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Military Standard MS28774-431 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-431 Teflon (PTFE) Retainer, Packing
PART #: SGP136795MFR PART #: MS28774-431Our Price: $16.59 (Each)QTY: Add to Cart -
Military Standard MS28774-433 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-433 Teflon (PTFE) Retainer, Packing
PART #: SGP136796MFR PART #: MS28774-433Our Price: $4.22 (Each)QTY: Add to Cart -
Military Standard MS28774-434 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-434 Teflon (PTFE) Retainer, Packing
PART #: SGP136797MFR PART #: MS28774-434Our Price: $219.73 (Each)QTY: Add to Cart -
Military Standard MS28774-437 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-437 Teflon (PTFE) Retainer, Packing
PART #: SGP136799MFR PART #: MS28774-437Our Price: $29.83 (Each)QTY: Add to Cart -
Military Standard MS28774-435 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-435 Teflon (PTFE) Retainer, Packing
PART #: SGP136798MFR PART #: MS28774-435Our Price: $14.39 (Each)QTY: Add to Cart -
Military Standard MS28774-438 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-438 Teflon (PTFE) Retainer, Packing
PART #: SGP136800MFR PART #: MS28774-438Our Price: $30.50 (Each)QTY: Add to Cart -
Military Standard MS28774-439 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-439 Teflon (PTFE) Retainer, Packing
PART #: SGP136801MFR PART #: MS28774-439Our Price: $33.59 (Each)QTY: Add to Cart -
Military Standard MS28774-443 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-443 Teflon (PTFE) Retainer, Packing
PART #: SGP136804MFR PART #: MS28774-443Our Price: $35.80 (Each)QTY: Add to Cart -
Military Standard MS28774-445 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-445 Teflon (PTFE) Retainer, Packing
PART #: SGP136806MFR PART #: MS28774-445Our Price: $26.72 (Each)QTY: Add to Cart -
Military Standard MS28774-442 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-442 Teflon (PTFE) Retainer, Packing
PART #: SGP136803MFR PART #: MS28774-442QTY: Add to Quote -
Military Standard MS28774-444 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-444 Teflon (PTFE) Retainer, Packing
PART #: SGP136805MFR PART #: MS28774-444Our Price: $24.96 (Each)QTY: Add to Cart -
Military Standard MS28774-018 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-018 Teflon (PTFE) Retainer, Packing
PART #: SGP136676MFR PART #: MS28774-018Our Price: $0.67 (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.