1、BRITISH STANDARD BS 5074:1974 Specification for Short and long solid-stem thermometers for precision use UDC 536.512:681.2187.4BS 5074:1974 This British Standard having beenapproved by the LaboratoryApparatus IndustryStandards Committee,was published underthe authority ofthe Executive Board on 29 No
2、vember 1974 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference LBC/4 Drafts for comment 73/51484 and73/53113 ISBN 0 580 08492 2 Co-operating organizations The Laboratory Apparatus Industry Standards Committee, under whose supervision this British Standa
3、rd was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Agricultural Research Council Associations for Science Education Association of Scientific, Technical and Managerial Staffs British Laboratory Ware Association* British
4、 Lampblown Scientific Glassware Manufacturers Association* British Pharmacopoeia Commission Chemical Industries Association* Chemical Society Department of Health and Social Security* Department of Trade and Industry (Laboratory of the Government Chemist)* Department of Trade and Industry (National
5、Physical Laboratory* Glass Manufacturers Federation Institute of Petroleum* Ministry of Defence* Ministry of Defence (Air Force Department) Pharmaceutical Society of Great Britain Royal Institute of Chemistry Scientific Instrument Manufacturers Association* SIRA Institute Society for Analytical Chem
6、istry Society of Chemical Industry Society of Glass Technology* Standardization of Tar Products Test Committee* The Government departments and scientific and industrial organizations marked with an asterisk in the above list, together with the following, were directly represented on the Committee en
7、trusted with the preparation of the British Standard: British Medical Association British Standards Institution (Test Centre) Meteorological Office Ministry of Defence (Army Department) Royal College of Nursing and National Council of Nurses of the UK Amendments issued since publication Amd. No. Dat
8、e of issue CommentsBS 5074:1974 BSI 08-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Type of thermometer 1 3 Temperature scale 1 4 Immersion 1 5 Glass 1 6 Liquid filling 1 7 Gas filling 1 8 Construction 1 9 Graduation and figuring 2 10 Accuracy 8 11 Inscr
9、iptions 8 Appendix A Thermometric glasses approved by the National Physical Laboratory (1974) 9 Appendix B Stabilization test 9 Appendix C Testing of British Standard thermometers 9 Figure 1 Short solid-stem thermometers for precision use 4 Figure 2 Long solid-stem thermometers for precision use 5 F
10、igure 3 Alternative types of graduation and figuring 7 Table 1a Dimensions for short solid-stem thermometers 3 Table 1b Dimensions for long solid-stem thermometers 3 Table 2a Graduation for short solid-stem thermometers 6 Table 2b Graduation for long solid-stem thermometers 7 Table 3a Uncertainty of
11、 test for certification of BS short solid-stem thermometers for precision use 10 Table 3b Uncertainty of test for certification of BS long solid-stem thermometers for precision use 11BS 5074:1974 ii BSI 08-1999 Foreword This British Standard is identical in content with the ISO Recommendations R653,
12、 “Long solid-stem thermometers for precision use”, and R654, “Short solid-stem thermometers for precision use”, two of four ISORecommendations specifying requirements for a basic series of long and short solid-stem and enclosed-scale thermometers for general use in precision work, which were drawn u
13、p by Technical Committee ISO/TC48. The United Kingdom participated fully in the work of preparing these ISORecommendations which were published in1968. However, it has been decided to publish as a British Standard only those concerned with solid-stem thermometers, as the enclosed-scale type is neith
14、er manufactured nor widely used in the United Kingdom. This British Standard complies with ISO Recommendation R386, “Principles of construction and adjustment of liquid-in-glass laboratory thermometers” which was being prepared as an International Standard at the time of issue of this British Standa
15、rd. Many of the thermometers specified in this British Standard can be regarded as potential replacements for total immersion thermometers of similar range and accuracy which have long been specified in BS593 “Laboratory thermometers”. The BSI committee responsible for both standards expects that th
16、e series of thermometers standardized internationally will gradually be taken into use in preference to the corresponding BS593 thermometers, but does not wish to define a specific transition period for this process. Accordingly, it has been decided that both standards will remain in being side by s
17、ide for some years, after which a further review will be undertaken in the light of the experience gained. In the meantime, comments will be welcome from users on the two sets of specifications and particularly on the relative convenience of the thermometers in use. Certification. Attention is drawn
