1、BRITISH STANDARD BS1902-5.5: 1991 Methods of testing Refractory materials Part 5: Refractory and thermal properties Section 5.5 Determination of thermal conductivity (panel/calorimeter method) (method1902-505)BS1902-5.5:1991 This British Standard, having been prepared under the directionof the Refra
2、ctory Products Standards Policy Committee, was published underthe authority of the Standards Board and comesintoeffect on 30August1991 BSI08-1999 The following BSI references relate to the work on this standard: Committee referenceRPM/1 Draft for comment89/41860DC ISBN 0 580 19640 2 Committees respo
3、nsible for this British Standard The preparation of this British Standard was entrusted by the Refractory Products Standards Policy Committee (RPM/-) to Technical Committee RPM/1, upon which the following bodies were represented: British Ceramic Research Ltd. British Steel Industry Engineering Equip
4、ment and Materials Users Association Refractories Association of Great Britain Refractory Contractors Association Society of Glass Technology Amendments issued since publication Amd. No. Date CommentsBS1902-5.5:1991 BSI 08-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1
5、Scope 1 2 Designation 1 3 Definition 1 4 Principle 1 5 Apparatus 1 6 Test panel 6 7 Procedure 7 8 Calculation of thermal conductivity 9 9 Test report 10 Figure 1 Vertical section through thermal conductivity apparatus 3 Figure 2 Horizontal section, showing arrangement of heaters 3 Figure 3 Basic cir
6、cuit for heater control system 4 Figure 4 Design of calorimeter and guard ring 5 Figure 5 Arrangements for measurements in different dimensions 7 Figure 6 Corresponding positions of thermocouples for arrangements in Figure 5 8 Table 1 Resistance wire for heaters 4 Table 2 Specific heat capacity of w
7、ater 10 Publication(s) referred to Inside back coverBS1902-5.5:1991 ii BSI 08-1999 Foreword This Section of BS1902-5 has been prepared under the direction of the Refractory Products Standards Policy Committee. The method described in this Section is one of three methods for the determination of ther
8、mal conductivity included in BS1902-5, as follows. Section5.5: Determination of thermal conductivity (panel/calorimeter method) (method1902-505); Section5.6: Determination of thermal conductivity (hot wire method) (method1902-506); Section5.8: Determination of thermal conductivity (split column meth
9、od) (method1902-508) 1) . This Section of BS1902 is a revision of the method previously included in BS1902-1A:1966 (obsolescent), which is withdrawn. NOTEThis Section is to be read in conjunction with BS1902-5.0 “Introduction” and BS1902-3.1 “Guidance on sampling”. Section5.0sets out the general arr
10、angement of BS1902 and lists the Sections of Part5. 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 itself confer immunity from legal ob
11、ligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to10, 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 t
12、he inside front cover. 1) In preparation.BS1902-5.5:1991 BSI 08-1999 1 1 Scope This Section of BS1902-5describes the panel method for determining the thermal conductivity of dense shaped and shaped insulating refractory products by a continuous flow calorimeter method. The panel/calorimeter method m
13、ay be used for preformed unshaped products and for ceramic fibre products. NOTE 1For details of the adaptations needed for ceramic fibre products, see BS1902-6. The panel/calorimeter method is intended for materials having a thermal conductivity in the range0.5W/(mK) to20W/(mK) and hot face temperat
14、ures in the range300 C to1400 C. For thermal conductivities below0.5W/(mK) seeBS1902-5.6. NOTE 2The titles of the publications referred to in this standard are listed on the inside back cover. 2 Designation The method of determining thermal conductivity by the panel/calorimeter method described in t
15、his Section is referred to by the designation: Method1902-505 3 Definition For the purposes of this Section of BS1902, the following definition applies. thermal conductivity (coefficient of thermal conductivity), 2, (in W/(mK) the rate of linear heat flow, under steady state temperature conditions,
16、through unit area of a test piece, per unit temperature gradient in a direction perpendicular to the area 4 Principle The quantity of heat flow unidirectionally through a test panel, heated on one face under controlled temperature conditions, is measured using a continuous flow water calorimeter. 5
17、Apparatus 5.1 General The apparatus consists of a furnace in which a system of heaters is used to induce a uniform, unidirectional heat flow through a test panel under stable temperature gradient conditions. A continuous flow water calorimeter with guard ring is used to measure the rate of flow of h
