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1、INTERNATIONAL STANDARD (13 aigi these documents are now in the process of being transformed into International Standards. As part of this process, Technical Committee lSO/TC 48 has reviewed IS0 Recommendation R 641 and found it technically suitable for transformation. International Standard IS0 641
2、therefore replaces IS0 Recommendation R 641-1968 to which it is technically identical. IS0 Recommendation R 641 was approved by the Member Bodies of the following countries : Australia Austria Belgium Brazil Canada Chile Colombia Czechoslovakia Egypt, Arab Rep. of Greece Hungary India Ireland Israel
3、 Italy Japan Netherlands New Zealand Poland South Africa, Rep. of Spain Switzerland Turkey United Kingdom U.S.A. U.S.S.R. Yugoslavia The Member Body of the following country expressed disapproval of the Recommendation on technical grounds : France* No Member Body disapproved the transformation of IS
4、O/R 641 into an International Standard. * Subsequently, this Member Body approved the Recommendation. 0 International Organization for Standardization, 1975 . Printed in Switzerland Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technica
5、l Standards 1/9972545001 Not for Resale, 04/27/2007 20:06:29 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD IS0 641-1975 (E) Laboratory glassware - Interchangeable spherical ground joints 0 INTRODUCTION The purpose of this International Standard is t
6、o ensure interchangeability between spherical ground glass joints, irrespective of where they are manufactured. Limiting dimensions for the ground glass zone and the external diameter of adjacent tubing, which will ensure interchangeability, are given in table 1. The finish of the ground surface is
7、also specified, and this is similar to the finish specified in ISO/R 383, interchangeable conical ground glass joints. A conventional designation is adopted, which consists of the code letter “S” in conjunction with the approximate spherical diameter of the joint in millimetres. The bore diameter wh
8、ich may be employed with each size of joint is controlled, for the purposes of this international Standard, only by the maximum diameter at the narrow end of the ground zone. A convenient leakage test, to be carried out on ungreased joints, is described in annex A, but this does not form an integral
9、 part of this International Standard. In annex B are listed, for convenience, the size designations of the joints specified in the British and U.S.A. standards which correspond to, or are interchangeable with, the joints listed in this International Standard. While reference is made in this Internat
10、ional Standard only to glass joints, these having come into general use, it is not thereby intended to exclude the development of joints made of other materials, which should be manufactured to the same dimensions. 1 SCOPE AND FIELD OF APPLICATION This International Standard specifies the essential
11、geometric requirements for interchangeability in relation to a series of ground glass joints for laboratory use. 2 NOMINAL SPHERICAL GROUND JOINT DIAMETER The diameter of the ground spherical zone shall be in accordance with the dimensions specified in table 1, columns 2, 3 and 4. These tolerances e
12、nsure that the diameter of the inner component (or ball member) is not greater than the nominal diameter and that the diameter of the outer component (or cup member) is not less than the nominal diameter. 3 DIMENSIONS The diameter at the wide end of the ground zone shall not be less than the corresp
13、onding dimension given in table 1, column 5, and the diameter at the narrow end of the ground zone shall not be greater than the corresponding dimension given in table 1, column 6. The relationship of the dimensions is illustrated in figure 1. 4 DIAMETER OF TUBING The external diameter of tubing adj
14、acent to the joint shall not exceed the dimensions given in table 1, column 7. NOTE - It is important to limit the external diameter of the tubing in order to facilitate interchangeability of clamps. 5 SURFACE FINISH The R, value ) of the ground surface shall not exceed 1 pm and should preferably be
15、 less than 0,5 pm. 6 TESTING OF INNER AND OUTER COMPONENTS (BALL AND CUP) OF SPHERICAL JOINTS For checking for compliance with the dimensional tolerances, normal engineering techniques (including pneumatic or radius gauges) shall be used. The degree of cleanliness of the ground surfaces is a vital f
16、actor affecting the rate of leakage. First rub the components with a cloth soaked in a suitable solvent, for example cyclohexane, then dip in the solvent and allow to dry. Remove any particles adhering to the surfaces, using a camel s-hair brush. Then place the components in turn in a vertical posit
17、ion in the apparatus and evacuate the system. No pressure, other than that exerted by the atmosphere, shall be applied to the joint. When the mercury gauge reading is above a value preselected by the operator, close the stopcock and note the scale reading. After a further 1 min or more, note the sca
