《ISO-720-1985.pdf》由会员分享,可在线阅读,更多相关《ISO-720-1985.pdf(7页珍藏版)》请在三一文库上搜索。
1、I nternational Standard ( 720 0 *. d!igB INTERNATIONAL ORGANIZATION FOR STANDARDIZATlONWbIEYHAPOflHAR OPTAHMSAUHA l-IO CTAHAPTH3ALMH.ORGANISATION INTERNATIONALE DE NORMALISATION Glass - Hydrolytic resistance of glass grains at 121 OC - Method of test and classification Verre - R b) a classification
2、of glass according to the hydrolytic resistance determined by the method of this International Standard. This International Standard is intended for use on the more resistant types of glass. For the less resistant glasses, the method specified in IS0 719 is preferable. NOTE - It is emphasized that t
3、here is no exact correlation between the classification laid down in this International Standard and that laid down in IS0 719, and it is therefore essential to identify which classification is being used. 2 References IS0 38511, Laboratory glassware - Burettes - Part 1: General requirements. IS0 38
4、512, Laboratory glassware - Burettes - Part2: Burettes for which no waiting time is specified. IS0 585, Test sieves - Woven metal wire cloth, perforated plate and electroformed sheet - Nominal sizes of openings. IS0 848, Laboratory glassware - One-mark pipettes. IS0 719, Glass - Hydrolytic resistanc
5、e of glass grains at 98 OC - Method of test and classification. IS0 1773, Laboratory glassware - Boiling flasks lnarrow- neckedl. IS0 3898, Water for laboratory use - Specifications. 1) ISQ 3819, Laboratory glassware - Beakers. ) 3 Principle The method of test is a test for glass as a material appli
6、ed on glass grains. Extraction of IO g of grains, of particle size be- tween 306 and 425 pm, with grade 2 water for 30 min at 121 OC. Measurement of the degree of the hydrolytic attack by analysis of the extraction solutions. 4 Reagents During the test, unless otherwise stated, use only reagents of
7、recognized analytical grade. 4.1 Grade 2 water, which complies with the requirements specified in IS0 3696 and which has been freed from dissolved gases, such as carbon dioxide, by boiling for at least 15 min in a boiling flask (5.6). Such water can normally be stored for 24 h in a stoppered flask w
8、ithout change of the pH value. When tested immediately before use the water shall be neutral to methyl red, i.e. it shall produce an orange-red (not a violet- red or yellow) colour corresponding to pH 55 f 0,l when four drops of the methyl red indicator solution (4.3) are added to 56 ml of the water
9、. NOTE - The water, so coloured, may also be used as a reference solution (see clause 7). 4.2 Hydrochloric acid, standard volumetric solution, c(HCI) = 0,02 mol/l. 4.3 Methyl red, indicator solution. Dissolve 25 mg of the sodium salt of methyl red (C15H14N3Na02) in 100 ml of the grade 2 water (4.1).
10、 4.4 Acetone ICH,COCH,). I) At present at the stage of draft. 1 IS0 720-1985 (El 5 Apparatus Ordinary laboratory apparatus, and 5.1 Balance, accurate to + 5 mg or better. 5.2 Burettes, having a capacity of 25 ml, 10 ml or 2 ml, complying with the requirements specified for class A burettes in IS0 38
11、5/2 (see also general requirements specified in IS0 385/l) and made of glass of hydrolytic resistance grain class HGA 1 as specified in this International Standard. ) The capacity of the burettes shall be chosen according to the expected consumption of hydrochloric acid (4.2). 5.3 Pipettes, having a
12、 capacity of 50 ml and complying with the requirements specified for class A pipettes in IS0 848. 5.4 Conical flasks, having a capacity of 250 ml and comply- ing with the requirements of IS0 1773. Before use, each new flask shall be pretreated by subjecting it to the autoclaving con- ditions describ
13、ed in clause 7. NOTE - Flasks made from vitreous silica may also be used, in which case pretreatment is not required. 5.5 Beakers, having a capacity of 50 ml and complying with the requirements of IS0 3819. Before use, each new beaker shall be pretreated by subjecting it to the autoclaving condi- ti
14、ons described in clause 7. 5.6 Boiling flasks, having a capacity of 1 000 ml, complying with the requirements of IS0 1773 and made of vitreous silica or borosilicate glass. Before use, each new flask shall be pretreated by subjecting it to the autoclaving conditions described in clause 7. 5.7 Beaker
15、s, having a capacity of 100 ml and complying with the requirements of IS0 3819. 5.6 Weighing bottles, having a capacity of about 20 ml. 5.9 Desiccator. 5.10 Hammer, having a mass of about 0,5 kg. 5.11 Mortar and pestle, made of hardened magnetic steel, and of the design and approximate dimensions sh
16、own in the figure. Approximate dimensions in millimetres Figure - Mortar and pestle 1) Glass of hydrolytic resistance grain class IS0 719-HGB 1 adequately meets the requirements of class HGA 1 specified in this International Standard. 2 5.12 Magnet. IS0 720-1985 (El 6.2 Crushing 5.13 Sieves, complyi
17、ng with the requirements of IS0 565 and comprising a set of 200 mm diameter square-aperture sieves, with stainless steel mesh, including : - a sieve A of 425 pm aperture; - a sieve B of 300 pm aperture; - a sieve 0 of a convenient aperture between 600 and 1000 pm. The cover, pan and, especially, the
