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BUR 140,16X3,00X1,02/1,27 BLACK NBR90 (BS254)
Part number: BUR254IB901801
Weight : 2.0000 gr.
Customs tariff code: 40169300
Country of origin: TW
BUR 140,16X2,18X1,14/1,35 BLACK NBR90 (BS161)
Part number: BUR161IB901801
Weight : 2.0000 gr.
Customs tariff code: 40169300
Country of origin: TW
BUR 140.16X2.18X1.14/1.35 BLACK NBR90 (BS161)
Part number: BUR161IB90XBL
Weight : 2.0000 gr.
Customs tariff code: 40169300
Country of origin: CN
BUR 140,41X4,65X1,52/1,93 BLACK NBR90 (BS357)
Part number: BUR357IB901801
Weight : 4.0000 gr.
Customs tariff code: 40169300
Country of origin: DE
BUR 141.00X5.99X2.44/2.97 BLACK NBR90 (BS433-R61)
Part number: BUR433IB90XBL
Weight : 10.0000 gr.
Customs tariff code: -
Country of origin: CN
BUR 143,33X3,00X1,02/1,27 BLACK NBR90 (BS255)
Part number: BUR255IB901801
Weight : 2.1000 gr.
Customs tariff code: 40169300
Country of origin: TW
BUR 143,59X4,65X1,52/1,93 BLACK NBR90 (BS358)
Part number: BUR358IB901801
Weight : 4.0000 gr.
Customs tariff code: 40169300
Country of origin: TW
BUR 144,17X5,99X2,44/2,97 BLACK NBR90 (BS434-R62)
Part number: BUR434IB901801
Weight : 2.9720 gr.
Customs tariff code: 40169300
Country of origin: TW
BUR 146,51X3,00X1,02/1,27 BLACK NBR90 (BS256)
Part number: BUR256IB901801
Weight : 0.5230 gr.
Customs tariff code: 40169300
Country of origin: CN
BUR 146.51X2.18X1.14/1.35 BLACK NBR90 (BS162)
Part number: BUR162IB90XBL
Weight : 2.0000 gr.
Customs tariff code: 40169300
Country of origin: CN
BUR 146,76X4,65X1,52/1,93 BLACK NBR90 (BS359)
Part number: BUR359IB901801
Weight : 1.1670 gr.
Customs tariff code: 40169300
Country of origin: TW
BUR 147,35X5,99X2,44/2,97 BLACK NBR90 (BS435)
Part number: BUR435IB901801
Weight : 3.0370 gr.
Customs tariff code: 40169300
Country of origin: TW
technical data
| Back-Up Rings | Profile | Material | Hardness | Temperature |
| BUR |  | NBR | 90 SH A | -20 to +100/+120 ºC |
| SPIRAL BUR |  | PTFE VIRGEN | -150 to +260 ºC |
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Rings that improve O-Rings performance
Back-up Rings are parts fitted together with an O-Ring. They do not properly have a sealing function but are rather dedicated to improving the performance of said O-Ring. Depending on the application and the housing, one or two BUR can be fitted around the OR allowing its use in static or dynamic systems, in reciprocating or rotating movements and achieving the use of a wide range of OR hardnesses.
Its profile is pretty basic since its most simple version is a rectangular section washer. However, the most standard profile is the concave cross-section washer that allows the O-Ring to be seated, improving the anti-extrusion effect.
The standard material that we usually stock is NBR90 although it can also be manufactured in FPM, PTFE, POM, PU,… on request.
Another very efficient profile in reciprocating applications is the spiral BUR made of virgin PTFE. These are two spiral windings cut at an angle at the end that can be fitted with an FPM OR when the working temperature requires it. Finally, we can highlight that BUR can be cut with different angles, which allows their assembly in closed housings.
To facilitate their identification, although obviously both the concave section rings in NBR90 and the spiral PTFE rings have very standard sizes in their respective ranges, the BS number of the AS-568 range is usually the easiest way to tie in a BUR with an OR. For example, instead of ordering a BUR which sizes are 32.16 × 3.00 × 1.00 / 1.27, it is easier to refer to the BUR218 as it will be fitted with a BS218 O-Ring (31,34×3.53).
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What are Backup Rings (BUR)?
Published : 07/08/2022 | Categories : Back-Up RingsBUR, the O-ring's protector BURs are special rings that provide extra support for O-rings with which they are fitted. Their main purpose is to provide increased extrusion resistance and [...]