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Pur is a thermoplastic polyurethane elastomer (TPU) on the polyester basis, relates to the group of polar and saturated elastomers. Because of the special raw material, Pur is an excellent material for manufacture of seals by a machining method and traditionally – by injection molding.

Pur is the first and simplest material among polyurethane elastomers, but in comparison with rubber elastomers it already exhibits excellent mechanical characteristics - low abrasion, low compression set and extremely low residual strain (20% at 70°C/70h).

Products made out of this material can be used in mineral oil (water content - not more than 0.2%), in water up to 40°C and in bio-degradable hydraulic oils like vegetable oils and synthetic esters from -30°С up to +110°С. Pur is resistant to ozone, weather and temperature’s effects. Also, this material has a very high resistance to radiation exposure.

Resistance

Good resistance Average resistance Low resistance
Hydraulic fluids based on mineral oil Non-ethanol fuel Aromatic hydrocarbons
Mineral oil and grease (modifying additives can cause the decrease) Biodegradable hydraulic fluid Ketones, methyl ethyl, glycols.
Water up to +40°С Fire-resistant hydraulic fluids HFA, HFB up to +30°С Brake fluids based on glycol
Aliphatic hydrocarbons (propane, butane) Silicone oil and grease Fire-resistant hydraulic fluids HFC and HFD
Compressed Air up to 110°С   Hot water, steam, alkali, amines, acids and base.
    Chlorinated hydrocarbons

Application

Pur mainly used for seals, resistant to mineral oils and in those cases, when it is necessary to provide high mechanical properties - wear resistance, low compression set, as well as easy installation to the groove with small dimensions. For example: seals, which require slight abrasion, minimal wear, simple installation and dismantling, compact sizes and increased longevity.

Operating practice of different seals shows that Pur has better wear resistance than the rubber elastomers (standard molding to a press-form) more than 8-15 times.

Pur has high hardness, so it has been used successfully for the seals, which are operated in a highly worn pairings at high pressure and must have a high resistance to extrusion.

Mainly used

  • Wipers
  • Piston seals
  • Rod seals
  • O-Rings
  • Rotor seals

Pur Material Data Sheet

Properties Value Unit Standard
Hardness 95+/-3 Sh A DIN 53505
Hardness 48+/-3 Sh D DIN 53505
Density 1,20 g/cm³ DIN 53479 or DIN EN ISO 1183-1
Compression set 70°C / 24 h, 20 % deformation ≤25 %  
Compression set 70°C / 70 h, 10 % deformation 20 % DIN 53517 or DIN ISO 815-1
Compression set 100°C / 24 h, 20 % deformation ≤30 %  
100 % modulus ≥15 N/mm2 DIN 53504
Rebound resilience 45 % DIN 53512
Tensile strength ≥35 N/mm2 DIN 53504
Elongation at break ≥400 % DIN 53504
Tear strength ≥100 N/mm DIN 53515 or DIN ISO 34-1
Abrasion 15 mm³ DIN 53516
Min. service temperature -30 °C  
Max. service temperature +110 °C

All above established data results from random tests which were taken from the functioning production. All data was stated based on standard test-products in accordance with ISO, DIN and ASTM standards and can substantially not be extended to the completed seal. Our practical technical recommendation, either oral, written or through tests is given in conformity with our best knowledge. However, this data is to be regarded as non-obligatory advice, also taking into consideration any protective rights of a third party, and does not acquit you from making tests with our product in relation to its adaptability for the assigned process and intendment. Utilization, application and processing of the products befall completely outside of our control and are therefore solely your liability. As regards the responsibility, it will be limited to all damages in the value of the product which we delivered and you applied. Certainly, we do assure the immaculate quality of our products in concordance with our general sales and delivery conditions.

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