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Military Standard MS28774-240 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-240 Teflon (PTFE) Retainer, Packing
PART #: SGP136759MFR PART #: MS28774-240Our Price: $2.81 (Each)QTY: Add to Cart -
Military Standard MS28774-242 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-242 Teflon (PTFE) Retainer, Packing
PART #: SGP136761MFR PART #: MS28774-242Our Price: $3.11 (Each)QTY: Add to Cart -
Military Standard MS28774-246 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-246 Teflon (PTFE) Retainer, Packing
PART #: SGP136764MFR PART #: MS28774-246Our Price: $5.81 (Each)QTY: Add to Cart -
Military Standard MS28774-338 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-338 Teflon (PTFE) Retainer, Packing
PART #: SGP136778MFR PART #: MS28774-338Our Price: $4.56 (Each)QTY: Add to Cart -
Military Standard MS28774-341 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-341 Teflon (PTFE) Retainer, Packing
PART #: SGP136781MFR PART #: MS28774-341Our Price: $5.81 (Each)QTY: Add to Cart -
Military Standard MS28774-345 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-345 Teflon (PTFE) Retainer, Packing
PART #: SGP136785MFR PART #: MS28774-345Our Price: $6.32 (Each)QTY: Add to Cart -
Military Standard MS28774-346 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-346 Teflon (PTFE) Retainer, Packing
PART #: SGP136786MFR PART #: MS28774-346Our Price: $3.89 (Each)QTY: Add to Cart -
Military Standard MS28774-347 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-347 Teflon (PTFE) Retainer, Packing
PART #: SGP136787MFR PART #: MS28774-347Our Price: $16.58 (Each)QTY: Add to Cart -
Military Standard MS28774-349 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-349 Teflon (PTFE) Retainer, Packing
PART #: SGP136789MFR PART #: MS28774-349Our Price: $10.54 (Each)QTY: Add to Cart -
Military Standard MS28774-425 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-425 Teflon (PTFE) Retainer, Packing
PART #: SGP136791MFR PART #: MS28774-425QTY: Add to Quote -
Military Standard MS28774-429 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-429 Teflon (PTFE) Retainer, Packing
PART #: SGP136793MFR PART #: MS28774-429Our Price: $5.56 (Each)QTY: Add to Cart -
Military Standard MS28774-430 Teflon (PTFE) Retainer, Packing
Military Standard MS28774-430 Teflon (PTFE) Retainer, Packing
PART #: SGP136794MFR PART #: MS28774-430Our Price: $17.56 (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.