1、BRITISH STANDARD BS 1041-7: 1988 Temperature measurement Part 7: Guide to selection and use of temperature/time indicators UDC 536.5:536.49:531.761:536.522.3BS1041-7:1988 This British Standard, having been prepared under the directionof the Industrial-process Measurement and Control Standards Commit
2、tee, was published under the authority ofthe Board of BSI and comesintoeffect on 30September1988 BSI 12-1999 First published June 1943 First revision September 1964 Second revision September 1988 The following BSI references relate to the work on this standard: Committee reference PCL/1 Draft for co
3、mment 86/21686 DC ISBN 0 580 16670 8 Committees responsible for this BritishStandard The preparation of this British Standard was entrusted by the Industrial-process Measurement and Control Standards Committee (PCL/-)toTechnical Committee PCL/1, upon which thefollowingbodieswererepresented: British
4、Coal British Gas plc British Pressure Gauge Manufacturers Association Department of Energy (Gas and Oil Measurement Branch) Department of Trade and Industry (National Weights and Measures Laboratory) Energy Industries Council Engineering Equipment and Materials Users Association GAMBICA (BEAMA Ltd.)
5、 Health and Safety Executive Institution of Gas Engineers Coopted members Amendments issued since publication Amd. No. Date of issue CommentsBS1041-7:1988 BSI 12-1999 i Contents Page Committees responsible Inside front cover Foreword ii Section 1. General 1 Scope 1 2 Definitions 1 Section 2. Indicat
6、ors that change shape or size 3 General 2 4 Pyrometric cones 2 5 Thermoscope bars 4 6 Bullers rings 5 Section 3. Colour-change indicators 7 General 8 8 Temperature indicating paints 8 9 Reversible colour-change indicators and paints 9 10 Temperature indicating labels 12 Figure 1 Form of pyrometric c
7、ones 2 Figure 2 Thermoscope bars on stand before and after firing 5 Figure 3 Bullers ring and gauge 6 Figure 4 Examples of trigger temperature-time relationships for some single-change paints 11 Figure 5 Examples of trigger temperature-time relationships for a multi-change paint 12 Table 1 Approxima
8、te touch-down temperatures of pyrometric cones 3 Table 2 Approximate bending temperatures of thermoscope bars 4 Table 3 Approximate temperature chart for Bullers rings 7 Table 4 Examples of single-change paints 10 Table 5 Examples of multi-change paints 10 Publications referred to Inside back coverB
9、S1041-7:1988 ii BSI 12-1999 Foreword This Part of BS1041 has been prepared under the direction of the Industrial-process Measurement and Control Standards Committee. It is arevision of BS1041-7:1964 which is withdrawn. It is Part7 of the standard and it differs somewhat from the other four specialis
10、t parts which deal with specific types of temperature measuring equipment, in that the devices considered herein are used primarily to indicate the effect of temperature and time by purely comparative means, as opposed to instruments which give a direct reading or recording of the temperature condit
11、ions. In the ceramic industry the effect of temperature-time treatment is generally referred to as “heat work”. 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 Briti
12、sh 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 to12, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments in
13、corporated. This will be indicated in the amendment table on the inside front cover.BS1041-7:1988 BSI 12-1999 1 Section 1. General 1 Scope This Part of BS1041 provides guidance on “change of state” devices used to indicate the amount of heat work which the subject being considered has undergone. The
14、 two groups of change of state devices which are included are those which change shape or size and those which change colour. Included in the former are the following: a) pyrometric cones; b) thermoscope bars; c) Bullers rings. Of the preceding, a) and b) change their shape during heating and c) cha
15、nge size. The change of colour devices are: 1) temperature indicating paints; 2) reversible colour change indicators and paints; 3) temperature indicating labels. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of th
16、is Part of BS1041 the following definitions apply. 2.1 heat work a qualitative indication of the effect of heat treatment, increasing with temperature and time spent at temperature NOTEIt is used especially in the firing of ceramics. 2.2 pyrometric cone a slender truncated trihedral pyramid of press
17、ed ceramic material that deforms under particular temperature/time treatment 2.3 touch-down temperature (end-point) the temperature at which a pyrometric cone will bend so that the tip touches the stand or plaque when heated at a specified rate of temperature rise 2.4 signal cone in a series of pyro
18、metric cones, the cone that deforms after the least heat work 2.5 indicator cone in a series of pyrometric cones, the cone whose tip touches the stand when the desired heat work has been applied 2.6 witness cone in a series of pyrometric cones, the cone that begins to deform next after the indicator