18、le reading again. I) See ISOIR 468. Surface roughness. 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 20:06:29 MDTNo reproduction or networking permitted without license from
19、IHS -,-,- IS0 641-1975 (E) External diameter of adjacent tubing M Bore diameter Diameter at narrow end of ground zone Diameter at wide end of ground zone c Inner component (ball) Outer component (cup) FIGURE 1 - Dimensions of spherical joints 2 Copyright International Organization for Standardizatio
20、n Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 20:06:29 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 641-1975(E) TABLE 1 - Dimensions and tolerances of spherical ground joints Dimensions in millimetr
21、es 1 Size designation 2 3 4 5 6 7 Spherical diameter Minimum Maximum Maximum I Tolerance Tolerance diameter diameter external Nominal on inner on outer at wide end at narrow diameter dimension component end of component of ground of adjacent (ball) (CUP) zone ground zone tubing s7 7,144 0 + 0.025 -
22、0,025 0 2 2.0 4-5 s13 12.700 i.025 + 0,025 0 12.5 - 7,O 9 s19 19,050 0 + 0,025 - 0,025 0 18,7 12.5 14 s29 28,575 0 + 0,025 0.025 0 28,0 19,0 22 - s35 34,925 0 + 0,025 0,025 0 34.3 - 275 30 s41 41,275 t 0,025 40,5 34 - E.025 0 30,o s51 50,800 0 + 0,025 0,025 0 50,o 36,0 43 - S64 63,500 0 + 0,035 - 0,
23、035 0 62.5 47.0 53 S76 76,200 0 + 0,040 - 0,040 0 75.0 58.0 64 s102 101,600 0 + 0,050 - 0,050 0 100,o 84.0 85 Having equalized the pressures inside and outside the system, turn the component on its axis through 90” and then repeat the test. Express the results as the increase in pressure in the syst
24、em in pascals per minute, averaged over the time interval between the two readings. For routine production testing, it is satisfactory to take the first reading immediately after closing the stopcock and the second testing 1 min later. For comparative laboratory tests, take the first reading 30 s af
25、ter closing the stopcock and the second reading after a further interval of 2 min. Cup members may conveniently be tested by this method in conjunction with gauging balls (for example of steel) of the dimensions shown in table 2. Ball members may also be tested by this method, using a two-stage proc
26、edure in which the cup members are first tested against steel balls and then the ball members are tested against cup members known to be satisfactory. For joints complying with the tolerances in table 1, practical experience shows that the following figures for leakage should not be exceeded : - for
27、 sizes S13 and smaller : an increase in pressure of 930 Pa per minute; - for sizes S19 and larger : an increase in pressure of 2 kPa per minute. TABLE 2 - Diameters of gauging balls for testing cups Spherical diameter of steel ball %ze designation of cup nominal dimension tolerance mm mm s7 7,144 t
28、0,003 0 , Sl3 12.700 t 0,005 0 s19 19,050 t 0,005 0 s29 28,575 t 0,008 0 S36 34,925 t 0,008 0 s41 41,275 t 0,008 0 s51 50,800 t 0,008 0 S64 63,500 t 0,010 0 S76 76,200 t 0,013 0 s102 101,600 t 0,015 0 3 Copyright International Organization for Standardization Provided by IHS under license with ISO L
29、icensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 20:06:29 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO641-1975 (E) ANNEX A LEAKAGE TEST FOR SPHERICAL JOINTS The leakage test is carried out on dry joints by observing the rate of increase in pre
30、ssure in a previously evacuated system in communication with the atmosphere via the leaking joint. A suitable apparatus is illustrated in figure 2, the details not being essential provided that the total capacity of the system is approximately 1.5 I. It is essential to render all joints in the testi
31、ng apparatus leak-proof and to check the apparatus before coupling in the joint to be tested. Any leakage found during checking must be negligible in comparison with the leakage measured during the test. - Rubber bung Joint under test Rubber bung or tubing, according to size of joint under test -) T
32、o vacuum line Scale covering pressure range of approximately 350 to 760 mmHg (45 to 100 kPa) in increments of 1 mm (0,133 kPa) FIGURE 2 - Suitable apparatus for leakage test on spherical joints 4 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee
33、=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 20:06:29 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 641-1975 (E) ANNEX B SIZE DESIGNATIONS OF SPHERICAL JOINTS Table 3 lists the size designations adopted for joints complying with this International
34、 Standard alongside the designations of the corresponding joints listed in some national standards, namely United Kingdom : B.S. 2761 : 1963, Sphericalgroundglass joints. U.S.A. : CS2 l-58, Interchangeable taper-ground joints, stopcocks, stoppers and spherical-ground joints. TABLE 3 - Corresponding
35、size designations IS0 Series s7 s13 B.S.2761 CS 21-68 - 711 s13c 12/l s13 12/l ,5 1212 1213 1215 s19 s19 1817 1819 s29 s29 28112 28115 S35 s35 35120 35125 I s41 I 541 I 40125 I s51 I s51 I 5Ol3Q 5 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 20:06:29 MDTNo reproduction or networking permitted without license from IHS -,-,-