1、BRITISH STANDARD BS 1704:1985 ISO 1770:1981 Incorporating Amendment No. 1 Specification for Solid-stem general purpose thermometers UDC 536.512/.513BS1704:1985 This British Standard, having been prepared under the directionof the Laboratory Apparatus Standards Committee,was published underthe author
2、ityof the BoardofBSIandcomes into effect on 28June1985 BSI 01-2000 First published February 1951 First revision June 1985 The following BSI references relate to the work on this standard: Committee reference LBC/4 Draft for comment 79/54294 DC ISBN 0 580 14258 2 Committees responsible for this Briti
3、sh Standard The preparation of this British Standard was entrusted by the Laboratory Apparatus Standards Committee (LBC/-) to Technical Committee LBC/4, upon which the following bodies were represented: British Laboratory Ware Association British Lampblown Scientific Glassware Manufacturers Associat
4、ion Ltd. British Medical Association Department of Health and Social Security Department of Trade and Industry (National Physical Laboratory) Institute of Petroleum Ministry of Defence Amendments issued since publication Amd. No. Date of issue CommentsBS1704:1985 BSI 01-2000 i Contents Page Committe
5、es responsible Inside front cover National foreword ii 0 Introduction 1 1 Scope and field of application 1 2 Reference 1 3 Temperature scale 1 4 Immersion 1 5 Glass 1 6 Liquid filling 2 7 Gas filling 2 8 Construction 2 9 Scale lines, immersion line and figuring 2 10 Accuracy 2 11 Inscriptions 3 Nati
6、onal appendix A Testing of British Standard thermometers 7 Figure Examples of scale lines and figuring 6 Table 1 Requirements for solid-stem general purpose thermometersformeasurements of lower accuracy 4 Table 2 Requirements for solid-stem general purpose thermometersformeasurements of higher accur
7、acy 5 Table 3 Uncertainty of test for certification of British Standard generalpurpose thermometers 7 Publication referred to 8BS1704:1985 ii BSI 01-2000 National foreword This British Standard has been prepared under the direction of the Laboratory Apparatus Standards Committee. This edition is ide
8、ntical with ISO1770:1981 “Solid-stem general purpose thermometers” published by the International Organization for Standardization (ISO) and incorporates a change to clause11 brought about by Amendment1 to ISO1770 issued in August1983. This standard supersedes BS1704:1951 which is withdrawn. The pri
9、ncipal differences between the1951 edition and this edition include the introduction of a series of greater accuracy intended for possible testing by a national verification laboratory, the withdrawal of thermometers marked in Fahrenheit, and changes to the scale division, accuracy and line thicknes
10、s. National appendix A gives details of testing of the thermometers J to W. Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those
11、 used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standa
12、rd, they should be read as “British Standard”. Cross-reference. The reference to ISO386, which only appears in clause0, is of an informative nature only and the lack at present of an equivalent British Standard therefore does not affect the validity of this standard. Additional information. Attentio
13、n is drawn to the requirement for marking in clause11 1) . Certification. Attention is drawn to the certification facilities described on the inside back cover. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for t
14、heir 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, pages1 to 8, an inside back cover and a back cover. This standard has been updated (s
15、ee copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. 1) Marking BS1704:1985 on or in relation to a product is a claim by the manufacturer that the product has been manufactured to the requirements of the standard. The a
16、ccuracy of such a claim is therefore solely the manufacturers responsibility. Enquiries as to the availability of third party certification to support such claims should be addressed to the Director, Quality Assurance Division, BSI, PO Box375, Milton Keynes MK146LO for certification marks administer
17、ed by BSI or to the appropriate authority for other certification marks.BS1704:1985 BSI 01-2000 1 0 Introduction Although the thermometers covered by this International Standard are not intended for use in any specific test method, the overall lengths of the series of higher accuracy are specified w
18、ith a tolerance so as to provide a degree of interchangeability for any special apparatus into which the thermometers are incorporated. For ease of reference, each thermometer has been allocated a designation consisting of a single letter representing the range of the thermometer and the indication