19、 cone 2.7 thermoscope bar a pressed ceramic bar that, when supported at each end in a horizontal position, deforms under its own weight under specified temperature/time treatment 2.8 bullers ring an annular ring of pressed ceramic powder that contracts with heat work 2.9 temperature indicating paint
20、 paint that undergoes a change in colour after exposure to a specified temperature for a specified time 2.10 single-change paint a temperature indicating paint that undergoes only one principal colour change under temperature/time exposure 2.11 multi-change paint a temperature indicating paint that
21、undergoes several colour changes after various specified temperature/time exposures 2.12 signal colour the colour which a temperature indicating paint turns after the specified temperature/time exposure 2.13 trigger temperature the temperature at which a temperature indicating paint changes colour a
22、t a particular exposure time 2.14 cut-off temperature the temperature below which a temperature indicating paint exhibits no colour change, no matter how long the exposure 2.15 reversible colour-change indicators indicators that revert to the original colour on cooling below the colour-change temper
23、ature 2.16 temperature indicating label an adhesive label containing a patch whose colour changes when the surface to which it is attached reaches a specified temperature NOTEOne label may contain several patches to indicate the attainment of a range of temperatures.BS1041-7:1988 2 BSI 12-1999 Secti
24、on 2. Indicators that change shape or size 3 General The temperature/time indicators that depend on the change of shape or size are largely used in the firing of ceramic wares such as grinding wheels, bricks, refractories, electrical porcelain, china, earthenware, sanitary ware, or tiles. These indi
25、cators can only be said to measure temperature/time treatment if they are used under the same conditions which existed when indicators of the same specification were compared with a temperature measuring instrument. Such an indicator does not replace a temperature measuring instrument but is used in
26、 conjunction with it; the instrument will indicate the temperature-time treatment at a particular spot in a kiln during a firing cycle, whereas a number of suitably positioned indicators can give a measure of the variation in thermal conditions within a kiln setting. Pyrometric cones and thermoscope
27、 bars are prepared from complex mixes containing various proportions of frits, fluxes, clays, calcium and magnesium compounds, silica, etc., designed to melt or soften within certain temperature ranges that depend on the rates of heating used. Cones deform and slump fairly sharply at a certain stage
28、 in the heating cycle. Bars, which are supported at their ends, bend in the middle. Bullers rings are prepared from clays, fluxes, and inert materials, and do not melt or deform but shrink progressively during a heating cycle; the effect of temperature and time (heat work) is assessed by measuring t
29、he shrinkage of the indicator. 4 Pyrometric cones 4.1 General Cones are manufactured in two sizes, the normal or standard cone with a height of about60mm, and the laboratory cone with a height of about30mm. Both can be used to monitor and control industrial kilns, but small cones are specified for d
30、etermining the refractoriness of raw materials in accordance with BS1902-5.2, ISO528, and DIN51063-1 and DIN51063-2. Cones from different sources vary in shape, manner of usage, and performance. 4.2 Characteristics 4.2.1 Construction. Pyrometric cones (seeFigure 1) are typically slender truncated tr
31、ihedral pyramids about30mm or60mm in height. 4.2.2 Cone numbers. Pyrometric cones are traditionally numbered from022 to20; this method of numbering has a historical basis, following original Seger practice, which is broadly accepted by other manufacturers. Temperature steps of15 C up to30 C exist be
32、tween each cone number, and42 cones cover the temperature range600 C to1535 C (seeTable 1). 4.2.3 Touch-down temperature. This is the temperature at which a cone set up in the correct manner (see4.3.1) will bend and touch the stand when heated in a kiln at a specified rate of rise of temperature. A
33、heating rate of60 C/h was used in preparing Table 1. Faster rates of heating will raise the touch-down temperature and vice-versa. Laboratory cones, because of their lower mass, and because they are subjected to faster heating rates, usually fall at higher temperatures than normal cones of the same
34、number and composition. NOTEThough the temperatures in Table 1 may correspond approximately to those in tables provided by overseas cone manufacturers, cones of the same number from different producers should not be regarded as interchangeable. Figure 1 Form of pyrometric conesBS1041-7:1988 BSI 12-1
