EPDM gaskets

EPDM is the abbreviation for ethylene-propylene-diene(monomer) rubber and belongs to the M-group of rubbers. Within the framework of the classification of rubbers, seals made of this sealing material are thus assigned to the non-polar saturated rubbers. The material is a high-quality, rubber-elastic, synthetic elastomer made of very long, saturated and highly stable molecular chains, the macromolecules ethylene, propylene and diene. Other trade names are, for example, BUNA-AP®, KELTAN® and NORDEL®. Due to the diverse properties and resistances of EPDM, the sealing material can be used in many areas of application.

Available EPDM materials at Rehm Dichtungen Ehlers GmbH

EPDM sealing material is available to us in various versions and different hardness ranges (approx. 25-80 Shore). We obtain a large part of it from the Austrian manufacturer Semperit. We are the second-largest dealer for Semperit. Semperit stands for the highest and most consistent product quality. Sustainability and good traceability of materials are also signs of the company. All EPDM qualities from Semperit are free of halogens and conflict materials. They are also REACH and RoHS compliant. In addition to Semperit qualities, the material is also available in import quality and CooperStandard. In the area of foamed materials in combination with EPDM components, we offer cellular rubber and sponge rubber.

Semperit: Standard qualities

Semperit: Special qualities

Fire protection materials

Newly developed EPDM qualities

Import qualities

CooperStandard

Other elastomers

The properties of EPDM as a sealing material

Even though EPDM is available in different mixing ratios (mainly due to the ethylene and diene content), the material has a number of fundamentally identical properties. Based on the saturated main chain, the synthetic rubber is characterised by very good ageing resistance and high resistance to ozone, UV radiation, heat and oxygen. In addition, seals and gaskets made of EPDM are resistant to heat and weather. Furthermore, the material is resistant to hot steam, hot water and polar media, including diluted acids and alkalis, alcohols, ketones, salt solutions and silicone oils. Finally, the high electrical resistance should be mentioned in the area of properties.

EPDM is usually sulphur cross-linked, but also exists as a peroxide cross-linked material. Peroxide cross-linking achieves a significantly higher temperature resistance. A higher ethylene content improves low-temperature flexibility and elasticity. A higher proportion of diene ensures a higher cross-linking speed and density as well as strength.

A disadvantage of this material is its resistance to non-polar media, such as greases, mineral oils and fuels.

The advantages and material properties of EPDM at a glance

Seals and sheets made of this material are characterised by the following advantages:

• Resistant to hot water and steam,
• Good resistance to polar media
  • against alcohols and ketones,
  • as well as against organic and inorganic (weak) acids and bases.
• fire-, heat- and weather-resistant,
• resistant to UV light and ozone,
• Good long-term behaviour or good ageing resistance
• and good electrical insulation properties.

In summary, EPDM is resistant to various chemical, mechanical and thermal stresses. Thanks to the molecular structure and its compounds, seals made of this material are flexible.

The limits and disadvantages of EPDM

When using EPDM gaskets, however, the limitations and disadvantages of the elastomer should also be taken into account. For example, flat or flange gaskets made of EPDM are not resistant to various chemical substances such as fuels, lubricants or solvents. Aggressive chemicals or cleaning agents in particular can cause damage to the EPDM gasket and thus impair its function. The sealing material NBR is suitable for oil-resistant seals. In addition, temperature restrictions apply to EPDM gaskets. The temperature range of the material is approximately between -10°C and +140°C. However, the exact temperature range depends on the respective composition of the material. The exact temperature ranges can be found on the respective technical data sheets. For higher temperature requirements, FKM or silicone should be considered in the elastomer area, as the elasticity of EPDM seals is lost at higher temperatures and the material becomes brittle. Another disadvantage of this material is its high gas permeability, which means that the use of EPDM gaskets for sealing gases such as oxygen or nitrogen is not recommended. Finally, the material is not suitable for applications with high mechanical loads, as it has a lower abrasion and tear resistance compared to other elastomers.

