Winegrowers Supplies  -  Rubber seals/gaskets - different types and their performance

PerbunanŽ represents a range of oil-resistant NBRs (acrylonitrile-butadiene rubbers) with a particularly high level of quality and properties. The product range includes grades with 18 to 45% acrylonitrile content and Mooney viscosity from 30 to 125. With PerbunanŽ, it is possible to obtain oil-resistant vulcanizates that can resist extremely low temperatures. In comparison with vulcanizates based on other NBRs, Perbunan vulcanizates show clearly better physical properties, heat aging resistance and abrasion and wear behavior.

PerbunanŽ was developed by Bayer in the 1930s as the first-ever oil-resistant rubber. Since then there have been several improvements and today it is manufactured according to principles that take into consideration not only the good physiological properties of the rubber but also protection of the environment.

PerbunanŽ is recommended for many technical rubber articles. PerbunanŽ is the first choice for oil seals. Here, the 'second generation' PerbunanŽ grades were developed to allow consistent and trouble-free production.

A series of special applications in the automotive and construction industries would not be possible without PerbunanŽ. For example, applications in the automotive industry, where the maximum operating temperature does not substantially exceed 120°C, are oil filter seals, torsional vibration dampeners, membranes, membranes in fuel injection systems, fuel and oil pipes, hose in hydraulic systems.

In machines and installations, PerbunanŽ is used in all sorts of static and dynamic seals, from O-rings to complicated shaft seals, in heat exchanger seals, in pressure hose, rolls and drive belts.

PerbunanŽ is suitable for food contact applications such as milk, inflation tubes, aerosol seals and food-carrying hoses.

Key Properties:-
- very good resistance to oils, greases and fuels
- very good low temperature flexibility
- good physical properties (modulus, compression set)
- good resistance to aging
- high resistance to wear
- low gas permeability

NBR (acrylonitrile-butadiene rubber; Nitril-Butadien-Kautschuk)
FDA-NBR - Approval in the food industry (FDA 177.2600)
NBR is suited to the following application areas: hydraulic oils, pneumatic, water glycol, water-in-oil emulsion, mineral oil and  products, animal and vegetable oil, petrol, fuel oil, water, butane, propane, methane, ethane etc.
Temperature range: between -25°C and +120°C.

NBR-HT (Nitril-Butadien-Kautschuk)
NBR-Hydrogene (Nitril-Butadien-Kautschuk)
FDA-NBR-HT - Approval in the food industry (FDA 177.2600)
An adjusted rubber-compound NBR-HT or NBR-Hydrogene. These specific rubber alloys facilitate use at temperatures between -25°C and +130°C (NBR-HT) or between -25°C and +150°C (NBR-Hydrogene). Both special alloys are in particular adapted to the UHT-use.

EPDM, Ethylene-Propylene-Diene-Monomer (M-class) rubber, is a type of synthetic rubber.
The M refers to its classification in ASTM standard D-1418. Approval in the food industry (FDA 177.2600).

EPDM exhibits satisfactory compatibility with fireproof hydraulic fluids, ketones, hot and cold water, and alkalis, but unsatisfactory compatibility with most oils, gasoline, kerosene, aromatic and aliphatic hydrocarbons, halogenated solvents, and concentrated acids.

The main properties of EPDM are its outstanding heat, ozone and weather resistance. The resistance to polar substances and steam are also good. It has excellent electrical properties.
Temperature range: between -40°C and +130°C.


FDA-EPDM-HT - Approval in the food industry (FDA 177.2600)
The same properties as EPDM Standard, but a temperature range: between -40°C and +150°C is possible.

Viton-FDA (Fluor-Kautschuk, Fluorkarbon-Kautschuk)
Viton A (Fluor-Kautschuk, Fluorkarbon-Kautschuk)
Viton B (Fluor-Kautschuk, Fluorkarbon-Kautschuk)
Viton G (Fluor-Kautschuk, Fluorkarbon-Kautschuk)

Approval in the food industry (FDA 177.2600) – only Viton-FDA
Viton-FDA, Viton-B, Viton-G und Viton-A have a brilliant permanence against high temperatures, ozone, oxygen, mineral oil, synthetic hydraulics liquids, fuels, aromatics, many organic solvents and chemicals.
Temperature range: between -20°C and +175°C.

The performance of fluoroelastomers in aggressive chemicals depends on the nature of the base polymer and the compounding ingredients used for moulding the final products (e.g. O-rings). This performance can vary significantly when end-users purchase Viton polymer containing rubber goods from different sources.
Viton is generally compatible with hydrocarbons, but incompatible with ketones such as acetone, and organic acids such as acetic acid.
O-rings made of Viton are typically color coded as black, but new gaskets, seals and O-rings should be green FKM or black FKM, but with a green mark on the outer edge.

Viton O-rings have been used safely for some time in the SCUBA diving world for divers who dive with gas blends referred to as Nitrox.
Viton is used because it has a lower probability of catching fire, even with the increased percentages of oxygen found in Nitrox. It is also less susceptible to decay under increased oxygen conditions.

Viton tubing or Viton lined hoses are commonly recommended in automotive and other transportation fuel applications when high concentrations of biodiesel are required. Studies indicate that types B and F (FKM- GBL-S and FKM-GF-S) are more resistant to acidic biodiesel; biodiesel fuel that is unstable and oxidising.