35、999 3 Table 1 Approximate touch-down temperaturesof pyrometric cones 4.3 Method of operation 4.3.1 General. The method described in4.3.2 to4.3.5 can be generally applied under most firing conditions for which cones are suitable. 4.3.2 Setting up. While single cones are sometimes used it is recommend
36、ed that three or four consecutively numbered cones are inserted into specially made unfired plaques which hold the cones at the correct angle to the vertical. These plaques have tapered holes and protrusions on one or more internal faces so that the cone is firmly held; during firing, plaque and con
37、e contract similarly so that the cone is held firmly throughout the firing. A cone may be set up in other ways, such as inserting its base into refractory clay, but the importance of maintaining a correct angle and a firm hold at all times cannot be over-stressed. Failure in these respects will caus
38、e the cone to bend unpredictably, and to give an incorrect assessment of the heat treatment. NOTECones from different sources differ in shape, size, and the manner in which they are set up before firing. Each producers instructions should therefore be studied carefully and strictly adhered to if sat
39、isfactory performance during firing is to be obtained. Some manufacturers make cones with thickened bases which do not require stands. 4.3.3 Choice of cones. The range of the three or four cones chosen should extend above and below that of the cone expected to indicate the desired heat treatment. 4.
40、3.4 Usage in kilns. Since the temperature throughout a kiln is rarely uniform several plaques of cones can be placed in different parts of the kiln, so that an estimate of the variation in heat work from place to place can be obtained. 4.3.5 Behaviour during firing. As the firing cycle progresses an
41、d the heat work approaches that at which the signal cone is affected, the cone will begin to soften and bend, and will continue to bend until the tip just touches the plaque on which the cone has been placed. This is considered to be the end-point of the cone. With further prolongation of the firing
42、 cycle, with soaking or increase in temperature, the cone will melt completely to form a blob on the plaque. The next cone of the series will begin to deform some time after the first started to bend and will continue to bend until its end-point is reached. The appropriate level of heat work will ha
43、ve been reached when the indicator cone has just reached its end-point. Under these firing conditions the witness cone will be only partially bent over. 4.4 Operating features of cones 4.4.1 General. Cones containing frits giving relatively low viscosity glasses are appropriate for low temperatures
44、e.g.less than1200 C) whereas mixtures of minerals reacting and melting to produce more viscous glasses are used for higher temperatures. Since cones consist partly of glass or glass-formers plus more refractory clays and silica it follows that cones do not have definite melting points; they deform
45、only when the decreasing viscosity of the liquid phase permits movement under the influence of gravity. The performance of cones is largely controlled by temperature, but time (e.g.rate of heating, soaking at a given temperature) and kiln atmosphere are also significant. Enamels and glazes fired at
46、the lower temperatures contain proportions of frit as do the cones. Many ceramic products are based on mixtures of silicate minerals as are the cones for higher temperatures. Because temperature and time affect ware and cones similarly, cones are useful for controlling the progress of firing of many
47、 ceramic products. The touch-down of a cone can indicate the point at which ware will mature under a controlled rate of heating and a particular set of atmospheric conditions, which should then be maintained. If such conditions do not alter, the cone will always touch-down at the same temperature. 4
48、4.2 Burnout of binder. As cones contain an organic binder, heating rates in the low temperature region should be slow enough to ensure that the binding material is completely burned out, as residual binder can prevent satisfactory behaviour of the cone later, and even cause swelling and instability
49、 Cone no. Temperatu re Cone no. Temperatur e Cone no. Temperature C C C 022 021 020 019 018 017 016 015 014 013 012 011 010 09 600 615 630 665 700 730 760 790 810 830 860 880 900 925 08 07 06 05 04 03 02 01 1 2 3 4 5 6 950 975 1000 1030 1060 1085 1105 1120 1135 1150 1165 1180 1195 1210 7 8 9 10 11 12 13 14 15 16 17 18 19 20 1230 1250 1270 1290 1310 1330 1350 1380 1410 1435 1460 1485 1510 1535 NOTE 1Each temperature given in the table is that at which the tip of a cone will bend sufficiently to touch the base, in an electric kiln with a heat
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