GB/T 5516-1985 Grain and oil inspection - Determination of grain viscosity
Some standard content:
GB5516—1985
National Standard of the People's Republic of China
Inspection of grain and oil seeds
Determination of viscosity of grain
Inspection of grain and oil seeds Methods for determination of viscosity of grain GB/T5516——1985
This standard applies to the determination of viscosity of commercial grain. 1 Capillary kinematic viscosity determination method
1.1 Instruments and appliances
1.1.1 Constant temperature water bath: It is composed of a glass cylinder (about 35cm in diameter and 40cm in height), a 25W electric stirrer, an electronic relay for temperature control (contact capacity not less than 5A), a 1kW U-type electric heating tube and a tube rack plate, an electric contact thermometer (20-50℃ or 100℃), a precision thermometer (scale 0.1℃) and an iron rack, a rack clamp, etc. The temperature control accuracy can reach 0.1℃;
1.1.2 Gelatinization device: It is composed of an electric heating jacket (2000W, volume 5000ml), a straight tube condenser, a 500ml conical flask and an iron rack, an iron clamp, etc.;
1.1.3 Capillary viscometer: There are four common apertures of 0.8, 1.0, 1.2 and 1.5mm, and a viscometer constant verification certificate is attached when leaving the factory. If the purchased capillary viscometer does not have a calibration constant or needs to be calibrated, it can be calibrated or calibrated as follows (preferably by the manufacturer or relevant scientific research and appraisal units in collaboration). Calibration method: Take pure No. 20 or No. 30 engine lubricating oil, and use a capillary viscometer with a known constant to measure its kinematic viscosity in a water bath at 50 ± 0.1°C (the deviation of the five measurement results should be less than 0.05 cSt). Then use the batch of engine oil to measure the flow rate of the uncalibrated capillary viscometer, measure five times, calculate the average value, and calculate the capillary viscometer constant. The capillary viscometer constant is calculated according to formula (1): Capillary viscometer constant (C)
Where: v
t,——engine oil outflow time, s. The
viscometer constant can also be directly calibrated with standard oil of known viscosity. 1.1.4 Crusher and mortar;
1.1.5 Standard copper wire sieve: 40 mesh, 60 mesh, 80 mesh, 100 mesh and sieve bottom; 1.1.6 Timer and stopwatch;
Balance: sensitivity 0.01g;
1.1.8 Electric oven;
1.1.9 Electric hair dryer;
1.1.10 Ear suction bulb, latex tube, etc.
1.2 Operation method
1.2.1 Sample preparation: Take about 100g of grain sample, and the rice sample shall be shelled and ground into standard 2 or standard 1 white rice. Use a crusher to crush and sieve, and then crush the sieved material repeatedly (or grind it with a mortar) until it is more than 90%. National Bureau of Standards 1985-11-02 Issued
1986-07-01 Implementation
GB5516-1985
The sample passes through a 60-mesh sieve (corn passes through a 40-mesh sieve). 1.2.2 Preparation of gelatinized liquid: First determine the water content of the sample, and then use a 1% balance to weigh rice flour, wheat flour or corn flour equivalent to 7.00g of dry matter or 8.00g of dry matter. The actual weight of the powder sample is: 7.00 (or 8.00) + (100-M) × 100 (M is the number of grams of water content in 100g of the sample). Put the sample into a 500ml conical flask, add 200ml of water preheated to 40-50℃, install a condenser and place it in a pre-opened electric heating mantle to heat. Make the sample liquid begin to boil in about 5 minutes and start timing immediately. Pay attention to adjust the height of the conical flask (together with the condenser) from the electric heating mantle at any time, strictly control to keep the sample liquid evenly boiling, and do not let the sample liquid rush into the condenser. After 30 minutes, remove the conical flask, quickly pour all the sample liquid into a 100-mesh copper wire sieve for filtration, rotate the sieve evenly to collect about 100ml of filtrate, which is the gelatinization determination solution.
1.2.3 Viscosity measurement: Quickly suck the gelatinized liquid into or pour it into a clean capillary viscometer (sucking method: after connecting the latex tube to the C port of the viscometer, insert the A port of the viscosity tube into the gelatinized measurement liquid, shake the gelatinized liquid evenly, then block the B port with your finger and use the ear suction bulb to suck air from the latex tube at the C port, so that the gelatinized liquid is slowly sucked into the capillary viscometer until the gelatinized liquid rises to the liquid storage ball). Immediately place the viscometer vertically in a constant temperature water bath at 50 ± 0.1℃, and immerse the two balls of the upper and lower scales of the viscometer completely under the water surface. Move the latex tube from port C to port A. After keeping the temperature constant for 10 to 12 minutes, use the ear suction ball to suck up the gelatinized liquid from port A, blow it down and stir it evenly, then suck up the gelatinized liquid to fill the upper ball of the viscometer, and then let the gelatinized liquid fall freely. Start the measurement after 15 minutes. During the measurement, suck up the gelatinized liquid to fill the upper ball (no bubbles), stop sucking, wait for the gelatinized liquid to flow freely down to the upper scale between the two balls, press the stopwatch to start timing, wait for the gelatinized liquid to continue to flow to the lower scale, press the stopwatch again to stop timing, and record the time (seconds) for the gelatinized liquid to flow through the upper and lower scales. Then perform the same operation for 2 to 3 consecutive measurements, and take the average value of the flow rate measurement results. Capillary viscometer
The aperture of the capillary viscometer should be selected so that the flow rate of the gelatinized liquid can be measured at 150-200g, not exceeding 300s and not less than 60s.
