《ISO-648-1977.pdf》由会员分享，可在线阅读，更多相关《ISO-648-1977.pdf（9页珍藏版）》请在三一文库上搜索。
1、INTERNATIONAL STANDARD 648 INTERNATIONAL ORGANIZATION FOR STANDARDlZATlON.MEX.UYHAPOJIHAR OPFAHAJAUHII II0 CTAHAF TH3ALWH.ORGANlsATlON INTERNATIONALE DE NORMALISATION Laboratory glassware - One-mark pipettes Verrerie de laboratoire - Pipettes ii un trait First edition - 1977-12-15 Gi UDC 542.3 Ref.
2、No. IS0 648-1977 (E) k al Descriptors : laboratory equipment, laboratory glassware, volumetric measurement, pipettes, specifications, dimensions, capacity, Pte- cision, marking, calibrating. Price based on 7 pages FOREWORD IS0 (the International Organization for Standardization) is a worldwide feder
3、ation of national standards institutes (IS0 member bodies). The work of developing International Standards is carried out through IS0 technical committees. Every member body interested in a subject for which a technical committee has been set up has the right to be represented on that committee, Int
4、ernational organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the IS0 Council, Inte
5、rnational Standard IS0 648 was developed by Technical Committee lSO/TC 48, Laboratory glassware and related apparatus, and was circulated to the member bodies in February 1976. It has been approved by the member bodies of the following countries : Australia Hungary Austria India Belgium Israel Canad
6、a Italy Chile Mexico Czechoslovakia Netherlands Germany Poland Romania South Africa, Rep. of Spain United Kingdom U.S,A. U.S.S.R. The member body of the following country expressed disapproval of the document on technical grounds : France This International Standard cancels and replaces IS0 Recommen
7、dation R 648-1968, of which it constitutes a technical revision. 0 International Organization for Standardization, 1977 l PrintedIin Switzerland -,-,- INTERNATIONAL STANDARD IS0 648-1977 (E) Laboratory glassware - One-mark pipettes 1 SCOPE AND FIELD OF APPLICATION This International Standard provide
8、s details of an inter- nationally acceptable series of one-mark pipettes, adequate for general laboratory purposes. The details specified are in conformity with IS0 384. 2 REFERENCES IS0 384, Laboratory glassware - Principles of design and construction of volumetric glassware. IS0 1769, Laboratory g
9、lassware - Pipettes - Co/our coding. 3 BASIS OF ADJUSTMENT 3.1 Unit of volume The unit of volume is the cubic centimetre (cm3), for which the name millilitre (ml) may be used. NOTE - The term millilitre (ml) is commonly used as a special name for the cubic centimetre (cm3), in accordance with the In
10、ternational System of units (SI). 3.2 Reference temperature The standard reference temperature, i.e. the temperature at which the pipette is intended to deliver its nominal volume (nominal capacity), is 20 “C. NOTE - When the pipette is required for use in a country which has adopted a standard refe
11、rence temperature of 27 C (the alternative specified in IS0 384 for tropical use), this figure shall be substituted for 20 “C. 4 VOLUMETRIC ACCURACY There shall be two classes of accuracy : - class A for the higher grade; - class B for the lower grade. 5. SERIES OF CAPACITIES The series of capacitie
12、s of one-mark pipettes is as follows : 0,5- I-2-5-IO-20-25-50-100and200ml Of these, the 0,5 ml size is specified without bulb, the 1 ml size is specified both with and without bulb and the 2 ml size is specified with bulb for class A accuracy, and both with and without bulb for class B accuracy. All
13、 the remaining sizes are specified with bulbs. All the sizes may be provided with a safety bulb above the graduation line, if required. NOTE - If other capacities are required than those listed above, it is recommended that they shall conform to the essential requirements of this International Stand
14、ard. 6 DEFINITION OF CAPACITY The capacity of a one-mark pipette is defined as the volume of water at 20 C, expressed in millilitres, delivered by the pipette at 20 C, when emptied as described below. NOTE - Where, exceptionally, the standard reference temperature is 27 “C, this value shall be subst
15、ituted for 20 C. The pipette in a vertical position shall be filled to a few millimetres above the graduation line and any drop adhering to the jet shall be removed. The falling meniscus shall then be adjusted to the line by one of the two methods detailed below : a) the meniscus is set so that the
16、plane of the upper edge of the graduation line is horizontally tangential to the lowest point of the meniscus, the line of sight being in the same plane; b) the meniscus is set so that the plane of the centre of the graduation line is horizontally tangential to the lowest point of the meniscus. The