18、 to the certification facilities described on the inside back cover of this standard. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of it
19、self confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1to 12, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be i
20、ndicated in the amendment table on the inside front cover.BS 5074:1974 BSI 08-1999 1 1 Scope This British Standard specifies requirements for two basic series of solid-stem thermometers: short solid-stem thermometers not exceeding250mm and long solid-stem thermometers not exceeding375mm in length su
21、itable for general use in precision work. NOTEThere are in existence many different specifications for thermometers of the general types covered by these series. It is intended that these series should, in due course, replace all such specifications except those for which there is a well-established
22、 justification. 2 Type of thermometer The thermometers shall be of the liquid-in-glass, solid-stem type, preferably with an enamel back. 3 Temperature scale The thermometers shall be graduated in accordance with the Celsius scale as defined in the current definition of the International Practical Te
23、mperature Scale adopted by the General Conference of Weights and Measures (CGPM). 4 Immersion The thermometers shall be graduated for use at “total immersion” i.e.the reading should be correct when the thermometer is immersed at least to the top end of the liquid column but not including the expansi
24、on chamber, in the medium the temperature of which is to be measured. NOTEIf, in special circumstances, it is required that the reading should be correct at complete immersion (i.e. when the entire thermometer is immersed in the medium) this shall be specified and the thermometer marked “complete” o
25、r suitable abbreviation. 5 Glass The glass shall be so selected and processed that the finished thermometer shows the following characteristics. 5.1 Stress in the glass shall be reduced to a level sufficient to minimize the possibility of fracture due to thermal or mechanical shock. 5.2 The bulb gla
26、ss shall be stabilized by suitable heat treatment to ensure that the accuracy requirements of Clause10 can be met. 5.3 The errors in the finished thermometer resulting from the thermometric properties of the glass used for the bulb shall be within the limits specified in Clause10. NOTEThe maximum te
27、mperature at which a glass may be used is related to the viscosity of the glass at the temperature concerned and hence depends on the degree of stability required. 5.4 The legibility of the reading shall not be impaired by devitrification or clouding. 5.5 The image of the meniscus shall be distorted
28、 as little as possible by defects or impurities in the glass. 5.6 A list of approved thermometric glasses is given in Appendix A. 6 Liquid filling Mercury shall be used as liquid filling, except forthermometers with a scale extending below38 C. For thermometers STC/0.5/ 55/+ 2 and STL/0.2/ 55/+ 5, t
29、he eutectic alloy of mercury and thallium (8.5% thallium by mass) shall be used. The filling shall be free from any contamination likely to interfere with the proper functioning of the thermometer. 7 Gas filling Only a dry, inert gas shall be used as gas filling. It is essential that thermometers in
30、tended for use above100 C shall be gas-filled. The pressure of the gas shall be high enough to raise the boiling point of the mercury sufficiently to minimize vaporization over the complete thermometer range. 8 Construction 8.1 Shape. The thermometers shall be straight and their external cross-secti
31、on shall be approximately circular. 8.2 Top finish. The top of the thermometer shall preferably be finished with a glass ring, the diameter of which shall not exceed that of the stem. Alternatively, a plain finish may be provided, and this is preferred for thermometers STC/1/290/410, STL/1/180/420 a
32、nd STL/2/0/600. 8.3 Capillary tube. The inside of the capillary tube shall be smooth. The cross-sectional area of the bore shall not show variations from the average greater than10% and the bore shall be wide enough to ensure that jumping of the meniscus does not exceed one-fifth of the graduation i
33、nterval.BS 5074:1974 2 BSI 08-1999 8.4 Expansion chamber. A thermometer should not be heated above its maximum working temperature. To avoid damaging the thermometer by accidental overheating, an expansion volume shall be provided at the top of the stem 1) . The volume above the scale shall be at le
34、ast equivalent to that occupied by an interval of80degrees Celsius of the scale. This volume shall preferably consist of an expansion chamber with at least 10 mm of unchanged capillary tube between the highest scale line and the commencement of the widening of the bore. Such a chamber shall be pear-
