GB/T 5526-1985 Vegetable oils and fats - Determination of specific gravity
Some standard content:
National Standard of the People's Republic of China
Inspection of vegetable oilsMethods for determination of specific gravity
Inspection of vegetable oilsMethods for determination of specific gravityThis standard applies to the determination of specific gravity of commercial vegetable oils. Liquid specific gravity balance method
1.1 Apparatus and utensils
1.1.1 Liquid specific gravity balance;
1.1.2 Beaker, pipette, etc.
1.2 Reagents
1.2.1 Washing liquid;
1.2.2 Ethanol, ether;
1.2.3 Distilled water without carbon dioxide;
1.2.4 Cotton wool, filter paper, etc.
1.3 Operation method
GB/T 5526-85
1.3.1 Weighing water: According to the instrument instructions, first calibrate the instrument, hang No. 1 on the hook, and inject distilled water into the measuring cylinder until the platinum wire on the float is immersed in the water for 1 cm. When the water is adjusted to 20℃, turn the screw on the balance seat to balance the balance, and do not move it. Pour out the water in the measuring cylinder, first use ethanol, then use ether to remove the water on the float, measuring cylinder and thermometer, and then use absorbent cotton to dry. 1.3.2 Weighing test: Inject the sample into the measuring cylinder until the platinum wire on the float is immersed in the sample for 1 cm. When the sample temperature reaches 20℃, move the weight on the groove of the balance to restore the balance. How to use the weight: First move No. 1 on the hook to the groove 9, and then fill in No. 2, No. 3, No. 4
on the groove to balance the balance.
1.4 Calculation of results
After the balance reaches equilibrium, calculate the result according to the position of the size code. Numbers 1, 2, 3, and 4 are the first, second, third, and fourth decimal places, respectively. For example, the oil temperature and water temperature are both 20°C, number 1 is at 9, number 220
is at 4, number 3 is at 3, and number 4 is at 5. At this time, the specific gravity d of the grease is 0.9435. The measured specific gravity is converted to the standard specific gravity according to formula (1): 20
Specific gravity (d) = d
Where: d
Specific gravity of the grease sample when the oil temperature is 20°C and the water temperature is 4°C; specific gravity of the grease sample when the oil temperature is 20°C and the water temperature is 20°C; (1)
Density of water at 20°C. The density of water at 20°C is 0.998230 g/ml. 20
If both the sample temperature and the water temperature need to be converted, calculate according to formula (2): 20t1
d=[d+0.00064×(t1-20)]dt2
Where: t1-sample temperature, °C;
t2——water temperature, °C;
Specific gravity measured at sample temperature t1 and water temperature t2; ..2)
Expansion coefficient of oil and fat for every 1°C difference between 10 and 30°C (average value). The allowable difference between the two test results is no more than 0.0004. The average is the test result. The test result is rounded to the fourth decimal place.
2 Pycnometer method
2.1 Apparatus and equipment
2.1.1 Pycnometer: 25ml or 50ml (with thermometer stopper); 2.1.2 Electric constant temperature water bath;
Pipette: 25ml;
Beaker, reagent bottle, mortar, etc.
2.2 Reagents
2.2.1 Ethanol, ether;
Distilled water without carbon dioxide;
Filter paper, etc.
2.3 Operation method
2.3.1 Washing bottle: Wash the pycnometer with detergent, water, ethanol, and water in sequence. 2.3.2 Determine the weight of water: Use a pipette to draw distilled water along the inner wall of the bottle mouth and inject it into the specific gravity bottle, insert the bottle stopper with a thermometer (no bubbles should exist in the bottle after the stopper is added), place the specific gravity bottle in a 20℃ constant temperature water bath, and when the water temperature in the bottle reaches 20±0.2℃, take out the specific gravity bottle and use filter paper to absorb the water overflowing from the drain pipe, cover the bottle cap, dry the outside of the bottle, and weigh it after about 30 minutes. 2.3.3 Determine the weight of the bottle: Pour out the water in the bottle, wash the water in the bottle with ethanol and ether, blow away the residual ether in the bottle with dry air, and blow dry the inside and outside of the bottle, then add the bottle stopper and bottle cap to weigh (the weight of the bottle should be subtracted from the weight of the air in the bottle, and the weight of 1cm**3 of dry air is 0.001293g~0.0013g under standard conditions). 2.3.4: Determine the weight of the sample: Take the clarified sample below 20℃, inject it into the bottle according to the water weight determination method, add a stopper, clean the outside with ether with filter paper, place it in a constant temperature water bath at 20℃, take it out after 30 minutes, clean the sample and the outside of the bottle overflowing from the drain pipe, cover the bottle cap and weigh it.
2.4 Calculation of results
The sample weight (W2) and water weight (W1) measured under the condition that the temperature of the sample and water is 20℃, first calculate the specific gravity (d20/20) according to formula (3):
Specific gravity dWww.bzxZ.net
Water weight, g:
Where: W1—
Sample weight, g;
Specific gravity of oil when the oil temperature and water temperature are both 20℃. The formula converted to the specific gravity at a water temperature of 4℃ and when both the sample and water temperature need to be converted are the same as formulas (1) and (2). Density of water at a certain temperature
The density of water at a certain temperature is shown in the following table:
Density table of water
Temperature, ℃
Additional notes:
Density, g/ml
This standard is proposed by the Ministry of Commerce of the People's Republic of China. This standard is drafted by the Grain Storage and Transportation Bureau of the Ministry of Commerce. 1
Temperature, ℃
The main drafters of this standard are Gao Xiuwu, Yang Haoran, Wu Yanxia and Lv Guifen.
Published by the National Bureau of Standards on November 2, 1985
Density, g/ml
Implementation on July 1, 1986
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