Description: Back-up rings are washer-like devices that are used in conjunction with O-rings for both static and dynamic sealing applications. They prevent extrusion of the O-ring when it is subjected to high pressure or when the extrusion gaps are excessive.

Back-up rings are not seals themselves, but are usually used in conjunction with O-rings in high-pressure applications (over 1500 psi) for support or as spacers. Typical applications include hydraulic cylinders, high-pressure hydraulic systems or high-pressure valves. In many applications it is best to use two back-up rings; one each side of the O-ring to provide maximum support. Back-up rings are available in two distinct face design configurations - a flat, washer style, and contoured.  The simplest form has two flat, parallel surfaces, much like a washer. In contoured back-up rings, one face is straight and the opposite face is curved or contoured. The contoured face is the one that comes in contact with the O-ring, providing better grip and support. Contoured back-up rings are commonly made of Nitrile (NBR) or Fluoroelastomer (FPM) rubber whilst solid, spiral and split back up rings are manufactured from PTFE, Hytrel or Polyurethane.

Applications: Back-up rings are usually used in conjunction with O-rings in high pressure applications throughout the hydraulic and pneumatic industries as well as all type of general engineering where a sealing solution resistant to extrusion is required.

Dichtomatik: Dichtomatik are able to supply back-up rings in all different materials and hardnesses and in sizes suitable for O-rings conforming to all British and International standards such as BS 1806, BS4518, ISO 3601-1, DIN 3771-1, SMS 1588, JIS 2401, AS 568, NF T47-501.

There are a number of different types of back-up rings available from Dichtomatik. Call us on 0845 463 1039 for further technical information, general enquiries and ordering or email us here.