1、BRITISH STANDARD BS 2765:1969 Incorporating Amendment No. 1 Specification for Dimensions of temperature detecting elements and corresponding pocketsBS2765:1969 This British Standard, having been approved by theInstrument Industry StandardsCommittee, waspublished underthe authorityof the ExecutiveBoa
2、rdon 20 June 1969 BSI 07-1999 First published July 1956 First revision June 1969 The following BSI references relate to the work on this standard: Committee references INE/4 andINE/4/4 Draft for comment 68/6626 ISBN 580 05530 2 Co-operating organizations The Instrument Industry Standards Committee,
3、under whose supervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: British Clock and Watch Manufacturers Association British Electrical and Allied Manufacturers Association* British Industrial
4、 Measuring and Control Apparatus Manufacturers Association* British Nautical Instrument Trade Association British Railways Board British Scientific Instrument Research Association British Steel Industry* Council of British Manufacturers of Petroleum Equipment Electrical Research Association Electric
5、ity Council, the Generating Board and the Area Boards in England and Wales* Electronic Engineering Association Engineering Equipment Users Association* Gauge and Tool Makers Association Institution of Chemical Engineers Institution of Electrical Engineers* Institution of Heating and Ventilating Engi
6、neers Institution of Mechanical Engineers* Institution of Production Engineers Ministry of Defence, Air Force Department Ministry of Defence, Army Department* National Coal Board National Physical Laboratory (Ministry of Technology)* Oil Companies Materials Association* Scientific Instrument Manufac
7、turers Association* Water Resources Board Water-tube Boilermakers Association 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 entrusted with the preparation of th
8、is standard: British Coal Utilisation Research Association Gas Council Institute of Physics and the Physical Society Institute of Refrigeration Ministry of Power Ministry of Technology Ministry of Technology, National Engineering Laboratory Society of Chemical Industry Amendments issued since public
9、ation Amd. No. Date of issue Comments 8317 December 1994 Indicated by a sideline in the marginBS2765:1969 BSI 07-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Dimensioning system 3 4 Temperature detecting elements 6 5 Thermometer pockets 6
10、 Appendix A Systematic errors 11 Figure 1 Component parts of plain thermometers 1 Figure 2 Means of attachment 3 Figure 3 Illustration of lagging extension length, T 3 Figure 4 Illustration of P, R and U 4 Figure 5 Illustration of detecting element dimensioning 5 Figure 6 A recommended design of fla
11、nged thermometer pocket 8 Figure 7 A recommended design of parallel-threaded thermometer pocket 9 Figure 8 A recommended design of taper-threaded thermometer pocket 10 Table 1 Text deleted 6 Table 2A Text deleted 6 Table 2B Text deleted 6 Table 3 Lengths of thermometer pockets 7BS2765:1969 ii BSI 07
12、-1999 Foreword This standard makes reference to the following British Standards. BS 10, Flanges and bolting for pipes, valves and fittings. BS 21, Pipe threads. BS 970, Wrought steels in the form of bars, billets and forgings, up to6 in ruling section, for automobile and general engineering purposes
13、. En series. BS 1041, Code for temperature measurement. BS 1560, Steel pipe flanges and flanged fittings (nominal sizes “ in to24in) for the petroleum industry. BS 1506, Steels for use in the chemical, petroleum and allied industries. BS 1916, Limits and fits for engineering. BS 3643, ISO metric scr
14、ew threads. BS Handbook No. 18. Metric standards for engineering. When this British Standard was first published in1956 under the authority of the Instrument Industry Standards Committee its purpose was to present a uniform terminology and dimensioning system. In that context it provided definitions
15、 of terms which were relevant to specific temperature-detecting elements. This revision has been prepared as a result of investigating the possibility of rationalizing the leading dimensions of thermometer pockets and temperature detecting elements and reducing the range of sizes to a minimum compat
16、ible with the requirements of most users. Diametral tolerances have been especially selected so as to ensure rapid response to temperature changes. The terminology in Section 1 of the1956 edition has been retained but only insofar as it provides definitions of the more general terms. In the light of
17、 the impending adoption of the metric system of measurement in the UnitedKingdom, it is considered appropriate that values which relate to the compatibility of detecting elements and pockets should be given in metric units. In order to provide for attachment of pockets to plant, recommended external
