GB/T 14901-1994 Determination of density of glass - Sink-float comparison method
Some standard content:
National Standard of the People's Republic of China
Sink-float comparison method
Determination of glass density
Test method for density of glass-Method of the sink-float comparisonSubject content and scope of application
GB/T14901--94
This standard specifies the instrument, determination steps and result calculation for determining the density of glass by the sink-float comparison method. This standard is applicable to the determination of the density of glass or other non-porous solids with a density of 1.1 to 3.3 g/cm3, and can also be used to determine the apparent density of ceramics or solids with known porosity.
2 Reference standards
GB/T2540 Determination of density of petroleum products (pycnometer method) 3 Summary of the method
Since the thermal expansion coefficient of the density solution is much larger than that of the glass reference standard and glass sample, when the temperature rises, the density value of the density solution decreases much more than the density value of the glass reference standard and glass sample. At room temperature of 20 ± 3°C, the density of the prepared density solution is greater than the density of the glass reference standard and the glass sample, so the glass reference standard and the glass sample float on the density solution. Then the three are heated at the same time. When the density of the density solution is less than the density of the standard and the sample, the standard and the sample settle at different temperatures. The density of the glass sample is calculated according to their settling temperatures. The glass reference standard settles in the prepared density solution at 30°C, and the glass sample settles in the range of 20 to 40°C. Therefore, the sample with a density value within ± 0.0200 g/cm2 from the standard can be measured. Note: 1) In order to facilitate the glass factory to quickly determine the density of the glass sample, the settling temperature of the glass reference standard can be set in the range of 25 to 35°C. 4 Instruments
The sinking and floating comparison density meter, as shown in Figure 1, consists of the following components: a glass water bathtub (cup) with a capacity of 4000 to 5000 mL. a.
A stirrer with a speed of 0~6000r/min, stepless speed regulation and a power of 25W. An immersion heater equipped with a rheostat or an electric furnace equipped with a rheostat, both with a power of 1000W. d. Two 100mL glass test tubes, one test tube contains density solution, glass reference standard and glass sample, and the other test tube contains the same density solution and a thermometer. A maximum of three samples can be measured in the test tube at the same time. If necessary, multiple test tubes containing density solutions of different densities can also be used. Two 20~~40℃ mercury thermometers with an accuracy of 0.1℃. e.
f. A heat-resistant and moisture-resistant cover plate (see Figure 2) for supporting test tubes, thermometers, etc., about 6mm thick. A pair of cooling water pipes made of copper tubes. g.
Approved by the State Administration of Technical Supervision on December 30, 1993 206
Implemented on October 1, 1994
Sinking and floating comparison density meter
1, 2-thermometer; 3-rubber stopper; 4-cover; 5-glass test tube; 6-glass water bathtub (cup); 7-cooling water pipe; 8-electric heater + 9-sample, 10 stirrer Figure 2 Cover
5 Density solution
5.1 Reagents
GB/T 14901--94
Reagents should be analytically pure or superior pure, and the prepared density solution must be stored in a light shielding device III. a. Isopropyl salicylate, density 1.10g/cm2 at 30℃; b. α-bromoethane, density 1.48 g/cm2 at 30℃; symmetric-tetrabromoethane, density 2.96 g/cm2 at 30℃; c.
d. methane iodide, density 3.32 g/cm2 at 30℃. 5.2 Preparation of density solution
The density solution is prepared using the two reagents in 5.1. The volumes of the two reagents vary with the density values of the density solution to be prepared. The required volume of each reagent can be obtained by the following formula: p,V,-pVi+p2V2
V,-Vi+V?
Wherein: P.---density of the prepared density solution, g/cm~; V.--volume of the prepared density solution, mL; Q1--density of reagent 1 at 30℃, g/cm; 02
-density of reagent 2 at 30℃, g/cm;
volume of reagent 1 at 30℃, mL;
volume of reagent 2 at 30℃, mL.
(1)
(2)
(3)
Measure reagent 1V,(mL) and reagent 2V,(mL), place in a beaker and mix. Preheat to 30°C on an electric furnace, place the glass reference standard in the density solution, add 1 or several drops of reagent 1 or reagent 2, and stir thoroughly until the standard begins to settle at 30°C. 5.3 Determination of temperature coefficient of density solution
The density of the density solution at 20°C and 40°C is determined by the method specified in GB2540. The temperature coefficient of the density solution C. can be calculated using formula (4): C. =bZxz.net
Where: C. -
Temperature coefficient of density solution, g/cm3.°C; Density of density solution at -20°C, g/cm3; PT, Density of density solution at -40°C, g/cm3; T-20°C;
Tz-40°C.
