Important Facts about Seal Materials

Material :

• 1. POLYURETHANE ANK PU : ANK PU is a hydrolysis - resistant polyurethane elastomer. It combines the engineering properties of polyurethane with a high resistance to hydrolysis which is otherwise rarely found in polyurethanes. It is stable in water upto +90°C (hydrolysis is degradation in water). Because of its resistance to hydrolysis, ANK PU can be used for water hydraulic applications in mining, tunnel construction, press manufacture and the food industry.
• ANK PU is resistant to : Minerals oils & greases, Fire resistant HFA, HFB, Biologically degradable hydraulic fluid & water upto 95°C.
• ANK PU is not resistant to : Alkalies & acids.
• 2. H-NBR Black : H-NBR is a hydrogenated acrylonitrile butadiene rubber.
• H-NBR is resistant to : Aliphatic hydrocarbons such as fuel, propane & butane, mineral oils & greases (resistant to short temperature loads of upto 170°C) vegetable & animal fat or oil, diluted acids, alkalies & salt solutions even at elevated temperatures, as well as glycol in water & silicone oils & greases if these contain anti corrosives, e-g. radiator antifreeze.
• H-NBR is not resistant to : Fuels with a high content of aromatic compounds (four star petrol, alcohol mixture), ketones, esters, ethers and chlorinated hydrocarbons such as trichloroethylene or tetrachloroethylene.
• 3. Nitrile Butadiene Rubber NBR Black : NBR is an elastomer based on acrylonitrile butadiene rubber which is used for U-cup seals, lip seals, chevron packings, special seals and various components. Due to its good resistance to the majority of mineral oil-based oils & greases, NBR is the material most frequently used in hydraulic & pneumatic systems. NBR has excellent mechanical properties such as abrasion resistance & elasticity.
• NBR is resistant to : Mineral oils & greases of HFA, HFB & HFC pressure fluids. Vegetable & animal oils & greases, fats, water & seawater upto approx 100°C.
• NBR is not resistant to : Glycol based brake fluids, HFD Fluids, aromatic & benzene chlorinated hydrocarbons, esters, ketones, amines, concentrated acids & bases.
• 4. Viton Brown : Ecorubber 2 is an elastomer based on Fluorine rubber. (Viton=registered trademark of Du Pont) which is used for U-Cup seals, lip seals, chevron packings, wipers, various components and special seals. Its outstanding properties are its high resistance to heat, chemicals, weathering and ozone. FPM is highly resistant to all mineral oil-based & synthetic-based hydraulic fluids.
• Viton Brown is resistant to : Mineral & synthetic oils & greases containing sulphur, fire resistant fluids HFD (phosphorous ethers & chlorinated hydrocarbons based) fuels, aliphatic, aromatic & chlorinated hydrocarbons, most inorganic acids in corresponding mixtures.
• Viton Brown is not resistant to : Anhydrous ammonia, caustic soda, caustic potash solutions, ketones, ethers, amines, low molecular organic acids, such as formic & acetic acids.
• 5. Teflon PTFE virgin White: Teflon is polytetrafluoroethylene which is used for backing rings, chevron packings, O-rings, seals and gaskets. Teflon is a material with the widest technical range of applications. Teflon has lowest coefficient of friction. Static & dynamic frictions are virtually identical. Depending on the load virgin PTFE has a tendency to creep or cold flow (at relatively low loads). For this reason pure PTFE is not used for sealing parts in hydraulic systems.
• Teflon is resistant to: Virtually all chemicals.
• Teflon is not resistant to: Liquid alkali metals & gaseous fluorine compounds at high pressures & temperatures.
• 6. Teflon PTFE-With fillers Grey: Teflon is polytetrafluoroethylene with glass fibre & MoS2 fillers which is used for guide (Slide)rings, low friction seals, thrust collars and bearing rings for chevron packings and guide rings. As a result of the special fillers Teflon achieves high firmness values at low creep when compared to pure PTFE. These additives reduce thermal expansion, increase thermal conductivity, and improve wear resistance & resistance to permanent deformation (cold flow). Since the material has no rubber-elastic properties, they are usually always used in conjunction with rubber-elastic materials or metal springs which provide the necessary contact pressure & preload.
• 7. POM (Acetal) Black: POM (Acetal) Black is a polyoxymethylene plastomer for anti-extrusion rings; guide rings bushes, scrapers and other high precision rotating parts. One of the most important technical thermoplastics with very good mechanical properties, low water absorption and good chemical resistance.
• POM (Acetal) Black is resistant to: Any mineral oil grease HFA, HFB & HFC fluids.
• POM (Acetal) Black is not resistant to: Concentrated acids and alkaline solutions.
• 8. Polyamide PA Black: Polyamide has good sliding properties which are used in guide rings and bearing components. This material is used instead of Ecotal for components from 250 mm upwards. Polyamide absorbs up to 8% water.
• Polyamide is resistant to: Mineral oil & greases, HFA, HFB & HFC fluids.

On request we will supply various materials for special applications.

EXPLANATIONS OF ABBREVIATIONS.

• HFA: Fire resistant fluids, oil in water.
• HFC: Fire resistant fluids, water/glycol.

• HFB: Fire resistant fluids, water in oil.
• HFD: Fire resistant synthetic fluid.