention has the following advantages: (1) Simple to operate and saves time; (2) Standard viscosity fluid is a Newtonian fluid with relatively stable viscosity values ​​and small measurement errors; (3) The viscosity range of the standard viscosity liquid can be determined as needed and can meet the range requirements of instrument calibration. Attached Figure Description

[0008] Figure 1 A schematic diagram of temperature calibration for a constant temperature bath; The markings in the diagram are as follows: 1. Upper horizontal plane of the working area; 2. Lower horizontal plane of the working area; 3. Precision thermometer; 4. Measuring constant temperature water bath; 5. Fixed thermometer; 6. Moving thermometer. Detailed Implementation

[0009] To better understand the purpose, structure, and function of this invention, the invention will be described in further detail below with reference to the accompanying drawings.

[0010] The Blaine viscometer calibration method in this embodiment is as follows: Figure 1 As shown.

[0011] Step 1: Measurement of temperature indication error, fluctuation, and uniformity. Set the temperature of the constant temperature bath of the Blaine viscometer to 60℃. Place a platinum resistance thermometer in the working plane at 1 / 2 of the liquid height in the constant temperature bath. After the temperature of the constant temperature bath stabilizes, read the temperature reading at a uniform interval of once per minute for at least 10 minutes to obtain 11 measurement values. Calculate the temperature reading error and temperature fluctuation. Temperature uniformity testing is conducted at 60℃. Test locations are typically chosen at uniformly distributed points on the upper and lower horizontal planes of the working area. (Point O is the center of the working area; A, B, C, and D are four points evenly distributed on the upper horizontal plane of the working area; E, F, G, and H are four points evenly distributed on the lower horizontal plane of the working area.) See [link / reference needed]. Figure 1Positions O, A, B, C, D, E, F, G, H are defined in the work area. A standard platinum resistance thermometer is inserted halfway into the work area and fixed at point O. Another thermometer is inserted as a movable thermometer into positions A, B, C, D, E, F, G, and H within the work area. Figure 1 As shown. After the temperature in the constant temperature bath reaches 60℃ and stabilizes for at least 10 minutes, start taking readings. Record the temperature values ​​at each point and calculate the temperature uniformity.

[0012] Step 2: Viscosity tube constant calibration The viscosity tube of the Blaine viscometer to be tested should be repeatedly rinsed with distilled water at a temperature above 70°C, then cleaned with alcohol or petroleum ether and dried. After that, the viscosity tube should be placed in the working area of ​​the constant temperature bath.

[0013] Calibration was performed by filling the viscosity tube with two standard viscosity solutions in succession: The lower end of the viscosity tube was sealed, and 110 mL of the first standard viscosity oil was added to the tube using a metering peristaltic pump. The temperature was kept constant for 10 minutes. After the temperature stabilized, the seal at the lower end of the tube was opened, and the measurement began. The time taken for the viscosity oil to pass through the photoelectric timer was obtained. kinematic viscosity of standard viscosity oil and dynamic viscosity A second filling of 110 mL was performed using a peristaltic pump, and the average of the two measurements was taken to obtain the timing, kinematic viscosity, and dynamic viscosity of the oil with the first viscosity. , , ; After cleaning and drying the viscosity tube, the above method was repeated twice using another standard viscosity liquid to obtain the time taken for the second standard viscosity oil to pass through the photoelectric timer, as well as the kinematic viscosity and dynamic viscosity values ​​of the standard viscosity oil. , , .

[0014] Based on the measurement results of the two viscosity oils, the system will automatically calculate the Blaine viscosity constants A and B of the measured oil, as well as the Blaine viscosity of the two standard viscosity oils. , .

[0015] Step 3: Calibration of Blaine viscometer reading error: Install the viscosity tube onto the Blaine viscometer to be tested, re-enter the constant value of the viscosity tube and the density value of the viscosity oil, and measure the Blaine viscosity of the two standard viscosity oils according to the instrument's operating conditions to obtain the Blaine viscosity values ​​of the two standard viscosity liquids. , The viscosity indication error is calculated using the following formula.

