1、BRITISH STANDARD BS ISO 4795:1996 Laboratory glassware Glass for thermometer bulbs ICS 17.200.20; 71.040.20BSISO4795:1996 This British Standard, having been prepared under the directionof the Sector Board for Materials and Chemicals, was published under the authority ofthe Standards Board and comesi
2、ntoeffect on 15 April 1997 BSI 09-1999 ISBN 0 580 27252 4 National foreword This British Standard reproduces verbatim ISO 4795:1996 and implements it as the UK national standard. The UK participation in its preparation was entrusted by Technical Committee LBI/36, Laboratory glassware and related app
3、aratus, to Subcommittee LBI/36/3, Thermometers, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UKinterests informed; monitor related internat
4、ional and European developments and promulgate them in the UK. A list of organizations represented on this subcommittee can be obtained on request. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Stand
5、ards Catalogue under the section entitled “International Standards Correspondence Index”, or using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for
6、their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theISO title page, page ii, pages 1 to 4 and a back cover. This standard has been up
7、dated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date CommentsBSISO4795:1996 BSI 09-1999 i Contents Page National foreword Inside front cover Foreword ii 1 Scope
8、1 2 Normative references 1 3 Definitions 1 4 Maximum temperature of use 1 5 Requirements 1 6 Marking 1 Annex A (normative) Determination of the average zero-point depression 2 Annex B (informative) Stabilization test 3 Annex C (informative) Zero-point depression of some types of thermometric glass 3
9、 Annex D (informative) Type of glass and identification 3 Table D.1 Certified thermometric glass 4ii blankBSISO4795:1996 ii BSI 09-1999 Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing
10、International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaiso
11、n with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication
12、as an International Standard requires approval by at least 75 % of the member bodies casting a vote. This International Standard ISO 4795 has been prepared by Technical Committee ISO/TC 48, Laboratory glassware and related apparatus, Subcommittee SC 3, Thermometers. Annex A forms an integral part of
13、 this International Standard. Annex B, Annex C and Annex D are for information only. Descriptors: Laboratory equipment, laboratory glassware, thermometers, tanks (containers), specifications, materials specifications, marking.BSISO4795:1996 BSI 09-1999 1 1 Scope This International Standard specifies
14、 the physical and chemical characteristics and the marking of thermometric glass and the test methods to be used for the selection of glass for the manufacture of the bulbs of liquid-in-glass thermometers. It is not applicable to the glass used in parts of the thermometer other than the bulb (e.g. t
15、he stem). However, the glass used for the other parts can be identical to that used for the bulb. The coefficient of linear thermal expansion of the bulb glass should not differ from that of the glass intended for the stem by more than 0,2 10 6K 1 . 2 Normative references The following standards con
16、tain provisions which, through references in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investi
17、gate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 719:1985, Glass Hydrolytic resistance of glass grains at 98 C Method of test and classification. ISO 7884-7:1987, Glas
18、s Viscosity and viscometric fixed points Part 7: Determination of annealing point and strain point by beam bending. 3 Definitions For the purposes of this International Standard, the following definitions apply. 3.1 strain point, F f4 the temperature determined in accordance with ISO7884-7 NOTEBy th
19、e beam-bending method, the viscosity of glass at the strain point may be evaluated as 10 14,7dPas. 3.2 zero-point correction, K correction of the thermometer at 0 C: K = 0 C t ind where t indis the temperature indicated 3.3 zero-point depression change of the zero-point correction after heating and
20、fast cooling of the thermometer 4 Maximum temperature of use The maximum temperature recommended for use shall not exceed (F f4 130) C, where F f4is the strain point determined in accordance with the method given in ISO 7884-7. 5 Requirements 5.1 Stability The indication at 0 C of a suitable test th
