ACM Polyacrylate HyTemp® -20°C ÷ 150°C
AEM Ethylene Acrylic Vamac® -30°C ÷ 150°C
AU, EU Polyurethane Desmopan® -40°C ÷ 100°C
CR Chloroprene Neoprene®
-40°C ÷ 100°C
EPDM EP Diene Nordel® -45°C ÷ 150°C
FFKM/FFPM Perfluoro Kalrez® -25°C ÷ 240°C
FKM/FPM Fluorocarbon Viton® -20°C ÷ 200°C
FVMQ Fluorosilicone Silastic LS® -55°C ÷ 175°C
HNBR Hydrogenated Nitrile Therban®, Zetpol® -30°C ÷ 150°C
IIR Isobutylene Isoprene Butyl® -40°C ÷ 110°C
NBR Acrylonitrile Butadiene
Nipol®, Krynac®
-30°C ÷ 100°C
NR Natural Rubber -50°C ÷ 80°C
PTFE Polytetrafluoroethylene Teflon® -200°C ÷ 260°C
SBR Styrene Butadiene Plioflex®, Stereon® -45°C ÷ 100°C
TFE-P/FEPM TFE Propylene Aflas® -10°C ÷ 200°C
TPU Thermoplastic PU Elastollan® -40°C ÷ 100°C
VMQ Silicone Silopren®
-55°C ÷ 200°C

AU, EU – Polyurethane

DIN/ISO 1629 Designation: AU, EU
ASTM D 1418 Designation: AU, EU
Standard Colour: Amber, Black
Hardness Range: 40 ÷ 90 Shore A
Temperature Range: -40°C (-40°F) ÷ 100°C (212°F)

Polyurethane is a polymer made from the reaction between an isocyanate and a polyol, and its characteristics depend strictly on the different combinations of hard (isocyanate) and elastic (polyol) components used. In addition to other additives, isocyanates (commonly TDI and MDI) and polyols (commonly polyethers and polyesters) allow polyurethanes to be an exceptionally complex group of materials with an extremely wide range of properties. Widely used and extremely versatile, Polyurethanes can be thermoplastic or thermoset. Compared to other/classic elastomers they have much higher mechanical properties, high resistance to abrasion, wear and extrusion, high tensile strength, low compression set and excellent tear resistance. Moreover, they are generally resistant to ageing and ozone, and show a good chemical compatibility, offering good resistance to mineral oils, hydrocarbon fuels, hydraulic fluids and greases.

CR – Chloroprene Rubber (Neoprene®)

DIN/ISO 1629 Designation: CR
ASTM D 1418 Designation: CR
Standard Colour: Black
Hardness Range: 40 ÷ 90 Shore A
Temperature Range: -40°C (-40°F) ÷ 100°C (212°F)

Chloroprene Rubber (CR), widely known with the trade name Neoprene®, is a homopolymer of Chloroprene (Chlorobutadiene) and is one of the first oil resistant synthetic rubbers developed as an alternative to Natural Rubber. Neoprene® is largely unaffected by sunlight and atmospheric ageing, has moderate resistance to petroleum based oils and fuels, good resistance to ozone and heat, relatively low compression set and reasonable production cost. It is a general purpose rubber with a good balance of physical and chemical properties combined with an excellent flame resistance that makes chloroprene one of the few self-extinguishing rubbers. Due to its broad base of working properties, Neoprene® can be used in numerous applications and because of its good resistance to Freon and ammonia, it is the preferred sealing material for the refrigeration industry. However, nowadays Neoprene® has been largely replaced by NBR, which is economically more competitive and has generally superior performance characteristics.

EPDM – Ethylene Propylene Diene Rubber

DIN/ISO 1629 Designation: EPDM
ASTM D 1418 Designation: EPDM
Standard Colour: Black
Hardness Range: 30 ÷ 90 Shore A
Temperature Range: -45°C (-49°F) ÷ 150°C (302°F)

EPDM rubber is a terpolymer of ethylene-propylene (EPM, sometimes also known as EP) with the addition of a third monomer (diene). Generally EPDM has a good resistance to hot water and steam, aging by both ozone and sunlight and chemicals, but it is totally unsuitable for use with mineral oil products (lubrificants and fuels). While EP can only be Sulphur cured, EPDM based elastomers can be either Sulphur or Peroxide cured. Sulphur cured compounds are less expensive, easier to process and often considered as standard, while peroxide cured EPDM compounds are suitable for higher temperature ranges and have a much lower compression set. EP and EPDM can be also compounded for FDA approved requirements and they find a wide application in the food and pharmaceutical industries. However, despite its widespread usage, EPDM rubber, unlike Nitrile, has very poor compatibility with mineral and petroleum based oils, lubricants, fuels and greases.