19、“TOTAL” or, for example, “75” relating to the intended immersion. Some of the thermometers described in the scope and field of application of this International Standard, and which are in current use, are of a lower quality than those strictly covered in ISO386. Accordingly, whilst this Internationa
20、l Standard is based on the provisions of ISO 386, it does not align with those which recommend the distance between consecutive scale lines to be greater than0,8mm and the maximum error to be one scale division. In order to avoid increasing the cost of the thermometers, some of the dimensions recomm
21、ended to be specified in ISO386 have also been omitted. 1 Scope and field of application This International Standard specifies requirements for two series of inexpensive “commercial quality” liquid-in-glass thermometers of the solid-stem type suitable for general purpose use in industry, schools and
22、 laboratories when great accuracy of measurement is not required: a) a series designated A to H, in which nominal ranges and maximum overall lengths are specified but which may not be acceptable for testing by a national verification laboratory; b) a series designated J to W of greater accuracy than
23、 in a) and with specified ranges and a tolerance on overall length, which may be acceptable for testing by a national verification laboratory. The temperature range covered by each series is from 100 C to +500 C. 2 Reference ISO 386, Liquid-in-glass laboratory thermometers Principles of design, cons
24、tructionand use. 3 Temperature scale The thermometers shall be graduated in accordance with the Celsius scale as defined in the current definition of the International Practical Temperature Scale (IPTS) adopted by the Confrence gnrale des poids et mesures, and in accordance with the International Sy
25、stem of Units(SI). 4 Immersion 4.1 The thermometers shall be adjusted for use either at total immersion (i.e.the reading shall be correct when the thermometer is immersed so that the top of the liquid column is in the same plane as, or no more than two scale divisions above, the surface of the mediu
26、m the temperature of which is required to be measured), or for partial immersion, as required. 4.2 In the latter case, the preferred immersion is75 1mm, and the adjustment of such a thermometer shall be carried out at the average emergent liquid column temperature detailed inTable 1 andTable 2. NOTE
27、 1Adjustment at partial immersion is not permitted for the thermometers with a scale extending below 38 C, because of the large errors likely to be caused in a spirit-in-glass thermometer by variations in temperature around the emergent portion of the stem. NOTE 2For guidance on the determination of
28、 the emergent liquid column corrections to be applied when the thermometer is used in situations where the average emergent liquid column temperature differs from that given inTable 1 andTable 2, seeannexB.6 andB.7 of ISO386. 5 Glass The thermometer bulb shall be made of suitable thermometric glass.
29、 2)The glass or glasses comprising the thermometer shall be selected and processed so that the finished thermometer shows the following characteristics. a) Stress in the glass of the bulb and capillary stem shall be reduced to a level sufficient to minimize the possibility of fracture due to thermal
30、 or mechanical shock. b) The bulb glass shall be stabilized by suitable heat treatment to ensure that the accuracy requirements of clause10 are met. c) The legibility of the reading shall not be impaired by devitrification or clouding. d) The meniscus or its image shall be distorted as little as pos
31、sible by defects or impurities in the glass. 2) An International Standard (ISO4795) dealing with glasses for thermometer bulbs is in preparation.BS1704:1985 2 BSI 01-2000 6 Liquid filling 6.1 Mercury shall be used as liquid filling except for thermometers with a scale extending below 38 C for which
32、a filling of an organic liquid shall be used which will remain liquid throughout the temperature range under the pressures prevailing inside the thermometer. 6.2 The organic liquid used as the liquid filling should preferably be coloured by means of a light-fast dye which does not stain the glass. 6
33、.3 The organic liquid used as the liquid filling should preferably be toluene or an isomer or suitable mixture of isomers of pentane. 7 Gas filling Thermometers containing mercury as the liquid filling shall be filled with a dry inert gas above the liquid filling. The pressure of the gas shall be hi
34、gh enough to raise the boiling point of the liquid sufficiently to minimize vaporization over the nominal range of the thermometer. 8 Construction 8.1 Shape The thermometers shall be straight. Their external cross-section should be approximately circular, but if required, an external lens-shaped dev