[0016] In the formula: —Relative error in viscosity measurement by the viscometer, % —The Blaine viscosity value measured by the Blaine viscometer for the i-th time, in mPa·s; —The Blaine viscosity value measured by the viscosity tube constant calibration device for the i-th time, in mPa•s; Two standard viscosity liquids were selected, and the one with the larger absolute value of the Blaine viscosity measurement error was taken as the viscosity indication error of the viscometer being tested.

[0017] For repeatability testing, the repeatability of the two measurements is calculated according to the Blaine viscosity reading when measuring the viscosity standard solution, and the larger value is taken as the repeatability of the viscometer.

[0018] Compared with the prior art, the present invention has the following advantages: (1) Simple to operate and saves time; (2) Standard viscosity fluid is a Newtonian fluid with relatively stable viscosity values ​​and small measurement errors; (3) The viscosity range of the standard viscosity liquid can be determined as needed and can meet the range requirements of instrument calibration.

[0019] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art will be able to make various modifications and improvements without departing from the principles of the present invention, and these modifications and improvements should also be considered to fall within the scope of protection of the present invention.

Claims

1. A method for calibrating a Brookfield viscometer, characterized in that, The temperature indication error, fluctuation and uniformity of the Brookfield viscometer constant temperature tank are calibrated as follows: The measurement temperature of the Brookfield viscometer constant temperature tank is set at 60℃, a platinum resistance thermometer is placed in the working plane at 1 / 2 of the liquid height in the constant temperature tank, after the temperature of the constant temperature tank is stabilized, the temperature indication is read at uniform intervals of 1 minute for at least 10 minutes to obtain 11 measurement values, and the temperature indication error and temperature fluctuation are calculated; The temperature uniformity test temperature point is selected at 60℃, a standard platinum resistance thermometer is used as a fixed thermometer, inserted into the working area at a depth of 1 / 2, fixed at the center point of the working area, and another thermometer is used as a mobile thermometer, sequentially inserted into four points on the upper horizontal plane and four points on the lower horizontal plane of the working area; after the temperature of the constant temperature tank reaches 60℃ and stabilizes for at least 10 minutes, the reading is started, the temperature values of the points are recorded, and the temperature uniformity is calculated; The viscosity tube constant is calibrated as follows: The viscosity tube of the measured Brookfield viscometer is repeatedly flushed with distilled water higher than 70℃, then cleaned with alcohol or petroleum ether and dried, and then the viscosity tube is placed in the working area of the constant temperature tank; Seal the lower end of the viscosity tube, through the quantitative peristaltic pump to the viscosity tube 110 mL of the first standard viscosity oil, constant temperature 10 min, temperature stability, open the lower end of the tube blocking, start measuring, get the viscosity oil through the photoelectric timer time ; standard viscosity oil kinematic viscosity and dynamic viscosity ; through the quantitative peristaltic pump for the second time 110 mL of liquid, take the average value of the first viscosity oil to get the timing time, kinematic viscosity, dynamic viscosity 、 、 ; After the viscosity tube is cleaned and dried, another standard viscosity liquid is used to repeat the measurement twice according to the above method to obtain the time of the second standard viscosity oil passing through the photoelectric timer, the kinematic viscosity of the standard viscosity oil, and the dynamic viscosity value , , ; The Bingham viscosity tube constant A, B value of the measured and the Bingham viscosity of two standard viscosity oils are calculated according to the measurement results of two kinds of viscosity oils 、 ; The Brookfield viscometer indication error is calibrated as follows: The viscosity tube is installed on the measured Brookfield viscometer, the constant value of the viscosity tube and the density value of the viscosity oil are re-input, the Brookfield viscosity of the above two standard viscosity oils is measured, and the Brookfield viscosity values of the two standard viscosity liquids are , The viscosity value error is calculated according to the following formula: ， In the formula: Relative error of viscometer viscosity measurement, %; - the Brookfield viscosity value measured at the i-th measurement, mPa-s; - the Brookfield viscosity value of the i-th measurement of the viscosity tube constant calibration device, mPa-s; Two standard viscosity liquids with large absolute value of Brookfield viscosity value measurement error are selected as the viscosity indication error of the measured viscometer.

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