17、eye is raised towards the plane and observes the front and back portions of the line apparently meeting the lowest point simultaneously. Any drop adhering to the jet of the pipette shall then be removed by bringing the surface of a glass vessel into contact with the tip of the jet. Delivery shall th
18、en be made, still holding the pipette vertically, into another glass vessel slightly inclined so that the tip of the jet is in contact with the inside of the vessel, but without movement of one against the other throughout the delivery and waiting periods. 1 IS0 648-1977 (E) The pipette shall be all
19、owed to empty until the meniscus comes to rest in the jet. To ensure that delivery is complete, a waiting period of approximately 3 s should be observed before removing the pipette from the receiving vessel in the case of pipettes where a definite waiting time is not specified. NOTE - The waiting pe
20、riod of approximately 3 s is specified only for the purpose of definition, In use, it is unnecessary to adhere closely to this period; it is sufficient to be certain that the meniscus has come to rest in the jet before removing the pipette from contact with the receiving vessel. In the case of pipet
21、tes where a waiting time of 15 s is specified, this period shall be observed before removing the pipette from the receiving vessel. NOTE - Pipettes of class A accuracy may eitherbe : a) without definite waiting time, in which case a waiting period of approximately 3 s is observed; b) with a waiting
22、time of 15 s. Pipettes of class I3 accuracy should be without definite waiting time as described under a). 7 LIMITS OF VOLUMETRIC ERROR 7.1 Errors in the volume delivered shall not exceed the limits shown in table 1. 7.2 Limits of error for class A pipettes are shown in relation to capacity in annex
23、 A and in relation to diameter of meniscus in annex 6. TABLE 1 - Limits of error Values in millilitre capacity 0,5 2 5 10 20 25 50 100 Limit of error Cless A Class B f f 0,005 0,Ol 0,066 0,015 0,Ol 0,02 0,015 0,03 0,02 0,04 0,03 0,06 0,03 .a 0,06 0,05 0,1 0,OB 0,15 O,l 02 8 CONSTRUCTION 8.1 Material
24、 One-mark pipettes shall be constructed of glass of suitable chemical and thermal properties, shall be as free as possible from visible defects and shall be reasonably free from internal stress. 8.2 Shape Pipettes of 0,5 ml capacity consist of a straight tube with a jet at the lower end. Pipettes of
25、 1 ml capacity and, in class B, of 2 ml capacity may be of similar straight pattern or may alternatively be of bulb pattern, as described herein for the larger sizes, All the larger pipettes consist of a bulb with suction and delivery tubes, the three portions being straight and co-axial. The genera
26、l form of the pipettes shall be as shown in the figure. If a safety bulb is provided, it should be of approximately spherical form and be situated between the graduated line and the top of the pipette, in accordance with the dimensions given in table 3. FIGURE - Example of a bulb pattern one-mark pi
27、pette 8.3 Dimensions Dimensions shall comply with the dimensional require- ments shown in tables 2 and 3. 8.4 Top of pipette The top of the pipette shall be finished square with the axis of the pipette and shall be free from any blemishes which might interfere with the required accurate control by t
28、he finger in setting the meniscus. The end may be lightly fire-polished or smoothly ground with a slight bevel on the outside. 8.5 Bulb The main portion of the bulb shall be cylindrical, except that 1 and 2 ml capacity pipettes may have an oval bulb, if desired. The two ends of the bulb shall merge
29、gradually into the suction and delivery tubes, the junctions being of tapered formation to facilitate drainage. 2 IS0 646-1977 (E) TABLE 2 - Dimensions Dimensions in millimetres Dimensions 0,5 1 2 Nominal capacity, ml 5 10 20 25 50 100 200 Overall length max. Straight pattern pipette 280 280 260 - -
30、 - _ - - _ Bulb pattern pipette - 325 350 410 450 520 530 550 600 650 Length of suction tubet) min. - 150 150 150 160 170 170 170 170 170 Length of delivery tubet) min. - 110 125 145 160 210 220 230 240 240 Internal diameter at the graduation line21 max. 2,33) 3 3,5 4 4,5 5,5 5.5 6 7,5 8.5 External
31、diameter of *lmm - 5 5.5 6.5 6.5 7 7 7,5 a 9 delivery tube1 ) Diameter of bulb ) max. 9 9 12 16 22 24 30 38 49 Diameter of tube, straight max. 5 6 7 - - - - - - - pattern pipette 1) Valid only for bulb pattern pipettes. 2) For straight pattern pipettes : maximum internal diameterrfor bulb pattern pi
32、pettes : maximum internal diameter of the suction tube. 3) Calculated from minimum distance of 120 mm from graduation line to tip of jet (see table 3). TABLE 3 - Dimensions applying to all capacities Dimensions in millimetres Distance of graduation line from top of pipette min. 100 Distance from gra
