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NBR O-Ring

O-rings is one of the most common seals in use today. They can be used in both static and dynamic applications and offer an economic and effective sealing solution. By choosing a compound and hardness it is usually possible to find a suitable O-ring for most applications. Rubber O-rings can operate in temperatures from -55 deg C to + 320 deg C and (with backup rings) at pressures of 400 Bar. They are available in a large range of standard imperial and metric sizes The most common international standards for O-Ring dimensions, in addition to ISO 3601/1 are:-
  • American Standard : AS-568
  • Great Britain : BS 1806 - BS 4518,
  • Germany: DIN 3771,
  • France: NF T 47 501,
  • Japan: JIS B 2401-77
CROSS SECTIONS
  • Common metric sections include 1.0mm, 1.5mm, 2.0mm, 2.5mm 3.0mm, 3,5mm, 4.0mm, 4.5mm 5.0mm, 6.0 etc.
  • Common Swedish sections include 1.6mm, 2.4mm, 5.7mm, 8.4mm
  • Common French sections include 1.8mm
  • Common Japanese Sections include 1.9mm, 2.7mm, 3.1mm 3.6mm,
  • Common Imperial sections are 1.78mm, 2.62mm, 3.53mm, 5.33mm and 6.99mm
It can be seen from the above that there is an o ring section to suit almost any requirement, inside dimensions range from less than 1mm to over 800 mm with bigger sizes than that available as Customer Specials ".
HARDNESS
Common rubber compounds are available in a range of hardness grades, the most common being 70 shore (Standard Hardness), 80 shore, 90 shore (Hard) is also available, with 40/50 shore (soft) being the least popular. Fluoro elastomer (VITON) O'rings to be slightly harder with 75/80 Shore being the norm.
Most Common Materials
FKM Viton -40 deg C + 230 deg C High Temperature, Synthetic and hydraulic fluids, many acids and alkalis
FKM Perfluoro elastomer (Viton) -30 deg + 320 deg C Very high temperature, Best chemical resistance of all Elastomers High performance material
MVQ Silicon -55 Deg C + 230 Deg C High Temp Air, Water, Oxygen, alkalis and some acids Static applications only
NBR Nitrile -40 deg C + 110 Deg C Mineral based Hydraulic and lubricating oils LPG Gas, Butane, Propane, Acetylene, Petrol, Diesel
EPDM Ethylene-propylene -55 deg C + 150 deg C Fire resistant hydraulic fluids, Brake fluids, Hot water, Steam Not resistant to mineral oils
PU Polyurethane -30 deg + 80 deg C Good wear and extrusion resistance Not resistant to glycol based fluids, acids or alkalis
PTFE Polytetrafluoroethylene -200 deg +260 deg C Very good chemical resistance except liquid alkaline metals No rubber elastic properties, static applications only
O-Rings Recessing Arrangement for AS-568 Series (American Standard)
Statically Recessed
O-Rings Cross Section Static Application Recess Radius (R)
Radial Compression Axial Compression
Depth 0 (D) -0.05 Width +0.2 (W) 0 Groove 0 Width -0.05 Step +0.1 Depth 0
1.78 1.31 2.4 2.38 1.2 0.5
2.62 2.09 3.6 3.57 2.0 0.75
3.53 2.86 4.8 4.76 2.8 1.0
5.34 4.38 7.1 7.14 4.2 1.0
6.99 5.57 9.5 9.52 5.5 1.5


Dynamically Recessed
O-Rings Cross Section Dynamic Application Recess Radius (R)
Depth 0 (D) -0.05 Width +0.2 (W) 0
1.78 1.43 2.4 0.5
2.62 2.26 3.6 0.75
3.53 3.1 4.8 1.0
5.34 4.75 7.1 1.0
6.99 6.1 9.5 1.5