FFKM/FFPM – Perfluoro Rubber (Kalrez®)

DIN/ISO 1629 Designation: FFPM
ASTM D 1418 Designation: FFKM
Standard Colour: Black
Hardness Range: 65 ÷ 90 Shore A
Temperature Range: -25°C (-13°F) ÷ 240°C (464°F)

Perfluoro Rubber (FFKM/FFPM), also known as Kalrez®, is a highly fluorinated elastomeric family of compounds that contains higher amounts of fluorine than FKM (approximately between 71% and 73%). Due to its excellent chemical properties and heat resistance, combined with the elastic qualities of an elastomer, FFKM is considered the elastomeric equivalence to PTFE (Teflon®). Perfluoroelastomer provides an exceptional resistance to degradation by aggressive fluids in addition to higher temperature resistance than any other elastomer in the market. However, because of its considerably high cost, perfluoro elastomer is only used where other materials cannot meet the specifications required and where extreme safety requirements or high maintenance and repair costs justify the higher expenditure. Typically FFKM can be found in the chemical, semiconductor and aerospace industries, and in all applications with either aggressive environments or high temperatures.

FKM/FPM – Fluorocarbon Rubber (Viton®)

DIN/ISO 1629 Designation: FPM
ASTM D 1418 Designation: FKM
Standard Colour: Black
Hardness Range: 50 ÷ 95 Shore A
Temperature Range: -20°C (-4°F) ÷ 200°C (392°F)

Fluorocarbon Rubber (FKM/FPM) is a fluoroelastomer most commonly known as Viton® available as a copolymer (two monomers), terpolymer (three monomers) or as a tetrapolymer (four monomers). FKM rubber compounds are known especially for their high resistance to high temperatures and harsh chemicals, they have excellent resistance to ageing, weathering and ozone, low gas permeability and are non-flammable. In addition to standard FKM, a number of special compounds with different compositions of polymer chains and varying fluorine contents (66% to 70%) are developed to offer better chemical resistance and low temperature performance. FKM rubber compounds are frequently used with mineral based oils and greases, the strong carbon-fluorine bonds that make up the polymer structure provide high thermo-chemical resistance, giving excellent ageing characteristics and low compression set also at elevated temperatures. It has strong compatibility with a range of chemicals, oils, and heat, making it one of the most used sealing materials. FKM compounds are commonly used in chemical, automotive, aerospace and industrial applications.

HNBR – Hydrogenated Acrylonitrile-Butadiene Rubber

DIN/ISO 1629 Designation: HNBR
ASTM D 1418 Designation: HNBR
Standard Colour: Black, Green
Hardness Range: 50 ÷ 90 Shore A
Temperature Range: -30°C (-22°F) ÷ 150°C (302°F)

Hydrogenated Nitrile rubber (HNBR), also known as highly saturated Nitrile, is a hydrogenated version of NBR (Nitrile Rubber) obtained by full or partial hydrogenation of the butadiene copolymer. The properties of the HNBR rubber depend mainly on the Acrylonitrile content (ACN) which ranges between 18% and 50% as well as on the degree of saturation of the polymeric chain. HNBR shows good mechanical properties, good oil and chemical compatibility, higher service temperatures and better wear resistance than non-hydrogenated nitrile (NBR) compounds. Depending on which properties are required, HNBR can be also cured either with sulphur or peroxide. Hydrogenated Nitrile is widely used as seal material in automotive and oil resistant applications, it maintains an excellent resistance to mineral oil-based hydraulic fluids, sour gases, diesel fuels, diluted acids and ozone, but like Nitrile, it is not recommended for exposure to ketones, esters, aldehydes and chlorinated hydrocarbons.

NBR - Acrylonitrile-Butadiene Rubber

DIN/ISO 1629 Designation: NBR
ASTM D 1418 Designation: NBR
Standard Colour: Black
Hardness Range: 20 ÷ 90 Shore A
Temperature Range: -30°C (-22°F) ÷ 100°C (212°F)

Commonly known as Nitrile rubber (NBR) or Buna-N, Acrylonitrile Butadiene Rubber is a copolymer of two monomers: acrylonitrile (ACN) and butadiene. Presently the most widely used and economical elastomer, NBR offers good mechanical properties together with excellent resistance to mineral oil-based lubricants and greases, hydraulic fluids, alcohols and water. NBR provides also a good balance of working properties such as low compression set, high tensile strength, and high abrasion resistance. Its properties are mainly determined by the acrylonitrile content which ranges between 18% and 50%, low ACN contents (<30%) ensure better flexibility at low temperatures, but offer limited resistance to oils and fuels, high ACN contents (>45%) increase resistance to hydrocarbon oils and fuels, but reduce flexibility at low temperatures. The standard NBR material, known as “Medium Nitrile”, offers an average ACN content of approximately 32% and due to its good overall balance suits a wide range of applications.

