1、BRITISH STANDARD BS 684-1.8: 1976 Incorporating Amendment No. 1 Methods of analysis of Fats and fatty oils Part 1: Physical methods Section 1.8: Determination of smoke point IMPORTANT NOTE. It is essential that this Section be read in conjunction with the information in the “General introduction” to
2、 BS 684, which is published separately. UDC 665.1.014:543:536.423.1.083BS684-1.8:1976 This British Standard, having been prepared under the directionof the Oils and FatsStandards Committee, waspublished under the authorityof the ExecutiveBoardon 29October1976 BSI 11-1999 The following BSI references
3、 relate to the work on this standard: Committee reference OFC/24 Draft for comment 74/50396 DC ISBN 0 580 09045 0 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 Bri
4、tish Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will b
5、e indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date of issue Comments 7982 November 1993 Indicated by a sideline in the marginBS684-1.8:1976 BSI 11-1999 i Contents Page 1 Scope 1 2 References 1 3 Definition 1 4 Principle 1 5 Apparatus 1 6 S
6、ampling and preparation of sample for analysis 1 7 Procedure 1 8 Expression of results 1 9 Test report 1 Figure 1 Smoke point cabinet 2 Figure 2 Cleveland open cup 3 Figure 3 Heating plate 4ii blankBS684-1.8:1976 BSI 11-1999 1 1 Scope This Section describes a method for the determination of smoke po
7、int of animal and vegetable fats and is based on the American Oil Chemists Society Official Method Cc 9a-48. 2 References The following standards publications are referred to in this Section: BS 1704, General purpose thermometers. BS 4689, Method for determination of flash and fire points of petrole
8、um products and other liquids by the Cleveland open cup. 3 Definition For the purposes of this Section of BS 684 the following definition applies. smoke point the temperature at which the sample begins to smoke when tested under the specified conditions of the test 4 Principle The liquid or melted f
9、at is heated under specified conditions so that its temperature rises at a specified rate. The temperature at which smoke is evolved is noted. 5 Apparatus An apparatus with the following essential features is required (see also BS 684 General introduction). 5.1 Cabinet, of construction and dimension
10、s shown in Figure 1. 5.2 Thermometer, GP400C/100, complying with the requirements of BS 1704. 5.3 Cleveland open flash cup, complying with the requirements of BS 4689, made of brass and conforming to the dimensions shown in Figure 2. The bevelled edge of the cup is at an angle of approximately 45 .
11、There may be a fillet of approximately 4 mm radius inside the bottom of the cup. 5.4 Heating plate, of brass, cast iron, wrought iron or steel, about 6 mm thick and 150 mm in diameter, as shown in Figure 3. There is a plane circular depression about 0.8 mm deep in the centre of the plate with diamet
12、er just sufficient to fit the cup and concentric with a circular opening cut through the plate, 55 mm in diameter. The plate is covered with a sheet of hard non-asbestos heat resistant board about 6 mm thick and of the same shape as the metal plate. 5.5 Heat source, e.g. gas burner, alcohol lamp or
13、electric heater with rheostat control. Whatever form of heat is used, under no circumstances should the products of combustion or free flame be allowed to come up around the cup. If a flame heater is used, it may be protected from draughts or excessive radiation by any suitable shield that does not
14、project above the upper surface of the non-asbestos heat resistant board. The heat source shall be centred under the plate opening and shall not produce local superheating. 6 Sampling and preparation of sample for analysis See BS 684 General introduction. 7 Procedure NOTEIt is essential that the app
15、aratus, especially the cup, is scrupulously clean and free from any substance that may cause smoke to appear before the true smoke point is reached. Fill the cup with the sample so that the top of the meniscus is exactly at the filling line and adjust the position of the apparatus so that the beam o
16、f light is directed across the centre of the cup. Suspend or secure the thermometer in a vertical position in the centre of the dish with the bottom of the bulb approximately 6 mm from the bottom of the cup. Heat the sample rapidly to within about 40 C of the smoke point. Thereafter, regulate the he
17、at so that the temperature of the sample increases at a rate of5 C to 6 C per minute. Record the thermometer reading when the sample begins to give off a thin continuous stream of bluish smoke. In some cases, a slight puff appears before the sample begins to smoke continuously. Disregard this. 8 Exp
18、ression of results Express as the smoke point of the fat the recorded temperature reading. 9 Test report See the general instructions and recommendations given in BS 684 General introduction.BS684-1.8:1976 2 BSI 11-1999 Figure 1 Smoke point cabinetBS684-1.8:1976 BSI 11-1999 3 Figure 2 Cleveland open
19、 cupBS684-1.8:1976 4 BSI 11-1999 Figure 3 Heating plateblankBS 684-1.8: 1976 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the internationa
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