PTFE U-Cups target automotive applications.

Press Release Summary:

Used on direct injection automotive systems to seal pump plunger driven by camshaft, Duo Forseal double-acting PTFE U-Cups are resistant to all types of motor oils and fuels, including E100. Seal can be used for plunger frequencies to more than 200 Hz and is easy to install due to its symmetrical seal configuration. Featuring stainless steel spring that provides reliable radial sealing forces, Duo Forseal offers operating life of more than 1 billion strokes.

Original Press Release:

Freudenberg-NOK Sealing Technologies Announces New PTFE U-Cup Design for Automotive Applications

New Duo Forseal design boosts performance and helps lower emissions

PLYMOUTH, Mich. — Freudenberg-NOK Sealing Technologies today announced that is has created Duo Forseal – a new design for double-acting polytetrafluoroethylene (PTFE) U-Cups that are used on direct injection automotive systems to seal the pump plunger driven by the camshaft.

The universal properties of PTFE make U-cups highly resistant to all types of motor oils and fuels but with the new Duo Forseal design, Freudenberg-NOK Sealing Technologies (Freudenberg-NOK) can offer a significantly improved and better performing injection plunger seal.

Engines with gasoline direct injection are very efficient but require higher pressures between advanced injection pumps and their corresponding injection nozzles than traditional air intake systems. The Duo Forseal makes an indirect contribution to emissions reduction because it is designed for this high pressure load. Additionally, its patented technology contributes directly to reduced emissions through lower leakage rates compared to traditional designs.

The new seal design provides all the technological characteristics of the current model lines, is cost efficient and offers universal resistance to all types of fuels including E100, and can be used for plunger frequencies to more than 200 Hz. It is also easy to install due to its symmetrical seal configuration and its leakage rate has been minimized below the required specifications of the automobile industry. Furthermore, the Duo Forseal design’s stainless steel spring provides reliable radial sealing forces.

The new PTFE compound used in the Duo Forseal shows an excellent abrasion resistance, especially in contact with plungers coated with diamond-like carbon (DLC), it has proven a long-term stability without affecting the coating.

With an operating life of far more than a billion strokes, the Duo Forseal injection plunger seal from Freudenberg-NOK offers a level of quality significantly above the standard demanded today.

Media Contacts:

Cheryl Eberwein, Director, Media Relations

Office: +1 734 354 7373


About Freudenberg-NOK Sealing Technologies

Freudenberg-NOK Sealing Technologies is the Americas joint venture between Freudenberg and Co. in Germany and NOK Corp. in Japan. Freudenberg-NOK is a leading producer – through its Automotive, Merkel, Process Seals and Simrit sales channels – of advanced sealing technologies for a variety of markets including: aerospace;  agriculture;  appliance; automotive; construction; diesel engine; energy; food and beverage; heavy industry; and pharmaceutical.

Founded in 1989 under the legal name Freudenberg-NOK General Partnership, Freudenberg-NOK is headquartered in Plymouth, Mich. and operates more than 20 facilities across the Americas. For additional information, please visit

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