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Military Standard MS28774-007 Teflon (PTFE) Retainer, Packing
PART #: SGP136665MFR PART #: MS28774-007Our Price: $1.67 (Each)QTY: Add to Cart -
Military Standard MS28774-237 Teflon (PTFE) Retainer, Packing
PART #: SGP136755MFR PART #: MS28774-237Our Price: $3.12 (Each)QTY: Add to Cart -
Military Standard MS9058-08 Teflon (PTFE) Retainer, Packing
PART #: SGP138585MFR PART #: MS9058-08Our Price: $2.87 (Each)QTY: Add to Cart -
National Aerospace Standard NAS1523AA6F Packing with Retainer
PART #: SGP140701MFR PART #: NAS1523AA6FOur Price: $2.72 (Each)QTY: Add to Cart -
Military Standard MS28774-219 Teflon (PTFE) Retainer, Packing
PART #: SGP136736MFR PART #: MS28774-219Our Price: $0.97 (Each)QTY: Add to Cart -
Military Standard MS28774-012 Teflon (PTFE) Retainer, Packing
PART #: SGP136670MFR PART #: MS28774-012Our Price: $0.73 (Each)QTY: Add to Cart -
National Aerospace Standard NAS1523C3B Packing with Retainer
PART #: SGP140725MFR PART #: NAS1523C3BOur Price: $7.71 (Each)QTY: Add to Cart -
Military Standard MS28774-214 Teflon (PTFE) Retainer, Packing
PART #: SGP136731MFR PART #: MS28774-214Our Price: $0.91 (Each)QTY: Add to Cart -
National Aerospace Standard NAS1523AA3Y Packing with Retainer
PART #: SGP140690MFR PART #: NAS1523AA3YOur Price: $3.43 (Each)QTY: Add to Cart -
Military Standard MS28782-4 Teflon (PTFE) Retainer, Packing
PART #: SGP137201MFR PART #: MS28782-4Our Price: $1.22 (Each)QTY: Add to Cart -
Military Standard MS28774-006 Teflon (PTFE) Retainer, Packing
PART #: SGP136664MFR PART #: MS28774-006Our Price: $1.39 (Each)QTY: Add to Cart -
Military Specification M8791/1-017 Teflon (PTFE) Retainer, Packing
PART #: SGP130279MFR PART #: M8791-1-017Our Price: $0.91 (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.