6 Reference standard and sample
Glass reference standard and glass sample should have a smooth surface, no cracks or flash, a weight between 0.25 and 0.38 g1, and a length-to-width ratio of no more than two times.
The density of the glass reference standard is accurately determined using Appendix A. Each standard can be cut from a glass sheet weighing 20g, and any standard with a density greater than ±0.0001g/cm2 of the standard shall be discarded. Note: 1) When determining the density of other substances, the weight of the reference standard and the sample shall be converted according to the volume of 0.10-0.15ml. 7 Determination steps
7.1 Treatment of glass reference standard and sample
Clean the cut glass reference standard and glass sample with anhydrous ethanol, dry them at room temperature, and carefully place them in a test tube containing 208 density solution
. The standard and sample are both in a suspended state. 7.2 Start the sink-float comparison density meter
GB/T 14901-94
7.2.1 Place all test tubes and thermometers in appropriate positions in the water bath. 7.2.2 Start the agitator and heater.
7.2.3 Adjust the heating rate of the water bath and density solution. Initially, the heating rate of the water bath is 1-2℃/min. When the water bath temperature is close to the sedimentation temperature of the sample (or standard), stop heating, connect the cooling water, and adjust the cooling water flow. The temperature of the water bath drops rapidly. When the temperature of the water bath and the density solution is close, turn off the cooling water. After more than ten minutes, the temperature of the water bath and the density solution gradually reaches equilibrium. When the temperature of the density solution is 2-4C lower than the predetermined sedimentation temperature of the sample (or standard), turn on the heater power supply and adjust the heater power to heat the water bath and the density solution at a heating rate of 0.10±0.02℃/min. 7.3 Record the sedimentation temperature
When the glass reference standard or glass sample settles to the midpoint mark of the test tube in the density solution, accurately record the respective sedimentation temperatures and water bath temperatures. The temperature difference between the water bath and the density solution should not exceed 0.4℃. 8 Calculation of results
8.1 Correction of sedimentation temperature of glass sample
When the sedimentation temperature of the glass reference standard is specified as 30℃, the sedimentation temperature of the glass sample must be corrected according to formula (5): Tc=T+(30-T)
-corrected sedimentation temperature of the glass sample, ℃; where: Te—
T——settling temperature of the glass sample, ℃;
T,——settling temperature of the glass reference standard, ℃. 8.2 Calculation of density
8.2.1 The density of the glass sample at sedimentation temperature T is calculated according to formula (6): Pr=p+C,(T---T,)
where: Pr-—density of the glass sample at sedimentation temperature T, g/cm\; p.—density of the glass reference standard at sedimentation temperature of 30℃, g/cm~; C is the same as formula (4);
T, T,——the same as formula (5).
8.2.2 When the linear expansion coefficient of the glass sample and the glass reference standard are the same, the density of the glass sample at 20℃ is calculated according to formula (7) and formula (8): P2o = pszo + (C, + 3αap,) (T--T,) Substituting formula (5) into formula (7), we get:
P20 = ps20 + (C, + 3αap,) (T,- 30) -- In the formula:
P20 is the density of the glass sample at 20℃, 8/cm; P20 is the density of the glass reference standard at 20℃, g/cm~, α, is the linear expansion coefficient of the glass sample and the glass reference standard, ℃-1, CpP, T, T --- the same as formula (6).
8.2.3 When the linear expansion coefficients of the glass sample and the glass reference standard are different, the density of the 20℃ glass sample is calculated according to formula (9): P2e-p:zo(1.0000-30)+3ap(T-20))+C,(T,-30)-.. In the formula:
Linear expansion coefficient of the glass reference standard, °C-1, -Linear expansion coefficient of the glass sample, °C-1; Ce~Ps20 ~P20, T, -Same as formula (7).
8.3 Preparation of density-temperature table
(5)
(6)
(7)
(9)
For each glass reference standard and density solution system, a data table of the corresponding relationship between the density of the 20℃ glass sample and its sedimentation temperature can be prepared.
