Støttering NBR

Product group:
STU back-up ring elastomer
Design:
AS/BS størrelser
Material:
NBR 90
Colour:
Black

Shape: KAV concave

Produktdata

Operational application limits

The max. permissible operating pressure depends on the gap dimensions.
Temperature (°C): -30 to + 100
The operational application limits use are dictated by the O-ring selected. It is only the resistance of the sealing system to pressure which can be increased by the STU back-up ring.

Media

Hydraulic oils H, HL, HLP as per DIN 51524 Part 1 – 3, mineral-oil based lubricants and greases, non-flammable hydraulic pressure fluids HFA, HFB, HFC as per VDMA 24317 to approx. + 50°C and water to max. + 80°C

Function

The STU back-up ring is a closed ring concave in cross-section. It is produced entirely as a closed ring with no seams, by the injection-moulding process. For our STU back-up rings we use an NBR material of 90° Shore-A hardness, so as to guarantee a high level of resistance to extrusion and abrasion.
The back-up ring’s concave cross-section provides the O-ring with a larger contact surface, having the effect of allowing the O-ring almost fully to retain its circular shape under high pressures and to be less liable to deformation. This means that the shape of the O-ring is supported better and it can therefore withstand higher pressure loads. This produces a better sealing effect and increases the seal’s service life. Due to its closed design, under high pressures it is not possible for the O-ring to be damaged by a sharp edge at the open-ended joint (as is the case with open back-up rings).
The STU back-up ring is of symmetrical profile. This allows it to be used in both internal and external sealing systems.

Installation

The groove widths b1 and b2 are presented in the following table:

STU
profile width
S=1.35 mm S=2.18 mm S=3.0 mm S=4.65 mm S=5.99 mm
b1 3.5 – 3.7 4.7 – 4.9 5.8 – 6.0 8.7 – 8.9 12.0 – 12.2
b2 4.6 – 4.8 5.8 – 6.0 6.8 – 7.0 10.2 – 10.4 14.4 – 14.6
S = Ref. H Ref. T
1,35 004-050 1,14 004-050 1,24
2,18 102-178 1,14 102-178 1,35
3,00 201-284 1,02 201-284 1,27
4,65 309-395 1,52 309-395 1,93
5,99 425-475 2,44 425-475 2,97