PTFE Back-up Ring_Ningbo Quantum Seal Co., Ltd

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PTFE Back-up Ring

Back-up Rings have no intended sealing function.
They are protective and supporting elements made from extrusion-resistant materials which generally have a rectangular cross section. They are installed in a groove together with an elastomeric sealing element preferably with a corresponding O-Ring in static applications.Due to the tight fit of the Back-up Ring in the housing, they prevent extrusion of the pressurised elastomeric sealing element into the sealing gap.

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Advantages

Use of O-Rings in high pressure applications
Use of O-Ring materials with a low hardness
Compensation of radial sealing gaps
Use for internal and external sealing applications - Reciprocating and rotating movements possible
Reciprocating and rotating movements possible
Compensation for large temperature fluctuations
Static and dynamic applications

Back-Up Ring Types, Uncut

BM

Seal Type

External sealing (Bore) Internal sealing (Rod)

Material: PTFE
Rectangular cross section
Standard: AS568, MS27595, JISB2407
Static and dynamic applications
Reciprocating and rotating movements possible
BCM

Seal Type

External sealing (Bore) Internal sealing (Rod)

Material: NBR,FKM,PTFE
Concave cross section
Standard: AS568
The large contact surface protects the O-Ring against
Deformation in case of high pulsating pressur
Dimensional stability of the O-Ring improves the sealing force and increases the service life
Preferably for static use
Reciprocating movements possible

Back-Up Ring Types, cut

BG

Seal Type

External sealing (Bore) Internal sealing (Rod)

Material: PTFE
Rectangular cross section
Cut angle of 30° or 45° or 20°
Static and dynamic use
Reciprocating and rotating movements possible
Preferred for installations in a closed groove where uncut Back-up Rings are not suitable
BCC

Seal Type

External sealing (Bore) Internal sealing (Rod)

Material: PTFE
Concave cross section
Cut angle of 30° or 45°
The large contact surface protects the O-Ring against
Deformation in case of high pulsating pressur
Dimensional stability of the O-Ring improves the sealing force and increases the service life
Preferably for static use
Reciprocating movements possible
Preferred for installations in a closed groove where uncut Back-up Rings are not suitable.

Back-up Ring Types, spiral

SP

Seal Type

External sealing (Bore) Internal sealing (Rod)

Material: PTFE;
Rectangular cross section;
Cut angle of 30° or 45°;
Consists as standard two spiral windings which are cut at the ends at an angle;
Static and dynamic use;
For reciprocating movements only
Preferred for installations in a closed groove where uncut Back-up Ring are not suitable;
Compensation of large temperature changes and tolerances without difficulties by a
screw-like elongation and contraction. Easy Installation in closed grooves for external sealing applications;
The dimensions are different compared to standard Back-up Rings.

Materials Selection

Back-up Rings are as standard manufactured from virgin PTFE. In view of the unfavourable cold flow behaviour of virgin PTFE, these Back-up Rings are used only for low to medium loads. For higher load requirements, filled PTFE materials (with glassfibre, bronze, carbon, etc.) have to be used. For sealing against high pressures, Back-up Rings made from specially modified thermoplastic materials are used.For the series production of larger quantities, injection moulded Back-up Rings can be manufactured, e.g. NBR 90 Shore A, FKM90 Shore A, or thermoplastic elastomers (TPE) on request.

Fields Of Application

- Injection moulding machines

- Machine tools

- Presses

- Excavators

- Agricultural machines

- Valves for hydraulic circuits

Technical Data

2m/s
Speed: Reciprocating or rotating up to approx. 2 m/s depending on the material
40 Mpa
Dynamic applications: Reciprocating up to approx. 40 MPa
15 Mpa
Oscillating/slowly rotating up to approx. 15 MPa
250 Mpa
Static applications: Up to approx. 250 MPa depending on the Back-up Ring material and sealing gap
-200°C to +260°C
Operating temperature: - 200 °C to + 260 °C depending on the material