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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 7908:1999 ICS 17.200.2
2、0; 55.020 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Packaging Temperature and time-temperature indicators Performance specification and reference testing Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:56:58 GMT+00:00 2006, Uncont
3、rolled Copy, (c) BSI BS 7908:1999 This British Standard, having been prepared under the direction of the Consumer Products and Services Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 January 1999 BSI 01-1999 The following BSI references rel
4、ate to the work on this standard: Committee reference PKW/1/8 Draft for comment 96/540311 DC ISBN 0 580 29595 8 Amendments issued since publication Amd. No.DateText affected Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee
5、 PKW/1, Packaging generalities, to Subcommittee PKW/1/8, Temperature and time-temperature indicators, upon which the following bodies were represented: Association of Drum Manufacturers British Adhesives and Sealants Association British Association for Chemical Specialities British Coatings Federati
6、on Ltd. British Fibreboard Packaging Association British Fruit and Vegetable Canners Association British Glass Manufacturers Confederation British Office Systems and Stationery Federation British Plastics Federation British Retail Consortium British Rubber Manufacturers Association Ltd. Chemical Ind
7、ustries Association China Clay Association Department of Trade and Industry (Consumer Safety Unit, C A Division) Environmental and Technical Association for the Paper Sack Industry Metal Packaging Manufacturers Association Ministry of Defence Pira International Road Haulage Association Ltd. Timber P
8、ackaging and Pallet Confederation The following bodies were also represented in the drafting of the standard, through subcommittees and panels: Association of the British Pharmaceutical Industry Campden and Chorleywood Food Research Association Cold Storage and Distribution Federation Dairy Industry
9、 Federation Flexible Packaging Association Food and Drink Federation Ministry of Agriculture, Fisheries and Food Shipowners Refrigerated Cargo Research Association Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:56:58 GMT+00:00 2006, Uncontrolled Copy, (c) BS
10、I BS 7908:1999 BSI 01-1999i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Definitions1 3General1 4Performance specification for temperature and time-temperature indicators2 5Reference testing procedure for temperature indicators2 6Reference testing procedure for time-tem
11、perature indicators3 Annex A (informative) Suggested design and dimensions of aluminium block5 Annex B (normative) Specification of temperature measuring system6 Annex C (informative) Determination of response rate constants, activation energy and Arrhenius plot6 Annex D (informative) Reliability of
12、 TTIs under non-isothermal conditions8 Bibliography9 Figure A.1 Suggested design and dimensions of aluminium block5 Figure C.1 Ideal Arrhenius response for indicators over temperature range 0 8C to 30 8C (273 K to 303 K) as governed by the equation in t = 1nF(X)A21 + (Ea/RT)7 Table 1 Performance tol
13、erance2 Table D.1 Temperature ranges8 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:56:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii BSI 01-1999 BS 7908:1999 Foreword This British Standard has been prepared by Subcommittee PKW/1/8 and originates from a f
14、ood industry specification: Technical manual No. 35, A food industry specification for defining the technical standards and procedures for the evaluation of temperature and time temperature indicators, published in February 1992, although it has subsequently undergone considerable development during
15、 committee discussions. 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 obligations. Summary of pages
16、This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 9 and a back cover. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:56:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BSI 01-19991 BS 7908:1999 1 Scope This British Standa
