1 PROPERTIES OF ELASTOMER

Basic propertyNBRHNBREPDM
Sulfur
EPDM
Peroxide
VMQFVMQFKMAU/EUCRFFKM
Compression Set ResistanceAACABBADBC
Tear StrengthBACBDCABBB
Abrasion ResistanceBBBBDCB/CABC
Aging ResistanceDBBBAAAABA
Ozone ResistanceDBBBAAAABA
Resistance to Oil and GreaseBBEECBABCA
Fuel Resistance D*CEEDBB*CCA
Resistance to Hot Water80℃100℃130℃150℃100℃100℃80℃50℃80℃depends on compound
Resistance to SteamEE130℃175℃120℃120℃EEEdepends on compound
High Temp-standard100℃150℃130℃150℃200℃175℃200℃100℃100℃260℃
High Temp-Special120℃n/an/an/a250℃n/an/an/an/a330℃
Low Temp-Standard-30℃-30℃-45℃-50℃-55℃-55℃-15℃-40℃-40℃-15℃
Low-Temp-Special-50℃-40℃n/an/an/an/a-35℃n/a-50℃-35℃

A=excellent   B=good   C=average   D= poor  E= not recommended  *better result with special compound

2  O-RING FAILURE ANALYSIS 

COMMON O-RING FAILURE MODES 

  • Extrusion or nibbling 
  • Explosive Decompression 
  •  Over-compression 
  •  Abrasion 
  •  Heat Hardening/Thermal Degradation 
  • Plasticizer Extraction
  • Spiral Failure 
  •  Installation Damage   
  • Chemical Degradation   
  • Weather or Ozone Cracking

3 O-RING SHELF LIFE GUIDELINE

O-rings and other rubber products may undergo changes in physical properties as they age. As such, guidelines exist regarding the maximum recommended shelf life for various elastomer types. The shelf life limits in the table to the right are recommendations from Military Handbook 695 and are considered to be quite conservative. 

O-ring shelf life can be maximized by maintaining proper storage conditions for the o-rings. The below offers storage condition recommendations.

Temperature: 

The ideal temperature for O-ring storage is 4℃-27℃. The temperature should not be permitted to exceed 49℃. The O-rings should be a minimum of 1.4 meter away from any direct heat source.

Humidity: 

Relative humidity should be maintained at less than 65%. Excessively dry conditions(relative less than 25%) should also be avoid. In addition, light, oxygen  and ozone exposure, deformation should be avoid as well. 

 

Elastomer type ASTM DesignationRecommended Shelf Life
Nitrile NBR 3-5 years
Styrene ButadieneSBR3-5 years
PolybutadieneBR 3-5 years
Polyisoprene NR,IR3-5 years
Chlorosulfonated PolyethyleneCSM5-10 years
Ethylene PropyleneEPDM5-10 years
Neoprene/ChloropreneCR5-10 years
PolyurethaneEU5-10 years
EpichlorotydrinECO5-10 years
Fluorocarbon ElastomerFKM up to 20 years
PerfluoroelastomerFFKM up to 20 years
SiliconeVMQup to 20 years
Fluorosilicone FVMQup to 20 years
Polyacrylate ACMup to 20 years