33、duation line to top of bulb min. IO Distance from graduation line to tip of jet Straight pattern pipettes Wall thickness Bulb pipettes of 1 and 2 ml Other pipettes Diameter of safen/ bulb, if fitted Distance from top of pipette to bottom of safety bulb Distance from top of pipette to top of safety b
34、ulb min. 120 min. 0,7 min. ItO approx. 25 max. 70 min. 30 3 -,-,- IS0 648-1977 (E) 8.6 Delivery jet 8.6.1 The delivery jet shall be strongly constructed with a smooth and gradual taper without any sudden constric- tion at the orifice. 8.6.2 The end of the jet shall be finished by one of the methods
35、listed below in order of preference : a) smoothly ground square with the axis, slightly bevelled on the outside and fire-polished; b) smoothly ground square with the axis and slightly bevelled on the outside. A fire-polished finish reduces the danger of chipping in use, but should not result in cons
36、triction as indicated in 8.6.1, or in undue stress. 8.7 Delivery time The delivery time is defined as the time occupied by the descent of the water meniscus from the graduation line to the point at which it appears to come to rest in the jet. The delivery time is determined with the pipette in a ver
37、tical position and with the receiving vessel slightly inclined so that the tip of the jet is in contact with the inside of the vessel, but without movement of one against the other. The delivery time thus determined shall be within the limits shown in table 4. 9 GRADUATION LINE The graduation line s
38、hall be a clean, permanent, uniform line completely encircling the tube, except that a gap, not exceeding 10 % of the circumference, may be permitted. The line shall lie in a plane at right angles to the longitudi- nal axis of the pipette. The line thickness shall not exceed 0,4 mm or one-half of th
39、e limit of volumetric error, whichever is smaller (see IS0 384). Dimensions limiting the position of the graduation line on the pipette are included in table 2. 10 INSCRIPTIONS 10.1 The following inscriptions shall be marked on all pipettes : a) a number indicating the nominal capacity and, adjacent
40、 or subjacent to this number, the symbol “cm3” or the symbol “ml” to indicate the unit in terms of which the pipette is graduated (see note to 3.1); b) the inscription “20 C” to indicate the standard reference temperature; NOTE - Where, exceptionally, the reference temperature is 27 “C, this value s
41、hall be substituted for 20 C. c) the letters “Ex” to indicate that the pipette has been adjusted to deliver its indicated capacity; d) the inscription “A” or “B” to indicate the class of accuracy for which the pipette has been adjusted; e) the maker s and/or vendor s name or mark; f) the waiting tim
42、e, if specified, in the form : “Ex + 15 s”. TABLE 4 - Delivery times Times in seconds Class of accuracy Class A, no definite min. waiting time max. Class A, waiting min. time 15s max. Class B min. max. Maximum permissible difference between observed and marked delivery times* 0.5 1 2 IO IO IO 20 20
43、25 4 5 5 8 9 9 4 5 6 20 20 25 2 2 2 Nominal capacity, ml 5 IO 20 25 50 100 200 15 15 25 25 30 40 50 30 40 50 50 60 60 70 7 8 9 IO 13 25 11 12 13 15 18 30 7 8 9 IO 13 25 40 30 40 50 50 60 60 70 3 3 4 4 5 5 5 + When the delivery time is marked on a pipette in accordance with 10.2 b), then the observed
44、 delivery time and the marked delivery time shall both be within the limits given in this table and shall not differ by more than the values shown. 4 IS0 648-1977 (E) 10.2 The following additional inscriptions shall be marked on class A pipettes intended for official verification or certification, i
45、f required by legal metrology; they should preferably be marked on other class A pipettes and may also be used, if desired, on class B pipettes : a) an identification number; b) the delivery time in seconds. 10.3 The limit of volumetric error according to table 1 may be marked on all pipettes, for e
46、xample by the inscription + . . . ml. 1 -I VISIBILITY OF GRADUATION LINE, FIGURES AND INSCRIPTIONS 11.1 All figures and inscriptions shall be of such size and form as to be clearly legible under normal conditions of use. 11.2 The graduation line, the figures and inscriptions shall be clearly visible
47、 and permanent. 12 COLOUR CODING Colour coding, if used on these pipettes, shall comply with the requirements of IS0 1769. 5 IS0 648-1977 (E) ANNEX A 80 Q 20 f b RELATIONSHIP BETWEEN CAPACITY AND LIMIT OF ERROR FOR CLASS A PIPETTES AS REQUIRED BY 4.4 OF IS0 384 5 10 20 25 50 100 200 Capacity of pipe
48、tte, ml 6 -,-,- IS0 648-1977 (E) 5 8 IO 14 183 12 181 ItO Of5 0,4 ANNEX B NOMOGRAPH INDICATING THE RELATIONSHIP BETWEEN LIMIT OF ERROR AND MENISCUS DIAMETER FOR CLASS A PIPETTES AS REOUIRED BY 4.7 OF IS0 384 Limit of class A error, #I 15 1 2 20 I 5 30 50 80 100 rs 3 20125 200 I I 2,3 3 3,5 4 4,5 5,5 6 7,5 8,5 Meniscus diameter, mm 7