What seals really have to accomplish

Where are seals and gaskets being used?

Whether in large systems, simple hydraulic cylinders or pneumatic cylinders, metering systems, pipe connections, grinders and much more – seals and gaskets can be found almost everywhere in a wide variety of shapes and materials. They meet a variety of different requirements and ensure that everything runs safely, efficiently and for a long time.

The field of application of seals extends from mega presses to automation systems to wood splitters in the private sector.

Even if many seals look mostly inconspicuous, their function is unavoidable for smooth operation.

Seals for high pressure

For high-pressure applications, seals incorporate specific geometries and shapes. Seals made from elastomers, such as piston seals and rod seals from PU, can be equipped with an additional backing ring made of a technical plastomer (POM) to prevent gap extrusion.

Seals that must endure high pressure are typically fabricated from harder elastomers (e.g., NBR 90°). Extremely high pressures, such as those encountered in hydrostatic presses, necessitate that the industrial seals employed are of outstanding quality and made from the most advanced materials.

Seals and Gaskets for special substances

The material of a seal or gasket is particularly important in the food industry, pharmaceutical industry, heavy industry and chemical industry. In these areas, very aggressive substances can occur, which the seal must withstand.

Examples of appropriately resistant sealing materials are FKM (Viton®, fluorinated rubber) or PTFE (polytetrafluoroethylene). These are often used in the above-mentioned industries, but there are also other, highly technical materials. 

Particularly in the food industry, care must also be taken to ensure that the material may come into contact with food and that contact does not impair the smell or taste of the food. 

In addition, the seal must be approved by the FDA (within the EU also: EU1935/2004). The FDA carefully checks that only harmless materials are used in food production. For example, there are special Teflon seals for filling systems.

Seals for high and low temperatures

Just like with special substances, high and low temperatures also present a challenge that a seal or gasket must overcome. Regardless of the temperature, a seal must maintain its technical properties.

Materials well-suited for high and low temperatures include PTFE and FKM. For applications in low temperatures, for example, low-temperature polyurethane or silicone (MVQ) is appropriate. At high temperatures, such as those found in blast furnaces, flat graphite gaskets or mica materials are utilized.

Seals for special movements

Seals are also utilized for rotational movements or swift lifting actions, employing special materials and geometries designed to endure high mechanical stresses. Often, for shaft seals (Simmerring seals), unique forms are found, or self-lubricating materials such as PU-MoS2 are used for other types of rotary seals. Due to their excellent sliding properties, Teflon seals are frequently used for lifting movements. These seals, preloaded as O-ring mechanical seals, are commonly found in many hydraulic cylinders.