18、 rings shall be of stainless steel or lacquered wood. NOTE - The use of sieve 0 is recommended to retain larger pieces of glass and to avoid heavy wear on sieve A. 5.14 Ball-mill The mill shall be made of agate or stainless steel with a volume of 250 ml. Two balls with a diameter of 40 mm or three b
19、alls with a diameter of 30 mm are suitable. 5.15 Sieving-machine A mechanical sieve-shaker or sieving-machine may be used to sieve the grains. 5.16 Ultrasonic cleaner (laboratory type). 5.17 Drying oven, suitable for operation up to 150 OC. 5.18 Autoclave or steam sterilizer, capable of with- standi
20、ng a pressure of at least 25 x lOaNlm* and of carrying out the heating cycle specified in clause 7. It should preferably be equipped with a constant-pressure regulator or other means of maintaining the temperature at 121 f 1 “C. The vessel shall have an internal diameter of at least 300 mm, and shal
21、l be equipped with a heating device, a thermometer or a calibrated thermocouple, a pressure gauge, a pressure-release safety device, a vent-cock, and a rack for supporting the flasks. The autoclave vessel and ancillary equipment shall be thoroughly cleaned before use. 6 Preparation of sample 6.1 Den
22、sity of the glass The density of the glass to be tested should, preferably, be 2,4 f 0,2 g/cm3 at 20 OC. Check that the articles as received have been annealed to a commercially acceptable quality. NOTE - If an article is not annealed to a commercially acceptable quality, this fact should be noted b
23、ecause the results can be affected. Such articles, if very badly annealed, may also break very easily and extra care should be taken when handling them. Further annealing should not be carried out before the test. Wrap the glass articles, which should, preferably, have a wall thickness greater than
24、I,5 mm, in clean paper and crush to pro- duce three 100 g samples of pieces not more than 30 mm across. 6.3 Manual preparation Place 30 to 40 g of pieces between 10 and 30 mm across, taken from a 100 g sample (see 6.2), in the mortar (5.111, insert the pestle (5.111, and strike it sharply, once only
25、, with the hammer (5.10). NOTE - If more than one hammer blow is used in crushing the glass, the very fine particles produced may be compacted into aggregates which may or may not be subsequently broken down and which can therefore introduce further variables into the test. Transfer the glass from t
26、he mortar to the upper sieve 0 of the assembled set of sieves (5.13). Repeat the crushing pro- cedure until the whole of the 100 g sample has been added to the sieve 0. Shake the set of sieves for a short time by hand and then remove the glass from sieves A and 0. Repeat crushing and sieving on this
27、 glass until only about 10 g of glass remain on sieve 0. Discard the glass from sieve 0 and from the receiving pan. Reassemble the set of sieves and shake by hand for 5 min. Transfer to the weighing bottle (5.8) those glass grains which pass through sieve A, but which are retained on sieve B. Repeat
28、 the crushing and sieving procedure with the other two 100 g samples and thus three samples of grains, each of which shall be in excess of 10 g, are obtained. Spread each sample on a piece of clean glazed paper and remove any iron particles using the magnet (5.12). Transfer each sample into a beaker
29、 (5.7) for cleaning. 6.4 Mechanical preparation Transfer about 50 g of the coarsely broken glass (see 6.2) into the mill-beaker (5.141, add the balls and crush thin-walled glass (wall thickness 1.5 mm) for 5 min. Transfer the grains to the upper sieve 0 of the assembled set (5.13) of the sieving mac
30、hine (5.15), sieve for about 30 s and * 2.5 x 105 N/m2 = 0.25 MPa = 2,5 bar 3 4 IS0 720-1985 (E) collect the grains retained on sieve S in the beaker (5.71, which shall be kept in the desiccator (5.9). Transfer the glass from sieves 0 and A back into the ball-mill and crush again for the time given
31、above. Repeat sieving and crushing until about 11 g of grains have been collected from sieve 6. Continue as specified in 6.3, last paragraph. the holding temperature is reached, then cool at a rate of 0,5 OC/min to 100 OC, venting to prevent formation of a vacuum. Remove the flasks from the autoclav
32、e, cool the flasks in run- ning water and complete the titration within 1 h. 6.5 Cleaning Add four drops of methyl red indicator solution (4.3) to each flask and titrate immediately with the hydrochloric acid solution (4.2) until the colour matches exactly that of the 50 ml of the Add to the grains
33、in each beaker (5.7) 30 ml of the acetone (4.4) and scour the grains by a suitable means, such as a rubber- or plastics-coated glass rod. NOTE - The method of scouring involves holding the beaker at an angle of about 30 to 45O firmly against the bench and pressing firmly the covered end of a glass r
