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.

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 change

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

Back-up ring profiles

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.

NDS PTFE Compounds

Color Temperature Application Characteristics
NDS-100
PTFE virgin
White -190 to +230 °C Chemical Industry, Food Industry High chemical restistance
NDS-123
PTFE +15% glass, +5% molybdenum disulfide
Grey -190 to +290 °C Medium-duty High chemical restistance, High creep resistance, Electrical properties like virgin PTFE
NDS-150
PTFE modified
Blue -190 to +230 °C Low-duty hydraulic applications Improved wear resistance
NDS-225
PTFE +25% carbon
Black -190 to +315 °C Pneumatics Rotary sealing High wear and creep restistance
NDS-235
PTFE +10% carbon fibre
Black -260 to +310 °C Water hydraulics, Seawater, Short strokes with high frequency Very good wear properties
NDS-415
PTFE +15% graphite
Antrachite -190 to +230 °C Low mechanical stress, Soft sealing Surfaces Chemical resistance
NDS-640
PTFE +40% bronze
Bronze -156 to +260 °C Medium and heavy mechanical stress, Hydraulic applications Outstanding wear and creep resistance
NDS-660
PTFE +60% bronze
Bronze -156 to +260 °C Heavy mechanical stress, Hydraulic applications Outstanding wear and creep resistance
NDS-750
PTFE + polyimide
Tan -260 to +310 °C High speed rotating applications Use against soft metals

Related PTFE Seals

Spring Energized Seals

The Synering® system is an advanced sealing concept designed to meet extreme demands regarding temperature, medium, etc. which cannot be covered by conventional sealing compounds.

Spring Energized Seals ► 

Rotary Seals

Rotary seals are used in applications with oscillating or rotating movements in order to retain liquid lubricants and to prevent the penetration of dirt and water.

Rotary seals ►

Rod Seals

The Rod Seal consists of a single-acting PTFE rod sealing ring and an O-ring. They are combined as a single unit and are appropriate for rods and plungers in hydraulic cylinders.

Rod seals ►

 

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NewDealSeals

+31 (0) 226 362 233

info@newdealseals.com

Energiestraat 2-5, 1749 DN Warmenhuizen, The Netherlands