1、BRITISH STANDARD CONFIRMED AUGUST 1997 BS 692:1990 Specification for Meteorological thermometers UDC 536.512/.513:551.508.26:006.3/.8BS692:1990 This British Standard, having been prepared under the directionof the Laboratory Apparatus Standards Policy Committee, was published underthe authority of t
2、he BoardofBSI and comes intoeffecton 31 May 1990 BSI 02-2000 First published July 1936 First revision November 1951 Second revision March 1958 Third revision December 1976 Fourth revision May 1990 The following BSI references relate to the work on this standard: Committee reference LBC/4 Draft for c
3、omment 88/56006 ISBN 0 580 17933 8 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Laboratory Apparatus Standards Policy Committee (LBC/-) to Technical Committee LBC/4, upon which the following bodies were represented: British Laboratory
4、 Ware Association British Medical Association Department of Health Department of Trade and Industry (National Physical Laboratory) Institute of Petroleum Medical Sterile Products Association Scientific Glassware Association Amendments issued since publication Amd. No. Date of issue CommentsBS692:199
5、0 BSI 02-2000 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Types 1 3 Temperature scale 1 4 Stem 1 5 Bulb 1 6 Annealing 1 7 Stabilization 1 8 Immersion 1 9 Scale lines 1 10 Figuring 1 11 Construction 1 12 Sheath 3 13 Top finish 3 14 Expansion chamber 3 15 Spirit f
6、illing 3 16 Maximum and minimum thermometers: special provisions 3 17 Inscriptions 4 Appendix A Thermometric glasses approved by the National Physical Laboratory 5 Appendix B Testing of meteorological thermometers 5 Appendix C Method of test for the absence of amines in spirit filling 5 Appendix D M
7、eteorological thermometers with a Fahrenheit scale 6 Figure 1 Suitable support for thermometers in a louvred screen 7 Figure 2 Typical graduation and figuring for British Standard Celsiusmeteorological thermometers 8 Figure 3 Details of button at top of ordinary thermometer 8 Figure 4 Details of cli
8、ps on thermometer support 8 Table 1 Dimensions for meteorological thermometers 2 Table 2 Ranges and tolerances for meteorological thermometers (Celsiusscale) 2 Table 3 Identification stripe(s) or approved abbreviations and normalmaximum working temperature of all glasses that have been approvedfor t
9、he manufacture of thermometer bulbs 5 Table 4 Ranges and tolerances for meteorological thermometers (Fahrenheitscale) 6 Publications referred to Inside back coverBS692:1990 ii BSI 02-2000 Foreword This British Standard has been prepared under the direction of the Laboratory Apparatus Standards Polic
10、y Committee and supersedes BS 692:1976 which is withdrawn. This British Standard was first published in 1936 and revisions were issued in1951, 1958 and 1976. This revision introduces technical changes to bring the standard up to date and in particular changes to the availability of glasses and arran
11、gements for calibration and testing. This revision reflects the change to the Celsius scale for all Meteorological Officeobservations and all dimensions are given in metric units. Any continuing requirement for thermometers with a Fahrenheit scale is catered for in Appendix D. Product certification.
12、 Users of this British Standard are advised to consider thedesirability of third party certification of product conformity with this BritishStandard based on testing and continuing surveillance, which may be coupled with assessment of a suppliers quality systems against the appropriate Part of BS 57
13、50. Enquiries as to the availability of third party certification schemes will be forwarded by BSI to the Association of Certification Bodies. If a third party certification scheme does not already exist, users should consider approaching an appropriate body from the list of Association members. A B
14、ritish 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 itself confer immunity from legal obligations. Summary of pages This document comprises a f
15、ront cover, an inside front cover, pagesi andii, pages1 to8, 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 indicated in the amendment table on the inside front cover.BS692:1990 BSI 02-2000 1 1 Scope T
16、his British Standard range of meteorological thermometers comprises the following types. thermometers protected by glass sheaths and suitable for mounting in a louvred screen (seeFigure 1). NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Types T
17、his British Standard range of meteorological thermometers comprises the following types. a) Maximum. Mercury-in-glass, graduated on the stem, with as high a vacuum as possible above the mercury. b) Minimum. Spirit-in-glass, graduated on the stem. c) Ordinary (i.e. wet or dry bulb). Mercury-in-glass