35、iation from the circular cross-section is permitted to facilitate reading. 8.2 Top finish The top of the thermometer shall be finished with a plain top, button top or glass ring. In all cases, the diameter of the top finish of the thermometer shall not exceed that of the stem. 8.3 Capillary tube The
36、 capillary tube should preferably incorporate an enamel back. The inside of the capillary tube shall be smooth in order to avoid possible sticking of the liquid filling. For the thermometers listed inTable 2, the cross-sectional area of the bore shall not show variations from the average greater tha
37、n10%. 8.4 Expansion volume (safety chamber) 8.4.1 An expansion volume shall be provided at the top of the capillary tube. This volume may take the form either of an extension of the bore or of an expansion chamber. NOTEOverheating a thermometer beyond its upper nominal limit is liable to change the
38、zero or other fiducial point of the thermometer, and a redetermination of this point will therefore become necessary if it takes place. 8.4.2 If an expansion chamber is incorporated, it shall, except when the stem is made from borosilicate glass, be pear-shaped with the hemisphere at the top. 8.5 En
39、largement of bore There shall be at least 10 mm of unchanged capillary between any enlargement and the nearest scale line or immersion line. 8.6 Dimensions The dimensions of the thermometers shall be as detailed inTable 1 andTable 2. The tolerance on the overall length of the thermometers of higher
40、accuracy given inTable 2 shall be 10mm. The bulb diameter shall not exceed that of the stem. 9 Scale lines, immersion line and figuring 9.1 The nominal ranges, figuring and scale divisions of the thermometers shall be as detailed inTable 1 andTable 2. 9.2 The scale lines shall be clearly etched or o
41、therwise durably marked and of uniform thickness not exceeding the values given inTable 1 and Table 2. The lines shall be at right angles to the axis of the thermometer. Typical schemes of graduation and figuring are shown in the Figure. 9.3 In the case of the thermometers listed inTable 1 with0 C a
42、s the lower nominal limit or100 C as the upper nominal limit, the scale shall be extended by at least three divisions beyond each of these limits. In all other cases, the scales may also be suitably extended beyond the nominal limits. 9.4 On thermometers adjusted for partial immersion the immersion
43、depth shall be indicated by a line on the stem at the appropriate distance from the bottom of the bulb (see clause4). This line shall be marked around the back of the thermometer and shall not cross the scale. 9.5 In the case of etched scales, the pigment filling shall remain in the scale lines, fig
44、ures, inscriptions and immersion line under normal conditions of use. 10 Accuracy The instrument error for the thermometers shall not be greater than the values given inTable 1 andTable 2. NOTEIn the case of thermometers of ranges0 to360 C and0 to500 C, an appreciable error may develop after long ex
45、posure at temperatures in the upper part of the scale range.BS1704:1985 BSI 01-2000 3 11 Inscriptions 11.1 The following inscriptions shall be durably and legibly marked on the thermometers: a) unit of temperature: abbreviation of the name Celsius, for example “C”, or the symbol “ C”; b) the designa
46、tion of the thermometer; c) for partial immersion thermometers, an indication of the immersion depth for which the thermometer is adjusted, for example “75mm”. No inscription is required for total immersion thermometers; d) vendors and/or makers name or readily identifiable mark; e) the number of th
47、is International Standard, i.e.ISO1170, or the number of the corresponding national standard; f) identification of the bulb glass, preferably by means of a coloured stripe or stripes, or by an inscription on the thermometer; 11.2 In addition to11.1 if the purchaser requires the thermometer to bear a
48、n identifying number, the following inscription shall also be durably and legibly marked on the thermometer: manufacturers identification or serial number, the last two digits of which should indicate the year of manufacture.BS 1704:1985 4 BSI 01-2000 Table 1 Requirements for solid-stem general purp
49、ose thermometers for measurements of lower accuracy Nominal range Scale division Longer lines ateach Line thickness Fractional figuring ateach Full figuring ateach Overall length Scale length (nominal range) Total immersion Partial immersion Designation (The immersion is added as appropriate, for example, “/75”) Maximum error Maximum error Average emergent liquid column temperature max. max. min. C C C mm C C mm mm C C C 100 to +30 35 to +30 0 to +60 0 to +100 0 to +160 0 to +250 0 to +360 0 to +500 1 0,5 0,5 1 1 1 2 5 5 1 1 5 5
