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Military Standard MS27595-239 Retainer, Packing
PART #: SGP136557MFR PART #: MS27595-239Our Price: $4.91 (Pack)QTY: Add to Cart -
Military Standard MS27595-242 Retainer, Packing
PART #: SGP136559MFR PART #: MS27595-242Our Price: $4.63 (Each)QTY: Add to Cart -
Military Standard MS27595-327 Retainer, Packing
PART #: SGP136564MFR PART #: MS27595-327Our Price: $2.45 (Each)QTY: Add to Cart -
Military Standard MS27595-325 Retainer, Packing
PART #: SGP136562MFR PART #: MS27595-325Our Price: $2.80 (Each)QTY: Add to Cart -
Military Standard MS27595-337 Retainer, Packing
PART #: SGP136567MFR PART #: MS27595-337Our Price: $6.52 (Each)QTY: Add to Cart -
Military Standard MS27595-444 Retainer, Packing
PART #: SGP136569MFR PART #: MS27595-444Our Price: $21.82 (Each)QTY: Add to Cart -
Military Standard MS27595-334 Retainer, Packing
PART #: SGP136565MFR PART #: MS27595-334Our Price: $6.61 (Each)QTY: Add to Cart -
Military Standard MS27595-443 Retainer, Packing
PART #: SGP136568MFR PART #: MS27595-443Our Price: $30.41 (Each)QTY: Add to Cart -
Military Standard MS27595-117 Retainer, Packing
PART #: SGP179327MFR PART #: MS27595-117Our Price: $1.57 (Each)QTY: Add to Cart -
Military Standard MS27595-007 Retainer, Packing
PART #: SGP165177MFR PART #: MS27595-007Our Price: $0.93 (Each)QTY: Add to Cart -
Military Standard MS27595-122 Retainer, Packing
PART #: SGP180476MFR PART #: MS27595-122Our Price: $1.36 (Each)QTY: Add to Cart -
Military Standard MS27595-146 Retainer, Packing
PART #: SGP185350MFR PART #: MS27595-146Our Price: $2.96 (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.