GB/T14901-94
When a large number of routine density measurements are required, a density-temperature table can be compiled and used. Calculate T. by formula (8) between 20 and 40°C, and compile a density-temperature table for the density value of the 20°C glass sample at each increase of 0.1°C. Before checking the density-temperature table, use formula (5) to convert the glass sample sedimentation temperature T into T. Then find T. on the density-temperature table. The corresponding density of the 20°C glass sample.
9 Records and reports
9.1 The report should include: product name, manufacturer, date of manufacture, sample number and density of the glass sample at 20°C. 9.2 The record should include: measurement date, density-temperature table, sample and sample numbers, sample and sample sedimentation temperature and corresponding water bath temperature.
10 Precision and accuracy
The standard error of this method is ±0.0001g/cm2. When the density value of the glass reference standard is accurate to ±0.00001 g/cm, the accuracy of this method is ±0.0002 g/cm.
GB/T14901---94
Appendix A
Determination of density of glass reference standard
Suspension method
(Supplement)
This method is applicable to the determination of the density of glass reference standard at 20-25℃. A1 Instruments and materials
Balance: Sensitivity 0.1 mg.
Thermometer: Measuring temperature range 15-30℃, minimum scale value 0.1℃. b
Nickel-chromium-iron or platinum alloy wire: Diameter 0.1-0.2 mm, used to make suspension wire and hanging basket, the metal wire should be free of surface grease or heated and purified in vacuum c.
Beaker: 500mL capacity
Distilled water: freshly prepared, boil again before use, let stand and cool to room temperature before use. A2 Sample
A2.1 Cut 20g of glass sample, the glass surface is smooth, without cracks or burrs. A2.2 The glass sample is first rinsed in hot nitric acid, then cleaned with distilled water and ethanol, and placed in a desiccator for testing. A3 Determination steps
A3.1 Measure the room temperature T and atmospheric pressure, and find the dry air density from Table A1. A3.2 Weigh the weight of the glass sample in the air. A3.3 Hang the hanging basket on the balance hook with a hanging wire, and put the sample in the hanging basket. Fix the beaker containing distilled water in a suitable position in the weighing room, and the sample is immersed in the distilled water. Add distilled water until the water surface reaches the reference position of the hanging wire. A3.4 Weigh the weight of the glass sample and the hanging basket in the distilled water. A3.5 Take out the sample and weigh the weight of the hanging wire basket in distilled water. A3.6 Measure the distilled water temperature T2 and find the density of air-free water from Table A2. Table A1 Density of dry air
Pressure, Pa
100792
100925
101059
101192
101325
101458
Result calculation
GB/T 14901—
Density of air-free water
A4.1 The weight of the sample in distilled water is calculated according to formula (A1): 0.5
0.998100.99808
Ww-Wr-W.
Wherein: Ww-
Weight of glass sample in distilled water, g; Wr——Weight of glass sample and wire basket in distilled water, g; W. —Weight of wire basket in distilled water, g. 0.99763
A4.2Glass density at laboratory average water-air temperature T, is calculated according to formula (A2): Pr
Wapw--WwP
Wa--Ww
Wherein: pr.Glass density at laboratory average water-air temperature T, g/cm-Weight of glass sample in air, g;
Density in air at room temperature T, g/cm;Density of air-free water at distilled water temperature T, g/cm. A4.3 The density of glass at the standard reference temperature T, is calculated according to formula (A3): Pr
p,=1+3α(T,=T,)
Wherein: -
Glass density at the standard reference temperature T, g/cm; standard reference temperature, °C;
-Glass linear expansion coefficient at the standard reference temperature T, °C1; T, average water-air temperature in the test room, °C; PT,\—same as formula (A2).
A5 Records and reports
A5.1 The report should include: sample type, manufacturer, sample number and density value of the sample at T,. A5.2 The record should include: T,, T2, PA, Pw, W, W. and WA values. 212
0.998060.998040.99801
Precision
GB/T 14901--94
When the laboratory temperature changes by ±0.5℃, the relative standard deviation of this method is ±0.01%. Additional remarks:
This standard was proposed by the State Bureau of Building Materials Industry. This standard was drafted by Qinhuangdao Glass Research Institute. The drafter of this standard was Wang Yexi.2 Weigh the weight of the glass sample in the air. A3.3 Hang the hanging basket on the balance hook with a hanging wire, and put the sample in the hanging basket. Fix the beaker containing distilled water in a suitable position in the weighing room, and let the sample be immersed in the distilled water. Add distilled water dropwise until the water surface reaches the reference position of the hanging wire. A3.4 Weigh the weight of the glass sample and the hanging basket with hanging wire in the distilled water. A3.5 Take out the sample and weigh the hanging basket with hanging wire in the distilled water. A3.6 Measure the distilled water temperature T2, and find the density of air-free water from Table A2. Table A1 Density of dry air
Pressure, Pa
100792
100925
101059
101192
101325
101458
Result calculation
GB/T 14901—
Density of air-free water
A4.1 The weight of the sample in distilled water is calculated according to formula (A1): 0.5
0.998100.99808
Ww-Wr-W.
