Storage of Seals

Most polymeric items including vulcanized rubber and other elastomers tend to change their properties during storage and may become unserviceable. This may be due to hardening, softening, cracking, crazing or other degradation and may be the result of oxygen, ozone, light, heat and/or humidity.

The following recommendations indicate the most suitable conditions for storing elastomeric items, whether as a single item or composite product.

1.  Temperature
   Storage temperatures should not exceed 50oc. Low temperatures are not permanently harmful provided the rubber items are handled carefully and not distorted. When taken from low temperatures items should be raised to approximately 30oc before they are used.
2.  Humidity
   Optimum humidity is about 65% in a draft-free atmosphere.
3.  Light
   Protection from direct sunlight and strong artificial light with a high ultraviolet content is important. Unless packed in opaque containers, it is advisable to cover windows with red or orange screens or coatings.
4.  Oxygen and Ozone
   Elastomeric items should be protected from circulating air wherever possible. As ozone is particularly harmful to rubber, storage rooms should be free from equipment that may give rise to electric sparks or discharge. Wrapping, storage in airtight containers or other suitable means should be used for vulcanised rubber items.
5.   Deformation
   Where possible, rubber items should be stored in a relaxed position, free from tension or compression. Laying the item flat and avoiding suspension or crushing keeps it free from strain and minimises deformation.
6.  Contact with Liquid and Semi-Solid Material
   Contact with liquids and semi-solid materials, particularly solvents, such as oils or greases should be avoided unless so packed by the manufacturer.
7.  Contact with Metals
   Metals such as manganese, iron and copper, or copper alloys can have a harmful effect on rubber. A layer of paper, polyethylene or cellophane will keep these separated.
8.  Contact with Non-Metals
   Contact with other rubbers or creosotes should be avoided.
9.  Stock Rotation
   Elastomers should be stored for as short a period as possible, and strict stock rotation should be practiced.
10.  Cleaning
    Organic solvents such as trichloroethylene, carbon tetrachloride and petroleum are the most harmful agents. Soap and water and methylated spirits are the least harmful, and all parts should be dried at room temperature before use.
11.  Shelf Life
    The table shows the storage life of seal components made from the more common materials under ideal conditions. Storing under less than ideal conditions will reduce the life.

Careful inspection of the following should be made before installation after storage:

1. Mechanical damage
   b. Permanent distortion
   c.  Cracks or surface crazing
   d.  Tackiness or surface softening/hardening

Thin components (less than 1.6mm {1/16in}) tend to be more critically affected.

The appearance of ‘bloom’ is relatively unimportant, except in certain non-toxic applications.

Storage Advices for Hydraulic and Pneumatic Sealing Elements

During storage rubber and plastic parts may be exposed to chemical and physical changes. This could be caused by combined factors.

• Oxygen
• Ozone
• Direct sun light
• High temperature
• Ultra-violet rays
• Humidity
• Dirt and chemical affects

Stored in good conditions, rubber and plastic products can keep their chemical and physical features in long periods.

Environment, moisture and temperature
Ideal temperature is between 5°C and 25°C and moisture rate should be about 60%. Less temperature rates do not result in technical changes, but before assembly, the temperature for seal is advised to be 20-25°C. In addition to those direct heat contacts are not recommended.

Dirt
It may change the mechanical features of products. Therefore, the environment should be cleaned before assembly and during storage.

Light and ultra-violet rays
Recommended storage conditions are the rooms protected from fluorescent lambs, ultra-violet rays, powerful light sources and direct sun lights. Red or orange colour lights are adviced.

Oxygen and ozone
They are oxidizing agents. What is suitable for seals is to store them by packing up with Polythene (PE) materials. Ozone is especially a destroying agent and so there should not be electrical equipments with high voltages such as motors, etc.

Deformation
Deformation should be avoided during storage. Rubber parts and thermo-plastic seals should be kept away from coercive forces and squeezing because they cause a rapid change in mechanical features and endurance against agents in nature.

Contact with grease and hydraulic liquids
Any contact with solvents, oils and other liquids should be avoided.

Contact with metals
Some metals (i.e. manganese and copper) may harm some seal types, therefore, contacting directly with metals or their alloys should be avoided.