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About this publication
PREFACE
1 SCOPE
2 REFERENCED DOCUMENTS
3 DEFINITIONS
4 GENERAL
5 DESICCATED PACKAGES
5.1 General
5.2 Reduction of humidity within the pack
5.3 Sources of moisture
5.3.1 General
5.3.2 Air inside the barrier
5.3.3 Air outside the barrier
5.3.4 Hygroscopic materials inside the barrier
5.3.5 Entrapped water
6 FACTORS GOVERNING SELECTION OF DESICCANT
6.1 General
6.2 Moisture sorption capacity in relation to bulk and mass
6.3 Stability and physical form of the desiccant
6.4 Influence of the normal temperature range on the moisture sorption capacity of desiccants
6.5 Types of desiccants
7 FACTORS DETERMINING QUANTITY OF DESICCANT
7.1 General
7.2 The effect of atmospheric conditions
7.2.1 Humidity and water vapour pressure
7.2.2 Temperature
7.3 Period of exposure to adverse conditions
7.4 The nature of the barrier material
7.5 The surface area of the barrier
7.6 The thickness of the barrier
7.7 The volume of air inside the barrier
7.8 The quality of the seals
8 GENERAL PACKAGING CONSIDERATIONS
8.1 Conditions in use
8.2 Outline of procedure
APPENDIX A
A1 ACCURACY OF CALCULATION—ROUNDING UP OF CALCULATED QUANTITIES
A2 RELATIONSHIP OF COMMERCIAL DESICCANTS TO BASIC DESICCANT
A3 FORMULAS FOR CALCULATING QUANTITY OF BASIC DESICCANT
A3.1 General
A3.2 Where the barrier is not completely impervious to water-vapour
A3.2.1 When the period of protection, water-vapour transmission rate (WVTR) and atmospheric conditions are specified or can be estimated
A3.2.2 When nothing is known about the needed period of protection, the atmospheric conditions are not specified or the WVTR is unknown
A3.3 Where the barrier is completely impervious to water-vapour
A3.4 Where the seal of the barrier is suspect
APPENDIX B
