BS 7714:2005 pdf free.Care and handling of seals for fluid power applications—Guide.
BS 7714 The following extract concerning the storage of vulcanized rubber is taken from BS ISO 2230:2002 andshould be noted as being applicable to any of the elastomeric materials referred to in Clause 3.
‘Many rubber products and components are stored for long periods before being put into service, and thusit is important they are stored in conditions that minimize unwanted changes in properties. Such
changes may result from degradation,in which case they may include excessive hardening, softening,cracking,crazing and other surface effects.Other changes may be caused by deformation, contaminationor mechanical damage.
It is recognized that some rubbers are more susceptible than others to deterioration by such factors asheat, light, ozone, oxygen and humidity.Exposure to these factors should therefore be minimized in orderto extend storage life and to do so a system of storage control, proper packaging and periodic inspectionbecomes necessary.”
The damaging effect of these factors can be minimized by careful choice of storage conditions;however,elastomeric materials should always be considered to have a finite shelf life, after which they should bediscarded.
Seals should be stored below 25 °C and preferably below 15 °C.At temperatures exceeding 25 °C, certainforms of deterioration can be accelerated sufficiently to affect the ultimate service life of the seal. Sourcesof heat in storage rooms should be so arranged that the temperature of no stored article exceeds 25 °℃.Theeffects of low temperature are not permanently deleterious to vulcanized rubber articles but they becomestiff if stored at low temperatures and care should be taken to avoid distorting them during handling atthese temperatures. When articles are taken from low temperature storage for immediate use, theirtemperature should be raised to approximately 30 °C throughout before they are put into service.4.2.2 Humidity
Moist conditions should be avoided and the storage conditions should be such that condensation on anyparticular article does not occur. Relative humidity should not exceed 65 %.
Vulcanized rubber should be protected from light, in particular strong sunlight and strong artificial lightwith a high ultraviolet content.Unless articles are packed in opaque containers, it is advisable to cover anywindows of the storage rooms with a red or orange coating or screen.
Where possible, vulcanized rubber should be protected from circulating air, for example by wrapping or bystorage in airtight containers.This applies particularly to articles with large surface area to volume ratios,for example proofed fabric, cellular rubber.
As ozone poses particular problems, storage rooms should not contain any equipment that is capable ofgenerating it, such as mercury vapour lamps, high voltage electrical equipment, electric motors or otherequipment which can give rise to electric or static electrical discharges.
Where vulcanized rubber articles are stored as separate components, they should be in a relaxed conditionfree from tension, compression or any other form of stress.
Particular care should be taken to protect sealing lips from general or localized distortion during storage.If necessary, suitable supports such as cardboard tubes should be provided.BS 7714 pdf download.