21、ermometer having a bulb made of the glass under consideration shall not change by more than 2 C after exposure to the maximum temperature recommended for use (see clause 4) for 500 h. This stability requirement can be determined in accordance with Annex B. 5.2 Zero-point depression When tested in ac
22、cordance with the procedure given in Annex A, a thermometer having a bulb made of the glass under consideration shall have an average zero-point depression not exceeding 0,05 C for “normal glass” or 0,03 C for borosilicate glass. NOTEThe zero-point depression of some types of thermometric glass is g
23、iven in Annex C. 5.3 Chemical resistance When tested according to the procedure and classification given in ISO 719, the glass shall comply with the requirements of class HGB 3 or better. 6 Marking 6.1 Thermometric glass complying with this International Standard shall be identified according to eit
24、her of the schemes given in 6.2 and 6.3. 6.2 The manufacturer of the thermometric glass shall incorporate an identification stripe or stripes in accordance with the approved list shown in Table D.1 (see Annex D). 6.3 The manufacturer of the thermometer shall mark it with an identification alphanumer
25、ic code in accordance with the approved list shown in Table D.1 (seeAnnex D) and shall, on request, supply a certificate of conformity provided by the manufacturer of the thermometric glass. NOTE 1The list of approved identification stripes and identification codes will be maintained under the respo
26、nsibility of the secretariat for this International Standard, on the basis of data provided by the national test authorities or notified bodies responsible for testing and certification of thermometric glass. NOTE 2Manufacturers wishing to claim, for a thermometric glass not listed in Table D.1, com
27、pliance with the requirements of this International Standard, should apply to their national standards body, who will register the glass with the secretariat for this International Standard. A certificate from a national test authority or notified body that the thermometric glass to be registered co
28、rresponds to the requirements of this International Standard is recommended.BSISO4795:1996 2 BSI 09-1999 Annex A (normative) Determination of the average zero-point depression NOTEThis annex is based on Annex B of International Recommendation OIML R7:1978, Clinical thermometers Mercury-in-glass with
29、 maximum device. A.1 Fabrication of test thermometers Using the glass under consideration for the bulb, make test thermometers with the following specifications. A.2 Confirmation of stabilization A.2.1 Heat the thermometer in a liquid bath or metal block oven from room temperature to the maximum rec
30、ommended temperature of use 5 C and keep it at this temperature for at least 5 min. A.2.2 Cool the thermometer to 50 C at a rate between 10 C/h and 15 C/h. A.2.3 Remove the thermometer from the bath or oven, determine the correction at 0 C and record its value(K 1 ). A.2.4 Heat the thermometer again
31、 to the maximum recommended temperature of use 5 C, using the same immersion depth as that employed in A.2.1 and keep it at this temperature for 24 h. A.2.5 Cool the thermometer as specified in A.2.2. A.2.6 Redetermine the correction as specified in A.2.3 and record its value (K 2 ). A.2.7 If the di
32、fference between K 1and K 2exceeds 0,15 C, reject the samples. Carry out the stabilization of fresh samples and repeat the procedures described in A.2.1 to A.2.6. If the difference between K 1and K 2is 0,15 C or less, carry out the depression of zero test (A.3). A.3 Depression of zero test A.3.1 Sel
33、ect m stabilized test thermometers (where m U 3), tested according to A.2, which have not subsequently been heated above room temperature. A.3.2 Keep each thermometer at a temperature of between 20 and 25 C for 7 days. Determine the correction at 0 C and record its value (K 3 ). A.3.3 Heat each ther
34、mometer to (100 1) C. Keep it at this temperature for 30 min, then remove it from the test bath and allow it to cool to room temperature without the bulb touching any object. Determine the correction at 0 C within 15 min of its removal from the test bath and record its value (K 4 ). A.3.4 Repeat ste
