MIL-HDBK-695E
3.3 Shelf life - The maximum period of time between the cure date and the date the elastomeric product is first removed or unpackaged for installation or fabrication into a component part of a subassembly, assembly, or system. During the shelf life time, the stored elastomeric product is expected to retain its characteristics as originally specified, if it is stored under proper storage conditions.
3.4 Service life. A general term used to quantify the average or mean life of an item once put in use. Service life, which is depicted in years, is the number of years of economical service reasonably expected of equipment as established in applicable DoD, Service, and/or Agency manuals, bulletins, regulations, instruction manuals, and/or the technical judgment of the item and/or equipment manager.
4. GENERAL GUIDANCE
4.1 Introduction. The key factor involved in the shelf life of rubber end products is the age resistance of the rubber from which the product was fabricated. External factors such as packaging and storage conditions (e.g. temperature, humidity, ozone, light, etc.) can reduce the effective shelf life of rubber products. Additionally, commodity specification requirements may contain criteria that influence end product shelf life. The relative importance of these factors is difficult to assess, especially because the age resistance of the raw rubber does not always correspond to the age resistance of the finished product. Note: SAE ARP5316 was used as a basis for developing Table I shelf life values and providing the external factors that influence an item's shelf life. Appendix A provides a cross reference of all materials (Table V) and specifications (Table VI) that have been removed from the previous revision of this handbook.
4.2 Type of rubber. Certain types of rubber are more age resistant than others. This is due to the inherent stability of the chemical bonds of those rubbers. For example, the bonds in silicone rubber are not susceptible to attack by oxygen or ozone, therefore it has a much higher age resistance than other rubbers. Table I indicates the age resistance generally associated with products based on various types of rubber.
4.3 External factors influencing shelf life. The following external factors should be considered so as to not shorten an item's shelf life.
4.3.1. Packaging. All rubber shelf life items should be adequately packaged to prevent any deterioration of the item. As contact with other materials, such as liquids, semi-solids, metals, other elastomers, etc., can affect item shelf life, it is recommended that rubber shelf life items be individually preserved.
4.3.2 Storage. Proper storage of rubber shelf life items is critical so as not to shorten the shelf life of the item. Important factors to consider when storing rubber shelf life items are specified in 4.3.2.1 - 4.3.2.5.
4.3.2.1 Temperature. Rubber end products should be stored below 100 °F (38 °C). It may be necessary to raise the temperature of the product if it was stored below its optimum use
4
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business