Ww-
Weight of glass sample in distilled water, g; Wr——weight of glass sample and wire hanging basket in distilled water, g; W. —weight of wire hanging basket in distilled water, g. 0.99763
A4.2 The glass density at the laboratory average water-air temperature T, is calculated according to formula (A2): Pr
Wapw--WwP
Wa--Ww
Wherein: pr. Glass density at the laboratory average water-air temperature T, g/cm-weight of glass sample in air, g;
Density in air at room temperature T, g/cm; Density of air-free water at distilled water temperature T, g/cm. A4.3 The density of glass at the standard reference temperature T, is calculated according to formula (A3): Pr
p,=1+3α(T,=T,)
Wherein: -
Glass density at the standard reference temperature T, g/cm; standard reference temperature, °C;
-Glass linear expansion coefficient at the standard reference temperature T, °C1; T, average water-air temperature in the test room, °C; PT,\—same as formula (A2).
A5 Records and reports
A5.1 The report should include: sample type, manufacturer, sample number and density value of the sample at T,. A5.2 The record should include: T,, T2, PA, Pw, W, W. and WA values. 212
0.998060.998040.99801
Precision
GB/T 14901--94
When the laboratory temperature changes by ±0.5℃, the relative standard deviation of this method is ±0.01%. Additional remarks:
This standard was proposed by the State Bureau of Building Materials Industry. This standard was drafted by Qinhuangdao Glass Research Institute. The drafter of this standard was Wang Yexi.2 Weigh the weight of the glass sample in the air. A3.3 Hang the hanging basket on the balance hook with a hanging wire, and put the sample in the hanging basket. Fix the beaker containing distilled water in a suitable position in the weighing room, and let the sample be immersed in the distilled water. Add distilled water dropwise until the water surface reaches the reference position of the hanging wire. A3.4 Weigh the weight of the glass sample and the hanging basket with hanging wire in the distilled water. A3.5 Take out the sample and weigh the hanging basket with hanging wire in the distilled water. A3.6 Measure the distilled water temperature T2, and find the density of air-free water from Table A2. Table A1 Density of dry air
Pressure, Pa
100792
100925
101059
101192
101325
101458
Result calculation
GB/T 14901—
Density of air-free water
A4.1 The weight of the sample in distilled water is calculated according to formula (A1): 0.5
0.998100.99808
Ww-Wr-W.
Ww-
Weight of glass sample in distilled water, g; Wr——weight of glass sample and wire hanging basket in distilled water, g; W. —weight of wire hanging basket in distilled water, g. 0.99763
A4.2 The glass density at the laboratory average water-air temperature T, is calculated according to formula (A2): Pr
Wapw--WwP
Wa--Ww
Wherein: pr. Glass density at the laboratory average water-air temperature T, g/cm-weight of glass sample in air, g;
Density in air at room temperature T, g/cm; Density of air-free water at distilled water temperature T, g/cm. A4.3 The density of glass at the standard reference temperature T, is calculated according to formula (A3): Pr
p,=1+3α(T,=T,)
Wherein: -
Glass density at the standard reference temperature T, g/cm; standard reference temperature, °C;
-Glass linear expansion coefficient at the standard reference temperature T, °C1; T, average water-air temperature in the test room, °C; PT,\—same as formula (A2).
A5 Records and reports
A5.1 The report should include: sample type, manufacturer, sample number and density value of the sample at T,. A5.2 The record should include: T,, T2, PA, Pw, W, W. and WA values. 212
0.998060.998040.99801
Precision
GB/T 14901--94
When the laboratory temperature changes by ±0.5℃, the relative standard deviation of this method is ±0.01%. Additional remarks:
This standard was proposed by the State Bureau of Building Materials Industry. This standard was drafted by Qinhuangdao Glass Research Institute. The drafter of this standard was Wang Yexi.
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