35、shaped with thehemisphere at the top except for thermometers STC/1/290/410, STL/1/180/420 and STL/2/0/600. If the expansion volume takes the form of unchanged capillary tube then there shall be at least30 mm above the highest scale line. For thermometers in which the upper limit of the scale is belo
36、w room temperature, the lower end of the “pear” shall be considerably elongated, to avoid the risk of a break in the liquid column at room temperature. 8.5 Contraction chamber. A thermometer in which the lower limit of the main scale is above0 C shall be provided with a contraction chamber to allow
37、for the inclusion of an auxiliary scale (seeFigure 1, Type B). The contraction chamber shall be elongated and as narrow as possible, to avoid the risk of a break in the liquid column at room temperature. 8.6 Position of chambers. No enlargement of the bore shall be so located as to produce any varia
38、tion in the cross-section of the capillary tube in the scale portion (other than that permitted in8.3), and in no case shall such an enlargement be located less than5mm from the nearest scale line. The distance from the top of the contraction chamber to the first scale line of the scale immediately
39、above it shall be not less than13mm, except that for thermometers STC/0.5/245/305, STC/1/190/310, STC/1/290/410, STL/0.5/190/310 and STL/1/180/420 this distance shall be not less than30mm. 8.7 Dimensions. The dimensions of the thermometers shall be as given inTable 1a andTable 1b andFigure 1 and Fig
40、ure 2. 9 Graduation and figuring 9.1 The scales and graduation intervals of the thermometers shall be as given inTable 2a andTable 2b. 9.2 The scale lines shall be clearly marked and of uniform thickness, which in no case shall exceed0.12mm. The lines shall be at right angles to the axis of the ther
41、mometer. 9.3 When the thermometer is held in a vertical position and viewed from the front, the left-hand ends of the scale lines shall lie on an imaginary vertical line and the longer lines shall be extended to the right-hand side. 9.4 The length of the shortest scale lines shall be about1min. 1) O
42、verheating is liable to change the indication of the thermometer, and a recalibration may be necessary.BS 5074:1974 BSI 08-1999 3 Table 1a Dimensions for short solid-stem thermometers (see alsoFigure 1) Table 1b Dimensions for long solid-stem thermometers (see alsoFigure 2) Dimension Short Type A Sh
43、ort TypeB Short TypeC mm mm mm Total length max. 250 250 250 Distance from top of bulb (shoulder) to lower nominal limit ofscale min. 20 20 Distance from top of bulb (shoulder) to0 C scale line min. 20 Length of main scale (nominal limits) min. 120 95 95 Distance from0 C scale line to top of thermom
44、eter min. 25 Diameter of stem 5.5 to 8.0 5.5 to 8.0 5.5 to 8.0 External diameter of bulb min. 5 5 5 max. not greater than that of stem Length of bulb to shoulder min. 15 15 15 Distance from shoulder of bulb to lower end of parallel-sided capillary tube max. 5 5 5 Distance from top of bulb funnel to
45、lowest scale line min. 13 13 13 Distance from bottom of contraction chamber to highest scale line on scale below it min. 5 5 Distance from top of contraction chamber to lowest scale line on scale above it min. 13 a 13 Distance from highest scale line to bottom of expansion chamber min. 10 10 10 a Ex
46、cept for thermometers STC/0.5/245/305, STC/1/190/310 and STC/1/290/410, for which this dimension shall be at least30mm. Dimensions Long Type A Long Type B mm mm Total length max. 375 375 Distance from top of bulb (shoulder) to lower nominal limit of scale min. 20 Distance from top of bulb (shoulder)
47、 to0 C scale line min. 20 Length of main scale (nominal limits) min. 240 195 Diameter of stem 5.5 to 8.0 5.5 to 8.0 External diameter of bulb min. 5 5 max. not greater than that of stem Length of bulb to shoulder min. 15 15 Distance from shoulder of bulb to lower end ofparallel-sided capillary tube
48、max. 5 5 Distance from top of bulb funnel to lowest scaleline min. 13 13 Distance from bottom of contraction chamber tohighest scale line on scale below it min. 5 Distance from top of contraction chamber tolowest scale line on scale above it min. 13 a Distance from highest scale line to bottom of ex
49、pansion chamber min. 10 10 a Except for thermometers STL/0.5/190/310 and STL/1/180/420, for which this dimension shall be at least30mm.BS 5074:1974 4 BSI 08-1999 NOTEThe position of the top ring may be either as shown or at right angles to this. Figure 1 Short solid-stem thermometers for precision useBS 5074:1974 BSI 08-1999 5 NOTEThe position of the top ring may be either as shown or at right angles to this. Figure 2 Long solid-stem thermometers for precision useBS 5074:1974 6 BSI 08-1999 Table 2a Graduation for
