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Military Standard MS28782-65 Teflon (PTFE) Retainer, Packing
PART #: SGP137221MFR PART #: MS28782-65Our Price: $5.70 (Each)QTY: Add to Cart -
Military Standard MS28782-8 Teflon (PTFE) Retainer, Packing
PART #: SGP137224MFR PART #: MS28782-8Our Price: $1.28 (Each)QTY: Add to Cart -
Military Standard MS28782-7 Teflon (PTFE) Retainer, Packing
PART #: SGP137223MFR PART #: MS28782-7Our Price: $1.10 (Each)QTY: Add to Cart -
Military Standard MS28782-9 Teflon (PTFE) Retainer, Packing
PART #: SGP137225MFR PART #: MS28782-9Our Price: $1.14 (Each)QTY: Add to Cart -
Military Standard MS28774-024 Teflon (PTFE) Retainer, Packing
PART #: SGP136682MFR PART #: MS28774-024Our Price: $0.87 (Each)QTY: Add to Cart -
Military Standard MS28774-118 Teflon (PTFE) Retainer, Packing
PART #: SGP136695MFR PART #: MS28774-118Our Price: $0.87 (Each)QTY: Add to Cart -
Military Standard MS28774-129 Teflon (PTFE) Retainer, Packing
PART #: SGP136706MFR PART #: MS28774-129Our Price: $1.11 (Each)QTY: Add to Cart -
Military Standard MS28774-140 Teflon (PTFE) Retainer, Packing
PART #: SGP136718MFR PART #: MS28774-140Our Price: $1.15 (Each)QTY: Add to Cart -
Military Standard MS28774-144 Teflon (PTFE) Retainer, Packing
PART #: SGP136721MFR PART #: MS28774-144Our Price: $1.19 (Each)QTY: Add to Cart -
Military Standard MS28774-149 Teflon (PTFE) Retainer, Packing
PART #: SGP136725MFR PART #: MS28774-149Our Price: $4.84 (Each)QTY: Add to Cart -
Military Standard MS28774-230 Teflon (PTFE) Retainer, Packing
PART #: SGP136748MFR PART #: MS28774-230Our Price: $1.43 (Each)QTY: Add to Cart -
Military Standard MS28774-234 Teflon (PTFE) Retainer, Packing
PART #: SGP136752MFR PART #: MS28774-234Our Price: $1.91 (Each)QTY: Add to Cart
Ask any Skygeek and they will tell you a back-up ring functions on the principle of "everything needs support." As its name implies, it is a sturdy ring that "backs-up" (usually a rubber) seal. It is designed specifically to hold or maintain this seal in its proper position.
In many assemblies, joints require a seal. This is done so as to prevent the leakage of fluid or gas. O-rings are often used as a seal. However, due to extreme pressures inherent in aviation, these seals may extrude or lose their place and thus compromise their intended use. Back-up rings prevent extrusion and thus are used in conjunction with O-rings.
Back-up rings, like their O-ring counterparts, are usually made of elastic polymers, the most common being nitrile butadiene rubber (NBR) and polytetrafluoroethylene (PTFE or Teflon). Like other materials, elastomers are often given a hardness rating (durometer). This identifies a material's resistive strength, especially when dealing with pressures and other external forces. For instance, when viewing a back-up ring, you might find a 70 or 75A in its name; these numbers refer to its durometer.
Besides material, back-up rings can be classified by type, three variations include: spiral, endless, and endless split. A spiral back-up ring is the most frequently used because of its ability to efficiently self-adjust to diametrical tolerances. Endless back-up rings are applied whenever problems occur with the rotation of screwed endcaps that may cause a spiral type to unwind. The endless split back-up ring is identical to the endless back-up ring, the only difference is it is split at a 30-degree angle; this facilitates assembly for some applications.
Finally, back-up rings conform to several military specifications and Skygeek carries them including: MS27595, M8791, and MS9058. Our inventory is growing so check in from time to time. Otherwise, click on the specific series of back-up rings and make sure your seals are supported.