35、p A.3.2 and determine K 5 ; repeat step A.3.3 and determine K 6 ; repeat step A.3.2 and determine K 7 ; repeat step A.3.3 and determine K 8 . A.3.5 Further repetitions of steps A.3.2 and A.3.3 may be carried out to obtain corrections up to K 2n+1and K 2n+2 ,where n (the number of zero depressions ob
36、tained) is greater than 3. A.4 Expression of results A.4.1 Calculate the average depression of zero from where Scale range at least: 3,0 C to + 3,0 C. Graduation: 0,02 C, 0,05 C, or 0,1 C. Distance between consecutive graduation lines: at least 0,7 mm for enclosed-scale thermometers or at least 1,0
37、mm for solid-stem thermometers. Expansion chamber: of sufficient volume that the thermometer can be heated 50 C above the maximum recommended temperature without damage. Stabilization: thermometers stabilized (see A.2). i is the serial number of the test thermometer; m is the total number of test th
38、ermometers; n is the number of zero depressions obtained.BSISO4795:1996 BSI 09-1999 3 A.4.2 If the standard deviation of the m n values of zero depression obtained is not greater than 0,01 C, report the average depression of zero as calculated in A.4.1. Annex B (informative) Stabilization test Heat
39、a suitable test thermometer to a temperature equal to the maximum recommended temperature of use (see clause 4) of the glass under consideration and keep it at this temperature for 5 min. Allow the thermometer to cool in the test bath or furnace to 50 C at a rate between 10 C/h and 15 C/h and then d
40、etermine the correction at 0 C. Heat the thermometer again to the maximum recommended temperature and keep it at this temperature for 500 h. Allow the thermometer to cool to 50 C at the same rate as before, and redetermine the correction under the same conditions as before. Report the difference bet
41、ween the two corrections in degrees Celsius. Annex C (informative) Zero-point depression of some types of thermometric glass Annex D (informative) Type of glass and identification The types of thermometric glass listed in Table D.1 are certified by the following national testing authorities as compl
42、ying with the particular requirements of this International Standard: National testing authorities: Type of glass Manufacturer Zero-point depression C DURAN SCHOTT GLASWERKE 0,011 NG 360 Russia 0,011 N16B SCHOTT ROHRGLAS 0,013 2954 III SCHOTT GLASWERKE 0,02 B49T Choisy-le-Roi 0,02 GGI 860 Saale-Glas
43、 0,024 TNIII Terumo 0,037 CNAM: LNE Paris, France NML: National Measurement Laboratory, Sydney, Australia PTB: Physikalisch-Technische Bundesanstalt, Braunschweig und Berlin, Germany NPL: National Physical Laboratory, Teddington, United Kingdom NPLI: National Physical Laboratory, New Delhi, India Cs
44、Mo: Slovak Laboratory for Metrology, Bratislava, Slovakia SU: Glass Institute, Hradec Krlov, Czech RepublicBSISO4795:1996 4 BSI 09-1999 Table D.1 Certified thermometric glass GLASS (NAME OR TYPE) MANUFACTURER IDENTIFICATION STRIPE(S) OR APPROVED ABBREVIATION SCHOTT N16B THERMOMETRIC NORMAL GLASS SCH
45、OTT ROHRGLAS GMBH, BAYREUTH, DE SINGLE RED STRIPE NORMAL GLASS WHITEFRIARS GLASS LTD, LONDON, GB SINGLE BLUE STRIPE NORMAL GLASS DIAL PLOWDEN & THOMPSON LTD, STOURBRIDGE, GB DOUBLE BLUE STRIPE B 49 T CRISTALLERIES ET VERRERIES, REUNIES DE CHOISY-LE-ROI, FR ONE BLUE AND ONE YELLOW STRIPE NORMAL GLASS
46、, 7560 CORNING GLASS CO., NEWYORK, US CN (IN GB ONLY) KIMBLE GLASS, R6 KIMBLE GLASS CO., TOLEDO, US R6 (IN GB ONLY) BOROSILICATE GLASS WHITEFRIARS GLASS LTD, LONDON, GB SINGLE WHITE STRIPE BOROSILICATE GLASS CORNING GLASS CO., NEWYORK, US CB (IN GB ONLY) CORNING GLASS 1720 CORNING GLASS CO., NEWYORK
47、, US C1720 (IN GB ONLY) SCHOTT SUPREMAX 8409 SCHOTT GLASWERKE, MAINZ, DE SPX8409 (IN GB ONLY) NORMAL GLASS KS90 SKLARNY KAVALIER, SAZAVA, CZ CR-KS90 (IN CZ ONLY) NORMAL GLASS JINTAN TERUMO CO. LTD JT (IN GB ONLY) NORMAL GLASS SANKYO KKEIRYOKI CO. LTD SK (IN GB ONLY) NORMAL GLASS KINTAL CLINICAL THER
48、MOMETER CO. (INDIA) LTD RK (IN GB ONLY) TOSHIBA GLASS TOSHIBA KOGYO LTD TK (IN GB ONLY) SCHOTT 8330 DURAN SCHOTT GLASWERKE, MAINZ, DE NORMAL GLASS 360 RUSSIA GLASS 360 GGI 860 SAALE GLAS DOUBLE WHITE STRIPE SCHOTT 2954 III SCHOTT GLASWERKE, MAINZ, DE SINGLE BLACK STRIPE SYLVANIA GLASS CHESEBOROUGH P
49、ONDS NEW YORK, US SG 80 ILMATHERM I860 TECHNISCHE GLASWERKE ILMENAU, DE THREE WHITE STRIPES5 blankBS ISO 4795:1996 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions BritishStandards are updated by amendment or revision. Users of BritishStanda