1.2.4 Calculation of results
The kinematic viscosity is calculated according to formula (2):
Kinematic viscosity (=
t, — sample outflow time,;
C viscometer constant, cSt/s.
Published by the National Bureau of Standards on November 2, 1985
Implementation on July 1, 1986
GB5516—1985
The allowable difference between double test results (two gelatinization test results) is as follows: the average viscosity value is below 3.0 cSt and does not exceed 0.2 cSt; the average viscosity value is below 3.1 to 6.0 cSt and does not exceed 0.5 cSt; the average viscosity value is below 6.1 to 10.0 cSt and does not exceed 0.8 cSt; the average viscosity value is below 10.0 cSt and does not exceed 0.8 cSt; the average viscosity value is below 20.0 cSt and does not exceed 0.6 cSt; the average viscosity value is below 3 ... Below 10.1, not exceeding 1.0 cSt; if it does not meet the above requirements, two more gelatinized liquids should be measured, and the measurement results that meet the above requirements should be averaged, with the average value taken to the first decimal place. 2 Engla viscosity measurement method
2.1 Engla viscometer composition
2.1.1 Double-layer metal pot and heating device: The inner pot is used to hold the measured liquid, and there are three L-shaped copper nails on the inner wall for liquid quantification and instrument level calibration. There is a liquid outflow hole in the center of the pot bottom. There are two holes on the inner pot cover, the middle hole is inserted into the outflow hole with a long cone wooden plug, and the other hole is a thermometer jack. The outer pot is a water bath pot, equipped with a stirrer and an automatically controlled thermometer, and an electric heater is installed at the bottom. 2.1.2 Tripod support: used to install the double-layer metal pot. 2.1.320 0m1 special measuring cylinder: used for mercury connection and quantitative outflow of liquid. 2.2 Operation method
2.2.1 Determine the outflow time of water: wash the inner pot and measuring cylinder with water or ethanol, take 20℃ water and inject it into the inner pot, so that the water surface is slightly higher than three nail heads. Inject 20℃ tap water into the outer pot, heat it with an electric heater, and stabilize the water temperature in the inner and outer pots at 20℃. After 10 minutes, lift the wooden stopper to make the water surface reach the 200ml scale, stop the stopwatch immediately, and record the outflow time (s). Repeat the test once more. The difference between the two tests should not exceed 0.5s, and the average value is taken as the outflow time of water (the outflow time of water of the Engela viscometer should be within the range of 51±1s, otherwise it needs to be repaired). 2.2.2 Sample preparation: (same as 1.2.1). Weigh The sample (which can be converted into 10g of anhydrous sample) is gelatinized. 2.2.3 Gelatinized sample: Pour the sample into a 500ml conical flask, measure 350ml of water, first use a small amount of water to make the sample into a thin paste, then pour all the remaining water into the conical flask, mix well, record the liquid level, connect a condenser, and place it in a boiling saturated salt water bath (100ml water plus about 36g of salt). Start timing from the boiling of the sample in the bottle, heat and boil for 30 minutes. During the heating process, if foam and "poof" occur in the bottle, use a hair dryer to blow cold air to the bottleneck or surround the bottleneck with a cold water towel to suppress it. After heating, take out the flask. If the liquid level in the bottle drops, add boiling water to the original liquid level, mix with a spoon, and then filter the thin paste into a beaker with a 40-mesh sieve while it is hot. 2.2.4 Determine the effluent time of the sample filtrate: Heat the water in the outer pot to 50°C, then drain the water in the inner pot, pour in the filtrate heated to 50°C, make the liquid level level with the three nail tips, and cover. Place a measuring cylinder directly below the outflow hole, wait until the filtrate temperature reaches 50°C and stabilizes for 5 minutes, and then measure the filtrate effluent time (seconds). 2.3 Calculation of results
Enger viscosity is calculated according to formula (3): bZxz.net
Enger viscosity (E50) =
Wherein: t—filtrate outflow time, s;
t2—water outflow time, s.
*··（3）
The allowable difference between the two test results: the outflow time is not more than 1s below 250s; not more than 3s between 251 and 500s; not more than 5s between 501 and 1000s. The average is the measurement result. Issued by the State Bureau of Standards on November 2, 1985
Implemented on July 1, 1986
GB5516—1985
Additional notes:
This standard was proposed by the Ministry of Commerce of the People's Republic of China. This standard was drafted by the Grain Storage and Transportation Bureau of the Ministry of Commerce. The main drafters of this standard are Gao Xiuwu, Yang Haoran, Wu Yanxia and Lv Guifen. Issued by the National Bureau of Standards on November 2, 1985
Implemented on July 1, 1986
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