18、(except for Ord. 4 which shall be spirit-in-glass), graduated on the stem. 3 Temperature scale The temperature scale to which this specification refers is the Celsius scale as defined in the current definition of the International Practical Temperature Scale adopted by the General Conference of Weig
19、hts and Measures (CGPM). The Fahrenheit scale values in this British Standard are derived from the Celsius scale. 4 Stem The stem shall be of lead glass or other thermometric glass appropriate to the temperature range, with an enamel back. 5 Bulb The bulb for ordinary thermometers shall be substanti
20、ally spherical, with its centre approximately in alignment with the axis of the stem. The bulb for maximum and minimum thermometers shall be either spherical or cylindrical. The bulb shall be of the thermometric glass approved by the National Physical Laboratory (see Appendix A). 6 Annealing Stress
21、in the glass shall be reduced to a level sufficient to minimize the possibility of fracture due to mechanical or thermal shock. 7 Stabilization The thermometer shall be stabilized before graduation using a process such that the maximum error and interval error of the finished thermometer are within
22、the limits specified in Table 2. 8 Immersion The thermometer shall be graduated for complete immersion. 9 Scale lines The scale lines shall be clearly etched or otherwise durably marked at each 0.5 C and shall be of uniform thickness not exceeding 0.15 mm. The lines shall lie in planes at right angl
23、es to the axis of the thermometer, and their left hand ends shall be on an imaginary line parallel with the axis of the thermometer. When the thermometer is held vertically so that the enamel back forms a suitable background to the scale lines and figuring, the long and medium lines shall extend to
24、the right, but the shortest lines shall not extend across the bore. 10 Figuring The thermometers shall be figured at each 5 C in bold figures of uniform thickness. The figures for ordinary thermometers shall be upright when the thermometer is held in a vertical position and viewed from the front and
25、 shall be placed so that each would be intersected by the line to which it refers if the line were extended. All negative figures shall have a minus sign placed above them. The figures for maximum and minimum thermometers shall be upright when the thermometer is held in a horizontal position with th
26、e bulb to the left and viewed from the front, and shall be placed so that they would be bisected by the line to which they refer if the line were extended. All negative figures shall have a minus sign placed before them. NOTEFigure 2 illustrates diagrammatically the graduation and figuring specified
27、 for typical thermometers. All scale lines and figures shall be durably marked in black. 11 Construction Each thermometer shall comply in all respects with the dimensions given in Table 1. The ranges and tolerances shall be in accordance with Table 2.BS692:1990 2 BSI 02-2000 Table 1 Dimensions for m
28、eteorological thermometers Table 2 Ranges and tolerances for meteorological thermometers (Celsius scale) Dimensions Type Ordinary Maximum Minimum mm mm mm Overall length 315 to 330 315 to 345 315 to 345 Length of scale, min. 190 190 190 Stem diameter 5 to 6.5 5 to 6.5 5 to 6.5 Length of parallel por
29、tion of boreabove and below scale, min. 10 10 10 Bulb diameter: spherical type Ord. 1 Ord. 2 Ord. 3 8.5 to 11.5 8.5 to 11.5 Not greater than 16.5 Ord. 4 11.5 to 14 cylindrical type Not greater than stemdiameter Not greater than stemdiameter Distance from bottom of bulb tobottom of scale, min. 50 50
30、50 Designation Filling Range Maximum error at any point Maximum error in an interval of 10 C (see note 2) Below 40 C 40 C to below 0 C 0 C to 25 C Above 25 C Below 0 C 0 C to 25 C Above 25 C C C C C C C C C Ord. 1/C Ord. 2/C Ord. 3/C Mercury Mercury Mercury 20 to + 55 30 to + 45 40 to + 35 0.3 + 0.2
31、 0.2 + 0.05 0.2 + 0.05 0.25 0.1 0.1 Ord. 4/C Spirit 55 to + 20 0.6 0.25 0.1 0.25 0.1 Max. 1/C Max. 2/C Max. 3/C Max. 4/C Mercury Mercury Mercury Mercury 10 to + 65 20 to + 55 30 to + 45 40 to + 35 0.3 + 0.2 0.2 + 0.05 0.2 + 0.05 0.25 0.1 0.1 Min. 1/C Min. 2/C Spirit Spirit 25 to + 50 35 to + 40 0.25
32、 0.1 0.25 0.25 0.1 0.25 Min. 3/C Min. 4/C Spirit Spirit 50 to + 25 70 to + 15 0.6 0.25 0.1 0.25 0.1 NOTE 1The range of the Ord. 3/C and the Max. 4/C thermometers extends down to 40 C, because the mercury usually remains liquid at this temperature due to supercooling below its freezing point of 38.8
33、C. NOTE 2The maximum error in an interval of 10 C refers to the algebraic difference between the errors at opposite ends of the interval, i.e. 0.1 C means that the change of error in any interval of 10 C does not exceed 0.1 C. NOTE 3The tolerance for the mercury-in-glass thermometers permit greater