Differentiation of EPDM from other sealing materials

The sealing materials EPDM and NBR are synthetic rubbers, but they have some differences to each other. While EPDM is produced by polymerizing ethylene and propylene, NBR is produced from nitriles and butadiene. Accordingly, the two materials differ in terms of their resistances. Among other things, seals made of EPDM have good chemical resistance to polar media and organic and inorganic acids and bases. In addition, the gasket material is resistant to UV light and ozone and is therefore considered to be resistant to weathering and aging. The resistance to weathering and aging represents a major difference from NBR, as nitrile butadiene rubber does not have this resistance. However, NBR seals stand out primarily because of their good resistance to fuels, oils and solvents. Another difference between the two materials lies in the temperature range in which they can be used. Flat or flange gaskets made of EPDM can be used in a wider temperature range than gaskets made of NBR.

There are also significant differences compared to FKM rubber. Fluororubber gaskets have a higher temperature range than EPDM gaskets. The chemical resistance of Viton and FKM should also be emphasized as a distinguishing feature. While EPDM is not resistant to oils, greases and fuels and therefore has limitations when used in mechanical engineering, FKM has excellent resistance to the aforementioned media. However, when selecting a suitable sealing material, the better resistance to ageing and the lower price of EPDM compared to FKM should not be neglected.

In terms of temperature range and low-temperature flexibility, silicone flat gaskets have a thermal advantage over EPDM gaskets, as they can be used in a wider temperature range.

EPDM resistances at a glance

Production of EPDM as a sealing material

The synthetic rubber EPDM consists of the three main components ethylene, propylene and diene. The mixing ratio of the three components varies depending on the formulation and influences the properties of the EPDM. As a result, there are different EPDM variants, making it a versatile material for a wide range of industrial applications. For the production of EPDM/SBR, SBR (styrene-butadiene rubber) is added to the mixture.

The production of EPDM begins with the polymerization of the three main components, which are chemically combined in this step using a catalyst. In the next step, additional substances, such as fillers, are added to the resulting raw polymer. The final stage of the manufacturing process is vulcanization, in which "loose" polymer chains are turned into solid chemical bonds between the polymer chains. Sulphur or peroxides can be used as vulcanization agents. The choice of agent has an influence on the temperature resistance of the EPDM quality.

The way to your EPDM flat gasket

The qualities presented and available at our company are first subjected to a quality control at goods receipt. Only then, after approval, is the sealing material stored in the form of rolls and sheets at the respective storage location. This enables us to guarantee a consistently high quality, also with regard to the respective sealing material.

EPDM belongs to the group of gasket materials that can be processed in all our manufacturing processes. The selection of the most suitable manufacturing process for your EPDM flat gaskets depends on the number of pieces, the respective contour and the thickness of the material. The unprocessed roll or sheet material is then processed into the individual EPDM flat gasket using the selected process. In addition, it is possible to apply a self-adhesive film to the roll or sheet material in advance and then process it into your self-adhesive EPDM gaskets using the manufacturing processes. Self-adhesive gaskets serve exclusively as an assembly aid without changing the properties of EPDM. In addition to the production of flange and flat gaskets, we also offer unprocessed rolls or sheets as well as cut-to-size yard goods made of EPDM for your own further processing. Here, too, we offer the option of applying self-adhesive finishes to the material.

After completion of the production and a renewed quality control, the seals are packed and shipped to you.

Application areas of EPDM gaskets

EPDM is used as a sealing material in many areas and industries. The elastomer is available in rolls and sheets. As a gasket manufacturer, we primarily cut these into flat gaskets, strips and blanks as required.

For example, seals made of this material are used in construction as pipe seals for drinking water and waste water.

EPDM is excellently suited as a sealing material of various water-bearing building elements such as in water pipes in outdoor areas, seals in water taps or door seals. Therefore, the flat and flange gaskets can also be used in water treatment plants to prevent leakages and leaks. The black elastomer is also well suited as a carpet pad for green roofs, as it is resistant to root penetration. In the automotive industry, EPDM seals and other components made of this material are increasingly being installed in safety-relevant parts of car brakes. Another application we know of is in the sealing of radiator, heating and ventilation hoses. In agriculture, too, seals made of EPDM are used in various agricultural machines such as combine harvesters or crop strippers, due to their very good aging resistance.

Other technical rubber products include the area around the topic of conveyor belts, which is also covered in depth under the item conveyor belts. Finally, we also stock EPDM materials with approvals for contact with drinking water and foodstuffs.

As a sealing material, the material offers a diverse range of applications and performs excellently, providing reliable protection.

We will be happy to answer whether the elastomer is also suitable for your purposes. Please contact our customer service, who will be happy to provide you with comprehensive advice.

FAQ