18、eat through the test panel. 5.2 Furnace, comprising a chamber, which accommodates a test panel230mm 230mm 76 (or64)mm deep, and a heater well nominally214mm 214mm 58mm deep formed from shaped insulating refractory (see Figure 1). The walls and floor of the heater well are formed of25mm thick insulat
19、ing refractory, of class150, complying with BS7225-1.1. The walls of the heater well are lined with8mm thick,50mm deep alumino-silicate refractory plates (60% to65% Al 2 O 3 ) which stand on a230mm square,8mm thick base of the same material. The wall plates which act as a support for the test panel
20、are pierced with16mm holes at25mm centres to accommodate the end of the main and side heater elements. Behind the walls a narrow chamber, which accommodates the outer heater and lower peripheral heater, is formed on the inside from8mm thick alumino-silicate refractory(60%to65%Al 2 O 3 ) and on the o
21、utside from25mm thick insulating refractory of class150, complying with BS7225-1.1. The remainder of the brickwork surrounding the heater well and test panel chamber is made of insulating refractory of class130, complying with BS7225-1.1, with a final76mm thickness of lower temperature insulation, e
22、.g.diatomite brick, to give overall furnace dimensions of690mm 690mm 380mm height. The furnace is encased in sheet metal, and supported in a steel frame, e.g.angle iron. NOTEAlternate holes may be extended into vertical grooves to facilitate the removal of the heaters, as shown in Figure 2. The uppe
23、r and middle peripheral heaters and a supplementary heater, consisting of coiled electrical resistance wire(see5.3), are laid in grooves cut in the insulating refractory. The upper and middle peripheral heaters are positioned12mm and38mm below the top level of brickwork and33mm behind the wall of th
24、e test panel chamber on all four sides. The supplementary heater is50mm below the base of the heater well and laid in a continuous groove having the form of a parallel-sided spiral covering an area of approximately310mm 310mm.BS1902-5.5:1991 2 BSI 08-1999 5.3 Heaters, in which the elements of the ma
25、in, side, outer and lower peripheral heaters are formed from platinum 20%rhodium wire, 0.5mm in diameter, wound on recrystallized alumina tube with12mm outside diameter, 8mm inside diameter (see Figure 1 and Figure 2). The six elements forming the main heater unit are wound with different spacing, b
26、eing more closely wound at the edge of the unit than at the centre. The two end elements (1and6in Figure 2) are wound with a5mm spacing, the next two inside elements(2and5in Figure 2) are wound with a5mm spacing at the ends with a7.5mm spacing over the middle114mm and the two centre elements (3and4i
27、n Figure 2) are wound with a7.5mm spacing over their full length. The elements of the side and outer heaters are wound with a spacing of3.8mm to4.0mm and those of the lower peripheral heaters with a spacing of3.3mm to3.5mm. The individual elements of the main, side, outer and lower peripheral heater
28、s are connected in series and are thinly coated with high purity alumina cement to reduce volatilization of the platinum at high temperature. The upper and middle peripheral heaters and the supplementary heater are each formed by coiling electrical resistance wire1.6mm in diameter on a steel former4
29、.5mm in diameter. The two peripheral heaters are drawn out to12or13turns for25mm. The gauge of wire, coil spacing and resistance data for all heaters is summarized in Table 1. 5.4 Power supply and temperature control, allowing each heater to be separately controllable. Various methods for achieving
30、adequate control of heater output are available including variable resistance, variable transformers and integrated circuit power controllers. A suitable control system utilizes solid state, phase-controlled, a.c. mains power regulators switched between adjustable low and high power settings by a si
31、ngle temperature controller operating through one of the hot face thermocouples (see clause6). The basic circuit for an appropriate control system is shown in Figure 3. 5.5 Calorimeter and guard ring, made of brass and having dimensions as shown in Figure 4. The base, sides and partition walls of bo
32、th components are made either by casting or by machining from solid brass. The outside surfaces of the sides and base and the tops of sides and partition walls are machine finished. The bases of both components are tested to confirm their flatness over their full area. The top covers, which carry th
33、e water inlet and outlet tubes are made from flat brass plate and are soldered to the base parts so that the sides and partition walls make water-tight joints with the cover. The dimensions of the calorimeter are76mm 76mm 25mm deep and of the guard ring are230mm 230mm 25mm deep. The two components a
34、re assembled so that a gap of0.8mm exists between their adjacent sidewalls. To ensure that the base surfaces of the calorimeter and guard ring are co-planar and that the calorimeter remains centred in the guard ring, the two are placed on a levelling plate with thin card spacers maintaining the gap