17、rd specifies performance requirements for temperature and time-temperature indicators, as well as reference testing procedures for use in confirming the performance quality of delivered devices or as a means of third party testing. The standard applies to indicators which are to be used in the food,
18、 pharmaceutical and other associated sectors for products stored at frozen, chilled or ambient temperatures. The standard covers partial and full history time-temperature indicators. The test procedures are not necessarily appropriate for quality release testing, due to the length of time required t
19、o complete individual tests. 2 Definitions For the purpose of this standard the following definitions apply: 2.1 temperature indicator (TI) a device which on activation exploits a physical property or physico-chemical reaction to produce an irreversible change once a predetermined threshold temperat
20、ure has been reached 2.2 critical reference temperature (CRT) a device which on activation exploits a temperature dependent physical property or physico-chemical reaction to produce an irreversible change, or predetermined end-point 2.3 full history time-temperature indicator (FHTTI) a device which
21、indicates the time-temperature history experienced from its point of initial activation 2.4 partial history time-temperature indicator (PHTTI) a device which indicates the time-temperature history above a critical reference temperature (CRT), experienced from its point of initial activation 2.5 crit
22、ical reference temperature (CRT) lowest temperature within the operating range at which the indicator of a PHTTI device provides a visible response 2.6 activation action of initiating the indicator to respond to temperature or time/temperature variables NOTEThis may be by mechanical means, or by rem
23、oving the device from an inactivating cold temperature, or any other method specified by the manufacturer. 2.7 batch quantity from which the test items are selected NOTEIf the testing is being done as part of manufacturing control this should be the manufactured batch. If the testing is being done a
24、fter delivery, the batch should consist of the delivered quantity. 3 General Operation of the device shall be irreversible and it shall not be re-usable. The end-point of the device shall be clearly visible to the naked eye and shall be either from light to dark or shall change from one colour to a
25、distinctly different colour. The manufacturer shall supply the customer with the following information: a) for TIs, the threshold temperature and its tolerance limits (3 3 standard deviation) to be stated in 8C, and a response time (inertia) in minutes; b) for TTIs, the maximum and minimum temperatu
26、re limits in 8C over which the device will function and the time to end-point with performance classification (Table 1) at sufficient numbers of temperatures throughout the range stated by the manufacturer (above the CRT in the case of PHTTIs). The number of temperatures and time to end-point combin
27、ations shall be not less than five. In the case of PHTTIs, the manufacturer should state the CRT in 8C and its tolerance; c) for TIs or TTIs, the storage conditions and the time that the device can be stored without affecting its performance. In addition there shall either be a declaration that the
28、performance of the device is not affected by conditions likely to be encountered during use other than temperature, or if the performance is affected by certain factors, the manufacturer shall state in what way; d) for all indicators, clear instruction for activation procedures. Licensed Copy: Londo
29、n South Bank University, London South Bank University, Fri Dec 08 10:56:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 BSI 01-1999 BS 7908:1999 4 Performance specification for temperature and time-temperature indicators 4.1 Temperature indicators When the threshold temperature (8C) is measured by t
30、he procedure in 5.1 it shall not deviate from the manufacturers stated value by more than the following: a) +/2 0.5 8C for TI Class 1 devices; b) +/2 1 8C for TI Class 2 devices; c) +/2 5 8C for TI Class 3 devices. A minimum of ten devices shall be tested from any one batch (see the note to 2.7). 4.
