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Back-up Rings

Back-up rings are used for static and dynamic applications in connection with O-rings, to prevent extrusion of the O-ring into the diametrical clearance.
The single cut and spiral design rings are easily installed into closed grooves while the single solid designs, recommended for highest pressures, are for installation in open grooves.

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Advantages Back-up Ring

  1. Pressures above 50 bar with O-rings possible
  2. Larger diametrical clearance possible

  3. Improved stability at high temperatures and strong pressure changes

Recommended when

We recommend to specify back-up rings when at least one of the following working conditions is present in cases where the intention is to seal with O-rings only:
> Pressure above 50 bar.
> Diametrical clearance exceeding 0,25 mm at p > 10 bar.
> High stroke frequency.
> High temperatures.
> Contaminated medium.
> Strong pressure pulsing or pressure changes.

Technical Specifications

Movement Type

Dynamic reciprocating/dynamic rotating, static

Available materials

PTFE, POM, PCTFE, PU

Profiles Back-up Rings

Profile T1

For reciprocating movements

Consists as standard two spiral windings
 which are cut at the ends at an angle.

Compensation of large temperature changes and tolerances.

Profile T2

Preferred for internal
 sealing applications

Preferred for internal
sealing applications when installed
in closed grooves where uncut
back-up rings are not suitable.
Reciprocating and rotating movements possible.
 Economic price level.

Profile T3

Reciprocating and rotating movements possible

A divisible groove is recommended
 for external sealing. Economic price level.

Profile T4

Preferred for internal sealing applications

Concave cross-section.
Reciprocating and rotating movements possible.
The large contact surface protects the O-ring against deformation in case of high pulsating pressure. Dimensional stability of the O-ring improves the sealing force and increases the service life.

Profile T5

Recommended for external sealing

Concave cross-section.
Reciprocating and rotating
movements possible.
The large contact surface protects the O-ring against deformation in case of high pulsating pressure.
Dimensional stability of the O-ring
improves the sealing force and
increases the service life.

Back-up Ring Materials

NDS® PTFE compound Characteristics Specifics Applications
NDS-100
PTFE virgin

Temperature range:

-190 to +230 °C

Chemical resistance:

Mechanical resist.:

Wear properties:

  • Most elastic PTFE type
  • Excellent chemical resistance
  • Excellent electrical insulating properties

O-rings, flat gaskets and light dynamic seals in food and chemical industry

NDS-123
PTFE +15% glass, +5% molybdenum disulfide

Temperature range:

-190 to +290 °C

Chemical resistance:

Mechanical resist.:

Wear properties:

  • Good dielectric properties
  • Increased creep resistance
  • Improved wear resistance

Piston seals, rod seals in medium duty dynamic applications, Valve seats

NDS-225
PTFE +25% carbon

Temperature range:

-190 to +315 °C

Chemical resistance:

Mechanical resist.:

Wear properties:

  • Good machinability, close tolerances and smooth surfaces possible
  • Excellent compression resistance
  • Good sliding and wear characteristics

Piston seals, rod seals, spring energized seals, bushings, wear guides.

NDS-235
PTFE +10% carbon fibre

Temperature range:

-260 to +310 °C

Chemical resistance:

Mechanical resist.:

Wear properties:

  • Good thermal conductivity
  • High wear resistance
  • Excellent sliding properties in water applications

Piston seals, rod seals, spring energized seals in water/fluid applications.

NDS-415
PTFE +15% graphite

Temperature range:

-190 to +230 °C

Chemical resistance:

Mechanical resist.:

Wear properties:

  • Excellent self lubricating properties
  • Low friction coëfficiënt

Piston seals, rod seals, spring energized seals for use against soft sealing surfaces.

NDS-640
PTFE +40% bronze

Temperature range:

-156 to +260 °C

Chemical resistance:

Mechanical resist.:

Wear properties:

  • Excellent creep resistance
  • Good thermal conductivity

Back-up rings and guiding strips. Rod and piston seals for heavy duty hydraulic applications.

NDS-660
PTFE +60% bronze

Temperature range:

-156 to +260 °C

Chemical resistance:

Mechanical resist.:

Wear properties:

  • Excellent creep resistance
  • Good thermal conductivity

Back-up rings and guiding strips. Rod and piston seals for heavy duty hydraulic applications.

NDS-750
PTFE + polyimide

Temperature range:

-260 to +310 °C

Chemical resistance:

Mechanical resist.:

Wear properties:

  • Low friction coëfficiënt
  • High wear resistance

Dynamic seals in (dry) running start-stop applications with a soft sealing surface.

Contact Us

We believe in the quality of our products and service. Fill out the form and one of our skilled engineers will contact you within the next business day.

Contact details

  • +31 (0) 226 362 233
  • info@newdealseals.com
  • Energiestraat 2-5, 1749 DN Warmenhuizen, Nederland