34、od of about 10 mm in diameter into the bottom corner and against the sides, so that the grains are trapped between it and the sides and the bottom of the beaker as the rod is rotated around the beaker. Continue the rotation for about 20 revol- utions. water of the reference solution plus four drops
35、of indicator con- tained in a similar conical flask. NOTE - When necessary, for obtaining a clearer end-point, the clear solution should be decanted into a separate 250 ml flask. Rinse the grains by swirling them in three separate 15 ml portions of the grade 2 water and add the washings to the main
36、solution. Add four more drops of the methyl red indicator solution (4.3). Then titrate and calculate the result as described below. In this case, add also 45 ml of grade 2 water and four more drops of methyl red indicator solution to the reference solution. After scouring, swirl the grains and decan
37、t as much acetone as possible. Add another 30 ml of the acetone, swirl and decant again and add a new portion of the acetone. Fill the bath of the ultrasonic cleaner (5.16) with water at room temperature, then place the beaker in the rack and immerse it until the level of the acetone is at the level
38、 of the water; apply the ultrasonics for 1 min. Swirl the beaker and decant the acetone as completely as possible and then repeat the ultrasonic cleaning operation. If a fine turbidity persists, repeat the ultrasonic cleaning and acetone washing until the solution remains clear. Swirl and decant the
39、 acetone, then dry the grains, first by putting the beaker with the grains on a warm plate to remove excess acetone and then by heating at 140 OC for 20 min in the drying oven (5.17). Transfer the dried grains from each beaker to separate weighing bottles (5.81, insert the stoppers and cool in the d
40、esic- cator (5.9). 7 Procedure Weigh IO,00 g of the cleaned and dried grains of each sample into separate conical flasks (5.4). Add 50 ml of the grade 2 water (4.1) into each by means of a pipette (5.3). Pipette 50 ml of the grade 2 water into another conical flask to serve as a reference solution.
41、Distribute the grains evenly over the flat bases of the flasks by gently shaking them. Cap the flasks with inverted beakers (5.5) so that the inner bases of the beakers fit snugly down onto the top rims of the flasks. Place all four flasks in the rack in the autoclave (5.181, containing water at amb
42、ient temperature, and ensure that they are held above the level of the water in the vessel. Close the autoclave lid securely, but leave the vent-cock open. Heat at a regular rate such that steam issues vigorously from the vent-cock after 20 to 30 min, and maintain a vigorous evolution of steam for a
43、 further 10 min. Close the vent-cock and increase the temperature at the rate of 1 “Urnin to 121 OC. Maintain the temperature at 121 f 1 OC for 30 f 1 min from the time when 4 8 Expression of results 8.1 Calculation Calculate the mean value of the results, in millilitres of hydrochloric acid solutio
44、n (4.2) per gram of sample, and, if required, its equivalent in alkali extracted, calculated as micrograms of sodium oxide (Na20) per gram of glass grains: 1 ml of hydrochloric acid solution c(HCI) = 0,02 mol/ll P 620 ug of sodium oxide If the highest and the lowest observed values differ by more th
45、an the permissible range given in table 1, repeat the test. 8.2 Classification Glass shall be classified as shown in table 2, according to the consumption of acid and its equivalent of alkali expressed as sodium oxide (Na20)1, when tested by the method specified in this International Standard. 8.3 D
46、esignation For convenience of reference to the hydrolytic resistance of glass as a material complying with the classification of this International Standard, the use of a designation as follows is recommended : Example: The designation for a glass with a consumption of 0,08 ml of hydrochloric acid s
47、olution c(HCI) = 0,02 mol/ll per gram of glass grains equivalent to 49,6 ug of sodium oxide per gram of glass grains (class HGA 1) shall be: Glass, hydrolytic resistance grain class IS0 720 - HGA 1 IS0 720-1995 (El 9 Test report The test report shall include the following information : a) a referenc
48、e to this International Standard; b) an identification of the sample; c) the consumption of hydrochloric acid solution fc(HCI) = 0,02 moMI, in millilitres per gram of glass grains, mean value; f) the wall thickness of the articles used for the test if it was 1,5 mm; g) the density of the glass if it
49、 was outside the range of 2,4 + 0,2 g/cm3 at 20 OC; d) in addition, if required, the equivalent of alkali, in h) a statement, if appropriate, that the glass article used micrograms of sodium oxide per gram of glass grains, mean for the test was not annealed to commercially acceptable value; quality. e) the hydrolytic resistance grain class HGA (designation of the glass tested) ; Table 1 - Permissible range of the values obtained Mean of the values obtained for the consumption of hydrochloric acid solution c(HCI) = 0.02 mol/ll (4.21 per gram of glass grains Permissible range of the
链接地址:https://www.31doc.com/p-3782351.html