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
- Pressures above 50 bar with O-rings possible
- Larger diametrical clearance possible
- 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.
PTFE COMPOUNDS
| Color | Temperature | Application | Information | |
|---|---|---|---|---|
| NDS-100 PTFE-virgin |
White | -190 to +230 °C | Chemical Industry, Food Industry | High chemical resistance Datasheet |
| NDS-123 PTFE +15% glass, +5% molybdenum disulfide |
Grey | -190 to +290 °C | Medium-duty |
High chemical resistance, High creep resistance, Electrical properties like virgin PTFE
|
| NDS-225 PTFE +25% carbon |
Black | -190 to +315 °C | Pneumatics Rotary sealing | High wear and creep resistance Datasheet |
| NDS-235 PTFE +10% carbon fibre |
Black | -260 to +310 °C | Water hydraulics, Seawater, Short strokes with high frequency | Very good wear properties Datasheet |
| NDS-415 PTFE +15% graphite |
Antrachite | -190 to +230 °C | Low mechanical stress, Soft sealing Surfaces | Chemical resistance |
| NDS-555 PTFE + mineral fibers |
Antrachite | -200 to +260 °C | Medium and heavy mechanical stress, Hydraulic applications | Chemical, wear and creep resistance Datasheet |
| 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.
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.
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.
CONTACT FORM
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NewDealSeals B.V.
+31 (0) 226 362 233
Boezemschop 8, Breekland, 1724 BJ Oudkarspel, The Netherlands