18、 connection sizes are included. Following the publication of BS EN61152:1994 “Dimensions of metal-sheathed thermometer elements” certain tables in BS2765:1969 conflict with BSEN61152. Amendment 1 to BS2765:1969 has therefore been implemented in order to delete the conflicting tables on the date of w
19、ithdrawal of conflicting national standards,1 December 1994, in accordance with CENELEC Internal Regulations. 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
20、 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, pages1to12, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incor
21、porated. This will be indicated in the amendment table on theinside front cover.BS2765:1969 BSI 07-1999 1 1 Scope This British Standard describes a dimensioning system for, and specifies dimensional requirements of, screwed and flanged thermometer pockets so as to ensure both interchangeability betw
22、een temperature detecting elements of the same nominal dimensions and a proper fit of such elements into the corresponding pockets. Dimensions which are not required to ensure such interchangeability and fit are not mandatory. A recommended design suitable for applications of moderate severity is il
23、lustrated. The pocket itself can be regarded as an integral part of the plant and since it should be designed so as to conform to the more usual methods of fixing employed in machinery and process plant, the means of attachment recommended in this standard are in inch units. It should be noted that
24、the inclusion of a particular size in this standard does not imply that it is suitable for use with all types of detecting element. The availability of sizes and limitations on immersion length should be determined by consulting instrument manufacturers. A pocket material considered suitable for mos
25、t applications is also recommended. No recommendations are given regarding sheaths; guidance on this subject will be found in BS1041 1) . 2 Definitions For the purposes of this British Standard, the following definitions apply: 2.1 thermometer a measuring instrument for ascertaining, and exhibiting
26、in some suitable manner, the temperature of the substance presented to it. Essentially, it includes a detecting element and a measuring element with some form of connecting means interposed (seeFigure 1) NOTEA temperature transmitter is a thermometer since it includes both a detecting and a measurin
27、g element, the value of the temperature being made available for transmission in the form of a variation of a conveniently measurable physical quantity which can operate a suitable receiver. 2.2 detecting element the part of the thermometer which responds directly to the temperature of the substance
28、 presented to it, and which comprises a sensitive portion which may or may not be mounted on an extension NOTEWhen a detecting element is intended for attachment to a pocket, it includes the entire assembly which is attached. Thus, if a resistance thermometer or thermocouple is mounted in a connecti
29、on head, the head being separated from the pocket by an extension piece, both head and extension piece are parts of the detecting element (seeFigure 5b). 2.3 sensitive portion the part of the detecting element which includes the temperature-sensitive material, or, if there is no enclosure, the tempe
30、rature-sensitive material itself 1) BS1041, “Code for temperature measurement”. Figure 1 Component parts of plain thermometersBS2765:1969 2 BSI 07-1999 2.4 extension the part of the detecting element which serves to support the sensitive portion. It is sometimes convenient to discriminate between th
31、e extension and the connecting means by a change of cross section 2.5 measuring element the part of the thermometer which responds to a signal from the detecting element and enables an evaluation to be made of the temperature of the substance 2.6 connecting means the part of the thermometer which se
32、rves to convey a signal from the detecting element to the measuring element, and which operatively connects the two 2.7 plain thermometer a thermometer not provided with integral means of attachment 2.8 Means of attachment The means by which a detecting element, pocket or sheath is attached to a pip
33、e, or vessel. It also covers the means of attachment of a detecting element to a sheath or pocket. NOTEIt is not expected that an element having fixed means of attachment would be used in a flanged pocket. 2.8.1 clamp attachment a removable attachment, adjustable along the extension of a detecting e
34、lement, pocket or sheath, and commonly taking the form of a flange or hook (see Figure 2a) 2.8.2 threaded attachment a threaded fitting rigidly attached to the extension of a detecting element, pocket or sheath (seeFigure 2b) 2.8.3 flange attachment a flange rigidly attached to the extension of a de