35、between them. Brass links are soldered between the two inlet tubes and similarly between the two outlet tubes so as to lock the calorimeter and guard ring together. In order to calculate the thermal conductivity it is necessary to know the area through which the calorimeter receives heat from the te
36、st panel; this is that area represented by the calorimeter plus half the gap between the calorimeter and guard ring. The area is calculated either: a) from direct measurements with vernier callipers to0.05mm; or b) during construction of the calorimeter and guard ring assembly, by measuring the dime
37、nsions of the calorimeter and those of the aperture into which it fits and taking the average of the two areas thus obtained. NOTEIt is essential that provision is made for the calorimeter/guard ring assembly, all metal piping and the furnace frame and case to be electrically earthed in conformity w
38、ith current Institute of Electrical Engineers (IEE) Regulations. 5.6 Water supply, to the calorimeter and guard ring from a brass manifold,22mm in diameter, via plastics feed tubes which are as short as possible. Similar plastics tubing is fitted to the outlets and incorporates valves for carrying t
39、he flow of water through the calorimeter and the guard ring. The outlet ends of the plastics tubes are terminated by jets made from glass tube. Water is fed to the inlet manifold from a constant head tank capable of supplying100L/h. NOTEThe temperature of the water should be maintained constant and0
40、.5K to2K below the ambient temperature.BS1902-5.5:1991 BSI 08-1999 3 Figure 1 Vertical section through thermal conductivity apparatus Figure 2 Horizontal section, showing arrangement of heatersBS1902-5.5:1991 4 BSI 08-1999 Table 1 Resistance wire for heaters Material Heater Wire diameter Resistance
41、at room temperature Length of wire Space between turns in heater Platinum-20% rhodium wire Main mm 0.5 7 9.3 m 9.1 mm two end elements: 5 two inside elements: 5 7.5over middle114 two centre elements:7.5 Side 0.5 9.7 9.4 3.8to4.0 Outer 0.5 12.1 11.5 3.8to4.0 Lower peripheral 0.5 13.2 12.8 3.3to3.5 Hi
42、gh temperature electrical resistancewire Middle peripheral 1.6 9.2 12.8 12to13turns per25mm of coil Top peripheral 1.6 9.2 12.8 Supplementary heater 1.6 23.1 33 even spacing (see note) NOTEThe spacing of the supplementary heater is not critical. NOTEThe circuit is repeated for each heater. The relay
43、 contacts RLA are operated by the temperature controller. The variable resistors VR1and VR2 allow adjustment of low and high current values. Values of R, VR1and VR2 for an individual heater circuit will depend on the type of heater element and specification of the power regulator. Figure 3 Basic cir
44、cuit for heater control systemBS1902-5.5:1991 BSI 08-1999 5 5.7 Four mercury in glass thermometers, for measuring the inlet and outlet temperatures of the calorimeter and guard ring. The thermometers have a certificate of calibration, are capable of measuring temperature over the range0 C to25 C, gr
45、aduated in0.1K and capable of being read to0.01K using an attached magnifier. NOTEMultiple thermocouples or platinum resistance thermometers may be used provided they are calibrated against a thermometer of certified accuracy and allow temperature difference between the calorimeter inlet and outlet
46、water to be read to0.02K. 5.8 Ten thermocouples, of type R (platinum/platinum13%rhodium) in accordance with BS4937-2, for measuring temperatures of the test panel (see clause6) and which are connected to a temperature measuring instrument(5.9) using compensating connectors and cable. Figure 4 Design
47、 of calorimeter and guard ringBS1902-5.5:1991 6 BSI 08-1999 5.9 Temperature measuring instrument, which is either: a) a calibration certified potentiometer for measuring temperatures via thermocouples(5.8) to a maximum error equivalent of 0.5K; or b) a calibration certified digital temperature indic
48、ator with a range at least0 C to1400 C capable of being read to0.1K with a calibration error, including traceability of standards, of 0.04%. 5.10 A multiple input selector switch, for connecting thermocouples(5.8) to the temperature measuring instrument(5.9). 5.11 Volumetric flasks, 100mL and250mL.
49、5.12 Stop watch, graduated in0.2s and accurate to0.2s in2min. 5.13 Vernier callipers, complying with BS887. 6 Test panel 6.1 Construction 6.1.1 The dimensions of a test panel are nominally230mm 228mm 76(or64)mm and consist of two or more prepared pieces, depending on whether the material is in the form of standard squares 230mm 114mm 76 (or64)mm or larger blocks or shapes. NOTE 1For sizes of refractory bricks, see BS3056-1. NOTE 2Where the test panel comprises pieces taken from different items, these shou
