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Military Standard MS27595-222 Retainer, Packing
PART #: SGP136541MFR PART #: MS27595-222Our Price: $1.87 (Pack)QTY: Add to Cart -
Military Standard MS27595-216 Retainer, Packing
PART #: SGP136535MFR PART #: MS27595-216Our Price: $1.59 (Pack)QTY: Add to Cart -
Military Standard MS27595-217 Retainer, Packing
PART #: SGP136536MFR PART #: MS27595-217Our Price: $1.87 (Each)QTY: Add to Cart -
Military Standard MS27595-219 Retainer, Packing
PART #: SGP136538MFR PART #: MS27595-219Our Price: $1.61 (Each)QTY: Add to Cart -
Military Standard MS27595-218 Retainer, Packing
PART #: SGP136537MFR PART #: MS27595-218Our Price: $1.17 (Each)QTY: Add to Cart -
Military Standard MS27595-228 Retainer, Packing
PART #: SGP136547MFR PART #: MS27595-228Our Price: $2.00 (Each)QTY: Add to Cart -
Military Standard MS27595-246 Retainer, Packing
PART #: SGP136561MFR PART #: MS27595-246Our Price: $4.28 (Each)QTY: Add to Cart -
Military Standard MS27595-236 Retainer, Packing
PART #: SGP136554MFR PART #: MS27595-236Our Price: $5.04 (Pack)QTY: Add to Cart -
Military Standard MS27595-238 Retainer, Packing
PART #: SGP136556MFR PART #: MS27595-238Our Price: $4.76 (Each)QTY: Add to Cart -
Military Standard MS27595-243 Retainer, Packing
PART #: SGP136560MFR PART #: MS27595-243Our Price: $5.06 (Each)QTY: Add to Cart -
Military Standard MS27595-237 Retainer, Packing
PART #: SGP136555MFR PART #: MS27595-237Our Price: $5.41 (Each)QTY: Add to Cart -
Military Standard MS27595-241 Retainer, Packing
PART #: SGP136558MFR PART #: MS27595-241Our Price: $5.02 (Pack)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.