35、tecting element, pocket or sheath (seeFigure 2c) 2.8.4 union attachment an attachment, comprising a seating part either rigidly attached to or adjustable on the extension, together with a corresponding union nut for attachment to a bushing, separable flange or pocket (seeFigure 5a) 2.9 pocket 2) a r
36、eceptacle, closed at one end, adapted to receive a detecting element, for insertion in a pipe or vessel by means of a pressure-tight joint. When assembled, the pocket is pressure-tight in relation to the pipe or vessel 2.10 sheath a receptacle closed at one end and adapted to receive a detecting ele
37、ment, but not provided with means primarily intended for pressure-tight insertion in a pipe or vessel 2.11 lagging extension the portion of a bushing or pocket, beyond the means for attachment to a pipe or vessel, intended to extend through the lagging 2.12 connection head a protecting housing, comm
38、only used with electrical thermometers arranged to contain a terminal block. Attachment to a thermometer pocket or sheath is usually made through an extension piece (seeFigure 5b) 2) In American terminology: Well or thermowell.BS2765:1969 BSI 07-1999 3 3 Dimensioning system For the purposes of this
39、standard, the dimensioning system shall comprise the following: 1) Pocket or sheath diameter (symbol P). The outside diameter of the pocket or sheath below the means of attachment. NOTEIt may be necessary to specify the position at which dimension P is measured. 2) Immersion length (symbol R). The l
40、ength from the lower end of the detecting element to the point of immersion in the medium, the temperature of which is being measured. NOTE 1Sufficient immersion depth is necessary for proper accuracy but the point of immersion may not be indicated physically. NOTE 2In the case of unmounted glass-st
41、em thermometers the working immersion length should be specified so that the thermometer may be calibrated accordingly. The construction of these thermometers is such that the sensitive portion length is not generally specified. NOTE 3When the terms “upper” and “lower” are used, it is assumed that t
42、he sensitive portion is at the “lower” end of the detecting assembly. 3) Lagging extension length (symbol T). a) Parallel threaded attachment. The length from the jointing face to the upper end of the portion intended to pass through the lagging of the vessel (seeFigure 3). b) Taper threaded attachm
43、ent. The length from the lower end of the external thread to the upper end of the portion intended to pass through the lagging of the vessel, less25mm nominal thread length (seeFigure 3). 4) Insertion length (symbol U). a) Flange attachment. The length from the lower end of the pocket to the lower f
44、ace of the flange (seeFigure 4). b) Parallel threaded attachment. The length from the lower end of the pocket to the jointing face. The thread length, which should be stated, is accordingly included in the insertion length. c) Taper threaded attachment. The length from the lower end of the pocket to
45、 the lower end of the taper thread (and not including the thread) (seeFigure 4b). NOTEU can also relate to a detecting element specified with a bushing suitable for direct attachment to a pipe or vessel without the use of a pocket. In this case, U is measured from the lower end of the detecting elem
46、ent. Figure 2 Means of attachment Figure 3 Illustration of lagging extension length, TBS2765:1969 4 BSI 07-1999 5) Sensitive portion length (symbol X). The length of the sensitive portion of the detecting element. NOTEFor unmounted glass-stem thermometers, see Note 2 in3 2). 6) Detecting element dia
47、meter (symbol Y). The outside diameter of the sensitive portion or the diameter of the smallest circumscribing circle if the section is not circular. 7) Detecting element length (symbol Z) (seeFigure 5). The length from the lower end of the detecting element to the shoulder of the element attachment
48、. If the detecting element is specified without a standard attachment the symbol Z shall not be used. If the detecting element is specified with adjustable means of attachment then Z shall be measured at the maximum limit of adjustment. NOTEThe difference between the detecting element length Z and t
49、he sensitive portion length X is sometimes termed the extension length and is given the symbol J. NOTEFor detail of P 1seeFigure 8 Figure 4 Illustration of P, R, and UBS 2765:1969 BSI 07-1999 5 Figure 5 Illustration of detecting element dimensioningBS2765:1969 6 BSI 07-1999 4 Temperature detecting elements 4.1 Dimensions of the elements. For dimensions of elements seeBSEN61152. When the means of attachment is rigidly fixed to the detecting element, i.e. not adjustable along the extension, then the element selected should be such that,