34、minus errors than plus errors in order to allow for the tendency of the zero of these thermometers to rise slowly with time. BS692:1990 BSI 02-2000 3 12 Sheath The outer glass sheath shall be of lead glass or otherthermometric glass appropriate to the temperature range, hermetically sealed to the st
35、em at a point near the bulb. The sheath shall be not more than 14mm in external diameter except at the point where the sheath is rejoined after graduation. No visible distortion of the scale shall be caused at this point. There shall be no excess diameter on the ordinary thermometer within 270 mm of
36、 the underside of the button. The top end of the stem shall be securely supported inside the sheath by a ring of rubber or cork, not exceeding 4 mm in width, fitted inside the sheath and over the stem and placed so as not to obscure the graduated scale, the safety chamber or the end of the bore. If
37、one or two similar supports are placed in a position between the seal and the bottom of the scale this shall not obscure the constriction of the maximum thermometer. The thermometer shall be so constructed that no visible condensation occurs inside the sheath when the thermometer is exposed to any t
38、emperature within its working range. If cork is used for the supporting ring(s) it shall be thoroughly dried before fitting. 13 Top finish Each ordinary thermometer shall be finished in the form of a button, as shown in Figure 3, which shall be of such size as to enable the thermometer to be easily
39、and securely suspended from the clip shown in Figure 4, and shall allow it to be withdrawn from the clip when in a vertical position. The maximum and minimum thermometers shall be finished with a plain top. 14 Expansion chamber The thermometers shall be so constructed as to withstand without damage
40、a temperature of 50 C or at least 3 C above that shown by the highest scale line, whichever is the higher temperature. There shall be no safety chamber or enlargement of the bore in the maximum thermometers, except if a pear-shaped expansion volume with the hemisphere at the top is provided in the o
41、rdinary and minimum thermometers. There shall be at least 10 mm of unchanged capillary tube above the highest scale line. 15 Spirit filling The spirit shall be absolute ethanol (ethylalcohol)containing not less than 99.4 % (V/V) i.e. 99.0 % (m/m) of ethanol, and having a density at20 C not greater t
42、han 0.7921 g/cm 3 . The ethanol shall comply in other respects with the provisions of BS 507, subject to the following modifications. a) Aldehydes and ketones. The ethanol when tested in accordance with BS 6392-3 shall not contain more than 0.02 % (m/m) of aldehydes and ketones, calculated as acetal
43、dehyde, CH 3 CHO. b) Esters. The ethanol, when tested in accordancewith BS 6392-8, shall not contain more than 0.02 % (m/m) of esters, calculated as ethyl acetate, CH 3 COOC 2 H 5 . c) Amines. The ethanol, when tested in accordance with Appendix C, shall give no indication of the presence of amines.
44、 16 Maximum and minimum thermometers: special provisions The maximum thermometer shall have a constriction situated in the bore below the lowest scale line so that as the temperature falls the mercury column is not drawn back past the constriction when the thermometer is inclined at an angle of 10 o
45、r less to the horizontal with the bulb at the lower end. The mercury shall shake through the constriction without undue effort when the thermometer is being re-set. The construction shall be such as to reduce as far as possible the tendency of the mercury column to draw away from the constriction wh
46、en the thermometer in the normal position of use, i.e.inclined at an angle of about 2 to the horizontal with the bulb at the lower end, is subject to vibration such as might be caused by opening the door of the screen. The minimum thermometer shall be provided with an index of dark glass in the bore
47、. The length of this index shall be about 20 mm but in the case of cylindrical bulbs, it shall be at least 5 mm greater than the length of the bulb. The construction shall be such that the thermometer acts as a minimum thermometer when mounted at an angle of about 2 to the horizontal with the bulb a
48、t the lower end.BS692:1990 4 BSI 02-2000 17 Inscriptions Each thermometer shall be permanently and legibly marked with the following information. a) The official symbol “ C”: An abbreviation of thename Celsius, e.g. “C” is also permitted. (Seealso Appendix D for the inscription of Fahrenheit thermom
49、eters.) b) An identification number. c) The makers and/or vendors name or readily identifiable trade mark. d) The designation: the code reference allotted to the thermometer, e.g. “Ord. I/C”. e) The number of this British Standard, i.e.BS692 1) . 1) Marking BS 692 on or in relation to a product represents a manufacturers declaration of conformity, i.e. a claim by or on behalf of t