31、2 Time-temperature indicators 4.2.1 Partial history time-temperature indicators 4.2.1.1 Critical reference temperature When the CRT (8C) is measured by the procedure in 6.1, it shall not deviate from the manufacturers stated value and tolerance. A minimum of ten devices shall be tested from any one
32、batch (see the note to 2.7). 4.2.1.2 Time-temperature integration above the CRT at constant temperature When tested in accordance with 6.2, the device shall produce a time to end-point at a specified reference temperature (see clause 3), which is within the tolerances given in Table 1 when compared
33、with the manufacturers declaration of time to end-point at the same temperature: Table 1 Performance tolerance Performance tolerance by category Category ACategory BCategory CCategory D up to2.5 % up to5 % up to10 % up to20 % 4.2.2 Full history time-temperature indicators When tested in accordance w
34、ith 6.2, the device shall produce a time to end-point at a specified reference temperature, which is within the tolerances given in Table 1 when compared with the manufacturers declaration of time to end-point at the same temperature. The test shall be carried out on five TTIs from the same batch at
35、 each of five different temperatures. These temperatures shall be selected so as to encompass the range of temperatures likely to be experienced by the indicators under normal conditions of use as well as under conditions of temperature abuse. In the case of PHTTIs one of the five selected temperatu
36、res shall be below the CRT and the rest above the CRT. 5 Reference testing procedure for temperature indicators 5.1 Temperature response and irreversibility test 5.1.1 Principle of test Temperature indicators can produce an irreversible change if products have become either too hot or too cold. To s
37、implify this and clause 6 of the standard, all references will be made to indicators that demonstrate a product has become too warm. The procedures are identical for indicators that show that a product has become too cold, except the temperature change is the reverse. The test is designed to measure
38、 three key properties of the TIs: the threshold temperature, the variation of the threshold temperature, and confirm the irreversibility of the indicator. The TI is kept in a constant temperature environment by placing it on a specially designed aluminium block in a constant temperature apparatus. T
39、he temperature is increased in steps, and time for equilibration is allowed at each new temperature until the device changes to its end-point. This is repeated with sufficient samples of TTIs that the mean and standard deviation of the threshold temperature can be obtained. Once the indicator has ch
40、anged the temperature is then reversed to typical in-use temperatures to confirm irreversibility. The test can be performed more quickly if more than one TI is placed in the aluminium block at one time, or more than one aluminium block is used. 5.1.2 Equipment 5.1.2.1 Constant temperature apparatus
41、A constant temperature environment shall be used which can maintain a set temperature with a maximum fluctuation of0.1 8C in the aluminium block. NOTEFor temperatures above 0 8C, the apparatus may be a water bath or forced-air cabinet, but for temperatures below the freezing point of water, glycol o
42、r similar secondary refrigerant or a forced-air cabinet may be used. 5.1.2.2 Aluminium block It is important to prevent any localized temperature gradients, and to do so, a suitably designed anodized solid aluminium block is used (see Figure A.1 for an example). In this example, the TTI is placed in
43、 the well at the top of the block and is covered and sealed by a 6 mm glass lid and an O ring gasket; a temperature sensor is placed in the hole located 10 mm below the well holding the device and penetrating to the centre of the block, and the temperature recorded is taken as the temperature of the
44、 TTI. 5.1.2.3 Temperature measuring system The temperature sensor in 5.1.2.2 is connected to a read-out, specified in annex B. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:56:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BSI 01-19993 BS 7908:1999 5.1.3 Met
45、hod 5.1.3.1 Determination of threshold temperature a) Store, handle and prepare the device, according to the manufacturers instructions and maintain it in those conditions until immediately prior to using it in the test. Switch on the constant temperature apparatus and allow it to equilibrate at a t
46、emperature equal to three times the Class increment, below the manufacturers stated threshold temperature and class. Place the aluminium block with the lid removed into the constant temperature apparatus to equilibrate. Once the block has been equilibrated to the environment temperature, activate a
47、TI in accordance with the manufacturers instructions and place in the well of the blocks and securely fasten the glass lid. Allow the TI to equilibrate the temperature of the block. NOTEIf preferred, the TI may be activated after placing it in the well of the block. b) Increase the temperature of th
48、e apparatus in steps of 0.25 8C for Class A devices, 0.5 8C for Class B devices, 2.5 8C and stabilize it for a time period of no less than 20 min. Record the temperature at which the device changes colour to its normal end-point. c) Confirm the TI class allocated by the manufacturer by calculating t
49、he mean standard deviation of the temperatures at which the TIs change. NOTEThe testing of each TI in the sample may be simultaneous or consecutive. 5.1.3.2 Irreversibility After each determination of the threshold temperature, allow the temperature of the apparatus to return to a temperature below the end point temperature, and to equilibrate. Check the indicator to establish that it has not altered from its end-point appearance before removal from the block well. 6 Reference testing procedure for time-temperature indicators 6.1 Critical reference