PTFE – Polytetrafluoroethylene (Teflon®)

DIN/ISO 1629 Designation: PTFE
ASTM D 1418 Designation: PTFE
Standard Colour: White
Hardness Range: 50 ÷ 60 Shore D
Temperature Range: -200°C (-328°F) ÷ 260°C (500°F)

Polytetrafluoroethylene (PTFE), commonly known by the trade name Teflon®, is a synthetic fluorocarbon-based polymer used in a vast range of applications. PTFE is a chemically inert (non-reactive) polymer, resistant to nearly all industrial chemicals even at elevated temperatures, incredibly versatile and hydrophobic (liquids hardly adhere to or absorb into it). In addition to its exceptionally wide working temperature range and its high resistance to most chemicals and solvents, PTFE has an extremely low friction value (one of the lowest coefficients of friction of any solid), an outstanding weather, tear, abrasive and ozone resistance. Its countless features make PTFE one of the most well-known fluoropolymer materials in sealing applications. In critical sealing situations and to improve its mechanical properties, PTFE is compounded with reinforcing fillers such as bronze, carbon, graphite and glass. Due to lack of elasticity, seals made from PTFE can be also combined with elastic energizing elements such as o-rings and metallic springs. PTFE seals are suitable for many manufacturing environments and are widely used in many industries including food and beverage, medical, pharmaceutical and chemical.

VMQ – Silicone Rubber

DIN/ISO 1629 Designation: VMQ
ASTM D 1418 Designation: VMQ
Standard Colour: Red (Rust)
Hardness Range: 20 ÷ 90 Shore A
Temperature Range: -55°C (-76°F) ÷ 200°C (392°F)

Silicone rubbers (VMQ) are synthetic polymers with a backbone structure composed of alternating silicon and oxygen atoms. The molecular structure of silicone rubber results in a very flexible but weak chain, VMQ offers an outstanding working temperature range, excellent heat resistance and low temperature flexibility, while on the low side, its tensile strength, tear and abrasion resistance are relatively low. Compared with other elastomers, Silicone rubber has good resistance to weather, ozone and UV rays, moreover, it is considered an excellent seal material also in terms of properties retention at high temperatures. Generally recognized as physiologically neutral and compatible with FDA regulations, it is often used in static applications in food and pharmaceutical industries. Even though a wide variety of special compounds can be synthesized to improve its mechanical properties, Silicone rubber due to its high friction characteristics is not recommended for sealing use in dynamic applications.

COMPARISON OF PROPERTIES OF COMMONLY USED SEALING MATERIALS (1 = Excellent; 2 = Good; 3 = Average; 4 = Fair; 5 = Poor)
Abrasion Resist. Acid Resist. Chemical Resist. Cold Resist. Flame Resist. Heat Resist. Imperm
Oil Resist. Ozone Resist. Set Resist.

Tear Resist.

Tensile Strength Steam Resist. Weather Resist.
ACM 2 4 4 4 4 1 1 1 1 3 2/3 3 4 1
3 3 2/3 2
1 1 3 1 2 4 2 3/4
1 4 2/3 2 4 3 2 2 1 3 1/2 1 4 1
CR 2 2/3 2/3 2/3 2 2 2 2/3 1/2 3 2/3 2 3 1
EPDM 1/2 2 1 1/2 4 1 2 4 1 1/2 1/2 1/2 1 1
FFKM/FFPM 4 1 1 3/4 1 1 2 1 1 2 3/4 2/3 1/2 1
FKM/FPM 2 1 1 3/4 1 1 2 1 1 1/2 3 1/2 2/3 1
FVMQ 4 2/3 1 1/2 2 1 4 2 1 1/2 4 3 3 1
HNBR 2 1 2/3 2 4 1 2 1 2 1/2 2/3 1 1 2
2/3 2 1 2 4 2 1 4 1/2 2/3 2 2 2 1/2
NBR 2 3 2/3 2 4 2 2 1 4 1/2 2/3 1/2 2/3 3
NR 1 2/3 2/3 2 4 3 3 4 4 2 1/2 1 2/3 3
PTFE 4 1 1 1 1 1 2 1/2 1 2 1 1 1 1
SBR 2 3 2/3 2 4 2/3 3 4 4 2 2/3 1/2 2/3 3
TFE-P/FEPM 1/2 1 1 4 1 1 2 1 1 2 3/4 2/3 1/2 1
TPU 1 4 2/3 2 4 3 2 2 1 3 1/2 1 4 1
VMQ 4 2/3 1/2 1 3 1 4 2/3 1 1/2 4 4 3 1